Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 230206
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1006 PM AST SAT NOV 22 2014

.UPDATE...LATEST SATELLITE WATER VAPOR IMAGERY SUGGESTS THE UPPER
LOW JUST SOUTHEAST OF PUERTO RICO GRADUALLY WEAKENING AND LIFTING
NORTH NORTHEAST AS HIGH PRESSURE CONTINUED TO BUILDS EASTWARD ACROSS
THE AREA FROM THE CENTRAL CARIBBEAN BASIN. THE NATIONAL WEATHER SERVICE
DOPPLER WEATHER RADAR SHOWED SHOWERS AND ISOLATED THUNDERSTORMS ACTIVITY
DIMINISHING ACROSS THE VIRGIN ISLANDS AND EASTERN PUERTO WITH MOST
OF THE ACTIVITY NOW TRAILING A WEAK LOW LEVEL TROUGH MOVING WESTWARDS
AND CROSSING THE MONA PASSAGE. STRONG SURFACE HIGH PRESSURE WILL REMAIN
ANCHORED ACROSS THE WEST AND CENTRAL ATLANTIC THROUGH THE WEEKEND AND
INTO THE EARLY PART OF NEXT WEEK...TO MAINTAIN A FAIRLY TIGHT LOCAL
PRESSURE GRADIENT AND CONSEQUENTLY STRONG EASTERLY TRADE WINDS.

EXPECT THE TRADE WINDS TO CONTINUE TO TRANSPORT FRAGMENTS OF LOW TO
MID LEVEL CLOUDS WITH INTERVALS OF PASSING SHOWERS ACROSS THE REGION
DURING THE OVERNIGHT AND EARLY MORNING HOURS. SOME SHOWERS WILL ONCE
AGAIN AFFECT PARTS OF THE EAST COASTAL SECTIONS OF THE ISLANDS...PRODUCING
PERIODS OF MODERATE TO LOCALLY HEAVY DOWNPOURS. ON SUNDAY LESS FREQUENT
ACTIVITY IS EXPECTED DURING THE DAY BUT THERE WILL SUFFICIENT MOISTURE
AVAILABLE FOR AFTERNOON CONVECTION WHICH MAY DEVELOP AND QUICKLY STREAM
WESTWARD MAINLY ACROSS PARTS OF THE INTERIOR AND WEST SECTIONS OF PUERTO
RICO. ONLY MINOR CHANGES MADE TO THE INHERITED SHORT TERM FORECAST PACKAGE
AT THIS TIME. DID HOWEVER UPDATE THE SHORT TERM WIND GRIDS AND THE MARINE
WAVE HEIGHTS BASED ON LATEST MODEL GUIDANCE AND PRESENT WEATHER CONDITIONS.

&&

.AVIATION UPDATE...VFR CONDITIONS EXPECTED ACROSS ALL THE TAF SITES
TONIGHT AND OVERNIGHT. BRIEF PASSING SHRA POSSIBLE ACROSS THE LEEWARD
AND USVI TERMINALS OVERNIGHT. HOWEVER...SHRA ACTIVITY EXPECTED TO
DIMINISH ACROSS THE FLYING AREA ON SUNDAY. LLVL WINDS OF 15-25 KTS
EXPECTED BLO FL200.

&&

.MARINE...FRESH TO STRONG EASTERLY TRADE WINDS WILL CONTINUE ACROSS
THE REGIONAL WATERS OVERNIGHT THROUGH AT LEAST TUESDAY...AND THEREFORE
MAINTAIN ROUGH AND HAZARDOUS SEAS. SMALL CRAFT ADVISORIES REMAIN
IN EFFECT FOR ALL COASTAL WATERS EXCEPT FOR THE NEAR SHORE COASTAL
WATERS OF SOUTHWEST PR. PLEASE REFER TO THE LATEST MARINE WEATHER
STATEMENTS AND COASTAL WATERS FORECAST ISSUED BY THE NATIONAL
WEATHER SERVICE WFO SAN JUAN PR.

