Caribbean - Central America Weather

[cycloneye]

It looks like the Caribbean rainy season has begun for most of the basin.What is worrisom is the Haiti situation as we know.

[cycloneye]

Midday discussion by NWS San Juan

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1052 AM AST SUN APR 18 2010

.DISCUSSION...MID TO UPPER LEVEL CLOUDINESS MOVING ACROSS THE FA
FROM THE SOUTHWEST AND LOW LEVEL MOISTURE MOVING ACROSS THE REGION
FROM THE EAST...WILL CONTINUE TO PROMOTE VARIABLY CLOUDINESS AND
THE DEVELOPMENT OF QUICK ISOLATED PASSING SHOWERS ACROSS THE
NORTHERN AND EASTERN PUERTO RICO...AS WELL AS ACROSS VIEQUES AND
CULEBRA DURING THE REST OF THE MORNING AND EARLY THIS AFTERNOON.
WINDS WILL CONTINUE TO DECREASE ACROSS THE REGION THIS
AFTERNOON...ALLOWING THE SEA BREEZE DEVELOPMENT ESPECIALLY ACROSS
WESTERN AND INTERIOR PUERTO RICO. THUS...THE SHOWER ACTIVITY WILL
CONCENTRATE ACROSS THE WESTERN AND INTERIOR SECTIONS OF THE ISLAND
DURING THE AFTERNOON AND EARLY EVENING HOURS. A CHANGE IN THE
PRESENT WEATHER PATTERN IS EXPECTED BY TOMORROW...AS A LOW
PRESSURE AREA DEVELOPS NORTH OF HISPANIOLA AND A MOIST AND
UNSTABLE TROPICAL LOW LEVEL FLOW MOVES ACROSS THE FA FROM THE
SOUTHEAST. SOME MINOR CHANGES WERE DONE TO THE PREVIOUS FORECAST
PACKAGE TO INCREASE THE POP`S IN FEW ZONES.

&&

.AVIATION...PERIODS OF MVFR CONDITIONS IN ISOLATED TO SCATTERED
PASSING SHOWERS ARE EXPECTED TO CONTINUE ACROSS TIST AND TJSJ UNTIL
AT LEAST 17/17Z. AFTER 17/17Z...MVFR CONDITIONS AND LOCAL MOUNTAIN
OBSCURATIONS ARE EXPECTED MAINLY OVER THE CENTRAL...WESTERN
INTERIOR...AND WEST SECTIONS OF PUERTO RICO. TJSJ 18/12Z SOUNDING
INDICATED A LIGHT AND VARIABLE WIND FLOW FROMM THE SURFACE TO AROUND
5K FEET...BECOMING FROM THE WEST SOUTHWEST ALOFT.

[cycloneye]

Afternoon discussion by NWS San Juan


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
257 PM AST SUN APR 18 2010

.SYNOPSIS...ISOLATED PASSING SHOWERS EXPECTED TO AFFECT THE
EASTERN PUERTO RICO TONIGHT. WINDS WILL DECREASE AND SHIFT
SOUTHEASTERLY ON MONDAY...ALLOWING FOR ABOVE NORMAL TEMPERATURES
...AND INCREASED SHOWER AND THUNDERSTORM ACTIVITY... ACROSS
NORTHERN PUERTO RICO THROUGH MID WEEK.

&&

.DISCUSSION...ISOLATED TO LOCALLY SCATTERED SHOWERS DEVELOPED
ALONG THE CORDILLERA CENTRAL EARLY THIS AFTERNOON. MOS OF THESE
SHOWERS WILL QUICKLY DISSIPATE AT AROUND SUNSET. LIMITED SHOWER
CONDITIONS ARE EXPECTED TO PREVAIL THROUGH AT LEAST LATE MONDAY AS
ONLY PASSING SHOWERS ARE EXPECTED ALONG THE EASTERN PORTIONS OF
PUERTO RICO TONIGHT AND ISOLATED TO SCATTERED SHOWERS ACROSS THE
WESTERN PORTIONS OF PUERTO RICO ON MONDAY AFTERNOON.

A SIGNIFICANT CHANGE IN THIS WEATHER SCENARIO IS EXPECTED TO OCCUR
ON TUESDAY...AS THE NAM AND THE GFS MODELS SUGGEST AN INCREASE ON
LOW LEVEL MOISTURE TO OCCUR ON TUESDAY AND WEDNESDAY. ALSO MUCH
MORE UNSTABLE CONDITIONS ARE EXPECTED TO PREVAIL ACROSS THE REGION FROM
TUESDAY THROUGH THURSDAY...ENHANCING THE SHOWERS AND THUNDERSTORMS
DEVELOPMENT.

&&

.AVIATION...PERIODS OF MVFR CONDITIONS IN ISOLATED TO SCATTERED
PASSING SHOWERS ARE EXPECTED TO CONTINUE ACROSS TIST AND TJSJ UNTIL
AT LEAST 18/22Z. AFTER 18/19Z...MVFR CONDITIONS AND LOCAL MOUNTAIN
OBSCURATIONS ARE EXPECTED MAINLY OVER THE CENTRAL...WESTERN
INTERIOR...AND WEST SECTIONS OF PUERTO RICO. TJSJ 18/12Z SOUNDING
INDICATED A LIGHT AND VARIABLE WIND FLOW FROMM THE SURFACE TO AROUND
5K FEET...BECOMING FROM THE WEST SOUTHWEST ALOFT.


