Caribbean - Central America Weather

[cycloneye]

Good morning. Scattered showers will move thru PR today thru Saturday as a low pressure and Tropical Wave pass by the area.

Hi abajan. Those are interesting observations from there. Let's see what happens with that low pressure.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
450 AM AST THU SEP 12 2013

.SYNOPSIS...A TUTT LOW WAS LOCATED SOUTH OF HISPANIOLA WITH
BROAD ASSOCIATED TROUGH EXTENDING NORTHWARDS INTO THE SOUTHWEST
ATLANTIC. THIS IS HELPING TO MAINTAIN A MOIST SOUTHERLY FLOW ACROSS
THE REGION AS MID TO UPPER LEVEL CONVECTIVE DEBRIS WAS BEING DRAWN
NORTHWARDS ACROSS THE REGION. FURTHER EAST...AN UPPER LEVEL ATLANTIC
RIDGE CONTINUED TO DIG SOUTHWARDS ACROSS THE LESSER ANTILLES...
SEPARATING ANOTHER STRONG TUTT LOW LOCATED ACROSS THE SUBTROPICAL
ATLANTIC. IN THE LOW LEVELS...AN AREA OF LOW PRESSURE WAS CENTERED
JUST NORTH OF THE BUOY 41040 WITH ASSOCIATED SURFACE TROUGH EXTENDING
WESTWARD TO JUST EAST AND NORTHEAST OF THE LEEWARD ISLANDS. A TROPICAL
WAVE WHICH HAS MERGED WITH THIS TROUGH WAS NOW NEAR 60 WEST. LATEST
SATELLITE IMAGERY SHOWED A SOLID CONVERGENCE BAND OF MOISTURE ASSOCIATED
WITH THE WAVE NOW REACHING THE NORTHERN LEEWARDS AND QUICKLY SPREADING
WESTWARDS ACROSS THE REMAINDER OF THE NORTHEASTERN CARIBBEAN.

&&

.DISCUSSION...SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORM
ASSOCIATED WITH THE MOISTURE BAND WAS NOW CROSSING THE NORTHERN LEEWARDS
AND QUICKLY APPROACHING THE VIRGIN ISLANDS EARLY THIS MORNING. EXPECT
CLOUDINESS WITH SHOWERS AND THUNDERSTORM ACTIVITY TO INCREASE ACROSS
THE ISLANDS AND REGIONAL WATERS THROUGHOUT THE DAY AS THIS FEATURE
WILL MOVE ACROSS THE AREA. IN ADDITION LOCAL AND DIURNAL EFFECTS AND
THE PROXIMITY OF THE TUTT LOW WILL ALSO HELP ENHANCE THE AFTERNOON
CONVECTION ACROSS PARTS OF THE ISLANDS...THUS LEADING TO PERIODS OF
LOCALLY HEAVY RAINFALL ESPECIALLY OVER PART OF THE INTERIOR AND WEST
SECTIONS OF PUERTO RICO.

ON FRIDAY AND INTO THE EARLY PART OF THE UPCOMING WEEKEND...
STILL EXPECT THE SURFACE TROUGH TO MOVE ACROSS THE NORTHEAST CARIBBEAN
AND BRING AN ADDITIONAL SURGE OF TROPICAL MOISTURE TO THE ISLANDS.
GFS MODEL GUIDANCE AS WELL AS LATEST SATELLITE IMAGERY SUGGEST A
BRIEF DRY SLOT WITH DECREASING MOISTURE/PWAT VALUES BY EARLY FRIDAY
IN ADVANCE OF THE TROUGH. HOWEVER...THIS INCREASES ONCE AGAIN ON
FRIDAY AFTERNOON THROUGH SATURDAY AS THE TROUGH MOVES ACROSS THE
REGION. THE COMBINATION OF INCREASING MOISTURE...WEAK RIDGING WEAK
ALOFT ALONG WITH LOCAL AND DIURNAL EFFECTS SHOULD BE ENOUGH FOR
CONVECTIVE ENHANCEMENT...AND THUS ALLOW FOR SLIGHTLY MORE ACTIVITY
WEATHER CONDITIONS ON FRIDAY AND FOR MUCH OF THE WEEKEND. OVERALL...A
FAIRLY MOIST WEATHER PATTERN IS TO PREVAIL ACROSS THE ISLANDS AT LEAST
FOR THE NEXT FEW DAYS WITH PERIODS OF EARLY MORNING SHOWERS...FOLLOWED
BY ADDITIONAL SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPMENT DURING
THE AFTERNOONS.

&&

.AVIATION...BRIEF PERIODS OF MVFR CONDITIONS AND AREAS OF MOUNTAIN
OBSCURATIONS WILL CONTINUE ACROSS TNCM AND TKPK UNTIL 12/16Z. AFTER
12/12Z PERIODS OF MVFR CONDITIONS WILL AFFECT THE USVI AND AFTER
12/14Z THE EASTERN SECTIONS PUERTO RICO. BY 12/17Z PERIODS OF MVFR
CONDITIONS WILL BE POSSIBLE OVER WESTERN AND INTERIOR PUERTO RICO
WITH MOUNTAIN OBSCURATIONS. TJSJ 12/00Z SOUNDING INDICATED AN EAST
NORTHEAST WIND FLOW OF 10 KNOTS OR LESS ALL THE WAY FROM THE SURFACE
TO AROUND 15K FEET...BECOMING FROM THE SOUTHEAST AND STRONGER ALOFT.

&&

.MARINE...SEAS WILL BE MAINLY 5 FEET OR LESS WITH LIGHT TO
MODERATE WINDS OF 14 KNOTS OR LESS TO PREVAIL TODAY. FOR NOW
FAIRLY TRANQUIL SEAS CAN BE EXPECTED OVER THE NEXT SEVERAL DAYS
AND INTO THE WEEKEND. FOR ADDITIONAL INFO...PLEASE REFER TO THE
LATEST COASTAL WATERS FORECAST ISSUED BY THE NATIONAL WEATHER
SERVICE CFO SAN JUAN PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 79 88 78 / 60 40 40 20
STT 87 79 89 79 / 60 40 50 30

[cycloneye]

8 AM Tropical Weather Outlook.

THE SHOWER ACTIVITY ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE
CENTERED ABOUT 500 MILES EAST OF THE LEEWARD ISLANDS REMAINS
LIMITED. ALTHOUGH SURFACE PRESSURES ARE FALLING SIGNIFICANTLY IN
THE AREA...ENVIRONMENTAL CONDITIONS DO NOT APPEAR TO BE FAVORABLE
FOR DEVELOPMENT. THIS DISTURBANCE HAS A LOW CHANCE...10 PERCENT...
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
UPPER-LEVEL WINDS COULD BECOME A LITTLE MORE FAVORABLE IN SEVERAL
DAYS...AND THIS SYSTEM HAS A LOW CHANCE...20 PERCENT...OF BECOMING
A TROPICAL CYCLONE DURING THE NEXT 5 DAYS AS IT MOVES TOWARD THE
WEST-NORTHWEST.

[Gustywind]

8 AM Tropical Weather Discussion.

A SHORTWAVE UPPER TROUGH IS DEVELOPING OVER THE LEEWARD
ISLANDS FROM 19N64W TO 11N59W SUPPORTING A SURFACE TROUGH THAT
IS APPROACHING THE LEEWARD ISLANDS EXTENDING FROM 24N65W 18N62W
TO 15N54W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 13N-
16N BETWEEN 53W-62W INCLUDING THE ISLANDS BETWEEN DOMINICA AND
SAINT LUCIA. ISOLATED SHOWERS ARE WITHIN 90/120 NM EITHER SIDE
OF THE TROUGH INCLUDING THE LEEWARD AND VIRGIN ISLANDS. A WEAK
PRESSURE PATTERN WILL PREVAIL ACROSS THE MOST OF THE ATLC.

