Area Forecast Discussion
Issued by NWS San Juan, PR

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000
FXCA62 TJSJ 280200
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1000 PM AST SUN JUL 27 2014

.UPDATE...THE PROXIMITY OF A TUTT LOW TO THE NORTH OF THE LOCAL
AREA RESULTED IN UNSTABLE CONDITIONS AND VERY COLD TEMPERATURES
ALOFT (-10.7 AT 500 MB). THIS...IN TURN...CONTRIBUTED TO THE DEVELOPMENT OF
A CLUSTER OF STRONG THUNDERSTORMS OVER INTERIOR PUERTO RICO SUNDAY
AFTERNOON WITH HAIL REPORTED IN JAYUYA. MOISTURE ASSOCIATED WITH
THIS LOW COULD ADVECT SOUTHWARD TONIGHT LEADING TO
ISOLATED/SCATTERED SHOWERS OVER THE U.S. VIRGIN ISLANDS AND
EASTERN SECTIONS OF PUERTO RICO. CURRENT FORECAST PACKAGE LOOKS ON
TRACK...SO NO CHANGES WILL BE DONE AT THIS TIME.

THE TUTT LOW SHOULD CONTINUE TO DRIFT SLOWLY SOUTH THROUGH MONDAY
NIGHT. THIS COULD KEEP THE LOCAL AREA UNDER COLD AIR
ALOFT...LEADING TO THE FORMATION OF AFTERNOON THUNDERSTORMS OVER
INTERIOR PUERTO RICO. ONE LIMITING FACTOR COULD BE CONVERGENCE
ALOFT AROUND THE BASE OF THIS LOW WHICH COULD RESULT IN ANY
CONVECTION BEING MORE ISOLATED IN NATURE. THE LOW WILL THEN BEGIN
TO MOVE NORTHWEST PUTTING THE LOCAL AREA UNDER A MORE FAVORABLE
UPPER LEVEL DIFFLUENT FLOW WHICH COULD LEAD TO AN INCREASE IN SHOWERS
AND THUNDERSTORMS BOTH TUESDAY AND WEDNESDAY AFTERNOON.


&&


.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES THROUGH
THE FCST PERIOD. HOWEVER AFTER 28/18Z...OBSCD MTN AND BRIEF MVFR
CIGS ARE EXPECTED DUE SHRA/TSRA DEVELOPING ACROSS THE WESTERN
INTERIOR OF PR AFFECTING MAINLY TJMZ. EASTERLY WINDS 5 TO 15 KTS UP
TO 10 KFT.


&&

.MARINE...SURFACE PRESSURE GRADIENT ACROSS THE NORTHEAST CARIBBEAN
WILL CONTINUE TO RELAX AS THE SURFACE HIGH PRESSURE
RIDGE...CENTERED OVER THE NORTH-CENTRAL ATLANTIC...CONTINUES TO
SLOWLY RETREAT NORTH. AS A RESULT SURFACE WINDS WILL SLACKEN WITH
SEAS SUBSIDING TO WELL BELOW 6 FEET THROUGH THE WEEK.


&&

.PREV DISCUSSION... /ISSUED 250 PM AST SUN JUL 27 2014/

DISCUSSION...ISOLATED TO LOCALLY SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPED OVER THE WESTERN INTERIOR SECTION BUT
QUICKLY DISSIPATED. THE DOPPLER RADAR IS STILL SHOWING A FEW
SHOWERS OVER THIS AREA..THEY ARE LIGHT TO MODERATE AND THEY WILL
DISSIPATE IN THE NEXT HOUR OR SO. TONIGHT...ISOLATED TO LOCALLY
SCATTERED SHOWERS WILL DEVELOP OVER THE LOCAL WATERS...SOME OF
THESE SHOWERS WILL MOVE ON SHORE AND AFFECT THE EASTERN PORTIONS
OF PUERTO RICO AND USVI.

RIDGE NORTH OF ISLANDS DOMINATE THE WEATHER AS DRY AIR CONTINUES
TO MOVE ACROSS LOCAL ISLANDS. PRECIPITATELY WATER REMAINS BELOW
SEASONAL NORMS AND LITTLE CHANGE IS EXPECTED MOST OF THIS WEEK.

AVIATION...ISOLD/SCT SHRA/TSRA WI MVFR UNLIKELY AT ANY TAF SITE
THRU MON. BUT FEW OBSCD MTNS DURING BOTH AFT OVER WESTERN INTERIOR
PR. LOW LEVEL WIND E 12-20 KT XCP NE FL100-FL200...WEAKENING TO 6-13
KT ON MON.

MARINE...AS WINDS CONTINUE TO RELAX ALSO THE SEAS WILL SUBSIDE
THROUGH AT LEAST TUESDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  80  90  80  90 /  20  20  20  30
STT  80  90  80  90 /  20  20  20  20

&&

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

$$

13/08





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