Caribbean - Central America Weather

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
254 PM AST WED SEP 16 2015

.SYNOPSIS...AT UPPER LEVELS...A WEAK TROUGH WITH AN EMBEDDED LOW
WILL CROSS PUERTO RICO AROUND NOON ON FRIDAY. THIS TROUGH WILL
CROSS THE LEEWARD ISLANDS ON SUNDAY AS A RIDGE BUILDS OVER
HISPANIOLA. ALTHOUGH A LOW WILL FORM IN THE TROUGH NORTHEAST OF
THE AREA AND DRAW CLOSER DURING THE WEEK THE RELATIVE POSITION OF
THESE FEATURES WILL CHANGE LITTLE NEXT WEEK.

AT MID LEVELS...WEAK GRADIENTS WILL PERSIST WITH GENERALLY
NORTHERLY FLOW OVER THE AREA THROUGH MID WEEK NEXT WEEK. DRIER AIR
WILL MOVE THROUGH SUNDAY THROUGH TUESDAY BEFORE MOISTURE RETURNS
AGAIN.

AT LOWER LEVELS... THE TROPICAL WAVE HAS MOVED OVER HISPANIOLA
WITH DRIER AIR FILTERING IN FROM THE LEEWARD ISLANDS. PATCHES OF
MOISTURE THEN MOVE ACROSS THE AREA FOR THE REMAINDER OF THE
FORECAST PERIOD.

&&

.DISCUSSION...MOISTURE HAS RE-BOUNDED A LITTLE AND THE LOCAL
SOUNDER REVEALS PRECIPITABLE WATER HAS CLIMBED BACK UP TO 2.3
INCHES. SHOWERS HAVE NOT BEEN RAPID TO FORM...BUT NAM HAS BEEN
RELIABLE IN THE LOCATION OF EXPECTED FORMATION...THE NORTHWEST
COASTAL PLAINS AND FOOTHILLS. CURRENTLY TOPS ARE MAXING OUT AT 30
KFT AND THIS IS WHERE MOISTURE BEGINS TO DIMINISH SOMEWHAT. EXPECT
FURTHER DEVELOPMENT TODAY AS MAXIMUM HEATING MAY NOT HAVE BEEN
REACHED. LOCAL SOUNDINGS SUGGEST THAT MID LEVELS WILL DRY OUT
FIRST THEN RE-MOISTEN BY SATURDAY. OVERALL MOISTURE IS SUPPOSED TO
DECLINE THROUGH MONDAY MORNING. WEAK VARIATIONS IN MOISTURE
SWIRLING AROUND WEAK BOUNDARIES WILL DOMINATE IN A PATTERN OF
LITTLE OVERALL FORCING AND NO MAJOR SYSTEMS PASSING THROUGH THE
TRADE WIND FLOW. HENCE SCATTERED SHOWERS IN THE TYPICAL DIURNAL
ISLAND PATTERN WILL PREVAIL INTO NEXT WEEK.

&&

.AVIATION...ISOLD SHRA/TSRA CURRENTLY OVER W PR WITH MVFR CIGS
POSSIBLE OVER TJMZ AND TJBQ THRU 16/21Z...WITH MOUNTAIN
OBSCURATIONS. AT THE OTHER TAF SITES...EXPECT MOSTLY VFR WITH VCSH
THROUGH THE PD. LOW LEVEL WINDS WILL BE MAINLY FROM THE
EAST SOUTHEAST AT 10 TO 15 KTS. DRIER AIR WILL FILTER IN ACROSS
THE REGION TOWARDS THE END OF THE PERIOD...SUPPORTING MOSTLY VFR
CONDITIONS WITH ONLY VCSH.

&&

.MARINE...SEAS WILL CONTINUE TO DIMINISH TO GENERALLY BELOW 3 FEET
EVERYWHERE...WITH LOCAL DIURNAL VARIATIONS DUE TO LOCAL WINDS.
SEAS WILL RISE SOMEWHAT DURING THE WEEKEND...BUT DIMINISH AGAIN
DURING THE LATTER PART OF NEXT WEEK TO AGAIN LESS THAN 3 FEET.
SMALL CRAFT ADVISORIES ARE NOT EXPECTED DURING THE NEXT 10 DAYS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 89 79 89 / 30 30 20 20
STT 79 89 77 88 / 30 30 20 20

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
511 AM AST THU SEP 17 2015

.SYNOPSIS...WEAK UPPER TROUGH/TUTT OVER THE WINDWARD PASSAGE WILL
SLOWLY MOVE EASTWARD OVER THE NEXT FEW DAYS...RELOCATING EAST OF
THE AREA DURING THE WEEKEND. PATCHES OF MOISTURE WILL MOVE ACROSS
THE REGION AT TIMES BRINGING SCATTERED SHOWERS ACROSS THE ISLANDS.
SAHARAN DUST WILL PERSIST OVER THE ISLANDS THROUGH LATE TONIGHT.
OVERALL...NO SIGNIFICANT WEATHER FEATURE WILL MOVE ACROSS THE
NORTHEAST CARIBBEAN OVER THE NEXT SEVERAL DAYS.

&&

.DISCUSSION...SOMEWHAT UNSTABLE CONDITIONS HAVE PREVAILED ACROSS
THE REGION DURING OVERNIGHT HOURS. MOSTLY CLOUDY SKIES WITH
SCATTERED TO NUMEROUS SHOWERS HAVE BEEN OBSERVED ACROSS THE LOCAL
WATERS. SOME SHOWERS HAVE MOVED INLAND ACROSS THE WINDWARD SIDE OF
THE ISLANDS...LEAVING RAINFALL ACCUMULATIONS OF 0.1-0.25 INCHES.

MOISTURE WILL REMAIN NEAR NORMAL THROUGH THE END OF THE WEEK. GFS
FORECAST SOUNDINGS SUGGEST A DRIER AND MORE STABLE AIR MASS WITH
SAHARAN DUST FILTERING AT LOW LEVELS TODAY BUT ALSO SHOW A FAIRLY
MOIST ENVIRONMENT AT MID-UPPER LEVELS. THEREFORE...THE COVERAGE
OF THE AFTERNOON SHOWER ACTIVITY WILL DEPEND GREATLY ON HOW
QUICKLY THE MID-UPPER CLOUDS FADE OUT. DIURNAL HEATING IS REQUIRED
TO TRIGGER THE AFTERNOON CONVECTION OVER WESTERN PR...SO PROBABLY
THE ONSET OF THE DIURNAL CONVECTION WILL BE DELAYED DUE TO THE
CLOUD COVER ALOFT.

LONG TERM...TRADE WINDS WILL CONTINUE TO PUSH PATCHES OF MOISTURE
ACROSS THE LOCAL ISLANDS FROM TIME TO TIME. ALTHOUGH...NO SIGNIFICANT
WEATHER FEATURE IS EXPECTED TO AFFECT THE LOCAL ISLANDS FOR THE
NEXT SEVERAL DAYS...TYPICAL EARLY MORNING SHOWERS OVER THE USVI
AND EASTERN PR AND THE AFTERNOON CONVECTION OVER WEST PR CANNOT
RULE OUT EACH DAY.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED ACROSS THE LOCAL FLYING
AREA WITH ONLY BRIEF PERIODS OF PASSING -SHRA/SHRA ACROSS TIST...
TISX AND TJSJ AND OVER THE LOCAL WATER UNTIL 17/14Z. LATEST TJSJ
SOUNDING INDICATED AN EAST SOUTHEAST WIND FLOW UP TO 20 KNOTS ALL
THE WAY FROM THE SURFACE TO 10K FEET...BECOMING LIGHT AND VARIABLE
10-25K AND WEST SOUTHWESTERLY AND A LITTLE STRONGER ALOFT.
SHRA/ISOLATED TSRA EXPECTED FROM 17/18Z-17/22Z OVER WEST INTERIOR
AND CENTRAL MOUNTAIN RANGE OF PUERTO RICO.

&&

.MARINE...SEAS OF 1-3 FEET WILL PREVAIL ACROSS THE NEARSHORE
WATERS. SLIGHTLY HIGHER SEAS UP TO 4 FEET ARE POSSIBLE ACROSS THE
OFFSHORE WATERS. NO MUCH CHANGE ARE ANTICIPATED OVER THE NEXT FEW
DAYS AS MODERATE TRADE WINDS WILL PREVAIL OVER THE REGION.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 79 89 78 / 30 20 20 30
STT 89 77 88 78 / 30 20 20 40

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
228 PM AST THU SEP 17 2015

.SYNOPSIS...AT UPPER LEVELS...A WEAK UPPER LEVEL TROUGH OVER
NORTHERN HISPANIOLA WILL ROTATE THROUGH PUERTO RICO AND THE U.S.
VIRGIN ISLANDS ON FRIDAY. LOW PRESSURE CONTINUES NORTHEAST OF THE
LEEWARD ISLANDS THROUGH TUESDAY BEFORE SLOWLY DRIFTING
WEST...AND NORTH OF THE AREA BY FRIDAY OF NEXT WEEK.

AT MID LEVELS...A WEAK LOW NORTHEAST OF THE AREA WILL APPROACH
PUERTO RICO AND THE US. VIRGIN ISLANDS TONIGHT THROUGH TUESDAY AND
THEN MOVE OFF TO THE WEST NORTHWEST...PASSING NORTH OF SAN JUAN
ON THURSDAY. A FILAMENT OF MOISTURE HANGING OFF THE MASS OF
MOISTURE ASSOCIATED WITH THE TROPICAL WAVE WILL FINALLY LEAVE THE
AREA SATURDAY NIGHT. MODERATELY DRY CONDITIONS WILL PERSIST
THROUGH THE FOLLOWING WEEK.

AT LOWER LEVELS...A WEAK TROUGH WILL PASS THROUGH THE AREA ON
SATURDAY MORNING...FOLLOWED BY RELATIVELY MOIST EAST SOUTHEAST
FLOW THROUGH THURSDAY. ALTHOUGH PRESSURE IS WEAKLY HIGHER TO THE
NORTH DURING THIS TIME LOW PRESSURES PERSIST IN THE WESTERN HALF
OF THE TROPICAL ATLANTIC THAT WILL KEEP WINDS LIGHT TO GENTLE.

&&

.DISCUSSION...THUNDERSTORMS WITH HEAVY RAIN AND OVER ONE THOUSAND
STRIKES PER HOUR DEVELOPED OVER NORTHWEST PUERTO RICO FROM SAN
SEBASTIAN TO CIALES EARLY THIS AFTERNOON. WINDS HAVE BEEN
RELATIVELY LIGHT AND THESE SYSTEMS HAVE NOT MOVED VERY
MUCH...ALLOWING EXCESSIVE AMOUNTS OF RAIN TO FALL. AN URBAN AND
SMALL STREAM FLOOD ADVISORY WAS ISSUED.

