Caribbean - Central America Weather

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
403 PM AST WED MAY 20 2015

.SYNOPSIS...BROAD UPPER TROUGH CONTINUED NORTH OF THE REGION
WITH SEVERAL SHORT WAVE PERTUBATIONS PROPAGATING EASTWARD ACROSS
THE WEST AND CENTRAL ATLANTIC. RIDGE OF HIGH PRESSURE EXTENDS
NORTHWARDS ACROSS THE FORECAST AREA FROM THE EASTERN CARIBBEAN.
THIS OVERALL PATTERN WILL MAINTAIN A WESTERLY WIND FLOW ALOFT
THROUGH THE END OF THE WEEK. SURFACE HIGH PRESSURE RIDGE EXTENDS
OVER THE SOUTHWEST ATLANTIC...WHILE A WEAK TROUGH CONTINUED TO
SHIFT WESTWARD ACROSS THE EASTERN CARIBBEAN.

&&

.DISCUSSION...THE SURGE OF MOISTURE ACCOMPANYING THE SURFACE TROUGH
MOVING ACROSS THE REGION...ALONG WITH LOCAL AND DIURNAL EFFECTS
AND GOOD VENTILATION ALOFT...AIDED IN THE CONVECTIVE DEVELOPMENT
TODAY. SOME SHOWERS AND THUNDERSTORM PRODUCED MODERATE TO LOCALLY
HEAVY RAINFALL WITH DANGEROUS CLOUD TO GROUND LIGHTING OVER PARTS
OF THE EAST INTERIOR SECTIONS OF PUERTO RICO AS WELL AS OVER PARTS
OF THE SAN JUAN METRO AREA. THIS LEAD TO URBAN AND SMALL STREAM
FLOODING IN SOME AREAS. SMALL CLUSTERS OF SHOWERS WERE ALSO
OBSERVED IN AND AROUND SOME OF THE U.S. VIRGIN ISLANDS BUT NO
SIGNIFICANT FLOOD PROBLEMS WAS OBSERVED OR REPORTED. EXPECT THE
SHOWER AND THUNDERSTORM ACTIVITY TO SLOWLY DIMINISH OVER LAND JUST
AFTER SUNSET WITH A GRADUAL CLEARING OVER LAND THEREAFTER.

DURING THE OVERNIGHT HOURS AND THROUGH THURSDAY...LOW LEVEL MOISTURE
ADVECTION EXPECTED TO GRADUALLY INCREASE OVER THE REGION WITH PRECIPITABLE
WATER APPROACHING TWO INCHES BY THURSDAY AFTERNOON. THE 20/12Z TJSJ
UPPER AIR SOUNDING...AND MIMIC TPW PRODUCT ALSO CONFIRMED INCREASING
LOW LEVEL MOISTURE ADVECTION. LATEST GFS MODEL GUIDANCE INITIALIZED
WELL AND CONTINUE TO SUGGEST GOOD POTENTIAL FOR ADDITIONAL CONVECTIVE
ACTIVITY ACROSS THE ISLANDS AND PORTIONS OF THE COASTAL WATERS ON
THURSDAY. UPPER LEVEL DIVERGENCE OVER THE AREA BY THURSDAY AFTERNOON
ALONG WITH LOCAL AND DIURNAL EFFECTS WILL PRODUCE PERIODS OF ENHANCED
AFTERNOON CONVECTION. THE PREVAILING EASTERLIES WILL ASLO BRING PERIODS
OF SHOWERS TO PARTS OF THE EAST COASTAL SECTIONS OF THE ISLANDS...
ESPECIALLY EASTERN PUERTO RICO DURING THE EARLY MORNING HOURS.

A GRADUAL DRYING TREND IS SO FAR FORECAST BY FRIDAY AND INTO THE
WEEKEND. MID TO UPPER LEVEL HIGH PRESSURE RIDGE WILL BUILD ACROSS
THE REGION AND AID IN SUPPRESSING SIGNIFICANT CONVECTION. IN
ADDITION...MODEL GUIDANCE CONTINUED TO SUGGEST THAT THE SAHARAN
AIR LAYER WILL SPREAD ACROSS THE REGION FROM THE TROPICAL ATLANTIC
OVER THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK.

&&

.AVIATION...SHRA/TSRA SLOWLY DIMINISHING FOR THE REST OF THE
AFTERNOON INTO THE EVENING. TJMZ AND POSSIBLY TJBQ SHOULD OBSERVE
LIGHT RAIN UNTIL ABOUT 20/23Z. MOSTLY VFR CONDS EXPECTED OVERNIGHT
WITH VCSH ACROSS THE LOCAL TERMINALS EXCEPT TJMZ. WINDS WILL BE
LIGHT AND EASTERLY OVERNIGHT...STRENGTHENING AFTER 21/12Z TO ABOUT
10 TO 15 KTS FROM THE EAST SOUTHEAST WITH SEA BREEZE VARIATIONS.
SHRA/TSRA DEVELOPMENT EXPECTED AGAIN AFTER 21/16Z WHICH WILL LIKELY
AFFECT TJSJ/TJBQ/TJMZ.

&&

.MARINE...WINDS AND SEAS CONTINUED AT 10 TO 15 KNOTS AND 4 FEET
OR LESS RESPECTIVELY. EXPECT FAIRLY TRANQUIL SEAS TO CONTINUE
THROUGH THE END OF THE WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 89 78 90 / 30 40 40 20
STT 77 86 78 87 / 50 50 40 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
410 AM AST THU MAY 21 2015

.DISCUSSION...MODELS...ESPECIALLY GFS...ARE STILL DOWNPLAYING THE
AMOUNT OF PRECIPITABLE WATER WE HAVE ACROSS THE AREA AND IS
PROBABLY STILL ABOUT 2 INCHES EVEN AT SAN JUAN AND SLIGHTLY MORE
AT THE WEST END OF PR. THE BEST STREAM OF MOISTURE IS SLIGHTLY NORTH
AND WEST OF THE ISLAND AND WILL GRADUALLY MOVE FARTHER NORTHWEST
AS GFS INDICATES. THERE IS ENOUGH MOISTURE FOR ANOTHER ROUND OF
HEAVY SHOWERS THIS AFTERNOON BUT WILL BE MORE LIKELY LIMITED TO
WESTERN PARTS THIS TIME WITH DRIER AIR GRADUALLY APPROACHING FROM
THE EAST.

THE MOISTURE STREAM WILL NOT MOVE VERY FAR NORTHWEST BUT AN
APPROACHING CUTOFF LOW FROM THE NORTHEAST WILL DRY US OUT
SOMEWHAT EARLY NEXT WEEK.

&&

.AVIATION...MOSTLY VFR CONDS EXPECTED THIS MORNING WITH VCSH ACROSS
THE LEEWARD AND USVI TERMINALS. AFTERNOON CONVECTION WILL PRODUCE
BRIEF MVFR/IFR CONDS ACROSS TJBQ...TJMZ AND POSSIBLY TJSJ BETWEEN 18-
21Z. MOUNTAIN OBSCURATIONS LIKELY ALONG THE CORDILLERA CENTRAL OF
PR. LLVL WINDS WILL PREVAIL FM THE ESE AT 10-15 KT WITH HIGHER GUST
NEAR TSRA. WX CONDS WILL IMPROVE LATE THU INTO FRI.

&&

.MARINE...NORTH OF THE LOCAL ISLANDS AT ABOUT 27N HIGH PRESSURE IS
MERGING EASTWARD AND INTO A LARGER RIDGE IN THE CENTRAL ATLANTIC.
THE RIDGE WILL STILL EXTEND BACK TOWARDS THE WEST AND CAUSE THE
TRADE WINDS TO BECOME A LITTLE STRONGER OVER THE WEEKEND...BUT
WAVES WILL STILL NOT BUILD TO MORE THAN 5 FEET ACROSS THE AREA.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 77 90 78 / 40 40 20 20
STT 86 79 87 79 / 50 40 30 30

[cycloneye]

AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
300 PM AST THU MAY 21 2015

.SYNOPSIS...STRONG SURFACE HIGH PRESSURE ACROSS THE NORTH CENTRAL
ATLANTIC IS KEEPING THE LOCAL AREA UNDER AN EAST SOUTHEAST WIND
FLOW FOR THE NEXT FEW DAYS. UPPER LOW TO THE NORTH OF THE LOCAL
ISLANDS WILL MOVE EAST DURING THE NEXT FEW DAYS. AVAILABLE
MOISTURE IS SLOWLY DECREASING WHILE SAHARAN DUST IS MOVING IN.

&&

.DISCUSSION...MID TO HIGH CLOUDS DOMINATED OVER THE LOCAL AREA
TODAY...WHICH LIMITED CONVECTION SIGNIFICANTLY TODAY. IN
ADDITION...THERE WAS DRIER AIR MOVING IN ALONG WITH SOME SAHARAN
DUST. MODEL GUIDANCE AS WELL AS OBSERVATIONS FROM THE MIMIC AND
SATELLITE IMAGERY SUGGESTS THAT THE DRIER AIR IS IN FACT MOVING IN
AND EVEN MORE SAHARAN DUST IS EXPECTED TO MOVE IN ACCORDING TO THE
NAAPS AEROSOL MODEL.

LATEST GUIDANCE SUGGESTS THAT AVAILABLE MOISTURE WILL REMAIN
PRETTY CONSISTENT WITH ABOUT 1.6 INCHES OF PRECIPITABLE WATER
THROUGH THE WEEKEND THEN MAYBE DECREASING A BIT MORE IN THE EARLY
PART OF NEXT WEEK. NAAPS AEROSOL MODEL HAS QUITE A LARGE AREA OF
SAHARAN DUST MOVING IN WHICH SUGGESTS THAT WE SHOULD OBSERVE HAZE
FOR THE NEXT SEVERAL DAYS...WHILE LIMITING CONVECTION IN THE
AFTERNOONS.

TYPICAL AFTERNOON CONVECTION DUE TO DAYTIME HEATING AND LOCAL
EFFECTS ARE EXPECTED FOR THE NEXT FEW DAYS...EXCEPT THAT DUE TO
THE SAHARAN DUST...THE CONVECTION IS EXPECTED TO BE LIMITED.

IN THE VERY LONG RANGE...THE NEXT BIG PULSE OF A SIGNIFICANT
INCREASE IN MOISTURE IS ON FRIDAY OF NEXT WEEK.