&&

.MARINE...SEAS WILL CONTINUE TO SUBSIDE TONIGHT AND WINDS ARE
EXPECTED TO SHIFT TOWARD A MORE SOUTHEAST COMPONENT ON MONDAY.

[Macrocane]

Intermitent showers and thunderstorms have been affecting parts of El Salvador this afternoon, as you can see moisture is moving from the Pacific to the Caribbean Sea:

[tropicana]

Regional Weather Summary
Sun Apr 18 2010

Sunday's Highs and rain (if any)

Piarco, C. Trinidad 34.7C 95F trace
Crown Point, Tobago 31.2C 88F

Point Salines, Grenada 31.3C 88F
Grantley Adams, Barbados 29.8C 86F 3.0mm
Arnos Vale, St Vincent 30.1C 86F 74.1mm
Hewannora, St Lucia 31.5C 89F 3.1mm
Vigie, St Lucia 29.6C 86F 7.9mm

Melville Hall, Dominica 28.2C 83F 2.3mm
Canefield, Dominica 32.0C 90F 0.1mm

Le Lamentin, Martinique 29.8C 86F 12.0mm
Le Raizet, Guadeloupe 29.3C 85F 10.2mm

Golden Rock, St Kitts 28.7C 84F 0.4mm
VC Bird, Antigua 28.9C 84F
San Juan, Puerto Rico 28.9C 84F

Norman Manley, Jamaica 27.4C 81F 88.0mm
Owen Roberts, Grand Cayman 30.7C 87F
Havana, Cuba 29.2C 85F 28.0mm

Nassau, Bahamas 27.7C 82F 49.3mm
Hamilton, Bermuda 22.5C 73F

[cycloneye]

Updated discussion by NWS San Juan

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
952 PM AST SUN APR 18 2010

.UPDATE...CONTINUED CLOUDY CONDITIONS PREVAILED ACROSS THE REGION WITH
LATEST SATELLITE VISIBLE IMAGERY SHOWING INCREASED LOW TO MID LEVEL
CLOUDINESS ACROSS THE NORTHEAST CARIBBEAN. LATEST TJSJ 00Z SOUNDING...AS
WELL AS MIMIC-TPW CONTINUED TO SHOW A GRADUAL INCREASE IN PRECIPITABLE
WATER ACROSS THE AREA...WITH VALUES NOW IN EXCESS OF 1.70 INCHES COMPARED
TO RECENT DAYS. EXPECT THIS TREND TO CONTINUE THROUGH MUCH OF THE WORK
WEEK WITH A SIGNIFICANT INCREASE IN DEEP LAYERED TROPICAL MOISTURE ACROSS
THE REGION ESPECIALLY LATE MONDAY THROUGH WEDNESDAY. IN ADDITION...THE
MID TO UPPER LEVELS WILL BECOME MORE FAVORABLE AS THE UPPER RIDGE NOW
OVERHEAD...WILL CONTINUE TO ERODE AS A BROAD UPPER TROUGH MOVES EASTWARDS
ACROSS THE WEST AND SOUTHWEST ATLANTIC. THAT SAID...EXPECT THE INDUCED
WARM MOIST SOUTH SOUTHEAST LOW LEVEL WIND FLOW...ALONG WITH FAVORABLE
MID TO UPPER LEVEL CONDITIONS...TO CREATE AN ENVIRONMENT RIPE FOR INCREASED
CLOUDINESS WITH ENHANCED SHOWERS AND DAILY ISOLATED THUNDERSTORM DEVELOPMENT
ACROSS PARTS OF THE ISLANDS AND SURROUNDING WATERS...AT LEAST THROUGH
THE MIDDLE OF THE WORK WEEK. THIS WILL THEREFORE RESULT IN INCREASED
POTENTIAL FOR URBAN AND SMALL STREAM FLOODING DAILY. ONLY MINOR ADJUSTMENTS
WERE MADE TO THE SHORT TERM PERIOD OF THE INHERITED FORECAST PACKAGE
BASED ON LATEST GFS MODEL GUIDANCE AND PRESENT WEATHER CONDITIONS.

&&

.AVIATION UPDATE...VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES
OVERNIGHT. INCREASING CLOUDINESS WITH SHOWERS ARE POSSIBLE AFTER
19/16Z...WITH BRIEF PERIODS OF MVFR CONDITIONS EXPECTED ACROSS
TJSJ...TJMZ...AND TJBQ IN SHRA AND POSSIBLE VCTS ACROSS THESE TAF
SITES. LATEST 19/00Z TJSJ SOUNDING SHOWED SOUTHEAST WINDS FROM THE
SURFACE UP TO 3K FEET BETWEEN 5 TO 10KT...SHIFTING RAPIDLY SOUTHWEST
AND STRONGER ABOVE.

[abajan]

Latest satellite imagery shows that while an area of convection just west of Barbados is diminishing, a new one is blooming to our East-Southeast. It should be an interesting next couple of days for the Eastern Caribbean region as a whole.

[cycloneye]

Good morning to all. A wet week is instore for the Eastern Caribbean for sure.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
325 AM AST MON APR 19 2010

.SYNOPSIS...MID-UPPER LEVEL RIDGE WITH AXIS TO THE EAST OF 60W WILL
WEAKEN AS A BROAD TROUGH ESTABLISHES ACROSS THE WRN ATLC AND S/W
PERTURBATIONS PRESS AGAINST THE RIDGE. DEEP TROPICAL MOISTURE WILL
OVERSPREAD THE REGION ON SOUTH SOUTHEAST WINDS.