MOISTURE CONTINUES AT RELATIVELY RICH CONCENTRATIONS IN LOWER
LEVELS...BUT MID LEVELS WILL SEE SOME DROP OFF OF MOISTURE
BEGINNING SATURDAY NIGHT. WITH NO STRONG FEATURES TO CREATE
FORCING THIS WILL ALLOW SHOWERS AND THUNDERSTORMS TO DEVELOP IN
RELATIVELY LIGHT TRADE WIND FLOW EACH DAY THROUGH THE NEXT 7 DAYS.
LIFTED INDICES HOWEVER SUGGEST THAT MUCH LESS ACTIVITY WITH MUCH
LESS INTENSITY WILL BE FOUND SUNDAY THROUGH TUESDAY...WITH A
RETURN IN SHOWER ACTIVITY AND HEAVY RAIN AFTER TUESDAY.
UNFORTUNATELY MOST OF THIS ACTIVITY WILL CONTINUE TO BE IN THE
WESTERN HALF OF PUERTO RICO...WITH ONLY MINOR AMOUNTS OCCURRING IN
THE U.S. VIRGIN ISLANDS AND THE EASTERN HALF OF PUERTO RICO.
SYSTEMS DEVELOPING IN THE TROPICAL ATLANTIC ARE NOT FORECAST AT
THIS TIME TO BECOME SIGNIFICANT OR MOVE INTO THE CARIBBEAN FOR AT
LEAST THE NEXT 10 DAYS. TEMPERATURES WILL GENERALLY REMAIN CLOSE
TO NORMAL DURING THE FORECAST PERIOD.

&&

.AVIATION...ISOLD SHRA/TSRA CURRENTLY OVER NW PR WITH MVFR CIGS
POSSIBLE OVER TJBQ THRU 2100Z...WITH MOUNTAIN OBSCURATIONS. AT THE
OTHER TAF SITES...EXPECT MOSTLY VFR WITH VCSH THROUGH THE PERIOD.
LOW LEVEL WINDS WILL BE MAINLY FROM THE EAST...SOUTHEAST AT 10 TO 15
KTS.

&&

.MARINE...MARINE CONDITIONS ARE EXPECTED TO BE BENIGN THROUGH THE
NEXT 10 DAYS. SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE
THROUGH THE PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 89 78 88 / 40 40 30 30
STT 80 88 78 87 / 40 40 40 40

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
450 AM AST FRI SEP 18 2015

.SYNOPSIS...TUTT WILL CONTINUE TO MEANDER TO OUR WEST THROUGH THE
UPCOMING WEEKEND WHILE WEAKENING. MEANWHILE...A MID TO UPPER LEVEL
TROUGH WILL CONTINUE TO AMPLIFY ACROSS THE CENTRAL ATLANTIC AND
INTO THE EASTERN CARIBBEAN. WEAK SURFACE HIGH PRESSURE OVER THE
WEST AND CENTRAL ATLANTIC...AND A BROAD TROUGH NORTHEAST OF THE
REGION...WILL MAINTAIN EASTERLY WINDS OVER THE NEXT SEVERAL DAYS.

&&

.DISCUSSION...MOSTLY CLEAR TO PARTLY CLOUDY SKIES PREVAILED
ACROSS THE LOCAL ISLANDS DURING THE OVERNIGHT HOURS. ISOLATED TO
LOCALLY SCATTERED SHOWERS WERE OBSERVED OVER LOCAL WATERS...WITH
SOME OF THEM AFFECTING THE NORTHEAST COASTAL AREAS OF PUERTO RICO
AS WELL AS SAINT THOMAS AND SAINT CROIX. RAINFALL ACCUMULATION
ASSOCIATED WITH THESE SHOWERS WERE MINIMAL. WINDS WERE LIGHT AND
VARIABLE WITH COASTAL TEMPERATURES IN THE UPPER 70S TO THE LOW
80S. OVER THE NEXT 7 DAYS...UNDER LIGHT TO MODERATE EASTERLY
WINDS...NO STRONG FEATURES TO CREATE FORCING...AND PRECIPITABLE
WATER NEAR NORMAL VALUES...EXPECT A SEASONABLE WEATHER REGIME
WITH SHOWERS AND THUNDERSTORMS DEVELOPING EACH DAY OVER AND WEST
OF THE CORDILLERA IN THE AFTERNOON HOURS. ELSEWHERE MOSTLY FAIR
WEATHER CONDITIONS WITH ISOLATED SHOWER ACTIVITY POSSIBLE.

&&

.AVIATION...VFR CONDITIONS WITH JUST A ISOLD VCNTY SHRA OVER
TIST/TISX/TJSJ/TJBQ/TNCM/TKPK. AT THE OTHER TAF SITES...EXPECT CLEAR
CONDS THROUGH THE PERIOD. AFT 18/12Z SOME SHRA ARE POSSIBLE IN THE
VCTY OF TIST/TJSJ AND IN THE AFT HRS MTN OBSC ARE EXPECTED. LOW CIGS
AND LIKELY VCTS AT JMZ/JBQ AND POSSIBLE AT JSJ. SFC WINDS ARE
EXPECTED MAINLY FROM THE E TO ESE AT 10 TO 15 KT WITH SEA BREEZE
VARIATIONS AND GUSTS NEAR SHRA/TSRA.

&&

.MARINE...TRANQUIL MARINE CONDITIONS EXPECTED OVER THE NEXT FEW
DAYS WITH SEAS UP TO 3 FEET AND WINDS 15 KNOTS OR LESS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 89 79 / 40 20 50 20
STT 89 80 91 80 / 40 40 40 20

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
238 PM AST FRI SEP 18 2015

.SYNOPSIS...AT UPPER LEVELS...THE WEAK LOW WEST OF THE AREA
DRIFTED SOUTH OF HISPANIOLA. THE TUTT LOW TO THE NORTHEAST WILL
APPROACH BUT IS NOT EXPECTED TO STRENGTHEN BEFORE IT PULLS BACK
NORTH LATE NEXT WEEK. NORTHERLY FLOW WILL CONTINUE THROUGH THE
PERIOD.

AT MID LEVELS...THE UPPER LEVEL PATTERN IS WEAKLY REFLECTED AT MID
LEVELS...ESPECIALLY THE TUTT LOW...HOWEVER ALL GRADIENTS AND WINDS
ARE QUITE WEAK. MOISTURE AT MID LEVELS WILL END ON SUNDAY AND
RETURN ONLY WEAKLY MONDAY THROUGH THE REST OF THE WEEK.

AT LOWER LEVELS...WEAK GRADIENTS BECOME EVEN WEAKER AS HIGH
PRESSURE TO THE NORTH RECEDES TO THE NORTHEAST CENTRAL ATLANTIC
AND LOW PRESSURE MOVES INTO THE WESTERN ATLANTIC AND CONTINUES TO
AFFECT THE AREA EVEN AFTER IT SPLITS. SOME LOW PRESSURE SYSTEM ARE
ALSO SEEN NORTHEAST OF THE AREA AS A REFLECTION OF THE TUTT LOW.

&&

.DISCUSSION...STRONG THUNDERSTORMS WITH HEAVY SHOWERS DEVELOPED
ACROSS THE SOUTH CENTRAL TIER OF PUERTO RICO AND NOW ALSO EXTEND
ACROSS THE CORDILLERA CENTRAL TOWARD AGUADA. FURTHER DEVELOPMENT
IS EXPECTED WITH FREQUENT LIGHTNING.

A BAND OF MOISTURE LAYING ACROSS PUERTO RICO SEPARATING MOIST AIR
FROM DRIER AIR TO THE NORTH WILL LAY ACROSS THE AREA FOR ONE MORE
DAY BEFORE THE DRIER AIR MOVES INTO PUERTO RICO. OVERALL MOISTURE
WILL PEAK AGAIN ON WEDNESDAY ACCORDING TO THE GFS. LOWER LEVEL
MOISTURE...HOWEVER...IS NOT SEEN LEAVING UNTIL LATE NEXT WEEK.

WINDS ARE UNUSUALLY LIGHT AS SURFACE GRADIENTS ARE WEAK. LOW
PRESSURE IS PERSISTING NORTHEAST OF THE AREA IN THE WESTERN
TROPICAL ATLANTIC AND IS GROWING IN THE WESTERN ATLANTIC OF THE
UNITED STATES EASTERN SEABOARD. THEREFORE EXPECT STRONG CONVECTION
TO PERSIST TOMORROW...DIMINISH SATURDAY THROUGH MONDAY AS MOISTURE
DIMINISHES AND THE LIFTED INDEX INCREASES...BUT SOME SHOWERS AND
THUNDERSTORMS SHOULD STILL BE EXPECTED. MOISTURE AND LIFTED
INDICES RETURN AFTER TUESDAY AND THIS WITH THE CONTINUED LIGHT
WINDS SUGGESTS STRONG AFTERNOON THUNDERSTORMS AND HEAVY RAINS WILL
RETURN TO PUERTO RICO.

LITTLE ACTIVITY IS EXPECTED ACROSS THE U.S. VIRGIN ISLANDS
ALTHOUGH STREAMERS FROM UPSTREAM ISLANDS COULD BRING SOME HEAVY
RAINS FOR A LITTLE WHILE DURING THE AFTERNOONS.

DUE TO THE UPPER LEVEL LOW AND SOME SHEAR IN THE AREA...TROPICAL
DEPRESSIONS MOVING TOWARD THE AREA DURING THE NEXT 10 DAYS ARE
ALL FORECAST TO MOVE NORTH BEFORE THEY CAN APPROACH THE AREA. TROPICAL
WAVES ARE SEEN TO BE BLOCKED AS WELL. THEREFORE ALMOST ALL WEATHER
DURING THE NEXT 10 DAYS WILL BE DUE TO LOCAL FORCING AND HEATING.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS MOST OF THE TAF
SITES...EXCEPT AT TJMZ AND TJPS WHERE SHRA/TSRA COULD PRODUCE MVFR
CONDS THRU 22Z. MOUNTAIN OBSCURATIONS OVER CENTRAL AND WEST
INTERIOR PR. LOW LEVEL WINDS WILL BE VARIABLE AT AROUND 10 KT FM
SFC TO FL200.

&&

.MARINE...WINDS AND SEAS REMAIN RELATIVELY GENTLE. NO SMALL CRAFT
ADVISORIES ARE EXPECTED DURING THE NEXT 10 DAYS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 88 79 89 / 30 50 20 20
STT 80 87 80 88 / 40 20 20 20

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
432 AM AST SAT SEP 19 2015

.SYNOPSIS...UPPER LEVEL LOW SOUTHWEST OF THE LOCAL ISLANDS AND SOUTH
OF THE HISPANIOLA WILL SHIFT WESTWARD OVER THE NEXT FEW DAYS WHILE
WEAKENING. TUTT WILL CONTINUE TO MEANDER ACROSS THE CENTRAL ATLANTIC
AND INTO THE EASTERN CARIBBEAN MUCH OF NEXT WEEK. WEAK SURFACE HIGH
PRESSURE OVER THE CENTRAL ATLANTIC...AND A BROAD TROUGH NORTHEAST OF
THE REGION...WILL MAINTAIN LIGHT TO MODERATE EASTERLY WINDS OVER THE
NEXT FEW DAYS.

&&

.DISCUSSION...MOSTLY CLEAR SKIES PREVAILED ACROSS THE LOCAL ISLANDS
DURING THE OVERNIGHT HOURS. ISOLATED TO LOCALLY SCATTERED SHOWERS
WERE OBSERVED OVER LOCAL WATERS...WITH SOME OF THEM BRUSHING THE
NORTHEAST COASTAL AREAS OF PUERTO RICO AS WELL AS SAINT THOMAS AND
SAINT CROIX. RAINFALL ACCUMULATION ASSOCIATED WITH THESE SHOWERS
WERE MINIMAL. WINDS WERE LIGHT AND VARIABLE WITH COASTAL
TEMPERATURES IN THE UPPER 70S TO THE LOW 80S.