&&

.AVIATION...AFTERNOON SHRA ACROSS THE INTERIOR OF PR SHOULD
DISSIPATE BY 21/23Z...LEAVING SCT CLOUDS AT AROUND FL030 AND
BKN AT AROUND FL050-060 UNTIL ABOUT 22/03Z. VCSH EXPECTED ACROSS
THE LOCAL TERMINALS OVERNIGHT AS ISOLD PASSING SHRA MOVE THROUGH
THE LOCAL AREA. WINDS WILL CONTINUE FROM THE ESE WITH SEA BREEZE
VARIATIONS AT ABOUT 10 TO 15 KT...BECOMING LIGHT AND VARIABLE
OVERNIGHT.


&&

.MARINE...WINDS AND SEAS 15 KNOTS OR LESS AND 4 FEET OR LESS
ARE EXPECTED TONIGHT. A SLIGHT INCREASE IN THE EASTERLY TRADE
WINDS EXPECTED ON FRIDAY AND INTO THE UPCOMING WEEKEND.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 77 90 78 89 / 40 20 20 20
STT 79 87 79 88 / 40 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
544 AM AST FRI MAY 22 2015

.SYNOPSIS...LOCAL REGION LIES BETWEEN AN UPPER LEVEL LOW TO THE
NORTH AND A SUBEQUATORIAL RIDGE TO THE SOUTH. THIS UPPER LEVEL
FEATURES HAVE CAUSED THE SUB-TROPICAL JET TO MODULATE OVER THE
LOCAL ISLANDS SINCE EARLY THIS WEEK. MID LEVEL DRY AIR WITH
SAHARAN DUST PARTICLES WILL GRADUALLY SPREAD OVER THE REGION
TODAY AND CONTINUE DURING THE WEEKEND. THIS WILL RESULT HAZY SKIES
AND LIMITED SHOWER ACTIVITY OVER THE NEXT FEW DAYS.

&&

.DISCUSSION...HIGH CLOUDS HAVE MAINTAINED THE LOCAL AREA UNDER
MOSTLY CLOUDY SINCE MIDNIGHT. RADAR OBS SHOWED MOST OF SHOWERS
AFFECTING THE OFFSHORE ATLANTIC WATERS...WITH LITTLE OR NO RAINFALL
OBSERVED OVER LAND AREAS. THE NASA/CIRA LAYER PRECIPITABLE WATER
ANALYSIS BETWEEN 850MB-700MB IS SUGGESTING THAT THE SAHARAN AIR
LAYER HAVE ENTERED INTO THE EASTERN CARIBBEAN. AS THE DAY PROGRESSES...
THIS SAHARAN AIR LAYER WILL SPREAD OVER PR/USVI RESULTING IN HAZY
SKIES AND LOWER VISIBILITIES. THIS DRY AND HOT AIR MASS WILL STRENGTHEN
THE SUBSIDENCE INVERSION ACROSS THE NORTHEAST CARIBBEAN ISLANDS...
SUPPRESSING THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS
THE LOCAL AREA. HI-RES MODEL GUIDANCE ONLY SUGGEST A FEW ISOLATED
SHOWERS OVER NW PUERTO RICO THIS AFTERNOON. THIS DRY PATTERN IS
FORECAST TO CONTINUE THROUGH THE UPCOMING WEEKEND.

FOR EARLY NEXT WEEK...MOISTURE RETURN TO NORMAL LEVELS AND TYPICAL
TRADE WIND PATTERN WILL ESTABLISH ONCE AGAIN ACROSS THE ISLANDS.
BY THE END OF NEXT WEEK...SOME OPERATIONAL MODELS ARE SUGGESTING
MORE ORGANIZED CONVECTION ACROSS THE NORTHEAST CARIBBEAN REGION.

&&

.AVIATION...AIR HAS TURNED QUITE DRY FL050 TO FL200 OVR PR/USVI WI
HIER MOISTURE AND SHRA/ISOLD TSRA CONT THIS MORNING FM HISPANIOLA TO
N OF PR ALG 20N. VFR PR/USVI XCPT LCL MVFR IN SHRA/ISOLD TSRA
XPCTD FRI/SAT AFT WESTERN PR...FEW OBSCD MTN. ISOLD SHRA ELSEWHERE
THRU TONITE. WIND SE 10-20 KT BCMG E 15-25 KT BY 12Z SAT.

&&

.MARINE...WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA
FOR ALL WATERS INTO NEXT WEEK. FOR TODAY...EXPECT WINDS AROUND 15 KNOTS
AND SEAS OF 2-4 FEET. A SLIGHT INCREASE IN THE EASTERLY TRADE WINDS
EXPECTED DURING THE WEEKEND. THIS MAY INCREASE THE SEAS UP TO 5 FEET
ACROSS THE OFFSHORE WATERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 91 79 89 78 / 20 10 20 20
STT 88 79 88 77 / 20 20 20 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
258 PM AST FRI MAY 22 2015

.SYNOPSIS...
ALOFT...THE ISLANDS LIES BETWEEN A TROUGH TO THE NORTH AND A RIDGE
TO THE SOUTH. BY TUESDAY...AN UPPER LEVEL TROUGH WILL BUILD OFF
TO THE NORTHEAST OF THE LOCAL AREA. A MID LEVEL RIDGE WILL MOVE
ACROSS EASTERN CARIBBEAN THROUGH SUNDAY...FOLLOWED BY A MID LEVEL
TROUGH. A SAHARAN AIR LAYER WILL CONTINUE MOVING ACROSS THE
EASTERN CARIBBEAN THROUGHOUT THE WEEKEND.

&&

.DISCUSSION...
LATEST MODEL FORECAST AND OBSERVATIONS ALONG WITH RECENT TJSJ RAOB
DATA CONTINUE TO SUGGEST THE SPREADING OF A SAHARAN AIR LAYER
ACROSS EASTERN CARIBBEAN. ADDITIONALLY...A SUB TROPICAL JET ALOFT
WILL CONTINUE TO PUSH HIGH CLOUDS INTO THE REGION THIS AFTERNOON
AND TONIGHT. THEREFORE...LIMITED CONVECTIVE SHOWER ACTIVITY IS
EXPECTED DURING THAT PERIOD...MOST OF THE ACTIVITY...IF ANY WILL
BE ACROSS THE INTERIOR AND WESTERN SECTIONS OF THE ISLANDS.
MODERATE TRADE WINDS AND HAZY CONDITIONS ARE EXPECTED TO PREVAIL
ACROSS THE LOCAL AREA TODAY. A SIMILAR PATTERN IS EXPECTED
THROUGHOUT THE WEEKEND ACROSS THE LOCAL AREA...WITH NOCTURNAL TRADE
WIND PASSING SHOWERS ACROSS THE EASTERN SECTIONS OF PR...THE USVI
AND THEIR SURROUNDING WATERS...AND AFTERNOON CONVECTION ACROSS
WESTERN PUERTO RICO EACH DAY.

FOR EARLY NEXT WEEK...MOISTURE IS EXPECTED TO INCREASE AND TYPICAL
TRADE WIND PATTERN AND AFTERNOON CONVECTION WITH T-STORMS ACROSS
WESTERN PR WILL ESTABLISH ONCE AGAIN ACROSS THE ISLANDS. THE
OPERATIONAL MODELS CONTINUE TO SUGGEST INCREASING TROPICAL
MOISTURE BY THE LATTER PORTIONS OF THE UPCOMING WEEK.

&&

.AVIATION...VFR CONDS FOR PR/USVI XCPT BRIEF LCL MVFR IN SHRA/ISOLD
TSRA BTW 18Z-22Z TODAY AND SAT MAINLY OVR WRN PR... FEW OBSC MTN TOP
OVR DUE TO SHRA/PSBL -TSRA. SCT-BKN LOW CLD LYRS BTW FL020- FL050.
WND FM SE 10-15 KTS BLO FL200...BCMG FM W ABV AND INCR W/HT MAX WND
65-70 KTS NR FL450. NO SIG WX FCST EN ROUTE BTW ISLANDS EXCPT FOR
SLGT HZ ALFT.

&&

.MARINE...PONCE BUOY IS INDICATING WIND DRIVING WAVES UP TO FIVE
FEET...AMONG THAT...THE LOCAL BUOY NETWORK CONTINUES TO INDICATE
FAIRLY TRANQUIL SEAS OF 5 FEET OR LESS AND WINDS AT 15 TO 20
KNOTS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 76 91 76 88 / 10 20 20 20
STT 78 89 77 87 / 20 20 20 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
548 AM AST SAT MAY 23 2015

.SYNOPSIS...UPPER LEVEL LOW SOUTH OF BERMUDA IS PRESSING AGAINST
THE SUBEQUATORIAL RIDGE OVER NORTHERN SOUTH AMERICA MAINTAINED
THE SUBTROPICAL JET OVER PUERTO RICO. AT MID-LEVEL...A WEAK RIDGE
IS DOMINATING THE EASTERN CARIBBEAN. SURFACE HIGH PRESSURE WILL
EXIT THE EASTERN US TONIGHT AND BUILD OVER THE WESTERN ATLANTIC ON
SUNDAY...THEN BE ABSORBED BY A BROAD HIGH PRESSURE OVER THE
EASTERN ATLANTIC ON MONDAY. DRY AND STABLE AIR MASS WITH SAHARAN
DUST PARTICLES WILL PREVAIL ACROSS THE LOCAL AREA TROUGH EARLY
NEXT WEEK. WETTER PATTERN POSSIBLE BY THE END OF THE MONTH.

&&

.DISCUSSION...SATELLITE LOOPS CONTINUE TO SHOW HIGH CLOUDS MOVING
WESTWARD ACROSS THE LOCAL REGION. RADAR DETECTED VERY SMALL SHOWERS
ACROSS THE REGIONAL WATERS EARLY THIS MORNING. NO MEASURABLE RAIN
WAS OBSERVED OVER THE ISLANDS. FOR THE REST OF THE MEMORIAL WEEKEND...
CONTINUE TO EXPECT DRY AND STABLE CONDITIONS DOMINATING THE LOCAL
ISLANDS. A STRONG SUBSIDENCE INVERSION BETWEEN 850MB-700MB ASSOCIATED
WITH THE SAHARAN AIR LAYER WILL KEEP THE CHANCES OF SHOWERS FOR
TODAY AND SUNDAY FAIRLY LOW. SUSPENDED SAHARAN DUST PARTICLES WILL
CREATE HAZY SKIES AND AREAS OF REDUCED VISIBILITIES. HI-RES MODEL
GUIDANCE ONLY SUGGEST A SHOWER OR TWO IN ISOLATED SPOTS OF WEST
PUERTO RICO THIS AFTERNOON.