&&

.PREV DISCUSSION... /ISSUED 253 PM AST SAT NOV 22 2014/

SYNOPSIS...UPPER TROUGH AFFECTING THE LOCAL AREA...WILL
DISSIPATED TONIGHT. UPPER LEVEL RIDGE WILL DOMINATE THE REGION
THROUGH AT LEAST TUESDAY. PATCHES OF LOW LEVEL MOISTURE WILL
CONTINUE TO AFFECT THE LOCAL REGION NEXT SEVERAL DAYS.

DISCUSSION...NUMEROUS SHOWERS WERE NOTED THIS MORNING AND
AFTERNOON AFFECTING MAINLY THE EASTERN HALF OF PUERTO RICO. THIS
ACTIVITY WAS ASSOCIATED WITH AN UPPER LEVEL TROUGH AFFECTING THE
LOCAL AREA. MORE SHOWERS ARE EXPECTED TO MOVE ACROSS THE LOCAL
AREA FROM TIME TO TIME THE REST OF THIS AFTERNOON AND TONIGHT.
MAXIMUM RAINFALL ACCUMULATION HAS BEEN AROUND 2 INCHES IN SOME
ISOLATED AREAS SINCE MIDNIGHT. UPPER LEVEL TROUGH WILL WEAKEN
TONIGHT...WHICH WILL ALLOW FOR AN UPPER LEVEL RIDGE TO BUILD FROM
THE WEST. SINCE AN IMPROVE IN WEATHER CONDITIONS IS THEN EXPECTED
STARTING TONIGHT INTO SUNDAY...AS THE UPPER RIDGE TAKES CONTROL
OF THE WEATHER LOCALLY...THE FLASH FLOOD WATCH WHICH WAS IN EFFECT
FOR THE EASTERN HALF OF PUERTO RICO WAS ALLOWED TO EXPIRED LATE
THIS MORNING.

FOR THE BEGINNING OF NEXT WEEK AND BEYOND...STRONG TRADES WILL
TRANSPORT PATCHES OF LOW LEVEL MOISTURE ACROSS THE LOCAL ISLANDS
FROM TIME TO TIME. HOWEVER...AT THIS TIME...NO SIGNIFICANT WEATHER
EVENTS ARE FORECAST TO AFFECT THE LOCAL REGION.

AVIATION...SCATTERED SHRA/ISOLD TSRA WILL CONTINUE TO AFFECT MOST OF
THE LOCAL FLYING AREA THIS EVENING INDUCING BRIEF PERIODS OF MVFR
CONDITIONS ACROSS TNCM...TKPK...TIST...TISX AND TJSJ UNTIL AT LEAST
23/02Z. CONDITIONS ARE EXPECTED TO IMPROVE FROM THE EAST AFTER THAT
WITH VCSH EXPECTED ACROSS MOST OF THE TAF SITES. LATEST TJSJ 12Z
SOUNDING INDICATED AN EASTERLY WIND FLOW UP TO 25 KNOTS ALL THE WAY
FROM THE SURFACE TO 30K FEET...BECOMING NORTHEAST AND A LITTLE
STRONGER ALOFT.

MARINE....WINDS WILL STRENGTHEN THROUGH TUESDAY. EXPECT WINDS
20-23 KT AND SEAS 6-8 FT. WINDS AND SEAS BEGIN TO SUBSIDE RAPIDLY
ON WEDNESDAY. SMALL CRAFT ADVISORIES IN EFFECT FOR ALL WATERS
EXCEPT AMZ745.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  84  76  84 /  20  30  30  30
STT  77  88  77  88 /  40  30  30  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 6 PM AST TUESDAY 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 PUERTO RICO OUT 10 NM-
     COASTAL WATERS OF NORTHERN USVI AND CULEBRA OUT 10 NM-
     COASTAL WATERS OF NORTHWESTERN PUERTO RICO OUT 10 NM-
     COASTAL WATERS OF SOUTHERN USVI VIEQUES AND EASTERN PUERTO
     RICO OUT 10 NM-MONA PASSAGE SOUTHWARD TO 17N.

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

&&

$$

11/09




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