OVER THE NEXT 7 TO 8 DAYS...UNDER LIGHT TO MODERATE EASTERLY
WINDS...NO STRONG FEATURES TO CREATE FORCING BUT ENOUGH CONVECTIVE
INSTABILITY EACH DAY...AND PRECIPITABLE WATER NEAR NORMAL VALUES...
EXPECT A SEASONABLE WEATHER REGIME WITH SHOWERS AND THUNDERSTORMS
DEVELOPING EACH DAY OVER AND WEST OF THE CORDILLERA IN THE AFTERNOON
HOURS. ELSEWHERE MOSTLY FAIR WEATHER CONDITIONS WITH ISOLATED
SHOWER ACTIVITY POSSIBLE. AFTERNOON SHOWERS AND THUNDERSTORMS WILL
BE SLOW MOVERS AND THEREFORE URBAN FLOODING EXPECTED WITH THE
STRONGEST SHOWERS TODAY.

TROPICAL DEPRESSION NINE AND TROPICAL STORM IDA WILL CONTINUE TO
MOVE WNW AND NW RESPECTIVELY ACROSS OPEN WATERS. PLEASE REFER TO
TCPAT AND TCDAT 4 AND 5 FOR ADDITIONAL INFORMATION.

&&

.AVIATION...VFR CONDITIONS WITH JUST A ISOLD VCNTY SHRA OVER
TIST/TISX/TNCM/TKPK THROUGH 18/16Z. SHRA/TSRA DEVELOPMENT EXPECTED
AFTER 19/16Z ACROSS PR...CAUSING LIKELY VCTS ACROSS
TJSJ/TJBQ/TJMZ/TJPS...WITH TEMPO MVFR CONDS POSSIBLE AT THOSE
TERMINALS WITH LOWER VIS DUE TO RAIN AND LOWER CIGS...ALONG WITH
GUSTY WINDS. SFC WINDS ARE EXPECTED MAINLY FROM THE E AT 10 KT
WITH SEA BREEZE VARIATIONS AND GUSTS NEAR SHRA/TSRA.

&&

.MARINE...TRANQUIL MARINE CONDITIONS EXPECTED OVER THE NEXT
SEVERAL DAYS WITH SEAS UP TO 3 FEET AND WINDS 15 KNOTS OR LESS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 90 79 / 50 20 40 20
STT 89 79 89 78 / 20 20 20 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
233 PM AST SAT SEP 19 2015

.SYNOPSIS...AT UPPER LEVELS...NORTHERLY FLOW WILL BECOME NORTHWEST
AS THE TUTT LOW WEAKENS AND MOVES WEST NORTHWEST...PASSING NORTH
OF THE AREA ON THURSDAY...BUT FIRST THE LOW WILL REACH ITS
CLOSEST POINT TO THE AREA ON SUNDAY AFTERNOON ABOUT 550 MILES TO
OUR EAST NORTHEAST.

AT MID LEVELS...WEAK LOW PRESSURE IN A BROAD AREA OF HIGH
PRESSURE WILL MOVE IN TANDEM WITH THE UPPER LEVEL LOW.

AT LOWER LEVELS...HIGH PRESSURE OVER THE CENTRAL ATLANTIC AND
LOWER PRESSURE IN THE SOUTHWEST CARIBBEAN WILL MAINTAIN GENTLE TO
MODERATE TRADE WINDS ACROSS THE AREA WITH PATCHES OF MOISTURE
BRINGING SCATTERED SHOWERS.

&&

.DISCUSSION...SHOWERS CONTINUED AROUND THE U.S. VIRGIN ISLANDS
DURING THE LATE MORNING AND EARLY AFTERNOON HOURS WHILE SHOWERS
DEVELOPED OVER MAINLAND PUERTO RICO DURING THE AFTERNOON
HOURS...FIRST DOWNSTREAM FROM EL YUNQUE AND THEN OVER VARIOUS
POINTS IN THE INTERIOR. EVENTUALLY SOME THUNDERSTORMS ARE
EXPECTED...BUT THERE IS CONSIDERABLY LESS MOISTURE BETWEEN 20 AND
30 THOUSAND FEET THAN YESTERDAY AND CONVECTION HAS NOT BEEN ABLE
TO MAKE IT PAST THIS DRIER LAYER.

MOISTURE AND INSTABILITY WILL DIMINISH OVERNIGHT BUT BOTH WILL
RECOVER SOME SUNDAY. AT THE SAME TIME HOWEVER...DRIER AIR WILL
MOVE IN FROM THE NORTHEAST AT MID LEVELS...CAUSING OVERALL
ACTIVITY TO DECREASE SUNDAY. THEN INSTABILITY AND MID LEVEL
MOISTURE WILL GRADUALLY INCREASE THROUGH THURSDAY AS WILL SHOWERS
AND THUNDERSTORMS ACROSS THE AREA. GRADIENTS REMAIN LIGHT AND
WINDS WILL REMAIN AT OR BELOW 15 KNOTS BELOW 23 KFT THROUGH THE
END OF THE MONTH.

THE WEAK WINDS WILL COUPLE WITH DAYTIME HEATING TO CREATE SHOWERS
AND SOME THUNDERSTORMS. SOME OF WHICH WILL DEVELOP SUFFICIENTLY TO
GENERATE URBAN AND SMALL STREAM FLOODING...MORE LIKELY AFTER
MONDAY. ALTHOUGH THERE MAY BE A BREAK ON FRIDAY...ACTIVITY MAY BE
STRONGEST ON SATURDAY OF NEXT WEEK....BUT BECAUSE MOISTURE WILL
DECREASE AFTER THURSDAY...SHOWER AND THUNDERSTORM ACTIVITY WILL
NOT BE AS WIDESPREAD THEN.

TROPICAL STORM IDA IS FORECAST TO STRENGTHEN ACCORDING TO THE GFS
MODEL AND MAY BECOME A HURRICANE LATE NEXT WEEK. HOWEVER
REGARDLESS OF INTENSITY IT IS FORECAST TO MOVE NORTH NORTHWEST AND
AWAY FROM THE AREA AFTER IT CROSSES 20 NORTH NEAR 50 WEST...SO IT
DOES NOT FIGURE INTO OUR FORECAST.

&&

.AVIATION...MOSTLY VFR CONDITIONS WITH ISOLD VCNTY SHRA OVER
THE EASTERN TERMINALS (TJSJ/TIST/TISX/TNCM/TKPK) THROUGH 20/15Z.
SHRA/TSRA DEVELOPMENT ACROSS INTERIOR/WEST PR EXPECTED AFTER 19/18Z
WITH VCTS ACROSS TJBQ/TJMZ/TJPS...WITH TEMPO MVFR CONDS POSSIBLE AT
THOSE TERMINALS WITH LOWER VIS DUE TO RAIN AND LOWER CIGS. SFC WINDS
SHOULD BE MAINLY FROM THE E AT 10 KT WITH SEA BREEZE VARIATIONS
AND GUSTS NEAR SHRA/TSRA THROUGH 19/22Z BECOMING VRB AFTER THAT.

&&

.MARINE...WEAK SURFACE GRADIENTS LEADING TO GENTLE WINDS WILL
LEAVE SEAS BELOW 3 FEET THROUGH MONDAY AND BELOW 4 FEET FOR MUCH
OF NEXT WEEK. SMALL CRAFT ADVISORIES ARE NOT EXPECTED THIS MONTH.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 90 79 89 / 20 40 20 20
STT 79 89 78 89 / 20 20 20 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
420 AM AST SUN SEP 20 2015

.SYNOPSIS...UPPER LEVEL LOW SOUTHWEST OF THE LOCAL ISLANDS AND
SOUTH OF THE HISPANIOLA WILL SHIFT WESTWARD OVER THE NEXT FEW
DAYS WHILE WEAKENING. TUTT WILL CONTINUE TO MEANDER NORTHEAST
OF THE LOCAL ISLANDS THROUGH THE END OF THE WORK WEEK. A LIGHT
TO MODERATE EAST SOUTHEAST WIND FLOW WILL PERSIST THROUGH MUCH
OF THE WEEK...BECOMING SOUTHERLY BY THE UPCOMING WEEKEND.


&&

.DISCUSSION...MOSTLY CLEAR SKIES PREVAILED ACROSS THE LOCAL ISLANDS
DURING THE OVERNIGHT HOURS. ISOLATED TO LOCALLY SCATTERED SHOWERS
WERE OBSERVED ACROSS THE LOCAL WATERS...WITH SOME OF THEM BRUSHING
THE EAST COASTAL AREAS OF PUERTO RICO AS WELL AS SAINT THOMAS AND
SAINT CROIX. RAINFALL ACCUMULATION ASSOCIATED WITH THESE SHOWERS
WERE MINIMAL. WINDS WERE LIGHT AND VARIABLE...WITH COASTAL
TEMPERATURES IN THE UPPER 70S TO THE LOW 80S.

AVAILABLE MOISTURE IS EXPECTED TO COMBINE WITH DIURNAL HEATING AND
LOCAL EFFECTS TO RESULT IN AFTERNOON SHOWERS AND THUNDERSTORMS OVER
AND WEST OF THE CORDILLERA AS WELL AS PORTIONS OF THE SAN JUAN METRO
AREA TODAY. ALTHOUGH DRIER AIR AT MID LEVELS WILL CAUSE AN OVERALL
DECREASE IN AREAL COVERAGE COMPARED TO PREVIOUS DAYS. THESE AFTERNOON
SHOWERS WILL BE SLOW MOVERS AND THEREFORE URBAN FLOODING IS EXPECTED
WITH THE HEAVIEST SHOWERS.

UNDER LIGHT TO MODERATE EAST SOUTHEAST WINDS...NO STRONG FEATURES
TO CREATE FORCING BUT ENOUGH CONVECTIVE INSTABILITY EACH DAY...
AND PRECIPITABLE WATER NEAR OR ABOVE NORMAL VALUES...EXPECT
SHOWERS AND THUNDERSTORMS DEVELOPING EACH DAY OVER AND NORTH OF
THE CORDILLERA IN THE AFTERNOON HOURS MONDAY THRU FRIDAY.
ELSEWHERE MOSTLY FAIR WEATHER CONDITIONS WITH ISOLATED SHOWER
ACTIVITY EXPECTED.

TROPICAL STORM IDA WILL CONTINUE TO MOVE WNW ACROSS OPEN WATERS.
PLEASE REFER TO TCPAT AND TCDAT 5 FOR ADDITIONAL INFORMATION.

&&

.AVIATION...PREVAILING VFR CONDITIONS WITH VCNTY SHRA OVER
TIST/TISX/TNCM/TKPK THROUGH 20/14Z. SHRA/TSRA DEVELOPMENT POSSIBLE
AFTER 20/14Z IN AND AROUND TJSJ/TIST/TISX. AFTER 20/17Z...SHRA/TSRA
EXPECTED TO DEVELOP IN PR...LIKELY CAUSING VCTS ACROSS
TJSJ/TJBQ/TJMZ/TJPS...TEMPO MVFR CONDS POSSIBLE AT THOSE TERMINALS...
ESPECIALLY AT TJMZ. SFC WINDS ARE EXPECTED MAINLY FROM THE E TO
E-SE AT AROUND 10 KT WITH SEA BREEZE VARIATIONS AND GUSTS NEAR
SHRA/TSRA.