FOR EARLY NEXT WEEK...WETTER TRADE WINDS WILL BRING SCATTERED
PASSING SHOWERS TO THE WINDWARD SIDE OF THE ISLANDS AND WILL ALLOW
SOME SHOWER DEVELOPMENT OVER THE INTERIOR AND WEST PR EACH AFTERNOON.
BY THE END OF MAY...OPERATIONAL MODELS ARE SUGGESTING DEEP MOISTURE
ADVECTING OVER PR/USVI IN RESPONSE TO AN AREA OF LOW PRESURE DEVELOPING
NEAR BAHAMAS.

&&

.AVIATION...VFR LIKELY THRU SUN. TIST/TISX ARE APPARENTLY HAVING
FALSE CIGS DUE TO SAHARAN DUST WI IMPVG CONDS XPCTD ON SUN. SCT
SHRA/TSRA WESTERN PR SAT/SUN BUT SLIM CHC MVFR. WIND BLO FL100 E 12-
20 KT INCR 15-25 TDY THEN 12-20 AGAIN ON SUN.

&&

.MARINE...LOCAL AND REGIONAL BUOYS ARE REPORTING SEAS OF 4 FEET
OR LESS WITH WINDS AROUND 15 KNOTS. WINDS AND SEAS WILL REMAIN
BELOW SMALL CRAFT ADVISORY CRITERIA FOR ALL WATERS THROUGH THE END
OF THE MONTH.

&&

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

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
305 PM AST SAT MAY 23 2015

.SYNOPSIS...AT MID AND UPPER LEVELS...THE JET STREAM OVERHEAD AT
UPPER LEVELS...WILL MOVE EAST AND A WEAK TROUGH WILL PASS THROUGH
MONDAY AFTERNOON OR EVENING. LOW PRESSURE WILL CUT OFF OVER THE
WEST CENTRAL ATLANTIC ON MONDAY NIGHT AND MOVE TOWARD THE AREA
WHILE DEEPENING TUESDAY AND TUESDAY NIGHT. THIS LOW WILL FILL
SLOWLY WHILE MOVING WEST STILL ABOUT 825 MILES NORTH OF PUERTO
RICO BY FRIDAY. HIGH PRESSURE WILL RIDGE OVER THE EASTERN
CARIBBEAN OVER THE FOLLOWING WEEKEND.

AT LOWER LEVELS...HIGH PRESSURE OFF THE VIRGINIA COAST WILL MOVE
INTO THE WESTERN ATLANTIC AND TIGHTEN THE GRADIENTS OVER THE LOCAL
AREA. THIS WILL KEEP TRADE WIND FLOW ACTIVE THROUGH THE FIRST
HALF OF THE WEEK. A TROPICAL WAVE NEAR 31 WEST EARLIER TODAY WILL
MOVE INTO THE AREA ON WEDNESDAY WITH SOME INCREASED SHOWER
ACTIVITY. LOW PRESSURE WILL BE GENERATED BY THE APPROACH OF THE
WAVE AND THE UPPER LEVEL LOW...MAINLY ABOVE THE SURFACE NORTH OF
THE LOCAL AREA...AND WILL GENERATE A SWATH OF SOUTHERLY FLOW OVER
THE AREA BEGINNING ON THURSDAY. THIS WOULD PULL CONSIDERABLE
MOISTURE ACROSS THE AREA FRIDAY AND SATURDAY IF IT DEVELOPS IN
THIS MANNER.

&&

.DISCUSSION...MOISTURE CONTINUED TO DEVELOP OVER THE LOCAL AREA
AND SHOWERS AND THUNDERSTORMS DEVELOPED JUST AFTER NOON FROM
GUAYNABO TO DORADO WITH SOME LOCAL URBAN AND SMALL STREAM FLOODING
IN GUAYNABO MUNICIPALITY. THEN STRONG SHOWERS AND THUNDERSTORMS
FORMED OVER THE WESTERN CENTRAL INTERIOR AND COASTAL
SECTIONS...WITH A NUMBER OF AREAS OF HEAVY RAIN NEEDING AN URBAN
AND SMALL STREAM FLOOD ADVISORY. THESE AREAS OF RAIN SHOULD
DISSIPATE AFTER SUNSET OVER LAND LEAVING A FEW SHOWERS...AND
CONTINUE FOR A FEW HOURS MORE OVER THE WATERS TO THE WEST. MORE
MOISTURE WILL MOVE INTO THE LOCAL AREA TONIGHT AND BRING SCATTERED
SHOWERS TO THE LOCAL ATLANTIC WATERS AND EASTERN PUERTO RICO. SOME
SHOWERS ARE ALSO EXPECTED ACROSS THE U.S. VIRGIN ISLANDS
TONIGHT...BUT ACCUMULATIONS SHOULD BE SLIGHT. THIS GENERAL
PATTERN WILL CONTINUE THROUGH THE WEEK WITH ENHANCEMENTS
WEDNESDAY AND THURSDAY DUE TO THE PASSING TROPICAL WAVE. THEN ON
FRIDAY...ACCORDING TO THE CURRENT SOLUTION OF THE
GFS...SIGNIFICANTLY BETTER MOISTURE WITH PRECIPITABLE WATER VALUES
OVER 2 INCHES WILL MOVE INTO THE AREA ON SOUTHERLY FLOW BRINGING
MUCH BETTER CHANCES OF RAIN IN MUCH GREATER QUANTITIES THAN HAD
LATELY.

&&

.AVIATION...SCT SHRA/TSRA OVER THE INTERIOR AND WESTERN PR WILL
CONTINUE AT LEAST THRU 22Z...CREATING MTN TOP OBSCD AND MVFR TO
BRIEF IFR CONDS MAINLY AT JMZ. VFR ELSEWHERE. LAND/SEA BREEZE
VARIATIONS AND EAST WINDS WILL CONTINUE AT 10-20 KT BLO
FL100...LIGHT AND VARIABLE OVERNIGHT AT THE SFC.

&&

.MARINE...WINDS AND SEAS WILL INCREASE SLIGHTLY CAUSING THE
SPREAD OF EXERCISE CAUTION CONDITIONS OVER THE EXPOSED WATERS
SUNDAY. WINDS AND SEAS SHOULD ABATE MID WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 88 77 88 / 30 30 40 40
STT 78 88 78 86 / 30 30 40 40

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
552 AM AST SUN MAY 24 2015

.SYNOPSIS...SURFACE HIGH PRESSURE OFF THE COAST OF VIRGINIA WILL
KEEP THE MODERATE TO LOCALLY FRESH TRADES ACROSS THE LOCAL REGION
THROUGH MIDWEEK. THE AFOREMENTIONED HIGH PRESSURE WILL BE ABSORBED
BY A STRONGER HIGH PRESSURE OVER THE CENTRAL ATLANTIC ON
WEDNESDAY. AT MID TO UPPER LEVELS...TROUGH PATTERN WILL DOMINATE
THE WESTERN ATLANTIC MOST OF THE WEEK. CUT-OFF LOW WILL DEEPEN
JUST NORTH OF PUERTO RICO BETWEEN TUESDAY AND WEDNESDAY...INDUCING
A SURFACE TROUGH/LOW LATER IN THE WEEK. WETTER PATTERN POSSIBLE BY
THE END OF THE WEEK/MONTH.

&&

.DISCUSSION...SATELLITE IMAGERY AND RADAR REFLECTIVITY DATA SHOW
LOW CLOUDS AND ISOLATED TO SCATTERED SHOWERS MOVING WEST ACROSS
THE REGION. ONLY A SHOWER OR TWO MOVE INLAND ACROSS EASTERN PUERTO
RICO SINCE MIDNIGHT. THE SAHARAN DUST ACROSS THE LOCAL AREA WILL
GRADUALLY DECREASE THROUGH MONDAY. PRECIPITABLE WATER WILL DROP
BELOW NORMAL AS THE DAY PROGRESSES LIMITING SOMEWHAT THE SHOWER
COVERAGE ACROSS THE ISLANDS TODAY. ALTHOUGH...MOISTURE WILL
DECREASE TODAY...SHOWERS AND ISOLATED THUNDERSTORMS ARE STILL
POSSIBLE OVER WESTERN PUERTO RICO DURING THE AFTERNOON HOURS...
HOWEVER THE SHOWER COVERAGE SHOULD BE LESS THAN YESTERDAY. THIS
TRADE WIND PATTERN WILL PERSIST THROUGH THURSDAY. MOISTURE WILL
RECOVER ON FRIDAY WHEN A DEEP LAYER LOW ESTABLISH NORTH OF THE
ISLANDS AND A TROPICAL WAVE APPROACHES FROM THE EAST. THE INDUCED
LOW WILL COMBINE WITH A TROPICAL WAVE TO PRODUCE A DEEP SOUTHERLY
FLOW ACROSS THE EASTERN CARIBBEAN. THIS SOUTHERLY FLOW WILL BRING
DEEP TROPICAL MOISTURE INTO THE AREA...ENHANCING THE SHOWER
ACTIVITY ACROSS THE NORTHEAST CARIBBEAN REGION. MODEL SOLUTION
COULD CHANGE FROM RUN TO RUN...THEREFORE WE WILL CONTINUE TO
MONITOR THE MODEL GUIDANCE OVER THE NEXT FEW DAYS TO SEE IF THE
WETTER PATTERN MATERIALIZE BY THE END OF THE WEEK.

&&

.AVIATION...VFR XCP VRY BRF MVFR CIG IN ISOLD SHRA...OR IN SCT
SHRA/TSRA SUN/MON AFT NR TJMZ. TIST/TISX STILL SHOWING OCNL FALSE
CIG DUE SAHARAN DUST...SHUD IMPRV LATE TDY AND BTR AGAIN ON MON.
WIND BLO FL100 E 14-22 KT BCMG 10-18 IN AFT-TONITE AND 8-14 KT MON.