&&

.DISCUSSION...MOISTURE RETURN ALREADY UNDERWAY AS SEEN ON LATEST TPW
AND GOES 3.9 AND 13 MICRON IMAGERY. MODELS SHOW PWAT VALUES
CLIMBING AOA 2.0 INCHES LATER TODAY WHICH ARE WELL ABOVE TWO
STANDARD DEVIATIONS ABOVE NORMAL FOR THIS TIME OF THE YEAR WITH DEEP
TROPICAL MOISTURE STAYING WITH US UNTIL THE END OF THE WEEK. AS BROAD
TROUGH ESTABLISHES ACROSS THE WRN ATLC...S/W PERTURBATIONS MOVING
TO THE NORTH OF PR WILL LIKELY AID IN THE DEVELOPMENT OF DAILY
SHOWERS SOME OF WHICH COULD PRODUCE VERY HEAVY TO EXCESSIVE
RAINFALL GIVEN HI PW AIR AND VERY LIGHT STEERING WINDS IN WHICH
SOME CASES MODELS SHOW NO WINDS AT ALL IN THE FIRST 3KM OF THE
ATMOSPHERE. 00Z GFS ALSO SHOWS THE POTENTIAL FOR MCS DEVELOPMENT
ACROSS CARIBBEAN WATERS ESPECIALLY TUE MORNING AS SEEN ON 250MB
DIVERGENCE FIELDS. WHILE IT LOOKS LIKE THERE COULD BE SVRL
EPISODES OF HEAVY RAINFALL THROUGHOUT THE WEEK...TIMING INDIVIDUAL
S/W PERTURBATIONS EMBEDDED IN FAST UPPER FLOW WILL MAKE TIMING OF
THESE RAINFALL EPISODES VERY CHALLENGING. BOTH GFS/ECMWF ALSO SHOW
A SFC TROUGH MOVING ACROSS THE AREA LATE THU WHICH COULD ALSO
ENHANCE THE PRECIP POTENTIAL. WHILE I HAVE A GOOD DEAL OF
CONFIDENCE THAT ANOTHER SIGNIFICANT HEAVY RAINFALL EVENT SIMILAR
TO WHAT HAPPENED LAST WEEK IN NORTHEAST PR WILL OCCUR AGAIN THIS
WEEK...EXACT TIMING AND LOCATION REMAINS TO BE SEEN YET.
OVERALL...VERY WET WITH HIGH RISK OF FLASH FLOODING ESPECIALLY
EASTERN THIRD OF PR.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS ALL TAF SITES
DURING THE NEXT 12 HOURS...WITH A PREVAILING SOUTHEASTERLY LLVL WND
FLOW AT 5 TO 10 KTS. A SIGNIFICANT INCREASE IN CLOUDINESS IS
EXPECTED ACROSS THE LOCAL AREA...RESULTING IN A GENERAL INCREASE IN
SHOWERS AND BRIEF PERIODS OF MVFR CIGS AT TIST...TISX...TJSJ...TJMZ
AND TJBQ IN SHRA AND POSSIBLE VCTS.


&&

.MARINE...SEAS EXPECTED TO STAY IN THE 3-5 FT RANGE IN NORTHEAST
SWELLS. HEAVY RAIN AND TSTMS THE MAIN HAZARD.

[cycloneye]

Midday discussion by NWS San Juan


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1057 AM AST MON APR 19 2010

.UPDATE....DISCUSSION...MID TO UPPER LEVEL CLOUDINESS MOVING ACROSS
THE FA FROM THE SOUTHWEST AND LOW LEVEL MOISTURE MOVING ACROSS
THE REGION FROM THE SOUTHEAST...WILL MAINTAIN PARTLY TO VARIABLY
CLOUDY SKIES TODAY ACROSS THE FA THIS AFTERNOON. THE SEA BREEZE
DEVELOPMENT THIS AFTERNOON WILL INDUCE A ROUND OF SCATTERED
SHOWERS A POSSIBLY A COUPLE OF THUNDERSTORMS MAINLY ACROSS
WESTERN...INTERIOR AND NORTHWEST SECTIONS OF PUERTO RICO. A HUMID
WEATHER PATTERN IS IN STORE FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS STARTING LATE TONIGHT AND CONTINUING THROUGH MOST OF
TUESDAY AND WEDNESDAY... RESULTING IN ADDITIONAL
CLOUDINESS...SHOWERS AND THUNDERSTORMS ACROSS THE REGION. IN
FACT...LATEST GFS MODEL GUIDANCE...INDICATED AN STEADY INCREASE IN
PWAT VALUES...FROM NEAR 1.0 INCH THIS MORNING TO AROUND 2.5 INCHES
LATE TONIGHT...TUESDAY AND WEDNESDAY.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS ALL TAF SITES
DURING THE NEXT 12 HOURS...WITH A PREVAILING SOUTHEASTERLY LLVL
WND FLOW AT 5 TO 10 KTS. A SIGNIFICANT INCREASE IN CLOUDINESS IS
EXPECTED ACROSS THE LOCAL AREA...RESULTING IN A GENERAL INCREASE
IN SHOWERS AND BRIEF PERIODS OF MVFR CIGS AT TIST...TISX...TJSJ...
TJMZ AND TJBQ IN SHRA AND POSSIBLE VCTS.