&&

.MARINE...TRANQUIL MARINE CONDITIONS EXPECTED OVER THE NEXT
SEVERAL DAYS WITH SEAS UP TO 3 FEET AND WINDS 15 KNOTS OR
LESS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 89 79 / 40 30 40 20
STT 89 78 89 78 / 30 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
239 PM AST SUN SEP 20 2015

.SYNOPSIS...AT UPPER LEVELS...LOW PRESSURE NORTHEAST OF THE
LEEWARD ISLANDS HOLDING NORTHERLY FLOW OVER THE LOCAL AREA WILL
MOVE NORTHWEST TO NORTH OF THE LOCAL AREA BY THURSDAY. HIGH
PRESSURE WILL BUILD OVER THE WESTERN CARIBBEAN LATE THIS WEEK AND
NORTHERLY FLOW WILL THEN RETURN.

AT MID LEVELS...LOW PRESSURE IN A BROAD AREA OF HIGH PRESSURE WILL
FOLLOW THE LOW IN THE UPPER LEVELS TO THE NORTHWEST. HIGH PRESSURE
WILL THEN CONTINUE OVER THE LOCAL AREA. MOISTURE AT MID LEVELS
WILL INCREASE TOMORROW AND REMAIN MODERATE NEXT WEEK.

AT LOWER LEVELS...HIGH PRESSURE IN THE CENTRAL ATLANTIC WILL BE
BUFFERED BY LOW PRESSURES IN THE WESTERN ATLANTIC AND THE WESTERN
TROPICAL ATLANTIC SO AS TO MAINTAIN WEAK GRADIENTS AND WINDS THIS
WEEK. MODERATE MOISTURE WILL CONTINUE THROUGH THE WEEK.

&&

.DISCUSSION...SHOWERS FROM MOISTURE OVER THE CARIBBEAN FORMED OVER
THE CORDILLERA AND DOWNSTREAM FROM EL YUNQUE EARLY IN THE
AFTERNOON. SOME PRODUCED SHOWERS SUFFICIENT FOR URBAN AND SMALL
STREAM FLOODING. SHOWERS CONTINUED TO DEVELOP FROM SAN JUAN TO
MAYAGUEZ WITH SCATTERED THUNDERSTORMS.

MOISTURE IS EXPECTED TO INCREASE TOMORROW THROUGH FRIDAY AS
PRECIPITABLE WATER EDGES UP AND MID LAYERS MOISTEN ON MONDAY.
MODEL LAPSE RATES FAILED TO SHOW THE INSTABILITY THAT OCCURRED
TODAY AND FORECASTS OF THE LIFTED INDEX FOR THE REST OF THE WEEK
ARE RELATIVELY STABLE AND LIKELY TOO HIGH. THEREFORE EXPECT GOOD
ACTIVITY EACH AFTERNOON WITH HEAVY THUNDERSTORMS...MAINLY IN THE
INTERIOR AND LIGHTER SHOWERS ON THE EAST COAST OF PUERTO RICO
DURING THE EARLY MORNING HOURS. THE U.S. VIRGIN ISLANDS WILL HAVE
LESS RAIN OVERALL...BUT SOME SHOWERS FROM AFTERNOON ACTIVITY AND
ALSO SHOWERS THAT DEVELOP OVER THE WATER DURING THE OVERNIGHT
HOURS AND STRAY OVER LAND. URBAN AND SMALL STREAM FLOODING WILL
LIKELY OCCUR IN PUERTO RICO RICO EACH AFTERNOON...BUT NOT IN THE
U.S VIRGIN ISLANDS.

CURRENTLY TROPICAL STORM IDA IS FORECAST TO STRENGTHEN A LITTLE AS
SHE TRAVELS NORTHWEST...BUT OTHER THAN A SLIGHT INCREASE IN WAVE
ACTION NEXT WEEK...IDA SHOULD NOT AFFECT THE LOCAL AREA...EVEN IF
THERE IS AN INCREASE TO HURRICANE STRENGTH NEXT WEEK AS THE GFS
FORECASTS.

&&

.AVIATION...SHRA/TSRA EXPECTED IN AND AROUND TJMZ...TJBQ...TJPS AND
POSSIBLY TJSJ. AS A RESULT...VCTS WITH BRIEF MVFR CONDS POSSIBLE IN
PASSING SHRA/TSRA THRU 22Z. MOUNTAIN OBSCURATIONS LIKELY ALONG THE
CORDILLERA CENTRAL. LOW LEVEL WINDS MAINLY FM THE ESE AT 10-15 KT.
SHRA WILL DISSIPATE AFT 21/02Z...BUT RE-DEVELOP AROUND 21/16Z.

&&

.MARINE...WINDS AND SEAS ARE TRANQUIL AND WILL REMAIN SO FOR AT
LEAST THE NEXT 5 DAYS. SMALL CRAFT ADVISORIES ARE NOT EXPECTED FOR
THE NEXT 10 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 79 89 79 89 / 30 40 20 20
STT 78 89 78 88 / 30 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
606 AM AST MON SEP 21 2015

.SYNOPSIS...SURFACE HIGH PRESSURE ACROSS THE NORTH CENTRAL
ATLANTIC WILL REMAIN IN PLACE FOR THE NEXT FEW DAYS UNTIL A
SURFACE LOW ACROSS THE WESTERN ATLANTIC MOVES NORTH NORTHEAST AND
INTO THE NORTH CENTRAL ATLANTIC BY THURSDAY. UPPER LOW TO THE
NORTHEAST OF THE CARIBBEAN WILL SLOWLY MOVE WEST OVER THE NEXT FEW
DAYS AND POSITION ITSELF TO THE NORTH OF THE LOCAL ISLANDS BY
WEDNESDAY AND THROUGH THE REST OF THE WORK WEEK. WINDS ARE
EXPECTED TO REMAIN RELATIVELY LIGHT FOR THIS WEEK. TROPICAL STORM
IDA IS EXPECTED TO REMAIN OVER THE OPEN ATLANTIC WATERS.

&&

.DISCUSSION...SCATTERED TO NUMEROUS SHOWERS WERE OBSERVED TODAY
ACROSS THE LOCAL FORECAST AREA WITH SOME OF THE SHOWERS AFFECTING
THE USVI AND EASTERN PR. EVEN THOUGH THE ACCUMULATIONS WERE FAIRLY
MINIMAL AND THE SHOWERS WERE BRIEF...THE OVERALL COVERAGE WAS
FAIRLY LARGE. TODAY WE EXPECT A VERY SIMILAR WEATHER PATTERN TO
WHAT WE HAVE OBSERVED THE PAST FEW DAYS. THE WINDS REMAIN LIGHT
AND THE OVERALL AVAILABLE MOISTURE IS ENOUGH TO ENHANCE THE
CHANCES OF SHOWERS AND THUNDERSTORMS TO DEVELOP ONCE IT COMBINES
WITH THE LOCAL EFFECTS AND DIURNAL HEATING. CENTRAL AND WESTERN PR
HAS THE HIGHEST CHANCE OF HEAVY RAINFALL. HOWEVER SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ACROSS OTHER SECTORS IN PR AS WELL. IN
ADDITION...SHOWERS COULD DEVELOP OVER THE USVI ONCE IT INTERACTS
WITH THE ISLANDS...WITH THE NORTHWESTERN SECTIONS OF THE ISLANDS
HAVING THE HIGHER CHANCE OF RAIN AND POSSIBLE THUNDERSTORMS.

THIS GENERAL WEATHER PATTERN IS NOT EXPECTED TO CHANGE MUCH FOR
THE NEXT SEVERAL DAYS AS THE OVERALL LARGER PATTERN AND AVAILABLE
MOISTURE IS EXPECTED TO REMAIN SOMEWHAT CONSTANT THROUGH
WEDNESDAY. SLIGHTLY DRIER AIR MOVES IN ON THURSDAY AND
FRIDAY...WHICH SHOULD LIMIT THE AMOUNT OF SHOWERS AND
THUNDERSTORMS THAT DEVELOP IN COMPARISON TO WHAT WE HAVE OBSERVED
THE PAST FEW DAYS AND WHAT WE EXPECT FOR THE NEXT FEW DAYS.

&&

.AVIATION...VFR XCP MVFR IN SCT SHRA...MORE NMRS OFFSHORE THRU
MORNING. MVFR IN SCT-NMRS SHRA/TSRA IN AFT ACRS PR...SPCLLY WEST AND
INTERIOR WI OBSCD MTNS...BUT ALSO WEST AND NORTHWEST OF USVI AND
INTO SAN JUAN METRO. SIMILAR CONDS XPCTD TONITE/TUE. WIND BLW FL100
E-ESE 5-14 KT THRU TUE...WIND N ABV FL100 AND INCR WI HGT THEN
BACKING TO W-NW TONITE-TUE.

&&

.MARINE...WINDS AND SEAS ARE RELATIVELY TRANQUIL AND WILL REMAIN
SO FOR AT LEAST THE NEXT 5 DAYS. SMALL CRAFT ADVISORIES ARE NOT
EXPECTED FOR THE NEXT SEVERAL DAYS. FOR TODAY...EXPECT WINDS AT
AROUND 10 KNOTS AND SEAS UP TO 4 FEET.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 78 / 40 20 30 30
STT 88 79 88 78 / 60 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
247 PM AST MON SEP 21 2015

.SYNOPSIS...AT UPPER LEVELS...THE LOW TO THE NORTHEAST OF THE AREA
WILL MOVE TO NORTH OF THE AREA THURSDAY ALLOWING NORTHWEST FLOW TO
SHIFT TO THE WEST...THEN HIGH PRESSURE WILL BUILD OVER THE WESTERN
CARIBBEAN GENERATING A JET OVER HISPANIOLA OF NORTHEASTERLY FLOW
THAT WILL WEAKLY INFLUENCE THE LOCAL AREA THROUGH THE END OF NEXT
WEEK.

AT MID LEVELS...WEAK GRADIENTS WILL PREVAIL IN GENERALLY HIGH
PRESSURE. THE UPPER LEVEL LOW WILL ALSO BE REFLECTED WEAKLY AT
MID LEVELS. A BAND OF MOISTURE WILL ROTATE AROUND THIS LOW SO AS
TO HOLD OVER THE FORECAST AREA THROUGH THURSDAY. DRIER AIR WILL
RETURN UNTIL THE FOLLOWING TUESDAY.

AT LOWER LEVELS...A RIDGE OF HIGH PRESSURE WILL EXTEND TO THE
SOUTHWEST OFF THE MAIN HIGH IN THE EAST CENTRAL ATLANTIC THAT
WILL MAINTAIN A GENTLE TO MODERATE EAST SOUTHEASTERLY TRADE WIND
FLOW ACROSS THE REGION. THIS FLOW WILL GAIN A SLIGHT NORTHERLY
COMPONENT ON MONDAY WHEN TROPICAL STORM IDA BEGINS TO MOVE NORTH
ON MONDAY FROM HER POSITION ALMOST 900 MILES NORTH OF THE LEEWARD
ISLANDS.