&&

.MARINE...BOATERS SHOULD EXPECT SEAS OF 3-5 FEET AND WINDS BETWEEN
15-20 KTS ACROSS THE REGIONAL WATERS OVER THE NEXT FEW DAYS. SMALL
CRAFT OPERATORS SHOULD EXERCISE CAUTION IN THE NEARSHORE WATERS OF
NORTH AND SOUTH PR THIS AFTERNOON DUE TO WINDS AROUND 20 KT.
ELSEWHERE...RELATIVELY TRANQUIL CONDITIONS WILL PREVAIL THROUGH
TONIGHT.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 77 87 77 / 20 20 20 20
STT 88 78 88 76 / 20 40 40 20

[cycloneye]

A big rain event is forecast for next weekend.Crossing fingers.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
552 AM AST MON MAY 25 2015

.SYNOPSIS...MID TO UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN
ACROSS THE CENTRAL ATLANTIC...WITH ASSOCIATED CUT OFF LOW
MEANDERING NORTH OF LOCAL ISLANDS TUESDAY THROUGH FRIDAY. DEEP
TROPICAL MOISTURE ADVECTION EXPECTED FRIDAY AND INTO THE WEEKEND.
AS CUT OFF LOW WEAKENS EARLY NEXT WEEK...RIDGE PATTERN WILL
BUILD ACROSS THE EASTERN CARIBBEAN.

&&

.DISCUSSION...PARTLY CLOUDY SKIES WERE OBSERVED ACROSS LOCAL
ISLANDS DURING THE OVERNIGHT HOURS. BRIEF SHOWERS WITH LITTLE
TO NO ACCUMULATIONS WERE OBSERVED OVER WINDWARD AREAS. THE
OVERNIGHT LOW TEMPERATURES WERE IN THE MID TO UPPER 70S ACROSS
COASTAL AREAS. THE WIND BECAME LIGHT AND VARIABLE.

ALTHOUGH TROFINNES WILL PREVAIL ACROSS THE AREA MUCH OF THIS
WEEK...MOISTURE WILL REMAIN UNDER 850MB THRU THURSDAY. THEREFORE
LOCAL WEATHER REGIME WILL BE MAINLY DICTATED BY DIURNAL HEATING
AND SEA BREEZES. AS A RESULT...EXPECT SOME TRADE WIND SHOWERS
ACROSS WINDWARD AREAS IN THE MORNING...FOLLOWED BY SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS OVER AND WEST OF THE CORDILLERA
IN THE AFTERNOON MONDAY THRU THURSDAY.

FRIDAY AND INTO THE UPCOMING WEEKEND..A SHARP INCREASE IN TROPICAL
MOISTURE IS EXPECTED AT ALL LEVELS. THIS WILL BRING A BETTER
CHANCE OF SHOWER AND THUNDER ACTIVITY ACROSS LOCAL ISLANDS WITH
SIGNIFICANT RAINFALL ACCUMULATIONS POSSIBLE DURING THE WEEKEND.
STAY TUNED.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED ACROSS ALL TERMINALS
THROUGH AT LEAST 25/16Z. BRIEF MVFR POSSIBLE AT JMZ WITH MTN TOP
OBSCD FROM 25/17Z THROUGH 25/22Z DUE TO POSSIBLE SHRA/TSRA OVER
THE INTERIOR AND WESTERN SECTIONS OF PR. SFC WINDS FROM THE E-NE
AT 10 TO 15 KT...GUSTING UP TO THE LOW 20S AFTER 25/14Z...SEA
BREEZE VARIATIONS DEVELOPING AROUND 25/14Z.

&&

.MARINE...TRANQUIL MARINE CONDITIONS ACROSS LOCAL WATERS WITH SEAS
BELOW 5 FEET AND WINDS 10 TO 15 KNOTS. SEAS AND WINDS EXPECTED TO
INCREASE DE UPCOMING WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 87 78 / 20 30 30 20
STT 88 77 88 77 / 20 30 30 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
250 PM AST MON MAY 25 2015

.SYNOPSIS...AS UPPER LEVEL TROUGH CONTINUES OVER THE CENTRAL
ATLANTIC A CUT-OFF LOW WILL DEVELOP JUST NORTH OF PUERTO RICO TOMORROW
MEANDERING AT LEAST UNTIL FRIDAY...AN INDUCED SURFACE TROUGH WILL
ACCOMPANY THE LOW. AS PATTERN EVOLVES...WINDS WILL TURN MORE
SOUTHERLY PULLING DEEP TROPICAL MOISTURE OVER THE FORECAST AREA
DURING THE WEEKEND.

&&

.DISCUSSION...SUNNY TO PARTLY CLOUDY SKIES PREVAILED DURING MUCH
OF THE DAY ACROSS ALL LOCAL ISLANDS. HOWEVER...SHOWER AND
ISOLATED THUNDERSTORM DEVELOPMENT WAS OBSERVED EARLY IN THE
AFTERNOON ACROSS THE CENTRAL AND WESTERN INTERIOR SECTIONS OF PR.
THIS ACTIVITY WILL CONTINUE AT LEAST UNTIL SUNSET. URBAN AND SMALL
STREAM FLOODING IS POSSIBLE WITH THE HEAVIEST SHOWERS.
OVERNIGHT...AS WINDS SHIFT MORE NORTHEASTERLY...PASSING SHOWERS
ARE EXPECTED ACROSS THE USVI AND THE NORTHEASTERN SECTIONS OF PR.

AT LEAST UNTIL THURSDAY...DIURNAL CONVECTION IS EXPECTED ALONG THE
CORDILLERA CENTRAL AND WESTERN PR WITH STREAMERS FORMING OFF THE
ISLANDS AND BRIEF PASSING SHOWERS OVER THE WINDWARD AREAS DURING
THE NIGHTTIME. AS DEEP SOUTHERLY FLOW ESTABLISHES DUE TO THE
CUT-OFF LOW AND SURFACE TROUGH...A WETTER PATTERN IS EXPECTED
DURING THE END OF WEEK...WITH MODEL GUIDANCE SUGGESTING ABOVE THAN
NORMAL PWAT VALUES ON FRIDAY AFTERNOON AND LASTING THRU NEXT
MONDAY. IN GENERAL...SHOWER AND THUNDERSTORM COVERAGE WILL
INCREASE DURING THE WEEKEND OVER THE ISLANDS.

&&

.AVIATION...VFR EXCEPT BRIEF MVFR POSSIBLE AT TJMZ AND FROM SW
PR TO WITHIN 15 MILES OF TJSJ WITH MTN TOPS OBSCD FROM 25/17Z
THROUGH 25/22Z DUE TO POSSIBLE SHRA/TSRA OVER THE INTERIOR AND
WESTERN SECTIONS OF PR. SFC WINDS FROM THE E-NE AT 10 TO 15
KT...GUSTING UP 24KT TIL 25/23Z. LAND BREEZES DEVELOPING AFT
26/00Z.

&&

.MARINE...NEARSHORE BUOYS ARE INDICATING SEAS OF 2 TO 4 FEET AND
EAST WINDS NEAR 15 KNOTS. SEAS ARE EXPECTED TO CONTINUE BELOW 5
FEET ACROSS THE OFFSHORE WATERS FOR MUCH OF THE WORK WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 87 78 88 / 50 50 20 20
STT 77 88 77 88 / 50 50 20 20

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
543 AM AST TUE MAY 26 2015

.SYNOPSIS...A MID TO UPPER LEVEL TROUGH AND ASSOCIATED LOW WILL
CONTINUE NORTH OF LOCAL ISLANDS THROUGH FRIDAY. THE TROUGH ALOFT
WILL INDUCE A SURFACE TROUGH ACROSS THE AREA...PROMOTING A MOIST
SOUTHEASTERLY WIND FLOW BY THE END OF THE WEEK. AS TROUGH ALOFT
WEAKENS EARLY NEXT WEEK...RIDGE PATTERN WILL BUILD ACROSS THE
EASTERN CARIBBEAN.

&&

.DISCUSSION...PARTLY CLOUDY SKIES PREVAILED ACROSS THE LOCAL
ISLANDS DURING THE OVERNIGHT HOURS...WITH BRIEF PASSING SHOWERS
OBSERVED ACROSS WINDWARD AREAS. THE OVERNIGHT LOW TEMPERATURES
WERE IN THE MID TO UPPER 70S ALONG THE COASTAL AREAS...WITH LIGHT
AND VARIABLE WINDS.

THE LOCAL ISLANDS WILL CONTINUE UNDER THE INFLUENCE OF A MID
TO UPPER LEVEL TROUGH AND ASSOCIATED LOW NORTH OF THE AREA. THIS
FEATURE WILL INDUCE A SURFACE TROUGH ACROSS THE NORTHEASTERN
CARIBBEAN WHICH WILL PROMOTE A MOIST SOUTHEASTERLY WIND FLOW BY
THE END OF THE WEEK. MEANWHILE MOISTURE WILL REMAIN UNDER 850MB
THRU THURSDAY.

EXPECT TRADE WIND SHOWERS ACROSS WINDWARD AREAS AS WELL AS
LOCALLY INDUCED AFTERNOON SHOWERS WITH THUNDERSTORMS OVER AND
WEST OF THE CORDILLERA EACH DAY THRU THURSDAY. FRIDAY AND INTO
THE UPCOMING WEEKEND...A SHARP INCREASE IN TROPICAL MOISTURE IS
EXPECTED AT ALL LEVELS UNDER A SOUTHEASTERLY WIND FLOW WITH
FAVORABLE UPPER LEVEL DYNAMICS. THIS WILL BRING A BETTER CHANCE
OF SHOWER AND THUNDER ACTIVITY ACROSS LOCAL ISLANDS WITH
SIGNIFICANT RAINFALL ACCUMULATIONS POSSIBLE DURING THE WEEKEND.
STAY TUNED.

&&

.AVIATION...VFR CONDITIONS EXPECTED THROUGH 26/17Z WITH SCT SHRA
ACROSS THE LOCAL WATERS THIS MORNING. SOME OF THEM WILL BRIEFLY
AFFECT TJSJ/TIST/TISX/TKPK/TNCM. FOR THE AFTERNOON...BRIEF MVFR
CONDS POSSIBLE AT TJMZ/TJPS WITH MTN TOPS OBSCD FROM 26/17Z THROUGH
26/23Z DUE TO POSSIBLE SHRA/TSRA OVER THE INTERIOR AND WESTERN
SECTIONS OF PR. SFC WINDS UNTIL 26/12Z FROM THE E-NE AT 5 TO 10
KTS...AFT 26/12Z...AT 10 TO 15 KT...WITH SEA BREEZE VARIATIONS...AND
GUSTING UP 25KT TIL 26/23Z.

