Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 270230 AAA
AFDSJU

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
1030 PM AST THU FEB 26 2015

.UPDATE...27/00Z SOUNDING CAME IN WITH THE TOP OF THE MOISTURE AT
8 KFT AND THE SOUNDING SOLIDLY CAPPED BETWEEN 9 KFT AND 20 KFT. AT
675 MB OR ABOUT 11.4 KFT THE SOUNDING WAS 4 DEGREES ABOVE THE
SURFACE LIFTED PARCEL. THIS WILL GREATLY LIMIT THE STRENGTH OF THE
SHOWERS THAT ARE NOW FORMING OVER THE WATER AND MOVING INLAND OVER
THE LOCAL ISLANDS. SAINT THOMAS DID HAVE A HUNDREDTH OF AN INCH
THIS EVENING AND AREAS OF EASTERN PUERTO RICO HAVE ALSO SEEN MINOR
MEASURABLE AMOUNTS. SHALLOW SHOWERS ARE EXPECTED TO CONTINUE THERE
DURING THE REST OF THE NIGHT.

&&

.DISCUSSION...IN THE LONGER RANGE...THE GFS IS SHOWING BETTER
MOISTURE ON MONDAY NIGHT...PERHAPS EVEN THE BEST OF THE NEXT 7
DAYS THOUGH ON AN ABSOLUTE SCALE IT IS UNIMPRESSIVE WITH ONLY 1.4
INCHES OF PRECIPITABLE WATER. NEVERTHELESS THE PASSAGE OF A WEAK
TROUGH JUST TO THE NORTH SHOULD FAVOR BETTER SHOWER FORMATION LATE
MONDAY. OTHERWISE ONLY SHALLOW SHOWERS WILL BE ABLE TO CONTINUE IN
THESE BREEZY CONDITIONS THROUGH MONDAY.


&&

.AVIATION...VFR CONDS AT ALL TAF TERMINALS DURG ENTIRE PD. ISOLD
-SHRA/SHRA EN ROUTE BTW PR AND NORTHERN LEEWARDS...SCT- OCNL BKN CLD LYRS
BTW FL020-FL060...FEW TCU W/ISOLD TOPS 100...MOSTLY SKC ABV. SFC WND
FM E 10-15 KTS OCNL HIGHER GUSTS ALONG COASTAL AREAS. RECENT 27/00Z
TJSJ UPPER AIR SOUNDING DATA SUGGEST WND BLO FL150 MAINLY FM E BTW
15-25 KT AND SHOULD PERSIST THRU FCST PD. NO SIG AVN OPERATIONAL WX
IMPACTS ATTM.


&&

.MARINE...EASTERLY WINDS CONTINUE THROUGH MUCH OF THE NEXT 7 TO 8
DAYS AND THIS WILL KEEP SMALL CRAFT ADVISORY CONDITIONS UP FOR
MOST EXPOSED WATERS FOR MOST OF THE WEEK. WITH LITTLE OR NO SWELL
FROM THE NORTH...PREDOMINANT PERIODS ARE EXPECTED TO BE LESS THAN
10 SECONDS MAKING FOR ROUGH SEAS. SHOWERS IN THE AREA HAVE PRODUCED
ISOLATED WIND GUSTS IN EXCESS OF 30 KNOTS.

&&

.PREV DISCUSSION... /ISSUED 144 PM AST THU FEB 26 2015/

SYNOPSIS...A SURFACE AND MID TO UPPER LEVEL RIDGE WILL CONTINUE TO
BUILD ACROSS THE REGION AND REMAIN IN PLACE THROUGH MOST OF THE
UPCOMING WEEKEND. THESE FEATURES WILL HELP TO SUPPORT FAIRLY STRONG
CAP INVERSION...WINDY CONDITIONS AND SIGNIFICANT DRYING TREND
THROUGH MOST OF THE PERIOD.

DISCUSSION...ONLY ISOLATED SHOWER ACTIVITY WAS OBSERVED SO FAR THIS
AFTERNOON ACROSS EASTERN AND WESTERN SECTIONS OF PUERTO RICO.
HOWEVER...THE SHOWERS WERE OF SHORT DURATION WITH MINIMAL RAINFALL
AMOUNTS. ELSEWHERE ACROSS THE LOCAL ISLANDS...NOT SIGNIFICANT
PRECIPITATION WAS DETECTED.