&&

.DISCUSSION...VIGOROUS SHOWERS AND THUNDERSTORMS GREW DURING THE
EARLY AFTERNOON HOURS OVER THE WESTERN TWO THIRDS OF PUERTO RICO
AND WERE STILL FIRING OFF AS OF 3 PM AST. SHOWERS AND
THUNDERSTORMS WILL LIKELY CONTINUE PAST SUNSET BY SEVERAL HOURS AS
INSTABILITY CONTINUES OVER THE AREA. THE GFS INDICATES THAT
MOISTURE AND INSTABILITY WILL BE VERY SIMILAR TUESDAY AND
WEDNESDAY. LOW LEVEL FLOW WILL REMAIN THE SAME ALTHOUGH UPPER
LEVEL FLOW WILL BACK TO THE WEST. THIS WILL CREATE VERY SIMILAR CONDITIONS
WITH HEAVY DOWNPOURS AND FREQUENT LIGHTING BOTH TOMORROW AND
WEDNESDAY. BEGINNING THURSDAY...STABILITY WILL SHOW A GRADUAL
INCREASE THROUGH SATURDAY WHILE MOISTURE BEGINS A STEADY DECLINE
UNTIL PRECIPITABLE WATER BECOMES AS LOW AS 1.25 INCHES. ALTHOUGH
THIS WILL NOT ELIMINATE THUNDERSTORM ACTIVITY IT SHOULD GRADUALLY
REDUCE IT THURSDAY THROUGH SATURDAY. URBAN AND SMALL STREAM
FLOODING EACH AFTERNOON WILL BE LIKELY THROUGH THURSDAY...BUT
SHOULD DIMINISH BY SATURDAY.

&&

.AVIATION...MVFR CONDITIONS EXPECTED IN SHRA/TSRA SPECIALLY ACROSS
WESTERN AND AND INTERIOR PUERTO RICO WITH MOUNTAIN OBSCD AFTER
21/17Z. SHRA AND POSSIBLE TSRA ALSO EXPECTED WEST AND NORTHWEST OF
USVI AND INTO SAN JUAN METRO. WIND BELOW FL100 FROM E-ESE AT 5-14 KT
THRU TUESDAY...WIND NORTH ABOVE FL100 AND INCREASING WITH HIGH THEN
BACKING TO W-NW TONIGHT-TUESDAY.

&&

.MARINE...SEAS WILL CONTINUE TO BE GENERALLY 4 FEET OR LESS
THROUGH THE FORECAST PERIOD. HOWEVER A FEW AREAS APPROACHING 5
FEET MAY BE FOUND IN THE NORTHERN OUTER ATLANTIC WATERS WEDNESDAY.
SEAS WILL CONTINUE LOWER IN THE CARIBBEAN. NO SMALL CRAFT
ADVISORIES ARE ANTICIPATED DURING THE NEXT 10 DAYS BUT A FEW
SHOWERS OVER THE AREA MAY BE VERY HEAVY AND HAVE GUSTY WINDS DURING
THE AFTERNOONS. SCATTERED SHOWERS ARE EXPECTED IN THE LOCAL WATERS
AROUND THE U.S. VIRGIN ISLANDS DURING THE OVERNIGHT HOURS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 89 78 89 / 20 40 30 30
STT 79 88 78 88 / 30 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
524 AM AST TUE SEP 22 2015

.SYNOPSIS...SURFACE HIGH PRESSURE ACROSS THE NORTH CENTRAL
ATLANTIC IS STILL EXPECTED TO REMAIN IN PLACE FOR THE NEXT FEW
DAYS UNTIL A SURFACE LOW ACROSS THE WESTERN ATLANTIC MOVES NORTH
NORTHEAST AND INTO THE NORTH CENTRAL ATLANTIC BY THURSDAY. UPPER
LOW TO THE NORTHEAST OF THE CARIBBEAN WILL SLOWLY MOVE WEST OVER
THE NEXT FEW DAYS AND POSITION ITSELF TO THE NORTH OF THE LOCAL
ISLANDS BY WEDNESDAY AND THROUGH THE REST OF THE WORK
WEEK...WEAKENING AND MOVING NORTH THEREAFTER. WINDS ARE EXPECTED
TO REMAIN RELATIVELY LIGHT THE REST OF THE WEEK. TROPICAL STORM
IDA IS EXPECTED TO REMAIN OVER THE OPEN ATLANTIC WATERS FOR
SEVERAL DAYS.

&&

.DISCUSSION...SCATTERED TO NUMEROUS SHOWERS WERE OBSERVED DURING
THE OVERNIGHT HOURS ACROSS THE LOCAL FORECAST AREA WITH SOME OF
THE SHOWERS AFFECTING THE USVI AND EASTERN PR. EVEN THOUGH THE
ACCUMULATIONS WERE FAIRLY MINIMAL AND THE SHOWERS WERE BRIEF...THE
OVERALL COVERAGE WAS FAIRLY LARGE. TODAY WE EXPECT A VERY SIMILAR
WEATHER PATTERN TO WHAT WE HAVE OBSERVED THE PAST FEW DAYS. THE
WINDS REMAIN LIGHT AND THE OVERALL AVAILABLE MOISTURE IS ENOUGH TO
ENHANCE THE CHANCES OF SHOWERS AND THUNDERSTORMS TO DEVELOP ONCE
IT COMBINES WITH THE LOCAL EFFECTS AND DIURNAL HEATING. CENTRAL
AND WESTERN PR HAS THE HIGHEST CHANCE OF HEAVY RAINFALL. HOWEVER
SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS OTHER SECTORS IN PR
AS WELL. IN ADDITION...SHOWERS COULD DEVELOP OVER THE USVI ONCE IT
INTERACTS WITH THE ISLANDS...WITH THE NORTHWESTERN SECTIONS OF THE
ISLANDS HAVING THE HIGHER CHANCE OF RAIN AND POSSIBLE
THUNDERSTORMS.

THIS GENERAL WEATHER PATTERN IS NOT EXPECTED TO CHANGE MUCH FOR
THE NEXT SEVERAL DAYS AS THE OVERALL LARGER PATTERN AND AVAILABLE
MOISTURE IS EXPECTED TO REMAIN SOMEWHAT CONSTANT THROUGH
WEDNESDAY. ACCORDING TO THE GFS MODEL...THE PRECIPITABLE WATER
VALUES SHOULD REMAIN AT AROUND 2 INCHES TODAY AND WEDNESDAY...SLIGHTLY
DRIER AIR MOVES IN ON THURSDAY AND EVEN DRIER ON FRIDAY...WHICH
SHOULD LIMIT SOMEWHAT THE AMOUNT OF SHOWERS AND THUNDERSTORMS
THAT DEVELOP COMPARED TO WHAT WE HAVE OBSERVED THE PAST FEW
DAYS...AND ALSO WHEN COMPARED TO WHAT WE EXPECT TODAY AND
WEDNESDAY. OTHER THAN THE UPPER TROUGH THAT IS EXPECTED TO REMAIN
TO THE NORTH OF THE LOCAL AREA...THERE IS REALLY NO OTHER FEATURE
SUCH AS A TROPICAL WAVE OR OTHER...EXPECTED TO HAVE A LOCAL
IMPACT FOR THE NEXT SEVERAL DAYS.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL TAF SITES IN THE MORNING HOURS
WITH VCSH POSSIBLE AT THE USVI AND LEEWARD TERMINALS AS WELL AS JSJ.
AFTER 22/16Z...MVFR CONDS AT JMZ/JBQ AND POSSIBLY JSJ IN SHRA/TSRA
THRU 22/23Z. WINDS ESE AT 10 TO 15 KNOTS WITH SOME SEA BREEZE
VARIATIONS.

&&

.MARINE...WINDS ARE EXPECTED TO REMAIN LIGHT TO MODERATE FOR THE
NEXT FEW DAYS WITH 10 TO 15 KNOT WINDS ACROSS MOST OF THE LOCAL
WATERS. SEAS ARE ALSO EXPECTED TO REMAIN RELATIVELY TRANQUIL AS
THEY ARE EXPECTED TO BE UP TO 4 FEET FOR THE NEXT FEW DAYS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 79 / 40 30 30 30
STT 89 78 88 79 / 30 40 40 40

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
212 PM AST TUE SEP 22 2015

.SYNOPSIS...SURFACE HIGH PRESSURE ACROSS THE NORTH CENTRAL
ATLANTIC IS STILL EXPECTED TO REMAIN IN PLACE FOR THE NEXT FEW
DAYS UNTIL A SURFACE LOW ACROSS THE WESTERN ATLANTIC MOVES NORTH
NORTHEAST AND INTO THE NORTH CENTRAL ATLANTIC BY THURSDAY. UPPER
LOW TO THE NORTHEAST OF THE CARIBBEAN WILL SLOWLY MOVE WEST OVER
THE NEXT FEW DAYS AND POSITION ITSELF TO THE NORTH OF THE LOCAL
ISLANDS BY WEDNESDAY AND THROUGH THE REST OF THE WORK
WEEK...WEAKENING AND MOVING NORTH THEREAFTER. WINDS ARE EXPECTED
TO REMAIN RELATIVELY LIGHT THE REST OF THE WEEK. TROPICAL STORM
IDA IS EXPECTED TO REMAIN OVER THE OPEN ATLANTIC WATERS FOR
SEVERAL DAYS.

&&

.DISCUSSION...SCATTERED SHOWERS AFFECTED THE EAST SECTION OF
PUERTO RICO AND THE SAN JUAN METROPOLITAN AREA EARLY THIS
AFTERNOON. SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED
THUNDERSTORMS DEVELOPED ACROSS THE CORDILLERA CENTRAL OF PUERTO
RICO...WITH RAINFALL ACCUMULATIONS OF OVER 2 INCHES IN LOCALIZED
AREAS. MAIN WEATHER FEATURE WHICH CONTINUES TO AFFECT THE LOCAL
REGION IS A DEEP UPPER LEVEL TROUGH LOCATED NORTH NORTHEAST OF
THE AREA. THIS TROUGH IS HELPING IN THE DEVELOPMENT OF SHOWER AND
THUNDERSTORM ACTIVITY ACROSS THE REGION. THIS TROUGH IS EXPECTED
TO LINGER NORTH OF THE AREA THROUGH THURSDAY. AS A
RESULT...SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP EACH
AFTERNOON ACROSS THE CORDILLERA CENTRAL OF PUERTO RICO. LOW LEVEL
WINDS WILL CONTINUE GENERALLY LIGHT AND VARIABLE.
THEREFORE...SIGNIFICANT RAINFALL ACCUMULATIONS CAN BE
EXPECTED...AS SHOWERS AND THUNDERSTORMS WILL REMAIN NEARLY
STATIONARY.

FOR FRIDAY AND THROUGH THE WEEKEND...A DRIER AIR MASS IS EXPECTED
TO ENCOMPASS THE REGION...AS UPPER TROUGH WEAKENS AND UPPER LEVEL
RIDGE TAKES CONTROL OF THE WEATHER LOCALLY. THEREFORE...CHANCES OF
SHOWERS WILL DECREASE SIGNIFICANTLY FROM FRIDAY THROUGH AT LEAST
SUNDAY.

&&

.AVIATION...MVFR OR EVEN IFR CONDITIONS EXPECTED TO CONTINUE IN
SHRA/TSRA ACROSS WESTERN AND INTERIOR PUERTO RICO WITH MOUNTAIN
OBSCD AFFECTING MOSTLY TJMZ AND TJBQ UNTIL 22/21Z. LATEST TJSJ
SOUNDING INDICATED A VERY LIGHT AND VARIABLE WIND FLOW ALL THE WAY
FROM THE SURFACE TO AROUND 25K FEET...BECOMING NORTHWESTERLY AND
STRONGER ALOFT.