&&

.MARINE...TRANQUIL MARINE CONDITIONS ACROSS LOCAL WATERS WITH SEAS
BELOW 5 FEET AND WINDS 10 TO 15 KNOTS. SEAS AND WINDS EXPECTED TO
INCREASE THE UPCOMING WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 88 78 / 70 20 20 30
STT 88 77 88 77 / 70 20 20 30

[cycloneye]

It looks like the Eastern Caribbean will have a good rain event starting on May 29 and lasting thru June 2 if all the forecasts are right.So fingers crossed to see if the drought conditions that some of the islands are going thru end or at least aliviates bigtime.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
225 PM AST TUE MAY 26 2015

.SYNOPSIS...MID TO UPPER LEVEL TROUGH AND ASSOCIATED LOW WILL
CONTINUE NORTH OF LOCAL ISLANDS THROUGH FRIDAY. THE TROUGH ALOFT
WILL INDUCE A SURFACE TROUGH ACROSS THE AREA...PROMOTING A MOIST
SOUTHEASTERLY WIND FLOW BY THE END OF THE WEEK. AS TROUGH ALOFT
WEAKENS NEXT WEEK...RIDGE PATTERN WILL BUILD ACROSS THE EASTERN
CARIBBEAN.


&&

.DISCUSSION...SUNNY TO PARTLY CLOUDY SKIES PREVAILED DURING MUCH
OF THE DAY ACROSS ALL LOCAL ISLANDS. HOWEVER BY EARLY IN THE
AFTERNOON...SHOWERS WERE FORMING ALONG THE CORDILLERA CENTRAL AND
SOUTHERN SLOPES OF PUERTO RICO. THIS ACTIVITY WILL CONTINUE AT
LEAST UNTIL SUNSET...WITH POSSIBLE ISOLATED THUNDERSTORMS. FOR
TONIGHT...PASSING SHOWERS EMBEDDED WITH THE NORTHEAST WINDS ARE
EXPECTED ACROSS THE USVI AND THE NORTHEASTERN SECTIONS OF PR.

AT LEAST UNTIL THURSDAY...DIURNAL CONVECTION IS EXPECTED ALONG THE
CORDILLERA CENTRAL AND SOUTHWESTERN PR WITH STREAMERS FORMING OFF
THE ISLANDS AND BRIEF PASSING SHOWERS OVER THE WINDWARD AREAS
DURING THE NIGHTTIME. AS DEEP SOUTHERLY WIND FLOW ESTABLISHES DUE
TO THE UPPER LEVEL LOW AND SURFACE TROUGH...A WETTER PATTERN IS
EXPECTED DURING THE END OF WEEK...WITH MODEL GUIDANCE SUGGESTING
ABOVE THAN NORMAL PWAT VALUES FROM FRIDAY AFTERNOON THRU EARLY
NEXT WEEK AND FAVORABLE UPPER AIR DYNAMICS. THEREFORE...SHOWER
AND THUNDERSTORM COVERAGE WILL INCREASE DURING THE WEEKEND ACROSS
THE FORECAST AREA. URBAN AND SMALL STREAM FLOODING IS LIKELY
DURING THIS PERIOD ACROSS MAINLAND PR.


&&

.AVIATION...SHRA DVLPG INTO TSRA TIL 26/21Z OVER AND JUST S OF
CORDILLERA CENTRAL. AREAS OF MVFR AND MTN OBSCURATIONS...MAINLY TJMZ
TIL 27/03Z. ELSW VFR TO PREVAIL EXC BRIEF MVFR IN SHRA TKPK AND
TNCM. SHRA AND TSRA TO RETURN TO PR SIMILAR PLACES BY 27/16Z. WINDS
BLO FL090 N-NE 10 TO 15 KT BMCG AFT 27/12Z BLO FL050 E UP TO 12 KT.
MAX WINDS OVR TJSJ NEXT 24 HRS AT FL460 W 45-55 KT.

&&

.MARINE...SEAS BELOW 5 FEET AND EAST TO NORTHEAST WINDS AROUND 10
TO 15 KNOTS ARE EXPECTED DURING THE NEXT FEW DAYS. WINDS WILL
INCREASE DURING THE WEEKEND AND SEAS UP TO 6 FEET ARE EXPECTED ON
SUNDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 88 78 87 / 20 20 30 30
STT 77 88 77 88 / 20 20 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
553 AM AST WED MAY 27 2015

.SYNOPSIS...UPPER TROUGH AND ASSOCIATED LOW WILL CONTINUE NORTH
OF LOCAL ISLANDS THROUGH FRIDAY. AN INDUCED SURFACE TROUGH NORTHEAST
OF AREA WILL PROMOTE A MODERATE EAST NORTHEAST TRADE WIND FLOW
THROUGH TODAY SURFACE HIGH PRESSURE OVER THE ATLANTIC WILL PREVAIL
FOR THE NEXT SEVERAL DAYS. TROPICAL MOISTURE IS EXPECTED TO
INCREASE BY THIS WEEKEND.


&&

.DISCUSSION...PASSING SHOWERS ONCE AGAIN AFFECTED THE LOCAL WATERS
AS WELL AS THE NORTH AND EASTERN SECTIONS OF PR AND THE USVI. THIS
AFTERNOON...SHOWERS AND THUNDERSTORMS ONCE AGAIN EXPECTED ACROSS
THE INTERIOR...WESTERN INTERIOR...AND SOUTHWESTERN PR...WITH A
SLIGHT CHANCE OF RAIN ELSEWHERE IN PR AND IN THE USVI. THIS IS A
TYPICAL PATTERN FOR THIS TIME OF YEAR AND IT IS ONCE AGAIN
EXPECTED ON THURSDAY. HOWEVER ON FRIDAY...TROPICAL MOISTURE IS
EXPECTED TO START INCREASING QUITE A BIT WITH PRECIPITABLE WATER
VALUES GETTING CLOSE TO 2 INCHES. IN COMBINATION WITH THE UPPER
TROUGH...THE INSTABILITY WILL ALSO INCREASE. THIS MAY LEAD TO
ENHANCED THUNDERSTORM ACTIVITY ACROSS THE LOCAL AREA STARTING ON
FRIDAY INTO SATURDAY.

LATEST GUIDANCE SUGGESTS THAT THE INSTABILITY WILL BE BETTER JUST
SOUTH OF THE LOCAL ISLANDS BUT INSTABILITY WILL STILL INCREASE
OVER THE ISLANDS. IN ADDITION...THE OVERALL MOISTURE AND THE
UPPER LEVEL DYNAMICS LOOK FAVORABLE FOR SHOWERS AND THUNDERSTORMS
OVER THE LOCAL ISLANDS. BASED ON THE 27/00Z RUN FROM THE GFS
MODEL...THE UPPER LEVEL DIVERGENCE WILL NOT BE THAT GOOD ON
FRIDAY...IN FACT IT SHOWS CONVERGENCE IN THE UPPER LEVELS ON
FRIDAY. HOWEVER...ON SATURDAY...THE MODEL SHOWS A SHARP INCREASE
UN UPPER LEVEL DIVERGENCE WITH CONVERGENCE AT THE SURFACE. THIS
MEANS THAT ALTHOUGH IT LOOKS RAINY ON FRIDAY WITH THE MOISTURE
ADVECTION AND THETA-E INCREASING...THE DAY WITH THE MOST
THUNDERSTORMS MAY ACTUALLY BE ON SATURDAY. THIS IS NOT TO SAY THAT
THERE WILL BE NO THUNDERSTORMS ON FRIDAY...IT JUST THAT THE LATEST
GUIDANCE SUGGESTS BETTER DYNAMICS ON SATURDAY FOR THUNDERSTORMS
OVER THE LOCAL ISLANDS COMPARED TO FRIDAY. SUNDAY LOOKS LIKE THERE
MAY STILL BE SOME THUNDERSTORM ACTIVITY BUT NOT AS MUCH AS
SATURDAY. STAY TUNED FOR THE LATEST ON THIS.

&&

.AVIATION...POSBL MVFR IN ISOLD/SCT SHRA THIS MORNING AND TONITE BUT
MOST TAF SITES WL NOT FALL BLW VFR. SCT TSRA THIS AFT INTERIOR AND
SW PR WI SOME OBSCD MTNS...AGAIN WI POSBL VFR AT TJMZ/TJPS. WIND BLW
FL100 ENE 12 KT EARLY TDY BCMG VRBL 12 KT OR LESS LATE TDY TO THU.

&&

.MARINE...SEAS MAINLY IN THE 2-4 FT RANGE TODAY AND LIKELY THROUGH
THE END OF THE WORKWEEK. WINDS WILL BE GENERALLY UP TO 15 KNOTS
THROUGH THE END OF THE WORKWEEK AS WELL. WINDS AND SEAS ARE
EXPECTED TO INCREASE SLIGHTLY DURING THE WEEKEND.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 86 76 88 78 / 40 20 20 20
STT 87 77 87 77 / 40 20 20 30

[cycloneye]

HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE SAN JUAN PR
1138 AM AST WED MAY 27 2015

...INCREASING MOISTURE AHEAD FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS BEGINNING FRIDAY...

AFTER A LONG PERIOD OF EXTENDED BELOW NORMAL PRECIPITATION...MAINLY
OUTSIDE OF WEST CENTRAL PUERTO RICO AND INCLUDING THE U.S. VIRGIN
ISLANDS...BETTER MOISTURE AND MORE FAVORABLE DYNAMICS WILL ARRIVE
BEGINNING FRIDAY. LIMITED MOISTURE...SITUATED BETWEEN A MID AND
UPPER LEVEL LOW AND AN ADVANCING AREA OF MOISTURE FROM THE
TROPICAL ATLANTIC WILL BRING SLIGHTLY DRIER CONDITIONS TODAY AND
THURSDAY...BUT MODELS HAVE BEEN CONSISTENT IN BRINGING MUCH MORE
MOISTURE TO THE AREA FROM THE SOUTHEAST FRIDAY...AND THIS MOISTURE
WILL CONTINUE THROUGH AT LEAST EARLY MONDAY.

AT PRESENT...THE LEAST THAT CAN BE EXPECTED IS A TURN IN THE
OVERALL CONDITIONS TO A MUCH MORE SHOWERY SCENARIO WITH SOME
THUNDERSTORMS...MORE RAINFALL COVERAGE AND HEAVIER RAINFALL WHERE
RAIN FALLS. THIS COULD BRING WATER TO NORMALLY DRY CREEKS AND GUTS
AND RAISE THE GENERAL LEVEL OF MOST RIVERS AND STREAMS IN THE
AREA.