[Gustywind]

[Gustywind]

[cycloneye]

Afternoon discussion by NWS San Juan

http://forecast.weather.gov/product.php ... glossary=1


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
247 PM AST MON APR 19 2010

.SYNOPSIS...MID-UPPER LEVEL RIDGE WITH AXIS TO THE EAST OF 60W WILL
WEAKEN AS A BROAD TROUGH ESTABLISHES ACROSS THE WESTERN ATLANTIC AND
SHORT WAVE PERTURBATIONS PRESS AGAINST THE RIDGE. DEEP TROPICAL
MOISTURE WILL CONTINUE TO MOVE OVER THE REGION ON A SOUTH
SOUTHEAST WINDS.

&&

.DISCUSSION...ISOLATED TO SCATTERED SHOWERS AND PROBABLY AN ISOLATED
THUNDERSTORM DEVELOPED OVER THE NORTHERN HALF OF PUERTO RICO DURING
THE EARLY AFTERNOON SHOWERS. AT THIS MOMENT MOST OF THESE SHOWERS
HAVE MOVE OVER THE ATLANTIC WATERS. THERE IS A POTENTIAL FOR MORE
SHOWERS AND THUNDERSTORMS TO DEVELOP ACROSS THE SIMILAR AREA FOR
THE REST OF THIS AFTERNOON.

A SURGE OF LOW LEVEL MOISTURE OVER THE LOCAL REGION WILL INCREASE THE
SHOWERS COVERAGE ACROSS THE LOCAL WATERS TONIGHT...MAINLY ACROSS
THE EASTERN HALF OF PUERTO RICO. A SURFACE TROUGH LOCATED OVER
EAST CUBA WILL DIG SOUTHEAST OVER THE LOCAL REGION IN THE NEXT 24
HOURS ENHANCING SEA BREEZE CONVERGENCE FROM TUESDAY AFTERNOON
THROUGH THURSDAY.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS ALL LOCAL TAF
SITES THIS EVENING...WITH A PREVAILING SOUTHEASTERLY LLVL WND FLOW
AT 5 TO 10 KTS. A SIGNIFICANT INCREASE IN CLOUDINESS IS EXPECTED
ACROSS THE LOCAL AREA AFTER 19/03Z...RESULTING IN A GENERAL
INCREASE IN SHOWERS AND BRIEF PERIODS OF MVFR CONDITIONS ACROSS
TIST...TISX AND TJSJ IN SHRA AND POSSIBLE VCTS. TJSJ 19/12Z
SOUNDING INDICATED A LIGHT SOUTHEASTERLY WIND FLOW FROM THE
SURFACE TO 5K FEET...BECOMING SOUTHWESTERLY AND STRONGER ABOVE
THAT LEVEL.

&&

.MARINE...MARINE CONDITIONS WILL CONTINUE TO IMPROVE AS SEAS WILL
CONTINUE SUBSIDE AND WINDS WILL BECOME LIGHT AND VARIABLE FOR THE
NEXT 48 HOURS. MARINER SHOULD BE IN THE LOOKOUT FOR STRONG
THUNDERSTORMS ACROSS THE LOCAL WATERS ESPECIALLY DURING THE
OVERNIGHT HOURS.

[tropicana]

Regional Weather Summary
Mon Apr 19 2010

Monday's Highs and rain (if any)

Piarco, C. Trinidad 35.9C 96F
Maraval, W. Trinidad 32.2C 90F 8.4mm
Crown Point, Tobago 31.6C 89F

Point Salines, Grenada 32.2C 90F trace
Grantley Adams, Barbados 31.1C 88F 1.2mm
Arnos Vale, St Vincent 30.0C 86F 13.0mm
Hewannora, St Lucia 30.2C 86F 15.8mm
Vigie, St Lucia 30.9C 87F 10.1mm
Canefield, Dominica 31.4C 88F

Le Lamentin, Martinique 30.7C 87F 0.2mm
Le Raizet, Guadeloupe 30.1C 86F 0.2mm

Golden Rock, St Kitts 29.6C 85F
VC Bird, Antigua 29.4C 85F
St Thomas, VI 30.0C 86F
St Maarten, VI 28.9C 84F
San Juan, Puerto Rico 32.2C 90F

Norman Manley, Jamaica 30.1C 86F
Montego Bay, Jamaica 34.0C 93F
Owen Roberts, Grand Cayman 29.5C 85F
Havana, Cuba 27.0C 81F

Nassau, Bahamas 26.8C 80F 0.7mm
Hamilton, Bermuda 19.8C 68F 6.6mm (to 8pm)

[cycloneye]

Updated discussion by NWS San Juan

AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
956 PM AST MON APR 19 2010