&&

.MARINE...SEAS UP TO 4 FEET AND WINDS UP TO 15 KNOTS ARE EXPECTED
OVER THE COASTAL WATERS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 89 79 91 / 30 30 30 30
STT 78 88 79 89 / 40 40 40 40

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
507 AM AST WED SEP 23 2015

.SYNOPSIS...SURFACE HIGH PRESSURE IN THE NORTH ATLANTIC IS
EXPECTED TO SLOWLY BE DISPLACED TO THE EAST AS A SURFACE LOW
MOVES ACROSS THE NORTHWESTERN ATLANTIC AND INTO THE NORTH CENTRAL
ATLANTIC BY THURSDAY. SURFACE LOW PRESSURES ACROSS THE WESTERN
ATLANTIC AND WESTERN CARIBBEAN WILL KEEP A LIGHT TO MODERATE EAST
SOUTHEAST WIND FLOW FOR THE NEXT FEW DAYS. TROPICAL STORM IDA IS
STILL EXPECTED TO REMAIN OVER THE OPEN ATLANTIC FOR THE NEXT
COUPLE OF DAYS...CURRENTLY DRIFTING SLOWLY TO THE EAST-SOUTHEAST.
UPPER TROUGH IS STILL TO THE NORTH OF THE LOCAL AREA BUT IT IS
EXPECTED TO SLOWLY LIFT NORTH BY FRIDAY.

&&

.DISCUSSION...ONCE AGAIN...SCATTERED SHOWERS WERE OBSERVED ACROSS
THE LOCAL WATERS...SOME OF THEM BRIEFLY AFFECTING THE USVI AND
EASTERN PR. ISOLATED TO LOCALLY SCATTERED SHOWERS ARE EXPECTED IN
THE MORNING HOURS TODAY. VERY LITTLE CHANGE IN PATTERN IS
EXPECTED FOR TODAY WHEN COMPARED TO THE LAST FEW DAYS. THERE IS
STILL ENOUGH MOISTURE TO ENHANCE THE CHANCES OF SHOWERS AND
THUNDERSTORMS ACROSS THE LOCAL ISLANDS. THE LIGHT EAST SOUTHEAST
FLOW SUGGESTS THAT ONCE AGAIN THE INTERIOR AND THE NORTHWEST
QUADRANT OF PR HAS THE HIGHEST CHANCE OF MODERATE TO HEAVY
RAINFALL THIS AFTERNOON. PORTIONS OF EASTERN PR AND THE SAN JUAN
METRO AREA MAY ALSO OBSERVE SIGNIFICANT SHOWERS AND ISOLATED
THUNDERSTORMS. THE SOIL ACROSS THE NORTHWESTERN QUADRANT OF PR
APPEARS TO BE SATURATED AND ANY HEAVY RAIN COULD RESULT IN
FLOODING. SOME RAIN COULD ALSO STREAM OFF THE NW SECTIONS OF THE
USVI...POSSIBLY AFFECTING THE NW CORNER OF ST CROIX AND ST THOMAS.

SLIGHTLY DRIER AIR IS STILL EXPECTED ON THURSDAY...BUT IT WILL
STILL HAVE PLENTY OF MOISTURE TO HELP DEVELOP SHOWERS AND
THUNDERSTORMS ACROSS THE INTERIOR...NORTH CENTRAL AND THE
NORTHWEST QUADRANT OF PR ON THURSDAY AFTERNOON...HOWEVER SLIGHTLY
LESS RAIN IS EXPECTED. SOME SHOWERS COULD STREAM OFF THE USVI AND
POSSIBLY AFFECT THE NW CORNERS OF THE ISLANDS SINCE THE STEERING
WINDS ARE EXPECTED TO BE FAIRLY LIGHT.

THE DRYING TREND IS EXPECTED TO CONTINUE ON FRIDAY...WITH
PRECIPITABLE WATER VALUES DOWN TO NEAR NORMAL FOR THIS TIME OF
YEAR. WHICH MEANS THAT THERE IS STILL ENOUGH MOISTURE FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP...JUST NOT AS MUCH AS WE HAVE
OBSERVED RECENTLY...IN ADDITION...THE UPPER TROUGH IS EXPECTED TO
LIFT NORTH...LEAVING LESS INSTABILITY OVER THE LOCAL AREA. AS OF
NOW...FRIDAY LOOKS LIKE IT WILL BE A PRETTY WARM DAY.

THE WEEKEND AND THE UPCOMING WEEK LOOKS LIKE THE OVERALL PATTERN
WILL BE ONE OF LIGHT E-SE WINDS AND LOWER THAN NORMAL MOISTURE.
THIS SHOULD LIMIT THE SHOWER AND THUNDERSTORM DEVELOPMENT TO A FEW
AREAS WHEN COMBINED WITH THE LOCAL EFFECTS...HOWEVER WITH THE
DRIER AIR MOVING IN AND THE WIND FLOW...THE TEMPERATURES COULD
RISE INTO THE LOW 90S IF THE FORECAST MODELS WERE TO VERIFY. THIS
IS STILL A BIT OUT TO BE TOO CONFIDENT BUT THE MODEL TREND IS TO
BE DRIER AND WARMER THIS UPCOMING WEEKEND INTO EARLY NEXT WEEK.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL TAF SITES IN THE MORNING HOURS
WITH VCSH POSSIBLE AT THE USVI AND LEEWARD TERMINALS AS WELL AS JSJ.
AFTER 23/16Z...MVFR OR EVEN IFR CONDS AT JMZ/JBQ AND POSSIBLY JSJ IN
SHRA/TSRA. WX CONDS IMPROVING AFTER 23/23Z. LOW LVL WINDS FROM SE AT
10 TO 15 KNOTS WITH SOME SEA BREEZE VARIATIONS.

&&

.MARINE...SEAS ARE EXPECTED TO REMAIN FAIRLY TRANQUIL FOR THE NEXT
SEVERAL DAYS. FOR TODAY WE EXPECT WINDS AT AROUND 10 KNOTS..MAYBE
UP TO 15 KNOTS AND SEAS OF 4 FEET OR LESS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 80 88 80 / 30 20 20 20
STT 84 83 83 83 / 30 40 30 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
258 PM AST WED SEP 23 2015

.SYNOPSIS... UPPER TROUGH IS STILL TO THE NORTH OF THE LOCAL AREA
BUT IT IS EXPECTED TO SLOWLY LIFT NORTH BY FRIDAY. SURFACE HIGH
PRESSURE IN THE NORTH ATLANTIC IS EXPECTED TO SLOWLY BE DISPLACED
TO THE EAST AS A SURFACE LOW MOVES ACROSS THE NORTHWESTERN
ATLANTIC AND INTO THE NORTH CENTRAL ATLANTIC BY THURSDAY. SURFACE
LOW PRESSURES ACROSS THE WESTERN ATLANTIC AND WESTERN CARIBBEAN
WILL KEEP A LIGHT TO MODERATE EAST SOUTHEAST WIND FLOW FOR THE
NEXT FEW DAYS.

&&

.DISCUSSION...NUMEROUS SHOWERS WITH SCATTERED THUNDERSTORMS
DEVELOPED THIS AFTERNOON ACROSS THE NORTHERN HALF OF PUERTO RICO.
VERY HEAVY RAINFALL WITH EXCESSIVE LIGHTNING WERE OBSERVED OVER
THIS AREA. THIS GENERAL WEATHER PATTERN IS NOT EXPECTED TO
CHANGE MUCH UNTIL THURSDAY. HOWEVER...SLIGHTLY DRIER AIR WILL MOVE
ACROSS THE LOCAL ISLANDS ON FRIDAY...WHICH SHOULD LIMIT SOMEWHAT
THE AMOUNT OF SHOWERS AND THUNDERSTORMS THAT DEVELOP COMPARED TO
WHAT WE HAVE OBSERVED THE PAST FEW DAYS. EVEN MORE DRIER AIR WILL
MOVE ACROSS THE LOCAL AREA DURING THE WEEKEND AND EARLY NEXT WEEK.
AFTER THURSDAY THIS WEEK...NO SIGNIFICANT WEATHER EVENT IS
EXPECTED TO HAVE A LOCAL IMPACT FOR THE NEXT SEVERAL DAYS.

&&

.AVIATION...PERIODS OF MVFR OR EVEN IFR CONDITIONS EXPECTED TO
CONTINUE IN SHRA/TSRA ACROSS WESTERN AND INTERIOR PUERTO RICO WITH
MOUNTAIN OBSCD AFFECTING MOSTLY TJMZ AND TJBQ UNTIL 23/22Z. MOSTLY
VFR CONDITIONS EXPECTED AFTER 23/23Z ACROSS THE LOCAL FLYING AREA.
LATEST TJSJ SOUNDING INDICATED A LIGHT AND VARIABLE WIND FLOW ALL
THE WAY FROM THE SURFACE TO AROUND 18K FEET...BECOMING WESTERLY AND
STRONGER ALOFT.

&&

.MARINE...SEAS UP TO 4 FEET AND WINDS UP TO 15 KNOTS ARE EXPECTED
OVER THE COASTAL WATERS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 88 80 87 / 20 20 20 30
STT 83 83 83 83 / 40 30 20 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
544 AM AST THU SEP 24 2015

.SYNOPSIS...AT MID AND UPPER LEVELS...THE LOW ABOUT 500 MILES
NORTH OF CABO SAN JUAN WILL WOBBLE OVER THE AREA AND THEN COME TO
WITHIN 250 MILES OF PUERTO RICO ON MONDAY. EARLY NEXT WEEK IT WILL
SLIDE WEST AND THEN INTO HISPANIOLA BY WEDNESDAY...LEAVING THE
LOCAL AREA UNDER THE TROUGH. A RIDGE WILL BUILD OVER AND NORTH OF
COLOMBIA LATE NEXT WEEK. MID LEVELS WILL BECOME DRIER TODAY BUT
MOISTURE WILL REMAIN VERY CLOSE BY TO THE NORTH AND BRUSH THE
AREA AGAIN MONDAY AND TUESDAY.

AT LOWER LEVELS...TROPICAL STORM IDA CONTINUES IN THE TROPICAL
ATLANTIC INTO THE WEEKEND. IT IS EXPECTED TO DRIFT WEST LATER NEXT
WEEK IN A MUCH WEAKER CONDITION. HIGH PRESSURE OVER CANADA WILL
MOVE INTO THE WESTERN ATLANTIC OVER THE WEEKEND AND INTO THE
CENTRAL ATLANTIC BY LATE NEXT WEEK. WITH QUASI PERMANENT LOW
PRESSURE IN THE SOUTHWEST CARIBBEAN...EAST SOUTHEAST TO SOUTHEAST
TRADE WIND FLOW WILL CONTINUE THROUGH THE NEXT 10 DAYS.

&&

.DISCUSSION...SHOWERS CONTINUED LATE INTO THE NIGHT IN THE
ATLANTIC WATERS AND THUNDERSTORMS WITH THEM. JUST A FEW HOURS
BEFORE DAWN SHOWERS DEVELOPED WEST OF AGUADA AND NORTH OF MONA
ISLAND AND WERE ALSO STRONG ENOUGH TO GENERATE A FEW LIGHTNING
STRIKES.