[abajan]

We've been getting thunder for the last 45 minutes or so and the sky is getting darker by the minute. Judging by the satellite loops, looks like a stormy day ahead for some of the Lesser Antilles.

[Gustywind]

We've been getting thunder for the last 45 minutes or so and the sky is getting darker by the minute. Judging by the satellite loops, looks like a stormy day ahead for some of the Lesser Antilles.

Thanks for that report . Continue to keep us informed. Yeah, you're right, Looks like wet weather in some islands.

[abajan]

We've been getting thunder for the last 45 minutes or so and the sky is getting darker by the minute. Judging by the satellite loops, looks like a stormy day ahead for some of the Lesser Antilles.

Thanks for that report . Continue to keep us informed. Yeah, you're right, Looks like wet weather in some islands.

We haven't had much rain to speak of as yet and the thunder ceased shortly after my last post. However, it's been rumbling constantly for the past hour or so and it's gradually getting louder. As I type, the rain has started to fall and the wind, which appears to be out of the north-northwest, is blowing stronger.

[cycloneye]

2 PM Tropical Weather Outlook.

THE SHOWER ACTIVITY ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE
CENTERED ABOUT 450 MILES EAST OF THE LEEWARD ISLANDS REMAINS
LIMITED. ALTHOUGH SURFACE PRESSURES ARE STILL FALLING IN THE
AREA...ENVIRONMENTAL CONDITIONS ARE NOT FAVORABLE FOR DEVELOPMENT.
THIS DISTURBANCE HAS A LOW CHANCE...10 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ALTHOUGH UPPER-LEVEL
WINDS COULD BECOME A LITTLE MORE FAVORABLE IN SEVERAL DAYS...THIS
SYSTEM STILL HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS AS IT MOVES TOWARD THE
WEST-NORTHWEST.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
300 PM AST THU SEP 12 2013

.SYNOPSIS...A BROAD AREA OF LOW PRESSURE WILL CONTINUE TO MOVE
WEST ACROSS THE LOCAL AREA NEXT COUPLE OF DAYS. SURFACE HIGH
PRESSURE ACROSS THE CENTRAL ATLANTIC WILL CONTINUE TO MAINTAIN
MODERATE TO FRESH TRADE WINDS ACROSS THE REGION THROUGH FRIDAY.
WINDS WILL DIMINISH DURING THE WEEKEND AND WILL SHIFT SOUTHERLY.


&&

.DISCUSSION...ACTIVE AFTERNOON ACROSS THE LOCAL AREA AS BROAD AREA
OF LOW PRESSURE...AND ASSOCIATED MOISTURE AFFECTED THE REGION.
HEAVY RAINFALL WITH CLUSTER OF THUNDERSTORMS WERE NOTED SOUTH OF
THE CORDILLERA CENTRAL...AS THIS MOISTURE COMBINED WITH SEA BREEZE
CONVERGENCE AND LOCAL EFFECTS. RAINFALL OBSERVED IN SOME U.S.G.S
SENSOR INDICATED AROUND 2 INCHES IN 1 HOUR OVER PORTUGUES RIVER IN
PONCE...AND RADAR ESTIMATES SHOWED BETWEEN 1 TO 2 INCHES OVER
JUANA DIAZ. LATEST SATELITE IMAGES SHOWS A DRIER AIR MASS EAST OF
THE LOCAL ISLANDS. THIS AREA OF RELATIVELY DRIER AIR WILL MOVE
ACROSS THE AREA TONIGHT AND EARLY FRIDAY...WHICH WILL LIMIT THE
SHOWER ACTIVITY ACROSS THE REGION. HOWEVER...AVAILABLE MOISTURE
WILL COMBINE WITH DAYTIME HEATING AND LOCAL EFFECTS TO PRODUCE
SOME SHOWERS AND THUNDERSTORMS OVER THE INTERIOR SECTION OF PUERTO
RICO.

WINDS WILL TURN MORE SOUTHEAST DURING THE WEEKEND WHICH WILL
INDUCE HIGHER THAN NORMAL MAXIMUM TEMPERATURES MAINLY ALONG THE
NORTH COAST OF PUERTO RICO. ALSO...AFTERNOON CONVECTION IS
EXPECTED TO DEVELOP MAINLY IN THE NORTHWEST SECTIONS OF PUERTO
RICO. IN THE LONG TERM AT THIS TIME...COMPUTER MODELS DOESN`T SHOW
ANY SIGNIFICANT WATER EVENT AFFECTING THE LOCAL AREA.


&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS ALL TERMINALS AS BAND OF
MOISTURE MOVED WESTWARD AND AWAY OF THE FCST AREA THIS AFTERNOON.
MID TO HIGH CLOUDS WILL PERSIST UNTIL TONIGHT OVER MAINLAND PUERTO
RICO. AFTER 13/10Z...SHOWERS WILL BE OVER THE WATERS NEAR TKPK AND
TNCM. THE WIND FROM SFC UP TO 3 KFT WILL BE MAINLY EAST NORTHEAST AT
5-15 KTS.


&&

.MARINE...SEAS OF 5 FEET OR LESS AND WINDS OF 17 KNOTS OR LESS ARE
EXPECTED OVER THE COASTAL WATERS.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 87 79 89 / 40 40 20 20
STT 79 89 79 88 / 40 50 30 30

[cycloneye]

8 PM Tropical Weather Outlook.

SHOWER ACTIVITY ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE
CENTERED ABOUT 450 MILES EAST OF THE LEEWARD ISLANDS REMAINS
LIMITED...AND ENVIRONMENTAL CONDITIONS ARE NOT FAVORABLE FOR
DEVELOPMENT. THIS SYSTEM HAS A LOW CHANCE...10 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. WHILE
UPPER-LEVEL WINDS COULD BECOME A LITTLE MORE FAVORABLE IN SEVERAL
DAYS...THIS SYSTEM STILL HAS A LOW CHANCE...20 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS AS IT MOVES
TOWARD THE WEST-NORTHWEST AT AROUND 10 MPH.

[Macrocane]

This map shows yesterday rainfall in El Salvador, as you can see the coast was very very wet, actually September 11, 2013 was the wettest day in the country since October 16, 2011:



Rainfall in selected locations:

Hacienda Melara 181 mm/7.13 inches
Jucuarán 162 mm/6.38 inches
Chiltiupán 136 mm/5.35 inches
El Salvador International Airport 131 mm/5.16 inches
La Hachadura 123 mm/4.84 inches
Conchagua 109 mm/4.29 inches

The bad news is that one man is missing after he was swept away by a river.

[Macrocane]

The rainy pattern in northern Central America will persist for a few more days, although the rains today were much lower than yesterday (at least in El Salvador, in Guatemala it's another story).

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 PM EDT THU SEP 12 2013

NOTE: A PROLONGED PERIOD OF HEAVY RAINS IS EXPECTED OVER EASTERN
AND SOUTHERN MEXICO INTO NORTHERN CENTRAL AMERICA. HEAVIEST RAINS
ARE EXPECTED ESPECIALLY ACROSS THE GULF OF MEXICO BASIN/SIERRA
MADRE ORIENTAL. MODELS ARE AGREEING ON SOME OF THESE AREAS
RECEIVING AMOUNTS OF 40 INCHES OR 1000MM DURING THE NEXT 05
DAYS...IN PARTICULAR DURING THE WEEKEND. THIS IS A VERY DANGEROUS
SITUATION WITH A HIGH RISK FOR FLASH FLOODS AND MUDSLIDES.