.UPDATE...ABUNDANCE OF MID TO UPPER LEVEL TROPICAL MOISTURE CONTINUED
TO SPREAD NORTH NORTHEASTWARD ACROSS THE REGION...AS THE SUBTROPICAL
RIDGE EXTENDING ACROSS THE NORTHEAST CARIBBEAN... CONTINUED TO ERODE
AND THE BROAD TROUGH ACROSS THE WEST ATLANTIC SHIFTS FURTHER EASTWARD.
THIS PATTERN WILL MAINTAIN A SOUTHWESTERLY FLOW ACROSS THE REGION AT
LEAST THROUGH WEDNESDAY...BUT WILL BECOME HIGH ZONAL/WESTERLY FOR
THE REMAINDER OF THE WEEK. IN THE MEANTIME...EXPECT MINOR SHORT
WAVE PERTURBATIONS TO EJECT EASTWARD AND MOVE TROUGH BASE OF
TROUGH WHICH WILL LINGER JUST NORTH OF THE AREA OVER THE NEXT FEW
DAYS. IN LOW LEVELS...FRONTAL TROUGH AND ASSOCIATED AREA OF LOW
PRESSURE EXTENDING ACROSS THE SOUTHWEST ATLANTIC...AND THE RECEDING
AREA OF HIGH PRESSURE ACROSS THE CENTRAL ATLANTIC...WILL MAINTAIN
THE FAIRLY LIGHT SOUTH SOUTHEASTERLY WIND FLOW ACROSS THE REGION
OVER THE NEXT SEVERAL DAYS. THIS SYNOPTIC PATTERN WILL INDUCE A
LOW LEVEL CONVERGENCE ZONE ACROSS THE LOCAL AREA AS THE TROUGH
LIFTS FURTHER EAST NORTHEAST ACROSS THE WEST AND WEST CENTRAL
ATLANTIC.

EXPECT THE PRESENT FLOW TO CONTINUE TO PUMP WARM MOIST AIR ACROSS
THE REGION DURING THE OVERNIGHT HOURS. THIS ALONG WITH LOW LEVEL
CONVERGENCE AND FAVORABLE MID TO UPPER LEVEL CONDITIONS WILL LEAD
TO INCREASED CONVECTION ACROSS THE LOCAL WATERS. SOME OF THE DEVELOPING
SHOWERS AND ISOLATED BUT STRONG THUNDERSTORMS WILL EVENTUALLY REACH
PARTS OF THE SOUTH AND EAST COASTAL SECTIONS OF PUERTO RICO...AS WELL
AS PARTS OF SAINT CROIX AND THE REST OF THE VIRGIN ISLANDS DURING
EARLY MORNING HOURS. PERIODS OF LOCALLY HEAVY RAINFALL WILL ACCOMPANY
THE PASSING SHOWERS AND STORMS AND AS A RESULT...URBAN AND SMALL STREAM
FLOODING WILL REMAIN POSSIBLE ESPECIALLY ACROSS THE EASTERN THIRD OF
PUERTO RICO AS WELL AS OVER PARTS OF THE ADJACENT ISLANDS TO INCLUDE
THE U.S VIRGIN ISLANDS. NO CHANGES WE MADE TO INHERITED FORECAST PACKAGE
AT THIS TIME...WHICH SEEMS TO HAVE MORE THAN ENOUGH POPS AND WEATHER
ACROSS THE FORECAST AREA FOR NOW BASED ON LATEST MODEL GUIDANCE...SO
HAVE DECIDED TO MAINTAIN CONSISTENCY WITH THE PREVIOUS PRECIPITATION
PROBABILITY AND EXPECTED WEATHER AT LEAST FOR NOW.

&&

.AVIATION...EXPECT MAINLY PREVAILING VFR CONDITIONS ACROSS ALL LOCAL
TAF SITES OVERNIGHT. HOWEVER...BRIEF PERIODS OF MVFR CONDITIONS ARE
POSSIBLE ACROSS TISX...TIST...TJSJ...AND TJPS IN PASSING SHOWERS.
FOR TOMORROW...PERIODS OF MVFR CONDITIONS WILL BE POSSIBLE ACROSS
ALL TAF SITES FROM TIME TO TIME...DUE TO INCREASING SHOWERS
ACTIVITY...WITH ISOLATED THUNDERSTORMS POSSIBLE. LATEST 20/00Z TJSJ
SOUNDING SHOWED SOUTH TO SOUTHWEST WINDS BETWEEN 5 TO 10 KTS FROM
THE SURFACE UP TO 10K FEET...AND STRONGER ABOVE.

[cycloneye]

Good morning to all.Rain is the prevalent word for today and the rest of the week.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
402 AM AST TUE APR 20 2010

.SYNOPSIS...BROAD TROUGH ACROSS THE WRN ATLC WILL PERSIST THROUGH
THE END OF THE WEEK. A SFC TROUGH WILL MOVE THROUGH PR MID WEEK
FOLLOWED BY A CDFNT ON SAT.

