Area Forecast Discussion
Issued by NWS San Juan, PR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXCA62 TJSJ 271438 AAA
AFDSJU

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
1038 AM AST WED AUG 27 2014

.UPDATE...MOSTLY SUNNY ACROSS WESTERN PUERTO RICO AND PARTLY CLOUDY
ACROSS EASTERN PR AND LOCAL ISLANDS WERE OBSERVED THIS MORNING. HAZY
CONDITIONS ARE PRESENT DUE TO AN AIR MASS OF SAHARAN DUST MOVING FROM
THE EAST...WHICH WILL BE OVER THE REGION UNTIL AT LEAST TOMORROW. LIGHT
SHOWERS MOVED IN ACROSS EASTERN SECTIONS OF PR THIS MORNING WITH NO
SIGNIFICANT ACCUMULATIONS. THEN THIS AFTERNOON...WE CONTINUE TO EXPECT
CONVECTION ACROSS WESTERN INTERIOR SECTIONS OF PR. LOCALIZED MODERATE
TO HEAVY RAINFALL AND STRONG GUSTY WINDS ARE POSSIBLE WITH THESE
THUNDERSTORMS.

&&

.AVIATION...VFR CONDS EXPECTED FOR ALMOST ALL TAF SITES. DAYTIME HEATING
AND LOCAL EFFECTS WILL AID IN DVLP OF ISOLD TSRA OVR W PR WITH TSRA
FOR TJMZ AND VCTS FOR TJBQ MAINLY BTW 27/17Z-27/22Z ALONG W/MTN OBCR
OVR CORDILLERA CENTRAL AND WESTERN PR. WIND BLO FL200 FM ESE 14-30
KT...STRONGEST BTW FL100-FL150...GRADUALLY BCMG FM EAST DURG THE AFN.

&&

.MARINE...SMALL CRAFT SHOULD EXERCISE CAUTION DUE TO WINDS UP TO 9 KNOTS
AND SEAS INCREASING UP TO 6 FEET DURING THE DAY.

&&

.PREV DISCUSSION... /ISSUED 517 AM AST WED AUG 27 2014/

DISCUSSION...UPPER LEVEL TROUGH EXTENDING SOUTHWEST TO JUST
NORTHEAST OF THE NORTHERN LEEWARDS FROM THE EASTERN ATLANTIC....
WILL CONTINUE TO DEVELOP AND SHIFT TO JUST NORTH OF THE REGION BY
THE END OF THE WORK WEEK. WEAK TROPICAL WAVE WILL CONTINUE TO MOVE
MAINLY SOUTH OF THE REGION TODAY HAVING LITTLE OR NO EFFECT ON THE
LOCAL ISLANDS. ANOTHER WEAK AREA OF LOW PRESSURE AND ASSOCIATED
TROPICAL WAVE NOW ACROSS THE OPEN TROPICAL ATLANTIC IS SO FAR
FORECAST TO ENTER THE EASTERN CARIBBEAN LATE FRIDAY...THEN MOVE
ACROSS THE NORTHEASTERN CARIBBEAN SATURDAY THROUGH SUNDAY.

DISCUSSION...LATEST SATELLITE IMAGERY AND DOPPLER WEATHER RADAR
SHOWED ONLY FEW LIGHT SHOWERS MOVING ACROSS THE REGION DURING THE
EARLY MORNING HOURS AS MOST OF LOW TO MID LEVEL MOISTURE ASSOCIATED
WITH WEAK TROPICAL WAVE WAS WELL SOUTH OF THE REGION. THIS FEATURE
WILL CONTINUE WESTWARDS TODAY AND HAVE NO DIRECT AFFECT ON THE
LOCAL ISLANDS AS IT WILL CONTINUE TO MOVE WELL SOUTH OF THE REGION.
WINDS ARE FORECAST TO BECOME MORE EASTERLY LATER TODAY THROUGH
THE END OF THE WEEK AS SURFACE HIGH PRESSURE REESTABLISHES ITSELF
NORTH OF THE REGION TO INDUCE MODERATE TRADE WINDS.

FOR THE REST OF THE DAY...AFTERNOON CONVECTION WILL BE MAINLY
DRIVEN BY SEAS BREEZE VARIATIONS AND LOCAL TERRAIN EFFECTS ACROSS
THE ISLANDS WITH THE MAIN FOCUS OVER THE WEST INTERIOR SECTIONS
OF PUERTO RICO. NO WIDESPREAD OR SIGNIFICANT RAINFALL IS EXPECTED
FOR THE NEXT COUPLE OF DAYS ACROSS THE FORECAST AREA. HOWEVER...
PERIODS OF LATE EVENING AND EARLY MORNING PASSING SHOWERS CAN BE
EXPECTED EACH DAY FOLLOWED BY LIMITED DIURNALLY DRIVEN AFTERNOON
CONVECTION. BY FRIDAY LOCAL WINDS ARE TO BECOME MORE NORTHEASTERLY
IN ADVANCE OF ANOTHER TROPICAL WAVE FORECAST TO ENTER THE EASTERN
CARIBBEAN. THEREAFTER...AFTERNOON CONVECTION SHOULD THEN BE STEERED
TOWARDS PARTS OF THE SOUTHWEST SECTIONS OF PUERTO RICO WITH SOME
ENHANCEMENT EXPECTED DUE TO THE PROXIMITY OF THE UPPER TROUGH.

INCREASING TROPICAL MOISTURE AND BETTER CHANCE OF SHOWERS AND
THUNDERSTORM ACTIVITY IS FORECAST FOR THE UPCOMING WEEKEND WITH
THE APPROACH OF THE NEXT TROPICAL WAVE...AS SUGGEST BY LATEST GFS
MODEL... WHICH HAS SO FAR BEEN INITIALIZING FAIRLY WELL.

MORE TO COME ON THIS FEATURE DURING THE NEXT COUPLE OF DAYS BUT
WILL CONTINUE TO MONITOR AND MAKE THE NECESSARY ADJUSTMENT TO THE
LONG TERM FORECAST GRIDS FOR THE WEEKEND AND BEYOND. FOR NOW...THE
BEST CHANCE FOR GOOD WETTING RAINS ACROSS THE FORECAST AREA LOOKS
LIKE LATE FRIDAY THROUGH SATURDAY.

AVIATION...THE PREVAILING EAST SOUTHEAST L/LEVEL WIND FLOW WILL
BECOME EASTERLY BY THIS AFN. BRIEF MTN OBSCURATIONS ERN PR AFT
27/10Z AS A BAND OF SHALLOW L/LVL CLOUDS WILL MOVES WEST ACROSS
THE LOCAL FLYING AREA. DAYTIME HEATING AND LOCAL EFFECTS WILL AID
IN DVLP OF ISOLD TSRA OVR W PR WITH VCTS FOR TJMZ AND TJBQ
MAINLY BTW 27/17Z-27/22Z ALONG W/MTN OBCR OVR CORDILLERA CENTRAL
AND WESTERN PR. WIND BLO FL200 FM ESE 14-25 KT...STRONGEST BTW
FL100-FL150...GRADUALLY BCMG FM DURG THE AFN.

MARINE...SMALL CRAFT SHOULD EXERCISE CAUTION DUE TO WINDS UP TO
20 KNOTS AND SEAS INCREASING UP TO 6 FEET DURING THE DAY. PLEASE
REFER TO THE LATEST COASTAL WATERS FORECAST ISSUED BY WFO SAN JUAN
PR.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  80  89  78 /  10  20  20  30
STT  89  81  90  80 /  20  20  20  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...NONE.
&&

$$

02/23




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.