DISCUSSION FROM SEPTEMBER 12/00UTC: SEASONALLY ACTIVE CONVECTION
IS PRODUCING VERY HEAVY RAINS ACROSS MOST OF SOUTHERN AND EASTERN
MEXICO/NORTHERN CENTRAL AMERICA. DEEP MOISTURE POOL...BROAD DEEP
CYCLONIC CIRCULATIONS...EASTERN PACIFIC ITCZ AND WEAK UPPER LEVEL
FLOW ARE LEADING TO WIDESPREAD TROPICAL CONVECTION. THE LATTER IS
STRENGTHENING AN UPPER HIGH THAT WILL MAINTAIN APPROPRIATE
VENTILATION...TO IN TERM SUSTAIN WET SPELL OVER SEVERAL FOLLOWING
DAYS. FURTHERMORE...BROAD SURFACE LOWS ARE ORGANIZING OVER BOTH
THE GULF OF CAMPECHE AND OFF THE COAST OF SOUTHWESTERN MEXICO
ALONG THE ITCZ. SEE THE NHC WEBSITE FOR UPDATES ON THE POTENTIAL
FOR TROPICAL CYCLONE FORMATION AND EVOLUTION. IN TERMS OF RAINFALL
AMOUNTS...THROUGH 36 HRS EXPECTING HEAVIEST AMOUNTS OVER
SOUTHEASTERN MEXICO INTO GUATEMALA WITH AMOUNTS OF 50-75MM AND
ISOLATED MAXIMA OF 125-250MM IN INTERACTION WITH OROGRAPHY.
LOCALLY HEAVY RAINFALL IS ALSO EXPECTED ACROSS TAMAULIPAS/NORTHERN
SIERRA MADRE ORIENTAL WITH AMOUNTS OF 15-30MM/DAY AND MAXIMA OF
40-80MM. ALONG THE SIERRA MADRE DEL SUR EXPECTING 15-20MM/DAY AND
MAXIMA OF 30-60MM. BY 36-84 HRS...EXPECTING HEAVIEST STILL ACROSS
SOUTHEASTERN MEXICO AND WESTERN GUATEMALA WITH AMOUNTS OF
75-100MM/DAY AND ISOLATED MAXIMA OF 200-300MM IN INTERACTION WITH
OROGRAPHY. ACROSS NORTHEASTERN MEXICO...A NEW SURGE IN CONVECTION
BY 60-84 HRS WILL INCREASE AMOUNTS ONCE AGAIN TO 15-30MM/DAY AND
MAXIMA OF 40-80MM.

NORTHERN CENTRAL AMERICA WILL ALSO REMAIN QUITE ACTIVE UNDER
DIRECT INFLUENCE OF THE EASTERN PACIFIC ITCZ AND FORMIDABLE
VENTILATION AS UPPER HIGH BUILDS TO THE NORTHWEST. LOW-LEVEL
SOUTHWESTERLIES WILL ENHANCE CONVECTION ESPECIALLY ACROSS THE
PACIFIC BASIN AND HIGHLANDS OF GUATEMALA-EL SALVADOR-HONDURAS
NORTHERN NICARAGUA. ON DAY 01 EXPECTING HEAVIEST OVER AND WEST OF
EL SALVADOR/GULF OF FONSECA WITH AMOUNTS OF 50-75MM/DAY AND MAXIM
OF 125-250MM. BY 36-84 HRS EXPECTING A DECREASE TO 10-15MM/DAY AND
MAXIMA OF 20-35MM. HIGHER AMOUNTS ARE EXPECTED IN WESTERN TIER.
THE YUCATAN PENINSULA WILL ALSO RECEIVE PERSISTENT HEAVY RAINS
WITH AMOUNTS GENERALLY IN THE 15-20MM/DAY AND MAXIMA OF 25-50MM
RANGE.

TO THE EAST...TUTT IS MEANDERING ACROSS THE CENTRAL CARIBBEAN
WHILE INTERACTING WITH WAVES IN THE EASTERLIES. TUTT IS ALSO
DRAWING THE ITCZ MOISTURE NORTHWARD LEADING TO STRONGEST AND MOST
WIDESPREAD DEEP CONVECTION ACROSS THE OPEN WATERS OF THE CENTRAL
CARIBBEAN/NORTHERN GUAJIRA PENINSULA WHILE ISOLATED CELLS DOT
NORTHERN SOUTH AMERICA. TUTT WILL MOVE LITTLE THROUGH THE CYCLE
WHILE SLOWLY MEANDERING NORTHWESTWARD. AS IT DOES SO...IT WILL
SUSTAIN DIURNAL THUNDERSTORMS OVER JAMAICA THROUGH THE CYCLE AND
SCATTERED THUNDERSTORMS OVER THE CAYMAN ISLANDS. UPPER VENTILATION
WILL REMAIN FAVORABLE WHILE TUTT PRESSES AGAINST UPPER RIDGE
ACROSS NORTHERN CENTRAL AMERICA. SOME ENHANCEMENT OF DIURNAL
CONVECTION IS ALSO EXPECTED ACROSS HISPANIOLA...AIDED BY SURGE IN
THE TRADES AND ASSOCIATED LOW-LEVEL MOISTURE CONVERGENCE ARRIVE.
OVER THE BAHAMAS...SURGE IN THE TRADES WILL ALSO ENHANCE
CONVECTION SLIGHTLY. THROUGH 36 HRS...EXPECTING HEAVIEST OVER
WESTERN CUBA WITH 10-15MM/DAY AND MAXIMA OF 20-30MM. BY 36-60
HRS...HEAVIEST WILL DOT HAITI AND THE HIGHLANDS OF THE DOMINICAN
REPUBLIC WITH AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. ON DAY
03...EXPECTING HEAVIEST OVER CUBA WITH AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-30MM.

SOUTHERN CENTRAL AMERICA AND COLOMBIA WILL REMAIN UNDER A
SEASONALLY DRY PATTERN. TUTT ACROSS THE CENTRAL CARIBBEAN WILL
ENHANCE A FEW ISOLATED DEEP CELLS OVER COLOMBIA INTO THE CARIBBEAN
COAST...BUT INFLUENCE WILL BE STRONGER OFFSHORE. EXPECTING
ISOLATED DEEP CONVECTION AND SCATTERED SHALLOW CONVECTION TO
DOMINATE MOST OF THE REGION. MOST CONVECTION WILL CLUSTER OVER THE
CHOCO-ANTIOQUIA-BAJO MAGDALENA-LAKE MARACAIBO AND GUAJIRA
PENINSULA. ON DAY 01...EXPECTING AMOUNTS OF 10-15MM/DAY AND MAXIMA
OF 20-30MM ALONG NORTHERN COAST...DECREASING AFTERWARDS. ELSEWHERE
IN THE REGION EXPECTING 05-10MM/DAY AND MAXIMA OF 15-25MM THROUGH
THE CYCLE.

ACROSS VENEZUELA TRANSIENT QUIET PATTERN IS DOMINATED BY ISOLATED
CONVECTION AS SUBSIDENCE INVERSION IS ADVECTED FROM THE NORTHEAST
AND MID/UPPER RIDGE BUILDS. PATTERN WILL GRADUALLY EVOLVE TO A
WETTER ONE TOWARDS DAY 03 AIDED BY SOUTHERN HEMISPHERE TUTT
ORGANIZING ACROSS CENTRAL AMAZONIA...AND TROPICAL WAVE ARRIVING IN
THE REGION FROM THE ATLANTIC. EXPECTING AMOUNTS TO INCREASE TO
05-10MM/DAY AND MAXIMA OF 15-25MM.