&&

.DISCUSSION...DEEP MOIST TROPICAL AIR NOW IN PLACE WITH PWATS VALUES IN
THE 2.25-2.5 INCHES BASED ON GOES AND MICROWAVE SOUNDERS. THIS AIR
MASS LOOKS LIKE WILL STAY WITH US THROUGH THE REST OF THE WEEK.
CONVECTION ACROSS THE CARIBBEAN SEA WILL TRACK SLOWLY NORTHEAST
BETWEEN 5-10 KTS AND AFFECT MAINLY SOUTHEAST PR THROUGH MID
MORNING BEFORE DECAYING. S/W TROUGH SEEN ON WATER VAPOR IMAGERY EXTENDING
FROM THE BAHAMAS TO THE WINDWARD PASSAGE WILL PASS MAINLY TO THE
NORTH OF PR WITHOUT MUCH EFFECT OVR OUR AREA. IT APPEARS SEA
BREEZE CONVERGENCE WILL BE THE MAIN TRIGGER FOR AFTERNOON CONVECTION
TODAY WHERE BREAKS IN THE CLOUDS OCCUR. WHILE THE CONVECTION TODAY
WILL BE CAPABLE OF PRODUCING TORRENTIAL DOWNPOURS GIVEN ABNORMALLY
HIGH PW AIR AND SLOW MOTION DONT THINK WILL SEE WIDESPREAD ENOUGH
FLOODING TODAY TO WARRANT A FLASH FLOOD WATCH. HOWEVER...FOR WED
THROUGH SAT GLOBAL MODELS AND GFES ENSEMBLE MEAN CONTINUE TO
PORTRAY A DANGEROUS FLOODING SITUATION FOR PR AS AREA WILL REMAIN
IN THE SRN EDGE OF THE WESTERLIES WITH A STRONG RIDGE OVR THE TROP
ATLC. UNDER THIS PATTERN...SFC FEATURES WILL BE VERY SLOW TO MOVE
THROUGH THE AREA AS UPPER FLOW BECOMES PARALLEL TO SFC BDRIES. A
CDFNT WILL ALSO WORK INTO THE AREA ON SAT KEEPING THINGS WET
THROUGH THE WEEKEND. BOTH 00Z ECMWF/GFS AND THE 00Z GFES MEAN
INDICATE PR IN THE BULLS EYE OF PRECIPITATION WITH SOME IMPRESSIVE
TOATLS CONSIDERING THEIR COARSE RESOLUTION BY THE TIME THE WEEK
ENDS. WILL HIGHLIGHT THIS EVENT STRONGLY IN HAZARDOUS WEATHER
OUTLOOK.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS ALL TAF SITES
DURING THE NEXT 12 HOURS. HOWEVER...PERIODS OF MVFR CONDITIONS WILL
BE POSSIBLE ACROSS ALL TAF SITES FROM TIME TO TIME...DUE TO SHOWER
ACTIVITY...WITH ISOLATED THUNDERSTORMS LIKELY. LATEST 20/00Z TJSJ
SOUNDING SHOWED SOUTH TO SOUTHWEST WINDS BETWEEN 5 TO 10 KTS FROM
THE SURFACE UP TO 10K FEET...AND STRONGER ABOVE.


&&

.MARINE...SEAS GENERALLY 2-4 FT IN NE SWELLS. TSTMS/CG LIGHTNING OVER THE
CARIBBEAN SEA THE MAIN HAZARD.


&&

[cycloneye]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE SAN JUAN PR
120 PM AST TUE APR 20 2010

PRC013-027-065-081-131-141-202015-
/O.NEW.TJSJ.FA.Y.0062.100420T1720Z-100420T2015Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
SAN SEBASTIAN PR-UTUADO PR-LARES PR-CAMUY PR-HATILLO PR-ARECIBO PR-
120 PM AST TUE APR 20 2010

THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY
FOR THE FOLLOWING MUNICIPALITIES...

IN PUERTO RICO
SAN SEBASTIAN...UTUADO...LARES...CAMUY...HATILLO AND ARECIBO

* UNTIL 415 PM AST

* AT 115 PM AST...NATIONAL WEATHER SERVICE RADAR DETECTED MODERATE
TO HEAVY RAINFALL ACROSS SECTIONS OF NORTHWESTERN AND NORTH
CENTRAL PUERTO RICO. THE HEAVIEST RAINFALL HAD FALLEN ACROSS
THE MUNICIPALITIES OF LARES...UTUADO AND SAN SEBASTIAN. THIS
SHOWER ACTIVITY WILL HAVE THE CAPABILITY OF PRODUCING RAPID RISES
IN SMALL STREAMS AND CREEKS...AS WELL AS MINOR FLOODING
ALONG ROADWAYS...THROUGH AT LEAST 415 PM AST.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

[cycloneye]

Afternoon discussion by NWS San Juan


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
324 PM AST TUE APR 20 2010

.SYNOPSIS...BROAD TROUGH ACROSS THE WESTERN ATLANTIC WILL PERSIST
THROUGH THE END OF THE WEEK. A SURFACE TROUGH WILL MOVE THROUGH
PUERTO RICO MID WEEK FOLLOWED BY A COLD FRONT ON SATURDAY.

&&

.DISCUSSION...SCATTERED TO NUMEROUS SHOWERS AFFECTED THE SOUTHEAST
PORTIONS OF PUERTO RICO. ENOUGH DIURNAL HEATING WAS AVAILABLE FOR
A SEA BREEZE TO DEVELOP ALONG THE NORTHERN COAST OF PUERTO RICO...
GENERATING CONVECTIVE SHOWERS ACTIVITY ACROSS THE NORTHERN
PORTIONS OF PUERTO RICO. SOME OF THESE SHOWERS GENERATED RAINFALL
ACCUMULATIONS OF BETWEEN .50 TO 1.5 INCHES MAINLY OVER NORTH
CENTRAL AND INTERIOR SECTIONS OF PUERTO RICO. AN AREA OF MOISTURE
NOW LOCATED OVER THE CARIBBEAN WATERS WILL MOVE NORTHWARD AND
AFFECT THE SOUTHERN COAST OF PUERTO RICO THROUGH THE EVENING
HOURS.