THERE IS A POSSIBILITY THAT SOME LOCAL AREAS...ESPECIALLY ALONG
THE CORDILLERA CENTRAL AND IN THE U.S. VIRGIN ISLANDS...MAY
RECEIVE EXCESSIVE RAINFALL RESULTING IN SOME LOCAL FLOODING OF
STREAMS...GUTS...LOCAL RIVERS AND LOW-LYING AREAS WHERE LOCAL
WINDS BRING REPEATED ROUNDS OF SHOWERS AND THUNDERSTORMS ACROSS
THE SAME AREA FOR MULTIPLE HOURS. THE HIGHEST PROBABILITY OF THIS
HAPPENING IS FROM FRIDAY AFTERNOON TO SUNDAY NIGHT.

RESIDENTS IN AREAS NORMALLY PRONE TO FLOODING SHOULD BEGIN TO TAKE
PRECAUTIONARY MEASURES WHICH WOULD INCLUDE PREPARING PLANS TO
MOVE OR PROTECT PETS...LIVESTOCK...EQUIPMENT AND PERSONAL
BELONGINGS. RESIDENTS SHOULD ALSO REVIEW SAFETY PROCEDURES AND
EVACUATION ROUTES FOR THE MUCH DELAYED ONSET OF OUR NORMAL RAIN
AND FLOOD SEASON. THESE PLANS SHOULD BE PUT IN PLACE IF AND WHEN
THE NATIONAL WEATHER SERVICE ISSUES A FLASH FLOOD WATCH.

THOSE THAT LIVE BELOW AREAS THAT HAVE BURNED SHOULD BE AWARE THAT
RUNOFF WILL OCCUR MUCH SOONER AND WILL BE MUCH FASTER THAN NORMAL
OVER THE SCORCHED AND CLEARED GROUND.

WETTER CONDITIONS...THOUGH NOT NECESSARILY FLOODING...ARE FORESEEN
THROUGH ALMOST ALL OF THE FOLLOWING WORK WEEK.

$$

SNELL

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
330 PM AST WED MAY 27 2015

.SYNOPSIS...AT UPPER LEVELS...LOW PRESSURE ALONG 60 NORTH EAST OF
FLORIDA WILL MOVE NORTHWARD AND REJOIN THE FLOW. THE SUB TROPICAL
JET WILL PULL NORTH OVER THE AREA THURSDAY NIGHT AND FRIDAY THEN HIGH
PRESSURE WILL BUILD OVER THE EASTERN CARIBBEAN OVER THE WEEKEND.
THIS RIDGE WILL SHIFT SLOWLY TOWARD THE WINDWARD PASSAGE DURING
THE UPCOMING WEEK.

AT MID LEVELS...LOW PRESSURE NORTHEAST OF PUERTO RICO WILL PULL
NORTH AND WEAKEN OVER THE WEEKEND THEN HIGH PRESSURE WILL FILL IN
OVER THE EASTERN CARIBBEAN. VERY DRY MID LEVELS WILL GIVE WAY TO A
LARGE AREA OF MOISTURE ON FRIDAY. THIS MOISTURE WILL WEAKEN ON
TUESDAY BUT WILL NOT GET VERY FAR AWAY.

AT LOWER LEVELS...ALTHOUGH HIGH PRESSURE DOMINATES THE CENTRAL
ATLANTIC...VERY WEAK LOWS AND WEAK GRADIENTS ARE FOUND JUST NORTH
AND NORTHEAST OF THE FORECAST AREA. THESE WILL SHIFT WEST AND
FLOW WILL CONTINUE FROM THE SOUTHEAST. TROUGHINESS TO THE WEST AND
THE SOUTHEAST FLOW WILL CONTINUE THROUGH THE UPCOMING WEEK.

&&

.DISCUSSION...SHOWERS FORMED MID MORNING AROUND THE U.S. VIRGIN
ISLANDS AND OVER EASTERN PUERTO RICO...BUT HEAVY SHOWERS ERUPTED
QUICKLY JUST AFTER NOON OVER PUERTO RICO...BEING FUELED BY
INTENSE HEATING UNDER THE PREVIOUS SUNNY SKIES. THESE SHOWERS
CONTINUE TO PRODUCE HEAVY RAIN IN THE CENTRAL PORTION OF THE
ISLAND.

THE GFS CONTINUES TO SHOW RELATIVELY DRY AIR OVER THE AREA UNTIL
FRIDAY MORNING THEN MOISTURE INCREASES SHARPLY. ALTHOUGH THE
MOISTURE COLUMN FORECAST FOR THE WEEKEND IS NOT QUITE AS DEEP AS
WAS PREVIOUSLY FORECAST EARLIER THIS WEEK...VALUES STILL HOLD
BETWEEN 1.9 AND 2.1 INCHES OVER THE AREA THROUGH THE WEEKEND AND
INTO MONDAY. THEREFORE THE POSSIBILITIES FOR HEAVY RAIN AND
FLOODING INCREASE. A HYDROLOGICAL OUTLOOK HAS BEEN ISSUED WITH
MORE DETAILS. THE GFS CONTINUES TO SHOW THE BEST BANDS OF
PRECIPITATION STRETCHING FROM SOUTH OF PUERTO RICO NORTHEAST
ACROSS THE U.S. VIRGIN ISLANDS AND SOME OF THE HEAVIEST RAINS MAY
FALL THERE AND IN THE CORDILLERA CENTRAL DUE TO OROGRAPHIC ACTION.

MOISTURE LEVELS WILL CONTINUE MUCH HIGHER NEXT WEEK THAN THIS
PAST WEEK...BUT THE MIDDLE OF THE WEEK SHOULD NOT BE AS WET AS
THIS WEEKEND.

&&

.AVIATION...VFR CONDS EXPECTED FOR MOST OF THE TERMINALS EXCEPT
TJMZ AND TJPS WHERE AFTERNOON CONVECTION MAY PRODUCE BRIEF
MVFR/IFR CONDS THRU 22Z. MOUNTAIN OBSCURATIONS AND MVFR/IFR CONDS
ARE LIKELY ACROSS THE CORDILLERA CENTRAL THROUGH THIS EVENING..
WINDS BELOW 3K FT WILL PREVAIL FROM THE NE AT AROUND 10
KT...VEERING TO THE SE AFTER 28/06Z.

&&

.MARINE...A SWELL OF 8 SECONDS PERIOD...UNDETECTED BY THE
MODELS...MOVED INTO THE ATLANTIC WATERS AND THE WATERS NORTH OF
THE FORECAST AREA RAISING SEAS NEARLY 2 FEET...NEVERTHELESS SEAS
WILL NOT EXCEED 5 FEET THIS WEEK OR WEEKEND SINCE WINDS ARE GENTLE
TO MODERATE. SOME GUSTY WINDS MAY BE ENCOUNTERED IN THUNDERSTORMS
OVER THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 75 90 76 89 / 20 20 20 40
STT 74 85 78 87 / 20 20 40 40

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
408 AM AST THU MAY 28 2015

.DISCUSSION...SOUTHERLY FLOW HAS ALREADY BEGUN ABOVE 850 MB ACROSS
THE EASTERN CARIBBEAN WHERE TROPICAL MOISTURE IS SURGING NORTHWEST.
THE FLOW WILL TURN MORE SOUTHEASTERLY BY TONIGHT WHICH WILL PUSH
THE HIGHEST MOISTURE MORE TOWARDS HISPANIOLA. ALL MODELS SHOW
PRECIPITABLE WATER OVER PR PAST 2 INCHES BY FRI MORNING...EXCEPT
THE NAM WHICH HOLDS OFF UNTIL LATE FRI NIGHT. BUT EVEN NAM SHOWS
GOOD RAINFALL AMOUNTS ON FRI AFTERNOON SO HAVE CONSERVATIVELY
PUSHED PROBABILITY OF RAINFALL INTO LIKELY CATEGORY FOR NORTHERN
PR WESTWARD FROM SAN JUAN FOR FRI AND SAT AFTERNOONS. GFS ALSO
SHOWS SOME 250 MB DIVERGENCE ON FRI WHICH COULD HELP DEVELOPMENT
BUT THE MODEL IS NOT VERY GOOD AT LOCATING THIS PARAMETER. THE
OTHER MAIN CAVEAT APPEARS TO BE THE AMOUNT OF HIGH CLOUDS WE MAY
HAVE WHICH WOULD REDUCE HEATING AND AFTERNOON CONVECTION. MODEL
SOUNDINGS SUGGEST PERSISTENT HIGH CLOUDS BUT IS LIKELY OVERDONE.
GFS SUGGESTS KEEPING PRECIPITABLE WATER IN THE VICINITY OF 2
INCHES ALMOST ALL OF NEXT WEEK AND COULD BE A GOOD WEEK FOR RAIN
ACROSS THE ISLANDS.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL LOCAL TERMINALS THROUGH
28/17Z WITH VCSH DUE TO QUICK SHOWERS ACROSS THE LOCAL AREA. FROM
28/17Z TO 28/23Z...MVFR PSBL MAINLY ACROSS TJBQ AND TJMZ DUE TO
AFTERNOON CONVECTION ACROSS THE NW QUADRANT OF PR. SFC WINDS WILL
REMAIN LIGHT AT AROUND 5KT THROUGH 28/13Z...BECOMING E-ESE AT AROUND
10KT WITH SEA BREEZE VARIATIONS THEREAFTER.

&&

.MARINE...GENTLE TO MODERATE TRADES WILL CONTINUE THROUGH FRIDAY
BUT INCREASE A LITTLE INTO THE WEEKEND. SHOWERS AND THUNDERSTORMS
WILL ALSO INCREASE BEGINNING ON FRIDAY AS TROPICAL MOISTURE
ARRIVES FROM THE SOUTHEAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 89 76 / 20 20 60 50
STT 86 77 86 78 / 20 40 40 50

[cycloneye]

Good afternoon.The afternoon discussion by the San Juan NWS looks very good in terms of getting plenty of rain from this rain event.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
321 PM AST THU MAY 28 2015

.SYNOPSIS...AT UPPER LEVELS...LOW PRESSURE NORTH OF THE AREA WILL
WEAKEN AND DRIFT NORTH NORTHEAST THROUGH THE WEEKEND. A BRANCH OF
THE SUBTROPICAL JET WILL CROSS OVER THE AREA FRIDAY MORNING AND
CONTINUE MOVING NORTH AS HIGH PRESSURE BUILDS OVER THE EASTERN
CARIBBEAN. HIGH PRESSURE WILL SPREAD INTO THE WESTERN CARIBBEAN
AND INTENSIFY THROUGH THURSDAY WITH A STRONG RIDGE EXTENDING
NORTH.