THE MOST REMARKABLE FEATURE IN THE EASTERN CARIBBEAN IS A SURGE IN
THE TRADES THAT IS ENHANCING LOW-LEVEL MOISTURE CONVERGENCE ALONG
A CORRIDOR FROM PUERTO RICO-CENTRAL ANTILLES TO BARBADOS AS IT
PROGRESSES SOUTHWESTWARD. MODELS ARE SHOWING THIS SYSTEM WEAKENING
AS THE CYCLE PROGRESSES WHILE PRODUCING STRONGEST CONVECTION
TODAY. ACROSS PUERTO RICO EXPECTING AMOUNTS OF 10-15MM/DAY AND
MAXIMA OF 20-30MM. ACROSS BARBADOS/CENTRAL ANTILLES/NORTHERN
WINDWARDS EXPECTING 05-10MM/DAY AND ISOLATED MAXIMA OF 15-30MM.
NEXT SURGE IN CONVECTION IS EXPECTED BY LATE CYCLE IN ASSOCIATION
WITH ARRIVING TROPICAL WAVE. THIS WILL PRODUCE AMOUNTS OF
05-10MM/DAY AND MAXIMA OF 15MM ACROSS THE LESSER ANTILLES
INCREASING LATER ON. OTHERWISE...EXPECTING LARGE SCALE SUBSIDENCE
AND ONLY SHALLOW CONVECTION IN COMPENSATION FOR WIDESPREAD
ACTIVITY ACROSS WESTERN CARIBBEAN/NORTHERN CENTRAL AMERICA AND
MEXICO.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL 24 36 48 60 72 84 96 TYPE
57W 60W 63W 66W 68W 71W 75W 78W TW
70W 74W 76W 79W 83W 86W 89W 91W EW
76W 78W 81W 85W 88W 91W 93W DISSIPATES TW

TROPICAL WAVE INITIALIZED ALONG 57W MOVES OVER THE SOUTHERN
LEEWARD ISLANDS EARLY IN THE CYCLE. MOISTURE SURGE IS BEHIND THE
WAVE AXIS. OVER THE ISLANDS...THIS IS EXPECTED TO PRODUCE RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-30MM. WAVE REMAINS IN
PHASE WITH A DEEP TUTT OVER NORTHEASTERN CARIBBEAN. TUTT IS
EXPECTED TO DECREASE CONVECTION ALONG THE NORTHERN PORTION OF THE
AXIS ON DAY 02. OVER EASTERN VENEZUELA AND THE GUIANAS...EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-30MM. THROUGH 72
HOURS...THE WAVE IS IN PHASE WITH THE CENTRAL CARIBBEAN TUTT OVER
THE GREATER ANTILLES. ACROSS HISPANIOLA AND JAMAICA...THIS IS TO
FAVOUR RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-25MM.

EASTERLY WAVE INITIALIZED ALONG 70W IS UNDER THE INFLUENCE OF A
TUTT OVER THE CENTRAL CARIBBEAN ALONG LONGITUDE 70-73W. THE WAVE
IS TO UNDERGO BRIEF EROSION OF MOISTURE...NORTH ALONG THE
AXIS...DUE TO UPPER LEVEL SHEAR. IN INTERACTION WITH THE ITCZ OVER
WESTERN COLOMBIA/PANAMA...IT IS TO FAVOUR RAINFALL AMOUNTS OF
10-15MM/DAY AND MAXIMA OF 20-30MM EARLY IN THE CYCLE. BY 72
HOURS...THE WAVE ENHANCES DIURNAL CONVECTION OVER CUBA...TO RESULT
IN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. OVER
NICARAGUA/COSTA RICA...EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-35MM. THROUGH 72 TO 96 HOURS...WAVE IS TO BECOME
ABSORBED BY A BROAD AREA OF LOW PRESSURE OVER SOUTHERN
MEXICO/GUATEMALA. THIS ENHANCES ORGANISED DEEP CONVECTION TO
RESULT IN HEAVY RAINFALL AMOUNTS.

LOW AMPLITUDE TROPICAL WAVE ALONG 76W CONTINUES TO ENHANCE
CONVECTION ALONG THE PACIFIC ITCZ EARLY IN THE CYCLE. THROUGH 36
HOURS SOME FORCING IS EXPECTED OVER PANAMA COSTA RICA...RESULTING
IN RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM. THROUGH
48 TO 84 HOURS...MOST ACTIVE CONVECTION IS EXPECTED OVER CENTRAL
AMERICA AS WAVE INTERACTS WITH DEEPENING LOW PRESSURE OVER THE
AREA. THIS ENHANCES DEEP CONVECTION OVER NICARAGUA/HONDURAS ON DAY
02. THE NHC GIVES THE AREA A HIGH CHANCE TROPICAL CYCLONE
DEVELOPMENT. WAVE INCREASES INSTABILITY OVER
NICARAGUA/HONDURAS...RESULTING IN RAINFALL AMOUNTS OF 10-15MM/DAY
AND MAXIMA OF 20-35MM.

MILLER...CINWS (CAYMAN ISLANDS)
ROBINSON...MSJ (JAMAICA)
GALVEZ...WPC (USA)

[cycloneye]

Good morning. Some showers will move thru PR today and thru the weekend as troughs move by the area.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
437 AM AST FRI SEP 13 2013

.SYNOPSIS...SURFACE LOW EAST OF THE LESSER ANTILLES AND BROAD ASSOCIATED
TROUGH WHICH EXTENDS FROM THE SOUTHEAST CARIBBEAN NORTHEASTWARDS
ACROSS THE WINDWARD ISLANDS THEN INTO THE TROPICAL ATLANTIC...WILL
MOVE SLOWLY WESTWARD INTO THE EAST AND CENTRAL CARIBBEAN BY SATURDAY...
AS THE ATLANTIC HIGH PRESSURE RIDGE BUILDS NORTH OF THE LOCAL
AREA. IN THE MID TO UPPER LEVELS...RETROGRESSING TUTT LOW LOCATED
SOUTH OF HAITI CONTINUED WESTWARD TOWARDS THE CENTRAL CARIBBEAN...AS
UPPER LEVEL RIDGE BUILDS ACROSS THE EASTERN CARIBBEAN. THE UPPER
RIDGE IS THEN EXPECTED LINGER OVER REGION THE THE NEXT FEW DAYS...AS
A LOW TO MID LEVEL TROUGH ENTERS AND CROSSES THE NORTHEAST CARIBBEAN
SATURDAY THROUGH EARLY SUNDAY. THIS EXPECTED PATTERN WILL THEN INCREASE
A LOW TO MID LEVEL SOUTHERLY FLOW THROUGH AT LEAST SUNDAY.

&&

.DISCUSSION...HIGH PRESSURE RIDGE NORTH OF THE AREA AND SURFACE TROUGH
EAST OF THE LESSER ANTILLES INDUCING A LIGHT TO MODERATE NORTHEASTERLY
FLOW ACROSS THE REGION AS THE TROUGH CONTINUED WESTWARD TOWARDS
THE AREA. LATEST SATELLITE IMAGERY SHOWED SLOT OF DRY AND STABLE
AIR FILTERING ACROSS THE NORTHEAST CARIBBEAN IN ADVANCE OF APPROACHING
TROUGH. DOPPLER WEATHER RADAR SHOWED ONLY LIGHT PASSING SHOWERS
MOVING SOUTHWESTWARDS TOWARDS THE REGION IN THE PREVAILING NORTHEAST
WIND FLOW. FEW SHOWERS WILL REACH PARTS OF THE NORTH AND EAST COASTAL
SECTIONS DURING THE EARLY MORNING HOURS... FOLLOWED BY GRADUAL CLEARING
BY LATE MORNING. ALTHOUGH PWAT VALUES HAVE DECREASE SINCE RECENT DAYS...
EXPECT SUFFICIENT LINGERING MOISTURE TO COMBINE WITH LOCAL AND DIURNAL
EFFECTS TO PRODUCE AFTERNOON CONVECTION ACROSS PARTS OF THE ISLANDS.
WITH THE EXPECTED WIND FLOW THE CONVECTIVE ACTIVITY TO BE FOCUSED MAINLY
ACROSS PARTS OF THE CENTRAL INTERIOR AND WEST TO SOUTHWEST SECTIONS
OF PUERTO RICO. SOME ACTIVITY MAY BE ENHANCED ACROSS THESE AREAS AND
COULD LEAD TO PERIODS OF LOCALLY HEAVY DOWNPOURS AND URBAN AND SMALL
STREAM FLOODING IN ISOLATED SPOTS.