A MID TO UPPER LEVEL TROUGH NOW LOCATED OVER THE HISPANIOLA WILL
CONTINUE TO MOVE SLOWLY EAST SOUTHEAST FOR THE NEXT 24 HOURS. THIS
WEATHER FEATURE WILL PRODUCE A WEST SOUTHWEST STEERING WIND
PATTERN THAT WILL PUSH ALL CONVECTIVE SHOWERS TOWARD THE EAST AND
NORTHEAST OF PUERTO RICO. THIS SCENARIO SHOULD PREVAIL THROUGH AT
LEAST FRIDAY. AFTERNOON SHOWERS AND THUNDERSTORMS WILL BE ENHANCE
BY A SUBTROPICAL JET NOW LOCATED JUST OVER THE LOCAL REGION.


&&

.AVIATION...A MOIST WIND FLOW AND SEA BREEZE CONVERGENCE WILL
CONTINUE TO PRODUCE BRIEF PERIODS OF MVFR CONDITIONS ACROSS
TJSJ...TJMZ...TJBQ AND TIST UNTIL 20/22Z. ELSEWHERE ACROSS THE LOCAL
TAF SITES MOSTLY VFR CONDITIONS ARE EXPECTED DURING THE REST OF THE
AFTERNOON AND EVENING HOURS. WITH A PREVAILING SOUTHEASTERLY LLVL
WND FLOW AT 5 TO 10 KTS...THE SEA BREEZE CONVERGENCE WILL PROMOTE
ABUNDANT MOISTURE ACROSS THE LOCAL AREA DURING THE NEXT FEW DAYS...
RESULTING IN SHOWERS AND THUNDERSTORMS AND BRIEF PERIODS OF MVFR OR
EVEN IFR CIGS ACROSS THE LOCAL TAF SITES...ESPECIALLY DURING THE
AFTERNOONS.


&&

.MARINE...SEAS GENERALLY 2-4 FT IN NE SWELLS. THUNDERSORMS AND LIGHTNING
OVER THE CARIBBEAN SEA THE MAIN HAZARD.

[tropicana]

Regional Weather Summary
Tue Apr 20 2010

Tuesday's Highs and rain (if any)

Piarco, C. Trinidad 36.0C 96F
Pointe-a-Pierre, SW Trinidad 34.0C 93F 57.9mm
Crown Point, Tobago 31.2C 88F

Grantley Adams, Barbados 31.2C 88F 7.0mm
Arnos Vale, St Vincent 31.5C 89F trace
Hewannora, St Lucia 31.4C 88F 0.5mm
Vigie, St Lucia 32.6C 91F
Canefield, Dominica 30.8C 87F

Le Lamentin, Martinique 32.6C 91F
Le Raizet, Guadeloupe 31.0C 88F 0.6mm

Golden Rock, St Kitts 30.2C 86F
VC Bird, Antigua 31.0C 88F trace
St Maarten, VI 30.3C 86F
San Juan, Puerto Rico 32.8C 91F 10.7mm

Santo Domingo, DR 31.0C 88F
Norman Manley, Jamaica 30.6C 87F
Montego Bay, Jamaica 30.9C 87F
Owen Roberts, Grand Cayman 28.9C 84F

Nassau, Bahamas 25.9C 78F
Hamilton, Bermuda 20.2C 68F trace

[cycloneye]

Updated discussion by NWS San Juan

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
939 PM AST TUE APR 20 2010

.UPDATE...SHOWERS LATE THIS AFTERNOON AFFECTED MAINLY THE SAN JUAN
METROPOLITAN AREA...WITH RADAR ESTIMATED BETWEEN 1 TO 1.5 INCHES
OF RAIN FELL OVER SOME PLACES. THIS ACTIVITY DISSIPATED AFTER
SUNSET LEAVING THE LOCAL AREA UNDER PARTLY CLOUDY SKIES. THIS
WEATHER PATTERN...WITH SHOWERS DEVELOPING DURING THE AFTERNOON HOURS
IS EXPECTED TO CONTINUE AT LEAST THROUGH THE END OF THE WEEK. GFS
COMPUTER MODEL INDICATED THAT ENOUGH MOISTURE WILL LINGER ACROSS
THE AREA BEYOND SATURDAY...WITH PRECIPITABLE WATERS VALUES
STAYING NEAR OR OVER 2.0 INCHES DURING THIS PERIOD. WINDS ARE
EXPECTED TO REMAIN LIGHT AND VARIABLE AT THE SURFACE...AS PRESSURE
GRADIENT REMAINS WEAK. HOWEVER...MOST OF THIS MOISTURE SHOWED BY
THE GFS IS BETWEEN THE 1000MB-700MB LAYER. AT 500MB...VERY DRY
AIR WILL BE IN PLACE STARTING ON SATURDAY...BECOMING EVEN DRIER
NEXT WEEK. WITH THIS IN MIND...ALTHOUGH SOME SHOWERS COULD PRODUCE
HEAVY RAINFALL IN SOME ISOLATED AREAS...LIKE IT WAS SEEN
TODAY...NO WIDESPREAD HEAVY RAINFALL IS ANTICIPATED AT THIS TIME.
MADE SOME UPDATES TO GRIDS TO SHOW THIS TREND.

&&

.AVIATION...MOST STATIONS WILL BE VFR THROUGH 21/16Z...HOWEVER DUE TO
HIGH DEW POINTS AND UNUSUAL WIND FLOW SOME STATIONS WILL HAVE
OCCASIONAL LOW CEILINGS...INCLUDING TIST AND TJBQ OVERNIGHT. AFTER
21/16Z SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER INTERIOR PUERTO
RICO AND THE CORDILLERA CENTRAL WITH MVFR CONDS AND MOUNTAIN
OBSCURATIONS THAT SPREAD NORTHEAST. MOST SHOWERS AND TSTMS WILL
DISSIPATE BY 22/00Z.