LOW PRESSURE AT UPPER LEVELS WILL CONTINUE TO INFLUENCE THE
PATTERN TODAY THROUGH SATURDAY WITH COOL TEMPERATURES IN ITS CORE
BRINGING INSTABILITY TO THE LOCAL AREA. THE GFS WAS ACTUALLY
FORECASTING A MINUS 9 LIFTED INDEX WITH RESPECT TO THE SURFACE
BASED PARCEL AND A MINUS 7 IN THE FORECAST PARCEL. THIS IS EVEN
MORE UNSTABLE THAN IT FORECAST YESTERDAY. IF IT WERE NOT FOR THE
FACT THAT MID LEVELS ARE FORECAST TO DRY SOMEWHAT...WOULD EXPECT
ACTIVITY SIMILAR TO YESTERDAY. EXAMINING THE MIMIC PRODUCT HOWEVER
LEAVES MORE ROOM TO DOUBT THAT SIGNIFICANT DRYING WILL ACTUALLY
OCCUR AS BANDING AROUND THE UPPER LEVEL LOW CONTINUES VERY CLOSE
TO PUERTO RICO AND THE U.S. VIRGIN ISLANDS. WITH SUCH GOOD
INSTABILITY EXPECTED IT SEEMED BEST TO KEEP POPS AROUND 80 FOR THE
NORTHWEST SECTION OF PUERTO RICO. THE UPPER LEVEL LOW WILL ALMOST
INSURE THAT FREQUENT LIGHTNING STRIKES WILL ALSO BE SEEN AROUND
THE AREA. EVEN AREAS NEAR THE COAST AND AROUND AND SOUTH OF SAN
JUAN ONE COULD SEE A THUNDERSTORM TODAY SINCE INSTABILITY IS
EXPECTED TO BE GREATER TODAY THAN YESTERDAY. MOISTURE WOULD SEEM
TO SUGGEST THAT ACTIVITY WILL DIMINISH OVER THE WEEKEND. BUT WITH
THE UPPER LEVEL LOW ACTUALLY APPROACHING THE AREA OVER THE
WEEKEND...SHOWERS ACCOMPANIED BY THUNDERSTORMS WITH HEAVY RAIN ARE
LIKELY EACH AFTERNOON.

TEMPERATURES WILL ALSO CONTINUE IN A SIMILAR MANNER FOR THE NEXT
WEEK OR SO. THE GFS HAS BEEN RUNNING TOO HIGH ON THE NORTH COAST
AS SEA BREEZES HAVE TEMPERED HIGH TEMPERATURES THERE AND KEPT THEM
GENERALLY BELOW 90 DEGREES NEAR SHORE. ALSO HEAVY CLOUD COVER
FROM VIGOROUS THUNDERSTORMS DURING THE AFTERNOON HAVE KEPT THE
EAST SOUTHEAST TO SOUTHEAST FLOW FROM HAVING ITS USUAL WARMING
EFFECT. THEREFORE WILL CONTINUE WITH TEMPERATURES BELOW 90 FOR THE
SAN JUAN AREA AND NEAR 90 JUST INLAND...INCLUDING THE PONCE AREA
WHICH IS ALSO BEING TEMPERED BY PERSISTENT AND MORE DIRECT SEA
BREEZES.

THE GFS IS INDICATING THAT MOISTURE WILL INCREASE MONDAY AND
TUESDAY TO NEAR THE LEVELS TO BE EXPERIENCED TODAY. PLUS THE GFS
IS FORECASTING TEMPERATURES AT 500 MB TO BE AROUND MINUS 8
YIELDING A VERY UNSTABLE ATMOSPHERE. IT IS DIFFICULT TO SEE HOW
THIS WILL NOT PRODUCE VERY HEAVY RAIN IN AREAS WITH SOME LOCAL
FLOODING AND THE POSSIBILITY OF SOME THUNDERSTORMS APPROACHING
SEVERE LEVELS. FORTUNATELY WINDS AT MID LEVELS ARE EXPECTED TO BE
15 KNOTS OR LESS MONDAY AND TUESDAY WHEN THE GREATEST INSTABILITY
IS FORECAST TO OCCUR. SO EXPECT ONLY VERY HEAVY RAINFALL AND SOME
GUSTY WINDS THEN. SMALL HAIL REMAINS A POSSIBILITY WITH WET BULB
ZERO LEVELS BELOW 12 THOUSAND FEET BOTH MONDAY AND TUESDAY.
AFTERNOON SHOWERS AND THUNDERSTORMS SHOULD CONTINUE...ALBEIT
SOMEWHAT WEAKER...THROUGH THE REST OF NEXT WEEK WHEN THE UPPER
LEVEL LOW MOVES THROUGH HISPANIOLA.

THUNDERSTORMS WILL TEND TO FORM OFFSHORE OVER THE ATLANTIC WATERS
EACH EVENING FROM TODAY INTO NEXT WEEK AS ACTIVITY OVER PUERTO
RICO DURING THE AFTERNOONS MOVES NORTHWEST WITH THE LOW LEVEL
FLOW AND IS ENHANCED BY THE HIGH SURFACE MOISTURE AND STRONG
INSTABILITY.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL TAF SITES IN THE MORNING
HOURS. VCSH POSSIBLE IN AND AROUND TJPS...USVI AND LEEWARD
TERMINALS. MOUNTAIN OBSC OVER THE CORDILLERA CENTRAL WITH LOW
CEILING IN SHRA/TSRA EXPECTED ONCE AGAIN AFT 24/16Z ACROSS THE WEST
AND NORTH PR. AS A RESULT...MVFR CONDS POSSIBLE AT TJBQ...TJMZ AND
TJSJ THRU 24/21Z. SFC WINDS ARE EXPECTED TO PREVAIL FM SE AT 10 TO
15 KNOTS...WITH SEA BREEZE VARIATIONS AND HIGHER GUSTS IN AND NEAR
SHRA/TSRA.

&&

.MARINE...MARINE CONDITIONS CHANGE VERY LITTLE DURING THE NEXT 7
TO 10 DAYS. SEAS ARE EXPECTED TO REMAIN AT OR BELOW 4 FEET WITH
WINDS RARELY EXCEEDING 15 KNOTS EXCEPT NEAR THUNDERSTORMS. SMALL
CRAFT ADVISORIES ARE NOT ANTICIPATED DURING THE NEXT 10 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 80 89 79 / 50 20 40 20
STT 87 80 88 80 / 30 20 10 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
206 PM AST THU SEP 24 2015

.SYNOPSIS...UPPER LEVEL TROUGH WILL REMAIN NORTH OF THE REGION
TONIGHT. THIS TROUGH IS EXPECTED TO AMPLIFY ACROSS THE REGION
FRIDAY AND DURING THE UPCOMING WEEKEND...AND MEANDER CLOSE TO THE
REGION UNTIL THE MIDDLE OF THE WEEK. DRY AIR AT MID LEVELS WILL
MOVE OVER THE REGION BY THE UPCOMING WEEKEND.

&&

.DISCUSSION...THE DOPPLER WEATHER RADAR INDICATED ISOLATED TO
SCATTERED SHOWERS MOSTLY ACROSS THE SURROUNDING COASTAL WATERS
LATE THIS MORNING. HOWEVER...EARLY THIS AFTERNOON...SHOWERS AND
THUNDERSTORMS STARTED TO DEVELOP ALONG CORDILLERA CENTRAL. THIS
ACTIVITY MOVED SLOWLY TO THE NORTH AND NORTHWEST AFFECTING THE
NORTH CENTRAL AND NORTHWESTERN MUNICIPALITIES OF PUERTO BY MID
AFTERNOON. THIS ACTIVITY IS EXPECTED TO DISSIPATES AROUND SUNSET.
THE UPPER TROUGH ACROSS THE CENTRAL ATLANTIC NORTH OF PUERTO
RICO...IS EXPECTED TO AMPLIFY OVER THE REGION FRIDAY AND DURING
THE UPCOMING WEEKEND AND THEN MEANDER ACROSS CLOSE TO THE LOCAL
ISLANDS UNTIL MID WEEK NEXT WEEK. THIS FEATURE WILL CONTINUE TO
PROMOTE THE DEVELOPMENT OF AFTERNOON SHOWERS AND THUNDERSTORMS
ACROSS WESTERN AND INTERIOR PUERTO RICO FOE THE NEXT SEVERAL DAYS.
HOWEVER...DRIER AIR IN THE MIDDLE LEVELS OF THE ATMOSPHERE WILL
ACT TO LIMIT THE THUNDERSTORMS DEVELOPMENT FOR THE UPCOMING
WEEKEND. IN FACTS...PWAT VALUES WILL REMAIN CLOSE TO 2.0 INCHES
TODAY...BUT WILL DECREASE TO AROUND 1.70 INCHES FRIDAY DECREASING
EVEN MORE BY THE WEEKEND. AN INCREASING IN INSTABILITY IS EXPECTED
EARLY NEXT WEEK.

&&

.AVIATION...MOUNTAIN OBSC OVER THE CORDILLERA CENTRAL WITH LOW
CEILING IN SHRA/TSRA EXPECTED TO CONTINUE UNTIL 24/22Z ACROSS THE
WEST AND NORTH PR. AS A RESULT...MVFR CONDITIONS WILL CONTINUE AT
TJBQ AND TJMZ THRU 24/22Z. MOSTLY VFR CONDITIONS EXPECTED ACROSS
THE LOCAL FLYING AREA AFTER 24/23Z. SFC WINDS ARE EXPECTED TO
PREVAIL FROM SE AT AROUND 10 TONIGHT.

&&

.MARINE...MARINE CONDITIONS CHANGE VERY LITTLE DURING THE NEXT 7
TO 10 DAYS. SEAS ARE EXPECTED TO REMAIN AT OR BELOW 4 FEET WITH
WINDS RARELY EXCEEDING 15 KNOTS EXCEPT NEAR THUNDERSTORMS. SMALL
CRAFT ADVISORIES ARE NOT ANTICIPATED DURING THE NEXT 10 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 89 79 89 / 20 40 20 30
STT 80 88 80 88 / 20 10 20 10

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
529 AM AST FRI SEP 25 2015

.SYNOPSIS...AT UPPER LEVELS...LOW PRESSURE ALMOST 600 MILES NORTH
OF ARECIBO PUERTO RICO WILL MOVE TO JUST NORTHEAST OF THE LEEWARD
ISLANDS BY MONDAY AND THEN TO PUERTO RICO ON TUESDAY BEFORE
PASSING SOUTH OF HISPANIOLA MID WEEK NEXT WEEK. FROM WEDNESDAY
ON...A TROUGH WILL EXTEND FROM THE CENTRAL ATLANTIC TO JUST SOUTH
OF PUERTO RICO AND THE U.S VIRGIN ISLANDS TO THIS LOW THROUGH THE
END OF NEXT WEEK.

AT MID LEVELS...GENERALLY HIGH PRESSURE WITH WEAK GRADIENTS AND
TRANSITORY LOWS WILL PERSIST THROUGH THE PERIOD. MID LEVELS WILL
BECOME INCREASINGLY DRY THROUGH SUNDAY NIGHT WITH ONLY WEAK
PATCHES OF MOISTURE DURING THE WEEK.

AT LOWER LEVELS...HIGH PRESSURE IN THE WESTERN ATLANTIC AND LOW
PRESSURE IN THE SOUTHWESTERN CARIBBEAN WILL MAINTAIN GENTLE TO
MODERATE EAST SOUTHEAST TRADE WIND FLOW ACROSS THE AREA THROUGH
THE END OF NEXT WEEK. THE REMNANTS OF TROPICAL STORM IDA WILL BE
FORCED WESTWARD SO AS TO PASS THROUGH THE ATLANTIC WATERS JUST
NORTH OF THE FORECAST AREA THURSDAY NIGHT WITH LITTLE OR NOT
DEFINITION.