FOR SATURDAY AND SUNDAY...OCCASIONAL SURGES OF TROPICAL MOISTURE
WILL MOVE ACROSS THE AREA AS THE SURFACE TROUGH ENTERS THE EASTERN
CARIBBEAN AND MOVES ACROSS THE REGION. THE AVAILABLE MOISTURE ALONG
WITH THE MEANDERING TUTT JUST WEST OF THE AREA WILL LEAD TO CONVECTIVE
DEVELOPMENT ESPECIALLY DURING THE EARLY MORNING AND AFTERNOON HOURS.
ALL IN ALL NO WIDESPREAD RAINFALL OR SIGNIFICANT WEATHER FEATURE IS
FORECAST TO DIRECTLY AFFECT THE LOCAL AREA DURING THE NEXT FEW DAYS
AND THROUGH THE UPCOMING WEEKEND.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED THIS MORNING ACROSS THE
LOCAL FLYING AREA. WINDS WILL BE FROM THE EAST NORTHEAST AFTER
13/12Z AT AROUND 10 KNOTS WITH SEA BREEZE VARIATIONS DEVELOPING
LATER...ESPECIALLY AT TJPS AND TJMZ. SHRA/TSRA EXPECTED TO DEVELOP
ACROSS THE INTERIOR AND SOUTHWEST PUERTO RICO WITH VCTS EXPECTED
AFTER 13/17Z...ACROSS TJBQ AND TJMZ.

&&

.MARINE...SEAS WERE HIGHEST NORTH OF THE LOCAL ATLANTIC WATERS WITH
BUOY 41043 REPORTING JUST OVER 5 FEET. OTHERWISE SEAS WERE GENERALLY
4 FEET OR LESS. WINDS MAY REACH 18 KNOTS BRIEFLY IN THE CARIBBEAN
SO MARINERS WILL NEED TO EXERCISE CAUTION THERE...BUT ELSEWHERE
RELATIVELY QUIET SEAS CAN BE EXPECTED WITH PROTECTED AREAS RUNNING
2 FEET OR LESS.
LIGHT WINDS AND TRANQUIL SEAS PREVAIL ACROSS THE ENTIRE
REGION...WITH SEAS OF AROUND 4 FEET OR LESS AND WINDS OF 17 KNOTS OR
LESS. HOWEVER...INCREASING CHANCE FOR THUNDERSTORMS ACROSS LOCAL
WATERS OVERNIGHT THROUGH SUNDAY AND POSSIBLY INTO MONDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 88 78 88 79 / 40 20 30 30
STT 89 79 88 80 / 40 30 30 30

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
248 PM AST FRI SEP 13 2013

.SYNOPSIS...BROAD SURFACE TROUGH ACROSS THE LESSER ANTILLES INTO THE
TROPICAL ATLANTIC WILL ENTER THE EASTERN CARIBBEAN SATURDAY. A MID
TO UPPER LEVEL RIDGE ACROSS THE FORECAST AREA WILL CONTINUE TO PREVAIL
OVER THE NEXT FEW DAYS. TUTT LOW OVER THE CENTRAL CARIBBEAN WILL
CONTINUE TO MEANDER WEST OF LOCAL ISLANDS DURING THE WEEKEND AS IT
DISSIPATES.

&&

.DISCUSSION...A GENERALLY FAIR WEATHER PATTERN PREVAILED ACROSS THE
LOCAL ISLANDS TODAY. SHOWERS WERE NOTED IN A COUPLE OF LOCATIONS...
MAINLY ACROSS NORTHEAST PR AS WELL AS SAINT THOMAS/SAINT JOHN IN THE
MORNING HOURS...AND OVER PORTIONS OF THE CORDILLERA CENTRAL...SOUTH
AND SOUTHWEST PUERTO RICO IN THE AFTERNOON. SOME OF THESE SHOWERS
WERE ACCOMPANIED BY ISOLATED THUNDERSTORMS.

TODAY`S SHOWER AND THUNDERSTORM ACTIVITY WILL DIMINISH AROUND SUNSET...
LEAVING PARTLY CLOUDY SKIES. FOR TONIGHT INTO SATURDAY MORNING...A
GENERALLY FAIR WEATHER PATTERN IS ALSO EXPECTED WITH A FEW SHOWERS
ACROSS THE NORTH AND EAST COASTAL AREAS OF PUERTO RICO/USVI. THESE
SHOWERS ARE STILL INCLUDED IN THE FORECAST DUE TO A MOISTURE SURGE
MOVING IN FROM THE NORTHEAST. HOWEVER...FORECAST SOUNDINGS SUGGESTED
PRECIPITABLE WATER VALUES BELOW 2.0 INCHES.

BROAD SURFACE TROUGH AND ASSOCIATED LOW LEVEL MOISTURE ACROSS THE
LESSER ANTILLES INTO THE TROPICAL ATLANTIC WILL ENTER THE EASTERN
CARIBBEAN SATURDAY. AS THIS FEATURE MOVES WEST OVER THE LOCAL AREA...
LOW LEVEL WINDS WILL SHIFT EAST SOUTHEAST. UNDER THE INFLUENCE OF
AFOREMENTIONED SURFACE TROUGH AND ASSOCIATED LOW LEVEL MOISTURE...
EXPECT PASSING SHOWERS ACROSS THE SOUTHEAST COASTAL SECTIONS OF THE
ISLANDS DURING THE MORNING HOURS...FOLLOWED BY AFTERNOON CONVECTION
WHICH WILL BE MAINLY FOCUSED ACROSS THE NORTHERN SLOPES INCLUDING
PORTIONS OF THE SAN JUAN METRO AREA BOTH DAYS...SATURDAY AND SUNDAY.
THIS SOUTHEASTERLY FLOW WILL ALSO RESULT IN WARMER TEMPERATURES.
MODEL GUIDANCE CONTINUED TO INDICATE A WETTER PATTERN DEVELOPING
EARLY NEXT WEEK...WITH PRECIPITABLE WATER VALUES REACHING 2 INCHES
BY MONDAY AFTERNOON.

&&

.AVIATION...MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS THE LOCAL
FLYING AREA FOR THE NEXT 24 HOURS. SFC WINDS UP TO 3 KFT WILL CONTINUE
FROM THE EAST NORTHEAST AT 5-15 KT...BCMG SOUTHEAST AFTER 14/12Z AT
AROUND 10 KT.

&&

.MARINE...TRANQUIL MARINE CONDITIONS EXPECTED OVER THE WEEKEND...
WITH SEAS OF UP TO 4 FEET AND WINDS OF UP TO 15 KNOTS.

&&

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

[cycloneye]

Good morning. Mainly dry and warm weather will prevail this weekend in PR with only the typical afternoon showers in the interior.



AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
538 AM AST SAT SEP 14 2013

.SYNOPSIS...SURFACE TROUGH ACROSS THE EASTERN CARIBBEAN EARLY THIS
MORNING WILL CONTINUE TO MOVE ACROSS THE LOCAL ISLANDS TODAY. MID
LEVEL RIDGE WILL PREVAIL ACROSS THE REGION DURING FOR THE REST OF
THE WEEKEND. TUTT LOW OVER THE CENTRAL CARIBBEAN WILL CONTINUE TO
MEANDER SOUTH OF HISPANIOLA DURING THE NEXT FEW DAYS.