[cycloneye]

Good morning to all.Wet days ahead until Saturday night in Puerto Rico.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
438 AM AST WED APR 21 2010

.SYNOPSIS...BROAD TROUGH ACROSS THE WESTERN ATLANTIC WILL PREVAIL
THROUGH THE END OF THE WEEK. A SURFACE TROUGH OR SHEARLINE WILL
MOVE THROUGH PUERTO RICO THURSDAY FOLLOWED BY A COLD FRONT SAT
NIGHT.

&&

.DISCUSSION...SUBSIDENCE HAS TAKEN PLACE OVR PR EARLY THIS
MORNING AS EVIDENCED BY CLEAR SKIES AS SEEN FROM VISUAL OBS AND
SATELLITE IMAGERY. A RECENT ACARS ALSO SHOWS SOME WEAK CAPPING IN
THE MID LEVELS. FOG IS LIKELY AFFECTING INTERIOR VALLEYS GIVEN
VERY MOIST GROUND...CALM WINDS AND MID LVL SUBSIDENCE. 4-KM
RESOLUTION OF NEAR INFRARED CHANNELS NOT HIGH ENOUGH TO DETECT FOG
THIS MORNING BUT RADAR IS AS EVIDENCE OF SOME ANOMALOUS
PROPAGATION OVER VALLE DEL TURABO.

PLENTY OF HEATING LATER THIS MORNING AND LIGHT WINDS WILL ALLOW
FOR SEA BREEZE TO DEVELOP EARLY. PLENTY OF MOISTURE TO FUEL
TSTMS. STILL DON`T SEE ANY MECHANISM TODAY OTHER THAN SEA BREEZE
CONVERGENCE TO SUSTAIN CONVECTION FOR A LONG TIME. HOWEVER...A
LITTLE CONCERN ABOUT SVRL MOISTURE GRADIENTS SEEN ON DIFFERENT WATER
VAPOR SOUNDERS EXTENDING FROM SOUTH AMERICA NORTHEAST TO THE USVI
SUGGESTING THAT THERE COULD BE A WEAK JET STREAK AROUND THAT COULD
ENHANCE CONVECTION.

THINGS CHANGE FOR THU THOUGH AS MODELS HAVE BEEN CONSISTENTLY
PREDICTING A SFC TROUGH OR SHEARLINE TO MOVE ACROSS THE ISLAND
DURING THE DAY. THIS SHOULD RESULT IN STRONGER LOW-LVL CONVERGENCE
THAT SHOULD ENHANCE RAINFALL RATES AND HELP TO SUSTAIN THE
CONVECTION LONGER. GIVEN THE CONSISTENCY IN THE MODELS WITH THIS
SCENARIO THIS LOOKS TO BE ONE OF THE MOST ACTIVE DAYS OF THE WEEK.

SFC WINDS TURN MORE NORTHEASTERLY FRI WITH CONVECTION SHIFTING
MORE TO SW PR.

CDFNT STILL FORECAST TO COME THROUGH THE AREA SAT EVENING. GFS AND
EUROPEAN INDICATING PLENTY OF LIFT IN THE LOW LEVELS AND STRONG
250MB DIVERGENCE WITH MOISTURE LAYER EXTENDING UP TO 600 MB WITH
PWATS AOA 2.0 INCHES. TIGHT HEIGHT GRADIENT ALOFT SHOULD SUSTAIN
THE BAROCLINICITY OF THIS FRONT. PLENTY OF DYNAMICS AND DEEP
MOISTURE TO SUSTAIN A LONG DURATION HEAVY RAINFALL EVENT. AS IS
TYPICAL WITH CDFNT THE NORTH CNTRL AND NORTHEAST PR ARE THE ONES
THAT USUALLY GET IMPACTED THE MOST. HAVE INCREASED CLOUDS AND POPS
BUT CAPPED AT 50% DUE TO LOCAL POLICY. SO LOOKING LIKE THU
AFTERNOON AND SAT-SAT NIGHT THE MOST ACTIVE DAYS OF THE WEEK.

MODELS HAVE FINALLY COME INTO AGREEMENT IN PUSHING THE FRONT
THROUGH THE AREA SAT EVENING WITH SHARP DRYING INDICATED ON
SUNDAY. SO A PRETTY WET FORECAST ON TAP THROUGH SAT NIGHT.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS ALL TAFS SITES
DURING THE NEXT 24 HOURS. BRIEF PERIODS OF MVFR ARE POSSIBLE ACROSS
TJSJ...TJMZ...TJBQ...TIST AND TISX AFTER 21/17Z...DUE TO SHOWERS AND
POSSIBLE THUNDERSTORMS. MOST SHOWERS AND TSTMS WILL DISSIPATE BY
22/00Z. ALSO...MOUNTAIN OBSCURATIONS ARE POSSIBLE ALONG THE
CORDILLERA CENTRAL.

&&

.MARINE...SEAS 2-4 FT IN NE SWELLS. SEAS BUILD TO 6 FT SUN NIGHT
BEHIND CDFNT. TSTMS/CG LIGHTNING THE MAIN HAZARD NEXT FEW DAYS.