&&

.DISCUSSION...A FEW SHOWERS DRIFTED ACROSS THE LOCAL WATERS FROM
THE EAST SOUTHEAST...BUT LITTLE ACCUMULATIONS WERE EXPERIENCED
OVER LAND WHERE A FEW OF THESE SHOWERS CROSSED THE SOUTHEAST COAST
OF PUERTO RICO.

MOISTURE WILL BEGIN TO DECREASE TODAY THROUGH SUNDAY...BUT THE
LIFTED INDEX WILL DECREASE ERRATICALLY TO A MINIMUM ON MONDAY
AFTERNOON. HENCE...ALTHOUGH SHOWER COVERAGE WILL DIMINISH TODAY
THROUGH SUNDAY...SHOWERS THAT DO DEVELOP WILL BE QUITE INTENSE AND
WILL STILL BE ABLE TO PRODUCE URBAN AND SMALL STREAM FLOODING.

SOME MOISTURE RETURNS ON MONDAY AND...WITH STABILITY AT A
MINIMUM...SO THIS COULD BE THE MOST CRITICAL DAY OF THE WEEK.
NEVERTHELESS STRONG THUNDERSTORMS WITH VERY HEAVY RAIN SHOULD BE
VERY LOCALIZED IN WESTERN PUERTO RICO AND PARTS OF THE INTERIOR.
STABILITY RISES AFTER MONDAY. MOISTURE DIMINISHES TUESDAY THROUGH
THURSDAY ALSO SO ACTIVITY WILL DIMINISH IN INTENSITY AND COVERAGE
CONSIDERABLY. SOME MOISTURE AND INSTABILITY RETURNS LATE NEXT
WEEK.

THE GFS IS NOW HAVING DIFFICULTY LOCATING THE WEAK UPPER LOW
DURING THE COURSE OF THE NEXT 7 DAYS. THIS COULD BE AN INDICATION
OF HOW THE LOW IS LOSING SOME INTENSITY IN THE FORECAST. AND MAY
ALSO LESSEN THE INTENSITY OF THE STORMS PREVIOUSLY EXPECTED. THE
EXACT POSITION WILL BE SOMEWHAT CRITICAL...BUT MOISTURE FORECASTS
REMAIN A LITTLE MORE RELIABLE AND HENCE HAVE FAIR CONFIDENCE THAT
STRONG THUNDERSTORMS WITH FREQUENT LIGHTNING AND VERY LOCALIZED
URBAN AND SMALL STREAM FLOODING WILL OCCUR...MAINLY IN WESTERN
PUERTO RICO. A DRYING TREND IS FORESEEN TUESDAY THROUGH THURSDAY.

THE GFS ALSO PAINTS THE LOW FROM TROPICAL DEPRESSION IDA DRIFTING
ACROSS THE ATLANTIC WATERS NORTH OF THE AREA AND WEAKENING.
ALTHOUGH THIS APPEARS FAIRLY STRAIGHT-FORWARD...EXAMINATION OF
THE 850 MB FLOW AND RELATIVE HUMIDITY SHOWS THAT THE CIRCULATION
IS SPLIT BETWEEN TWO CENTERS EARLY NEXT WEEK AND THE MOISTURE
BECOMES SHEARED INTO LONG BANDS THAT BEAR LITTLE RESEMBLANCE TO
THE FORMER CIRCULATION. THE LARGER PICTURE REVEALS THAT SOME WEAK
TROUGHS MOVING IN FROM THE EAST NORTHEAST WILL OBSCURE MOST OF THE
SYSTEM SIGNATURE AND HENCE IT SHOULD PASS WITH LITTLE EFFECT ON
THURSDAY.

MOS CONTINUES TO OVER ESTIMATE THE HIGH TEMPERATURES ON THE NORTH
COAST AND U.S. VIRGIN ISLANDS...BUT EAST SOUTHEAST FLOW HAS ALSO
ALLOWED A LITTLE WARMING...SO HAVE WARMED THE HIGHS SLIGHTLY BUT
STILL LEFT THE FORECAST BELOW GUIDANCE. STRONGLY SHEARED
THUNDERSTORM TOPS ARE STILL PROTECTING MOST OF THE ISLAND FROM
THE FULL EFFECTS OF SOLAR HEATING AND SOUTHEASTERLY FLOW.

&&

.AVIATION...XPCT VFR AT TAF SITES XCP IN SCT AFT SHRA/TSRA TJMZ/TJBQ
WI OBSCD MTNS NW QUARTER PR. SIMILAR CONDS SAT. OTHW ISOLD SHRA
MAINLY OFFSHORE. WIND BLW FL100 VRBL AOB 12 KT THRU SAT.

&&

.MARINE...SOME WEAK SWELL FROM THE NORTH HAS BOOSTED SEAS TO
BETWEEN 4 TO 5 FEET AT THE OUTER BUOY 41043 AND TO BETWEEN 3 TO 4
FEET ON THE NORTH COAST. THIS IS EXPECTED TO DIMINISH OVER THE
WEEKEND. WE CONTINUE IN RELATIVELY TRANQUIL CONDITIONS WITH NO
SMALL CRAFT ADVISORIES EXPECTED FOR THE NEXT 10 DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 79 90 79 / 20 20 10 10
STT 89 80 89 80 / 20 20 10 10

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
333 AM AST SAT SEP 26 2015

.DISCUSSION...WIND FLOW FROM 500 MB AND BELOW HAS RESEMBLED A
MID-LATITUDE BLOCKING PATTERN WITH LOW PRESSURE NORTHEAST OF
BAHAMAS AND REMNANTS OF IDA STILL EAST OF 50W AND A RIDGE IN
BETWEEN. THE PATTERN WILL CONTINUE TO VERY SLOWLY WEAKEN WHILE THE
RIDGE MIGRATES SLOWLY ACROSS PR NEXT COUPLE OF DAYS. MOISTURE WILL
REMAIN SLIGHTLY BELOW SEASONAL LEVELS FOR USVI/PR THROUGH SUNDAY.
GFS AND ECMWF AGREE IN PUSHING THE BAND OF HIGHER PRECIPITABLE
WATER CURRENTLY N-NE OF LEEWARD ISLANDS SLOWLY WEST BUT FOLLOWING
THE RIDGE INTO USVI/PR EARLY MON. SO IN SPITE OF FAIR INSTABILITY
DO NOT EXPECT CONVECTION OVER PR TO BE MUCH DIFFERENT ON SAT/SUN
THAN IT WAS FRI. SO REDUCED THE CHANCE OF SHOWERS SLIGHTLY THROUGH
THE WEEKEND.

SOUTHERLY FLOW HELD OFF THE SEA BREEZE AT SAN JUAN FRI WHICH
CAUSED THE TEMPERATURE AT AIRPORT TO REACH 95. THIS FLOW IS ONLY
A LITTLE WEAKER TODAY AND MAV GUIDANCE GAVE 93 TODAY AND 92 ON
SUNDAY...LOOKED LIKE THE BETTER BET VS. MET GUIDANCE AT 91 BOTH
DAYS. BUT TEMPERATURES ARE EXPECTED TO REACH PRETTY TOASTY VALUES
AGAIN TODAY WHERE NO SEA BREEZE EXPECTED.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL TAF SITES THRU THE OVERNIGHT
HOURS WITH SOME VCSH POSSIBLE IN AND AROUND THE LEEWARD TERMINALS.
SHRA/TSRA EXPECTED ONCE AGAIN AFT 26/17Z ACROSS THE WEST AND NORTH
PR. AS A RESULT...BRIEF PDS OF MVFR CONDS POSSIBLE AT TJBQ AND TJMZ
THRU 26/21Z. WINDS LIGHT AND VARIABLE OVRNGHT...BCMG E-SE BY 26/14Z
AT 10 TO 15 KNOTS...WITH SEA BREEZE VARIATIONS AND HIGHER GUSTS IN
AND NEAR SHRA/TSRA.

&&

.MARINE...BOTH GFS AND ECMWF PUSH IDA REMNANTS WESTWARD AND STILL
BE NORTH OF USVI/PR BY MIDDLE/LATE NEXT WEEK. THIS WILL PREVENT
HIGH PRESSURE FROM FORMING THAT WOULD INCREASE THE TRADES BEYOND
GENTLE/MODERATE ACROSS THE ISLANDS. HOWEVER A MINOR SWELL (4-6
FT) WILL REACH THE ATLANTIC WATERS FROM THE REMNANTS AROUND MID-
WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 93 80 92 78 / 20 10 20 20
STT 89 80 90 80 / 20 10 10 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
348 AM AST SUN SEP 27 2015

.DISCUSSION...TWO AREAS OF DRY AIR ARE ENCROACHING ON USVI/PR. ONE
IS CURRENTLY OVER THE EASTERN CARIBBEAN SEA AND THE OTHER A LARGE
AREA DRAWN SOUTH BY TROPICAL DEPRESSION IDA BETWEEN 60W AND 50W.
INBETWEEN THE DRY AREAS IS A NARROW BAND OF MOISTURE NEAR AND TO
THE NORTH OF LEEWARD ISLANDS AND MOVING SOUTHWEST. BUT MODELS DRY
THAT OUT SOMEWHAT BEFORE REACHING THE LOCAL AREA. GFS NO LONGER
SHOWS USVI/PR WITH MORE THAN A SEASONAL LEVEL OF PRECIPITABLE
WATER AT ANYTIME THIS WEEK THOUGH GFS AND ECMWF STILL AGREE IN
PUSHING THE BEST VALUES ACROSS ON MON/TUE.

SCATTERED SHOWERS AND A LITTLE THUNDER CAN BE EXPECTED OVER INTERIOR
TO WESTERN PR THIS AFTERNOON...SIMILAR TO LAST COUPLE OF DAYS AND
PROBABLY SOMEWHAT BETTER ON MON. ELSEWHERE CANNOT SEE MUCH MORE
THAN ISOLATED SHOWERS THROUGH AT LEAST MID-WEEK.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL TAF SITES OVERNIGHT WITH SOME
VCSH POSSIBLE. SHRA/TSRA EXPECTED ONCE AGAIN AFT 27/16Z ACROSS WEST
AND NORTH PR. AS A RESULT...BRIEF PDS OF MVFR CONDS POSSIBLE AT TJBQ
AND TJMZ THRU 27/20Z. WINDS LIGHT AND VARIABLE OVRNGHT...BCMG E-SE
BY 27/14Z AT 10 TO 15 KNOTS...WITH SEA BREEZE VARIATIONS AND HIGHER
GUSTS IN AND NEAR SHRA/TSRA.

&&

.MARINE...THE CONTINUED PRESENCE OF IDA...CROSSING 50W TODAY AND
ANOTHER LOW JUST NORTHEAST OF THE BAHAMAS WILL PREVENT HIGH
PRESSURE FROM DEVELOPING AND CAUSING THE USUAL TRADES...PERHAPS
ALL OF THIS WEEK. SOME UNUSUAL ALBEIT WEAK WIND FLOWS WILL INSTEAD
OCCUR. SEAS WILL ALSO CONTINUE LOW THROUGH AT LEAST MON THEN A 4
FT SWELL FROM IDA WILL ENTER ON TUE/WED FOR THE LOCAL ATLANTIC
COASTAL WATERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 92 79 91 78 / 20 20 20 30
STT 89 80 90 78 / 10 20 20 30