&&

.DISCUSSION...LATEST RADAR IMAGES THIS MORNING DEPICTED ISOLATED TO
SCATTERED SHOWERS MOSTLY ACROSS THE SURROUNDING COASTAL WATERS. FEW
OF THESE SHOWERS AFFECTED THE EASTERN SECTIONS OF PUERTO RICO AS
WELL AS VIEQUES...CULEBRA AND THE USVI. THIS ACTIVITY WAS ASSOCIATED
WITH A WEAK SURFACE TROUGH MOVING ACROSS THE LOCAL AREA TODAY. A MID
TO UPPER LEVEL RIDGE ACROSS THE REGION WILL INHIBIT THE DEVELOPMENT
OF SIGNIFICANT SHOWERS AND THUNDERSTORMS ACTIVITY. AS THE TROUGH
MOVES FURTHER WESTWARD THIS AFTERNOON...THE WINDS FLOW IS EXPECTED
TO BECOME FROM THE SOUTHEAST. THE SOUTHEASTERLY WIND FLOW IN
COMBINATION WITH DAYTIME HEATING...SEA BREEZE DEVELOPMENT AND LOCAL
EFFECTS ARE EXPECTED TO INDUCE SHOWERS AND A FEW THUNDERSTORMS
MOSTLY ACROSS THE NORTHERN AND NORTHWESTERN SECTIONS OF PUERTO RICO
THIS AFTERNOON. HOWEVER...NO SIGNIFICANT OR WIDESPREAD PRECIPITATION
IS EXPECTED AT THIS TIME AS THE MID LEVEL RIDGE REMAINS OVER THE
REGION. WARMER THAN NORMAL TEMPERATURES ARE ALSO EXPECTED THIS
AFTERNOON AND SUNDAY MAINLY ACROSS NORTHERN COASTAL MUNICIPALITIES
OF PUERTO RICO.

THE GFS MODEL GUIDANCE SUGGESTS THAT A TUTT LOW OVER THE CENTRAL
CARIBBEAN SOUTH OF HISPANIOLA AND CUBA WILL MEANDER OVER THAT AREA
FOR THE NEXT FEW DAYS WHILE DISSIPATES. ONLY THE TYPICAL AFTERNOON
CONVECTION ARE EXPECTED FOR THE REST OF THE WEEKEND. HOWEVER...A
SURGE OF TROPICAL MOISTURE WILL ENCOMPASS THE REGION FROM THE
SOUTHEAST EARLY NEXT WEEK. THESE FEATURE WILL INDUCE AN INCREASE IN
CLOUDINESS...SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE FA.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS THE LOCAL TERMINALS
OVERNIGHT. WINDS WILL BE MAINLY LIGHT FROM THE NORTHEAST UNTIL ABOUT
14/14Z WHEN THE WIND IS EXPECTED TO SHIFT TO A SOUTHEASTERLY
DIRECTION WITH SEA BREEZE VARIATIONS AT AROUND 10KTS. SHRA/TSRA
DEVELOPMENT EXPECTED AFTER 14/16Z ACROSS THE NORTHERN HALF OR
PR...WHICH COULD CAUSE SHRA/TSRA IN AND AROUND TJSJ...TJBQ...AND TJMZ.

&&

.MARINE...TRANQUIL MARINE CONDITIONS EXPECTED TO CONTINUE OVER THE
WEEKEND...WITH SEAS OF UP TO 4 FEET AND WINDS OF UP TO 15 KNOTS.

&&

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

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
247 PM AST SAT SEP 14 2013

.SYNOPSIS...SURFACE LOW ABOUT 500 MILES NORTHEAST OF THE FORECAST
AREA WILL CONTINUE TO INDUCE A SOUTHERLY FLOW ACROSS THE LOCAL REGION
OVER THE NEXT COUPLE DAYS. TUTT LOW OVER THE CENTRAL CARIBBEAN WILL
PROVIDE DIVERGENCE/DIFFLUENCE ALOFT AND A SOUTH TO SOUTHWEST FLOW
AT UPPER LEVEL DURING THE WEEKEND. THEN...THE TUTT LOW WILL DISSIPATE
AS MOVES NORTHEAST IN RESPONSE TO AN UPPER LEVEL RIDGE BUILDING
OVER THE EASTERN CARIBBEAN EARLY NEXT WEEK.

&&

.DISCUSSION...MOISTURE ADVECTION INTERACTING WITH THE ISLAND
TOPOGRAPHY AND GOOD UPPER LEVEL DYNAMICS RESULTED IN THE DEVELOPMENT
OF SHOWERS AND THUNDERSTORMS LATE THIS MORNING AND AFTERNOON ACROSS
PORTIONS OF THE SAN JUAN AREA...NORTH CENTRAL AND NORTHWESTERN PUERTO
RICO. THE MOST ACTIVE AND PERSISTENT RAINFALL DEVELOPED DOWNWIND OF
EL YUNQUE NATIONAL FOREST...AFFECTING THE SAN JUAN METRO AREA. AS
A RESULT...THE HEAVIEST RAINFALL WAS OBSERVED IN PORTIONS OF CAROLINA
AND SAN JUAN WHERE RAINFALL ACCUMULATIONS RANGED BETWEEN ONE TO
THREE INCHES OF RAIN. SEVERAL REPORTS OF URBAN AND SMALL STREAM
FLOODING WERE RECEIVED WITH THIS ACTIVITY...HOWEVER NO REPORTS OF
FLASH FLOODING OR MAIN RIVER FLOODING HAVE OCCURRED SO FAR THIS
AFTERNOON. CONVECTION WILL TAPER OFF NEAR THE SUNSET.

SATELLITE DERIVED PWAT ANALYSIS SHOWS A DRIER AIR MASS UPSTREAM
OF THE LOCAL ISLANDS. THIS AIR MASS WILL MOVE OVER THE FORECAST
AREA TONIGHT THROUGH SUNDAY MORNING...LIMITING THE SHOWER ACTIVITY
DURING THIS TIME PERIOD. MOISTURE LEVELS WILL RECOVER AGAIN SUNDAY
AFTERNOON AND REMAIN NEAR 1.9 INCHES THROUGH MIDWEEK. IN ABSENCE
OF SYNOPTIC FORCING...EXPECT THE TYPICAL AFTERNOON CONVECTION
DEVELOPING OVER WESTERN PUERTO RICO EACH AFTERNOON. ELSEWHERE...
BRIEF ISOLATED TO SCATTERED SHOWERS ARE POSSIBLE FROM TIME TO TIME.

&&

.AVIATION...SHOWERS ENDING SHORTLY WITH VFR CONDITIONS NEXT 18 HRS.
WINDS <6 KT TONIGHT. VCTS POSSIBLE TOMORROW AT JSJ AND JBQ.

&&

.MARINE...NO SIGNIFICANT WIND WAVES OR SWELLS ARE EXPECTED OVER
THE NEXT SEVERAL DAYS. SEAS WILL REMAIN BETWEEN 2-4 FT WITH MODERATE
WINDS.

&&

.CLIMATE...AT 230 PM AST...RAIN GAGE AT THE LUIS MUNOZ MARIN
INTERNATIONAL AIRPORT HAVE MEASURED 2.88 INCHES SO FAR TODAY.
THIS BREAKS THE OLD RECORD OF 1.98 INCHES SET IN 1928 AT SAN
JUAN...PUERTO RICO.


.PRELIMINARY POINT TEMPS/POPS...
SJU 77 89 78 89 / 10 40 20 30
STT 80 89 79 90 / 20 20 30 30

[Gustywind]

Oh boy, another record for PR

[cycloneye]

Good morning. Normal weather for this time of the year will prevail for the next few days in PR with only the typical afternoon showers in the interior of the island spreading to the NW part.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
522 AM AST SUN SEP 15 2013

.SYNOPSIS...A SURFACE TROUGH EXTENDING FROM THE LESSER ANTILLES INTO
A LOW PRESSURE OVER THE ATLANTIC NORTHEAST OF THE REGION...WILL
MOVE SLOWLY ACROSS THE EASTERN AND NORTHEASTERN CARIBBEAN TODAY...
MAINTAINING AN EAST SOUTHEAST LOW LEVEL WIND FLOW ACROSS THE
REGION. TUTT LOW OVER THE CENTRAL CARIBBEAN WILL CONTINUE TO
MEANDER SOUTH OF HISPANIOLA TODAY WHILE MOVING SLOWLY NORTHWARD
AND DISSIPATES EARLY IN THE WEEK.