SURFACE HIGH PRESSURE AND A MID TO UPPER LEVEL RIDGE
WILL CONTINUE TO BUILD ACROSS THE NORTHEAST CARIBBEAN FOR THE NEXT
SEVERAL DAYS. AS THE SURFACE HIGH PRESSURE STRENGTHENS OVER THE
NORTHEAST CARIBBEAN DURING THE WEEKEND...THE LOCAL PRESSURE GRADIENT
IS EXPECTED TO TIGHTEN. THIS WILL LEAD TO FAIRLY STRONG EASTERLY
TRADE WINDS AND MOSTLY FAIR WEATHER CONDITIONS ACROSS THE LOCAL
ISLANDS. THEREFORE A GRADUAL DRYING TREND AND BREEZY CONDITIONS ARE
IN STORE FOR THE NEXT SEVERAL DAYS. HOWEVER...SMALL PATCHES OF LOW
LEVEL MOISTURE EMBEDDED IN THE EASTERLY TRADES WILL INDUCE THE
DEVELOPMENT OF BRIEF PASSING SHOWERS ACROSS EASTERN SECTIONS OF
PUERTO RICO...VIEQUES...CULEBRA AND ACROSS THE U.S. VIRGIN ISLANDS
DURING THE NIGHTS AND EARLY MORNING HOURS WITH LIMITED CONVECTION
OVER WESTERN AND INTERIOR PUERTO RICO DURING THE AFTERNOONS.

AVIATION...VFR CONDITIONS EXPECTED ACROSS THE LOCAL FLYING AREA
THRU THE FORECAST PERIOD. ONLY A FEW VCSH POSSIBLE ACROSS THE USVI
AND LEEWARD TERMINAL TONIGHT AND EARLY FRIDAY. LATEST TJSJ SOUNDING
INDICATED AN EASTERLY WIND FLOW UP TO 25 KNOTS ALL THE WAY FROM THE
SURFACE TO 15 KFT.

MARINE...EASTERLY WINDS WILL CONTINUE TO STRENGTHEN OVERNIGHT AND
REMAIN STRONG UP TO AT LEAST 15 KFT THROUGH THE FORECAST PERIOD.
THESE WINDS WILL GENERATE ROUGH SEAS OF 6 TO 8 FEET. SMALL CRAFT
ADVISORY WILL REMAIN IN EFFECT FOR MOST OF THE LOCAL WATERS ALONG
WITH A HIGH RISK OF RIP CURRENTS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  75  87  75  86 /  10  20  20  20
STT  73  85  75  85 /  10  20  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...FIRE WEATHER WATCH FROM 10 AM AST FRIDAY THROUGH FRIDAY
     AFTERNOON FOR SOUTH COASTAL PLAINS AND MONA ISLAND.

VI...FIRE WEATHER WATCH FROM 10 AM AST FRIDAY THROUGH FRIDAY
     AFTERNOON FOR ST CROIX.

COASTAL WATERS...     SMALL CRAFT ADVISORY UNTIL MIDNIGHT AST SUNDAY NIGHT FOR ANEGADA
     PASSAGE SOUTHWARD TO 17N-ATLC WATERS OF PUERTO RICO AND
     USVI FROM 10NM TO 19.5N-CARIBBEAN WATERS OF PUERTO RICO
     FROM 10 NM TO 17N-COASTAL WATERS OF NORTHERN USVI AND
     CULEBRA OUT 10 NM-COASTAL WATERS OF SOUTHERN USVI VIEQUES
     AND EASTERN PUERTO RICO OUT 10 NM.

     SMALL CRAFT ADVISORY UNTIL 6 PM AST FRIDAY FOR COASTAL WATERS OF
     SOUTHERN PUERTO RICO OUT 10 NM.

     SMALL CRAFT ADVISORY UNTIL MIDNIGHT AST SUNDAY NIGHT FOR MONA
     PASSAGE SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY UNTIL 6 PM AST SATURDAY FOR COASTAL WATERS
     OF NORTHERN PUERTO RICO OUT 10 NM.

&&

$$

09/12




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