AT MID LEVELS...LOW PRESSURE NORTH OF THE AREA WILL DRIFT NORTH AS
HIGH PRESSURE EXTENDS WESTWARD OVER THE CARIBBEAN SEA THROUGH MID
WEEK. HIGH PRESSURE DOMINATES THE CARIBBEAN SEA THROUGH THE
REMAINDER OF NEXT WEEK. MOISTURE WILL INCREASE SIGNIFICANTLY
BEGINNING ON FRIDAY.

AT LOWER LEVELS...LOW PRESSURE EAST OF THE BAHAMAS NORTH OF THE
AREA WILL DRIFT EAST AND WEAKEN LEAVING MODERATELY STRONG HIGH
PRESSURE OVER THE CENTRAL ATLANTIC AND MODERATE TO FRESH EAST
SOUTHEAST TRADE WINDS OVER THE LOCAL AREA BY SUNDAY. DURING THE
WEEK THE HIGH WILL PULL NORTHEAST AND GRADIENTS WILL
WEAKEN...ALLOWING WINDS TO DIMINISH AND TURN TO THE SOUTHEAST.
MUCH BETTER MOISTURE WILL MOVE INTO THE AREA ON FRIDAY FROM THE
SOUTHEAST AND CONTINUE AT HIGHER LEVELS THROUGH THE ENTIRE WEEK
AHEAD.

&&

.DISCUSSION...MOISTURE THIS MORNING AT 12Z WAS SIMILAR TO THAT
YESTERDAY AT 27/12Z...BUT WINDS BELOW 7500 FEET TURNED
DEFINITIVELY TO THE SOUTHEAST AND CONVECTION WAS NOT QUITE AS
QUICK TO FORM. SOME THUNDERSHOWERS WITH HEAVY RAIN DID APPEAR FROM
ANASCO TO VEGA ALTA. VEGA BAJA REPORTED ABOUT 6 TENTHS OF AN INCH
OF RAIN WITH SOME SMALL HAIL WITH HIGHER AMOUNTS POSSIBLE TO THE
NORTH. MOISTURE CAUSED CLOUDY SKIES IN THE BARBADOS THIS MORNING
AND SKIES CLOUDED UP IN SANTA LUCIA AND GUADELOUPE DURING THE DAY
WITH SHOWERS IN THE AREA...CONFIRMING WHAT MIMIC AND THE MODELS
ALREADY TOLD US...THAT DEEP MOISTURE IS HEADED TOWARD THE AREA.
THE GFS SUGGESTS THAT THE DRIEST AIR WILL PASS OVERHEAD AROUND
29/06Z FOLLOWED ABRUPTLY BY AIR WITH COLUMNAR MOISTURE OF OVER 1.8
INCHES ARRIVING BY 28/12Z. ALTHOUGH THE MODEL SENDS THE BEST
MOISTURE INTO THE DOMINICAN REPUBLIC AND OVER THE LOCAL OUTER
CARIBBEAN WATERS...THERE STILL APPEARS TO BE PLENTY OF MOISTURE
FOR SHOWER AND THUNDERSTORM DEVELOPMENT DURING THE DAY FRIDAY FOR
PUERTO RICO AND THE U.S. VIRGIN ISLANDS. THESE SHOWERS AND SOME
THUNDERSTORMS WILL LINGER WELL INTO THE NIGHT WITH GENERAL AMOUNTS
IN THE NEXT 24 TO 29 HOURS RANGING FROM 1 TO 3 INCHES IN THE
WETTER AREAS. SOME AREAS MAY RECEIVE LESS THAN ONE HALF INCH
DURING THE SAME TIME PERIOD. THEN ON SATURDAY MOISTURE WILL
INCREASE AND BETTER RAINFALL IS EXPECTED OVER A WIDER AREA.

A DECISION ON WHETHER TO ISSUE A WATCH WILL BE MADE NO LATER THAN
FRIDAY MORNING...IF NEEDED...AND CURRENT FORECASTS SUGGEST THAT
FLASH FLOODING ON SMALL RIVERS AND URBAN AND SMALL STREAM FLOODING
ARE LIKELY IN A FEW SPOTS AND POSSIBLE IN MORE THAN JUST A FEW
AREAS. CURRENTLY MODELS SUGGEST THAT THE U.S. VIRGIN ISLANDS WILL
HAVE A SIGNIFICANT AMOUNT OF RAINFALL WILL OCCUR THERE FRIDAY
THROUGH SUNDAY. SHOWERS WILL CONTINUE THROUGH AT LEAST
MONDAY...ALTHOUGH THE BEST MOISTURE APPEARS TO OCCUR SATURDAY
EVENING OVER THE FORECAST AREA AND SUBSIDES SLOWLY OVER THE
FORECAST AREA THROUGH WEDNESDAY. MOISTURE WILL INCREASE SOMEWHAT
THURSDAY NIGHT THROUGH FRIDAY NEXT WEEK.

&&

.AVIATION...BETWEEN 28/17Z AND 28/23Z...MVFR PSBL...MAINLY ACROSS
TJBQ AND TJMZ DUE TO AFTERNOON CONVECTION AND MOUNTAIN OBSC ACROSS
THE INTERIOR...WEST AND NW QUADRANT OF PR. SFC WINDS FROM THE
E-ESE AT 10 TO 15 KT WITH HIGHER GUSTS AND SEA BREEZE VARIATIONS
THROUGH 28/23Z... FOLLOWED BY LIGHT SFC WINDS AT AROUND 5KT
THEREAFTER. INCREASING SHOWERS AND THUNDERSTORMS BEGINNING NOW IN
TNCM AND TKPK AND SPREADING THROUGH 28/14Z TO PR AND USVI.
WIDESPREAD OBSCURATIONS OF HIGHER TERRAIN AFT 28/16Z.

&&

.MARINE...WINDS AND SEAS INCREASE FRIDAY NIGHT THROUGH SATURDAY
NIGHT WITH SHOWERS AND THUNDERSTORMS INCREASING OVER THE AREA.
CONDITIONS ARE NOT EXPECTED TO REACH SMALL CRAFT ADVISORY
LEVELS...BUT LOCAL GUSTY WINDS IN EXCESS OF 30 KNOTS COULD BE
ENCOUNTERED IN THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 87 75 / 20 20 70 60
STT 86 77 84 77 / 20 40 70 70

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
624 AM AST FRI MAY 29 2015

.SYNOPSIS...UPPER LOW WILL REMAIN TO THE NORTH OF THE LOCAL AREA
FOR THE NEXT FEW DAYS AS IT SLOWLY SHIFTS TO THE WEST...THEN AN
UPPER RIDGE WILL DOMINATE OVER THE LOCAL AREA BY TUESDAY. A
TROPICAL WAVE IS EXPECTED TO MOVE IN LATER TODAY AND INCREASE THE
AVAILABLE MOISTURE THROUGH THE WEEKEND ANS INTO EARLY NEXT WEEK.

&&

.DISCUSSION...A RATHER INTERESTING SETUP IS IN STORE FOR TODAY AND
INTO THE WEEKEND. AT THE TIME...CONFIDENCE IS MODERATE AS WE SEEM
TO HAVE SEVERAL QUESTIONS ABOUT THE IMPACT BE OF SUCH AS
SETUP...CONSIDER THE LACK OF RAINFALL THAT EASTERN PR AND THE USVI
HAS OBSERVED IN THE PAST SEVERAL MONTHS...THE TROPICAL WAVE MOVING
IN WITH THE UPPER LOW TO THE NORTH OF THE LOCAL AREA...THE HIGH
CLOUDS MOVING IN FROM THE SOUTH AND THE DISCREPANCY FROM THE
DIFFERENT MODEL SOLUTIONS FOR TODAY AND SATURDAY. HOWEVER...THE
MAIN FORECASTER CONSENSUS IS THAT AN INCREASE IN SHOWER AND
THUNDERSTORM ACTIVITY IS EXPECTED STARTING TODAY AND LASTING
THROUGH AT LEAST SUNDAY. OCCASIONAL STRONG THUNDERSTORMS WITH
LOCALLY HEAVY RAIN ARE EXPECTED THIS WEEKEND ACROSS DIFFERENT
SECTORS IN THE LOCAL FORECAST AREA. AT LEAST SOME URBAN AND SMALL
STREAM FLOODING IS EXPECTED WITH THE SHOWERS AND THUNDERSTORMS.