&&

.DISCUSSION...LATEST RADAR IMAGES THIS MORNING DEPICTED ISOLATED TO
SCATTERED SHOWERS MOSTLY ACROSS THE SURROUNDING COASTAL WATERS. FEW
THUNDERSTORMS ALSO PERSISTED OVERNIGHT OVER THE WATERS NORTHWEST
OF PUERTO RICO. NO SIGNIFICANT SHOWER ACTIVITY WAS DETECTED OVER
LAND AREAS SO FAR THIS MORNING. LATEST SATELLITE IMAGES EARLY IN
THE MORNING DEPICTED AN AREA OF GENERALLY DRY AIR ACROSS THE
NORTHEAST CARIBBEAN. THIS FEATURE WILL LIMIT THE SHOWERS DEVELOPMENT
ACROSS THE FA FOR THE REST OF THE MORNING HOURS. HOWEVER...A
SURFACE LOW NORTHEAST OF THE REGION AND AN ASSOCIATED SURFACE
TROUGH EXTENDING FROM THE AFOREMENTIONED LOW PRESSURE CENTER INTO
THE LESSER ANTILLES...WILL MOVE SLOWLY ACROSS THE EASTERN AND
NORTHEASTERN CARIBBEAN THIS AFTERNOON. THE MOISTURE ASSOCIATED
WITH THIS FEATURE WILL COMBINE WITH DIURNAL HEATING...SEA BREEZE
DEVELOPMENT AND LOCAL EFFECTS TO INDUCE THE DEVELOPMENT OF SHOWERS
AND THUNDERSTORMS ACROSS THE REGION THIS AFTERNOON. DUE TO THE
EAST SOUTHEAST LOW LEVEL WIND FLOW...THE MOST AFFECTED AREAS WILL
BE THE WESTERN...INTERIOR AND NORTHWEST SECTIONS OF PUERTO RICO.

A TUTT LOW JUST SOUTH OF HISPANIOLA...WILL CONTINUE TO MOVE SLOWLY
NORTHWARD WHILE DISSIPATES EARLY IN THE WEEK. THUS...FOR THE NEXT
SEVERAL DAYS...IN ABSENCE OF SYNOPTIC FORCING...EXPECT ONLY THE
TYPICAL AFTERNOON CONVECTION OVER WESTERN AND INTERIOR PUERTO
RICO EACH AFTERNOON WITH ISOLATED TO SCATTERED PASSING SHOWERS
ACROSS EASTERN SECTIONS OF PUERTO RICO AS WELL AS ACROSS
VIEQUES...CULEBRA AND THE USVI EACH MORNING.

&&

.AVIATION...VFR CONDS WILL PREVAIL ACROSS THE LOCAL TAF SITES DURG
THE PRD. WINDS WILL BE LIGHT FM THE SOUTHEAST AND VEERING H/HT UP TO
FL400. DURG THE AM TIL 15/14Z...FEW PASSING -SHRA ACROSS THE COASTAL
WATERS OF LCL FLYING AREA WITH SCT L/LVL CLD LYRS AT FL020-FL070.
LOCAL SEA BREEZE VARIATIONS AFT 15/15Z AND DAYTIME HEATING WILL LEAD
ISOLD-SCT SHOWERS AND ISOLD TSTMS MAINLY ACROSS THE NRN HALF OF PR.
AS A RESULT PSBL MVFR CONDS DUE TO CLDS/SHRA/ISOLD TSTM...IN AND
AROUND TJSJ...TJBQ...AND TJMZ.

&&

.MARINE...QUIET MARINE CONDITION WILL PREVAIL ACROSS THE REGIONAL
WATERS TODAY WITH SEAS OF 2 TO 4 FEET AND WINDS OF 15 KNOTS OR
LESS. HIGHER WINDS AND SEAS ARE POSSIBLE THIS AFTERNOON NEAR
SHOWERS AND THUNDERSTORMS ACROSS THE WESTERN COASTAL WATERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 90 78 89 78 / 40 20 30 20
STT 88 79 89 80 / 20 30 30 40

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
245 PM AST SUN SEP 15 2013

.SYNOPSIS...UPPER LEVEL LOW JUST SOUTH OF HISPANOLA WILL WEAKEN
DURING THE NEXT 24-36 HRS AS MOVES NNE INTO THE WESTERN ATLANTIC.
A TROUGH PATTERN WILL ESTABLISH OVER THE WESTERN ATLANTIC THE
FIRST PART OF THE WEEK. THIS WILL ALLOW THE UPPER LEVEL FLOW TO
REMAIN FROM THE SOUTH TO SOUTHWEST THROUGH AT LEAST MIDWEEK. MOISTURE
LEVELS WILL REMAIN RELATIVELY HIGH MOST OF THE WEEK. IN GENERAL...
THIS WET ENVIRONMENT ALLOW THE DEVELOPMENT OF SCATTERED SHOWERS
EVERY DAY...WITH THE HEAVIEST RAINFALL ACTIVITY EXPECTED OVER
WESTERN PUERTO RICO WHERE SCATTERED THUNDERSTORMS ARE LIKELY
EACH AFTERNOON.

&&

.DISCUSSION...A WEAKENING SURFACE TROUGH NORTHEAST OF THE LOCAL
ISLANDS CONTINUES TO MOVE NW ACROSS THE ATLANTIC. UPPER LEVEL LOW
OVER DOMINICAN REPUBLIC WILL CONTINUE TO PROVIDE DIFFLUENCE ALOFT
AS WELL AS A STRONG SE FLOW ALOFT. ALTHOUGH...UPPER LEVEL DYNAMICS
ARE GOOD TO SUPPORT THUNDERSTORMS...UPPER LEVEL CLOUDINESS AND A
RELATIVELY LOW MOISTURE CONTENT HAVE LIMITED THE SHOWER AND
THUNDERSTORM COVERAGE ACROSS MAINLAND PUERTO RICO TODAY. DOPPLER
RADAR HAVE DETECTED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS
PORTIONS OF NORTH CENTRAL AND NORTHWEST PR. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE POSSIBLE OVER THESE AREAS UNTIL SUNSET.

OPERATIONAL MODELS SHOW REGION OF CONVECTIVE INSTABILITY AND LOW
LEVEL CONVERGENCE MOVING INTO THE ISLANDS ON MONDAY...AND PERSISTING
IN THE AREA DURING SEVERAL DAYS. BEST MOISTURE CONVERGE ACROSS THE
FORECAST AREA SEEMS TO BE TUESDAY AND FRIDAY. BASICALLY...EXPECT
UNSETTLED WEATHER PATTERN MOST OF THE WEEK WITH SHOWERS AND SCATTERED
THUNDERSTORMS EACH AFTERNOON OVER THE INTERIOR AND WESTERN PUERTO
RICO. GFS AND ECMWF FORECAST SOUNDINGS INDICATED WEAK STEERING
FLOW AT LESS THAN 10 KT. THIS WILL RESULT IN LOCALIZED HEAVY
RAIN...ESPECIALLY WITH THE THUNDERSTORMS.

&&

.AVIATION...BKN HIGH CLOUDS NEXT 24 HRS. LOW LEVEL MOISTURE
INCREASES FROM THE SOUTHEAST TONIGHT AND MON WITH INCREASING CHANCES
OF SHOWERS AND THUNDERSTORMS. TSTMS COULD DEVELOP ABOUT ANYWHERE
TOMORROW. FOR NOW VCTS FOR USVI...JSJ AND JPS TERMINALS THRU 18Z
THEN AFT 18Z AT JMZ AND JBQ.

&&

.MARINE...QUIET MARINE CONDITIONS WILL PREVAIL OVER THE NEXT SEVERAL
DAYS WITH SEAS OF 2 TO 4 FEET AND WINDS OF 15 KNOTS OR LESS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 78 89 78 90 / 30 30 20 20
STT 79 89 79 88 / 50 50 40 40

[cycloneye]

Good morning. Mainly dry weather with only the typical afternoon showers will dominate the weather for this week in PR.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
520 AM AST MON SEP 16 2013

.SYNOPSIS...AT UPPER LEVELS...A WEAK UPPER LEVEL LOW OVER THE
DOMINICAN REPUBLIC IS PRODUCING SOUTHERLY FLOW OVER PUERTO RICO
AND THE U.S. VIRGIN ISLANDS. THAT LOW WILL MOVE NORTHEAST...BUT
WEAK TROUGHINESS WILL REMAIN UNTIL THE WEEKEND.

AT MID LEVELS...HIGH PRESSURE TO THE NORTHEAST WILL MOVE OVER THE
LEEWARD ISLANDS AND THE GREATER ANTILLES DURING THE WEEK. HIGH
PRESSURE REMAINS OVER THE EASTERN CARIBBEAN OVER THE WEEKEND AND
INTO NEXT WEEK. MOISTURE AT MID LEVELS REMAINS FAIRLY WEAK.

AT LOWER LEVELS...GENERALLY MOIST AND RELATIVELY WEAK FLOW
CONTINUES OVER THE AREA AS LOW PRESSURE PERSISTS ACROSS THE
SOUTHERN CARIBBEAN AND HIGH PRESSURE RIDGING FROM THE NORTHEAST
INTO THE CARIBBEAN SHIFTS TO BETWEEN 20 AND 30 NORTH LATITUDE
LATER IN THE WEEK AND SURFACE FLOW BECOMES MORE SOUTHEASTERLY.
MOISTURE IS SHALLOW AND FADES ABOVE ABOUT 6 THOUSAND FEET.

&&

.DISCUSSION...SCATTERED SHOWERS WERE OBSERVED OVER THE LOCAL
CARIBBEAN AND ATLANTIC WATERS WITH ONE GROUP OF THUNDERSTORMS TO
THE NORTHWEST OF AGUADILLA PRODUCING PRODIGIOUS AMOUNTS OF
LIGHTNING OVERNIGHT FROM CLOUDS THAT TOPPED NEAR THE TROPOPAUSE
AT 55 KFT. ONLY A FEW SHOWERS MOVED ON SHORE IN EASTERN PUERTO
RICO AND THESE DISSIPATED QUICKLY. CURRENT MODELS SUGGEST THAT THE
BEST MOISTURE WILL PASS THROUGH ON TUESDAY AFTERNOON AS WINDS
BEGIN TO SWITCH TO THE SOUTHEAST. BEST SHOWERS WILL ALSO SWITCH TO
NORTHWEST PUERTO RICO TUESDAY AFTERNOON AND THE FOCUS WILL REMAIN CLOSER TO
THE NORTH COAST THAN THE SOUTH COAST FOR THE REST OF THE FORECAST
PERIOD. CURRENTLY THE GFS SHOWS THE DRIEST WEATHER ON SUNDAY...SO
IF THE MODEL VERIFIES ONLY LIMITED SHOWERS WOULD OCCUR
THEN...WITH A QUICK RETURN OF MOISTURE EARLY IN THE WEEK NEXT
WEEK. CONFIDENCE IN THESE LAST SEVERAL FEATURES IS MODEST ONLY SO
FAR OUT IN THE FUTURE. ALTHOUGH NO SIGNIFICANT EVENTS ARE FORESEEN
IN THE NEXT 10 DAYS...WIND SPEEDS HAVE DIMINISHED OVER THOSE OF
LAST WEEK AND THIS MEANS THAT THUNDERSTORMS COULD LINGER IN ONE
PLACE LONGER THAN THEY HAVE IN THE PAST WEEKS AND MONTHS. HENCE
URBAN AND SMALL STREAM FLOODING WILL BECOME MORE LIKELY TODAY AND
TOMORROW...MAINLY OVER THE WESTERN INTERIOR AND NORTHWEST PUERTO
RICO. ISOLATED TO OCCASIONALLY SCATTERED SHOWERS WILL CONTINUE
AROUND THE U.S. VIRGIN ISLANDS UNTIL SUNDAY.

&&

.AVIATION...VFR CONDS WILL PREVAIL ACROSS ALL TERMINALS. FOR THE
REST OF THE MORNING HOURS...VCSH ARE EXPECTED DUE TO PASSING SHRA
ACROSS THE COASTAL WATERS AFFECTING MAINLY THE LOCAL ISLANDS AND
EASTERN PR. LIGHT AND VARIABLE WINDS EXPECTED...AFT 16/12Z MAINLY FM
THE EAST AROUND 10 KTS WITH SEA BREEZE VARIATIONS. AFTER 16/16Z SCT
SHRA AND ISOLD TSTMS WILL DEVELOP OVER THE INTERIOR OF PR. LEADING TO
BRIEF MVFR CONDITIONS OVER TJSJ...TJBQ AND TJMZ.

&&

.MARINE...WINDS REMAIN LESS THAN 18 KNOTS AND SEAS LESS THAN 6
FEET ACROSS THE LOCAL WATERS. SEAS WILL DIMINISH SOMEWHAT AFTER
MID-WEEK. BUT LIGHTNING WILL CONTINUE RUNNING SOMEWHAT ABOVE
NORMAL IN SCATTERED THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 89 78 90 78 / 30 20 20 40
STT 89 80 89 80 / 50 40 40 40

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
241 PM AST MON SEP 16 2013

.SYNOPSIS...UPPER LEVEL LOW NORTH OF THE DOM REP WILL MOVE ENE
NEXT 24 HRS WITH AXIS MOVING ACROSS PR EARLY WED. ANOTHER TROUGH
WILL EMERGE OFF OF THE U.S. EAST COAST MID WEEK TUE AND BECOME
CUTOFF OVR THE WRN ATLC AT THE END OF THE WEEK.

&&

.DISCUSSION...UNDER THE INFLUENCE OF AN UPPER LEVEL TROF MOST OF
THE WEEK...DEEP MOISTURE AND LIGHT SFC FLOW...CONDITIONS WILL
REMAIN FAVORABLE FOR DAILY AFTERNOON SHOWERS AND THUNDERSTORMS
OVER NWRN PR. STEERING FLOW WILL REMAIN BETWEEN 5-10 KTS FROM THE
SOUTHEAST WHICH SHOULD FAVOR SLOW STORM MOTION AND RISK OF
LOCALIZED HEAVY RAINFALL.

SOME DRYING WILL TAKE PLACE AT THE END OF THE WEEK AND EARLY NEXT
WEEK AS AREA BECOME UNDER CONVERGENT FLOW ALOFT ON THE WEST SIDE
OF UPPER LEVEL TROUGH AXIS.

&&

.AVIATION...MAINLY VFR CONDITIONS EXPECTED AT ALL TAF SITES EXCEPT
IN AND AROUND TJBQ AND TJMZ WHERE AFTERNOON CONVECTION WILL CONTINUE
PRODUCE PERIODS OF MVFR CONDS BTWN 16/17Z-21Z. MOUNTAIN OBSCURATIONS
ARE LIKELY OVER WESTERN PUERTO RICO THROUGH 16/21Z. LLVL WINDS WILL
CONTINUE FM THE E TO ESE THROUGH THE FORECAST PERIOD.

&&

.MARINE...SEAS 2-4 FT AND WINDS 10-15 KT. CG LIGHTNING IS THE MAIN
HAZARD.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU 80 90 80 91 / 20 30 30 30
STT 81 89 81 88 / 50 50 50 50