CURRENTLY WE HAVE AN UPPER LOW TO THE NORTH NORTHEAST OF THE LOCAL
ISLANDS AND THE TROPICAL WAVE MOVING IN FROM THE EAST. THE
AVAILABLE MOISTURE WILL INCREASE TODAY WITH PRECIPITABLE WATER
VALUES JUMPING TO ALMOST 2 INCHES BY THIS AFTERNOON. WHEN THIS
MOISTURE ADVECTION IS COMBINED WITH THE DAYTIME HEATING AND THE
LOCAL EFFECTS...SOME GOOD SHOWERS AND THUNDERSTORMS NORMALLY
DEVELOP ACROSS THE LOCAL AREA. HOWEVER...SATELLITE IR IS SHOWING
AN AREA OF HIGH CLOUDS MOVING INTO THE LOCAL AREA THIS MORNING BUT
THE RADAR HAS YET TO DETECT ANY SIGNIFICANT RAINFALL ASSOCIATED
WITH THE CLOUDINESS OVER THE LOCAL CARIBBEAN WATERS. HAVING SAID
THAT...THE GUADELOUPE RADAR DOES SHOW SOME SHOWER ACTIVITY AND THE
SHOWERS ARE MOVING RATHER FAST TO THE NORTH NORTHEAST. A FEW OF
THOSE SHOWERS LOOK MODERATE TO LOCALLY HEAVY. THIS CLOUDINESS IS
QUITE LARGE ANS MAY LINGER OVER PR AND THE USVI AT LEAST THROUGH
THE MORNING HOURS...WHICH WILL LIMIT SURFACE HEATING OVER THE
ISLANDS...LIMITING THE THUNDERSTORM DEVELOPMENT. HOWEVER...MODEL
GUIDANCE IS SHOWING SOME GOOD DIVERGENCE ALOFT THIS AFTERNOON
ACROSS THE LOCAL WATERS AND OVER PR AND THE USVI. THIS IS
BASICALLY THE OPPOSITE TO WHAT THE SAME MODEL HAS BEEN SAYING FOR
THE PAST 5 DAYS OR SO. UP UNTIL TODAY...THE GFS MODEL INDICATED
CONVERGENCE FOR TODAY IN THE UPPER LEVELS...STRONG DIVERGENCE
ALOFT WOULD BE CONDUCIVE TO SHOWER AND THUNDERSTORM DEVELOPMENT.
THE HI- RES MODELS SUCH AS THE WRF 2KM AND 6KM AND THE NMM ARE
SHOWING LITTLE TO NO SHOWER ACTIVITY TODAY OVER THE ISLANDS...THE
GFS SHOWS SOME ACTIVITY BUT THE ONLY MODEL THAT IS RATHER BULLISH
ON THE PRECIP IS THE ARW MODEL WHICH SHOWS A SIGNIFICANT AMOUNT OF
PRECIP ACROSS THE CARIBBEAN WATERS AND NW- PR...WITH SOME ISOLATED
AREAS OF PRECIP ELSEWHERE. OUR FORECAST WAS ADJUSTED SLIGHTLY BUT
IT STILL SHOWS A STEADY INCREASE OF SHOWER AND THUNDERSTORM
ACTIVITY THROUGH THE DAY WITH THE CARIBBEAN WATERS HAVING NUMEROUS
SHOWERS AND THE INTERIOR OF PR INTO NW-PR DEVELOPING SHOWERS AND
THUNDERSTORMS IN THE AFTERNOON...SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ELSEWHERE.

SATURDAY STILL LOOKS LIKE A PRETTY ACTIVE DAY. HOWEVER...THE GFS
MODEL USED TO BE PRETTY CONSISTENT SHOWING UPPER LEVEL DIVERGENCE
THROUGH THE DAY SATURDAY...THE 29/00Z RUN STILL SHOWS THAT
DIVERGENCE ALOFT BUT DURING THE EVENING HOURS...WHILE THE 29/06Z
RUN ONCE AGAIN SHOWS THAT DIVERGENCE ALOFT DURING THE DAY AND THEN
LINGERING INTO THE EVENING. EITHER CASE...THE DIVERGENCE ALOFT IS
QUITE STRONG ACCORDING TO THE GFS MODEL...WITH AVAILABLE MOISTURE
STILL VERY GOOD WITH PRECIPITABLE WATER VALUES STILL HOVERING AT
AROUND 2 INCHES. THE NMM MODEL AND WRF ARE ALSO NOT LIKING THIS
SETUP VERY MUCH AND ARE SHOWING A RELATIVELY DRY SATURDAY...HOWEVER
THE ARW MODEL BRINGS IN A LOT OF SHOWERS AND THUNDERSTORMS TO THE
LOCAL ISLANDS...ESPECIALLY THE NORTHERN HALF OF PR AND THE USVI.
ACCORDING TO THE LATEST GFS MODEL THE AVAILABLE MOISTURE WILL BE
GOOD AND THE DIVERGENCE ALOFT WILL BE STRONG THROUGH AT LEAST
SUNDAY.

SO WE DO EXPECT A RATHER ACTIVE WEEKEND...EVEN WITH SOME OF THE
HI-RES MODELS INDICATING LITTLE TO NO PRECIP THESE NEXT FEW DAYS.
THE BIG PICTURE SETUP IS CONDUCIVE TO SHOWER AND THUNDERSTORM
ACTIVITY ACROSS THE LOCAL AREA...AT LEAST ON FRIDAY AND
SATURDAY...HOWEVER FORECAST SOUNDINGS SHOW A PROFILE MORE
CONSISTENT WITH HIGH CLOUDINESS BUT NOT AS MUCH PRECIP FOR SUNDAY
AND MONDAY.

THERE ARE QUESTIONS ON THE POTENTIAL IMPACT THE SHOWERS AND
THUNDERSTORMS WILL HAVE OVER THE ISLANDS. THE DISCREPANCY BETWEEN
THE GLOBAL AND THE HI-RES MODELS AND THE FACT THAT EASTERN PR IS
SO DRY...IT WAS DECIDED TO HOLD OFF ON A FLASH FLOOD WATCH UNTIL
WE SAW HOW THE MODELS ARE HANDLING THIS PATTERN AND HOW MUCH RAIN
IT ACTUALLY FALLS TODAY ACROSS THE LOCAL ISLANDS. WE HAVE TO TAKE
INTO ACCOUNT NOT ONLY METEOROLOGICAL CONDITIONS BUT ALSO
HYDROLOGICAL CONDITIONS...AND RIGHT NOW THE HYDROLOGICAL
CONDITIONS ARE THAT THE RIVERS ARE RUNNING VERY LOW AND THE SOIL
ACROSS EASTERN PR IS IN NEED OF SOME WATER...IT WILL TAKE A LOT OF
RAIN TO CAUSE RIVER FLOODING ACROSS EASTERN PR...NOT SO MUCH FOR
THE WESTERN HALF OF PR WHICH HAS OVSERVED CONSISTENT RAINFALL FOR
THE PAST SEVERAL DAYS.

STAY TUNED FOR POSSIBLE CHANGES AS WE GATHER MORE INFORMATION ON
THIS EVENT TODAY.

WEATHER CONDITIONS ARE EXPECTED TO IMPROVE BY TUESDAY AND INTO THE
REST OF THE WEEK...WITH A MORE TYPICAL PATTERN OF MORNING SHOWERS
ACROSS THE WATERS AND AFTERNOON CONVECTION DUE TO LOCAL EFFECTS.

&&

.AVIATION...INCREASING SHRA AND TSRA EN ROUTE FROM THE
WINDWARD ISLANDS WILL AFFECT THE FLYING AREA OF TNCM AND TKPK THRU
THE FCST PERIOD...SPREADING THROUGH SOUTHEASTERN PR AND THE USVI BY
14Z. MVFR/IFR POSSIBLE AND WIDESPREAD OBSCURATIONS LIKELY IN HIGHER
TERRAIN AND NORTHWESTERN PR AFT 16Z. SE WINDS OF 10-15 KT EXPECTED
BELOW 5 KFT WITH HIGHER GUSTS NEAR TSRA...SW-W WINDS ABV/INCREASING
W/HEIGHT. UNSETTLED WEATHER CONDITIONS WILL CONTINUE THRU THE
WEEKEND.


&&

.MARINE...WINDS AND SEAS WILL CONTINUE AT 4 FEET OR LESS AND 10
KNOTS OR LESS RESPECTIVELY TODAY. DETERIORATING CONDITIONS EXPECTED
TONIGHT AND SATURDAY DUE TO INCREASED POTENTIAL FOR THUNDERSTORM
DEVELOPMENT AND INCLEMENT WEATHER ACROSS PORTIONS OF THE REGIONAL
WATERS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 87 75 / 60 40 80 50
STT 84 77 86 76 / 50 50 70 60

[cycloneye]

Raining hard in parts of Puerto Rico.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
257 PM AST FRI MAY 29 2015

.DISCUSSION...HEAVY SHOWERS AND STRONG THUNDERSTORMS DEVELOPED
OVER THE NORTH CENTRAL SECTIONS OF PUERTO RICO INCLUDING THE SAN
JUAN METROPOLITAN AREA. RADAR ESTIMATES WERE BETWEEN 2 TO 3 INCHES
MAINLY OVER THE MUNICIPALITIES OF BAYAMON AND VEGA BAJA. AT THIS
MOMENT MOST OF THESE SHOWERS AND THUNDERSTORMS HAVE SOME
INTENSITY. THESE SHOWERS ARE EXPECTED TO CONTINUE THROUGH THE
EVENING HOURS.

RADAR AND SATELLITE IMAGES ARE SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS OVER THE LOCAL CARIBBEAN WATERS. THESE SHOWERS AND
THUNDERSTORMS WILL MOVE SLOWLY NW AND AFFECT THE EASTERN AND
SOUTHERN PORTIONS OF PUERTO RICO FROM LATE TONIGHT THROUGH
SATURDAY MID MORNING.

ON SATURDAY EXPECT A COMBINATION OF DAYTIME HEATING AND DIVERGENCE
ALOFT TO ENHANCE CONVECTION ACROSS PARTS OF THE ISLANDS. THIS WILL
INCREASE THE POTENTIAL FOR STRONG THUNDERSTORMS AND EVENTUALLY
LEAD TO URBAN AND SMALL STREAM FLOODING IN SOME AREAS...ESPECIALLY
ACROSS PARTS OF THE NORTHERN HALF OF PUERTO RICO.

THE UPPER LEVEL TROUGH AND ASSOCIATED LOW WILL CONTINUE
TO SHIFT WEST SOUTHWEST TO JUST NORTH OF HAITI THROUGH TONIGHT.
THIS WEATHER PATTERN WILL MAINTAIN THE SUBTROPICAL JET STREAM
ACROSS THE THE REGION WHICH HELP TO LIFT DEEP TROPICAL MOISTURE
ACROSS THE AREA THROUGH EARLY SUNDAY.

&&

.AVIATION...MVFR CONDITIONS WILL CONTINUE TO PREVAIL ACROSS TJSJ
THROUGH AT LEAST 29/23Z. MAINLY VFR CONDITIONS ARE EXPECTED TO
PREVAIL ACROSS ALL TAF SITES THROUGH 30/12Z. HOWEVER...PASSING
SHOWERS WILL AFFECT THE LOCAL TAF SITES FROM TIME TO TIME. LOW LEVEL
WINDS WILL BE MAINLY SOUTHEAST AT 10 KTS.

&&

.MARINE...WINDS AND SEAS WILL CONTINUE AT 4 FEET OR LESS AND 10
KNOTS OR LESS RESPECTIVELY TONIGHT. DETERIORATING CONDITIONS
EXPECTED TONIGHT AND SATURDAY DUE TO INCREASED POTENTIAL FOR
THUNDERSTORM DEVELOPMENT AND INCLEMENT WEATHER ACROSS PORTIONS OF
THE REGIONAL WATERS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 78 87 75 / 60 40 80 50
STT 84 77 86 76 / 50 50 70 60