AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
957 PM AST FRI JUL 8 2011

.UPDATE...MOST ACTIVITY DISSIPATED NEAR SUNSET...WITH ONLY LIGHT
PASSING SHOWERS PREVAILING ACROSS THE EASTERN HALF OF PUERTO RICO
AND IN THE VICINITY OF THE U.S. VIRGIN ISLANDS. SINCE A DRIER
AIR MASS IS EXPECTED TO MOVE ACROSS THE REGION THROUGH THE
WEEKEND...MADE SOME CHANGES TO SHORT TERM GRIDS ACCORDINGLY.

&&

.AVIATION...INTMT PDS OF LOW LVL CLDS AND PASSING SHRA WILL CONT
ESPECIALLY EN ROUTE BTW PR AND THE NRN LEEWARDS. PREVAILING VFR
CONDS ARE EXPECTED AT MOST TAF SITES THROUGH 09/12Z. AFT 09/16Z
LOCAL AND DIURNAL EFFECTS WILL INCR CLOUD COVER LEADING TO AREAS OF
MVFR/PSBL IFR CONDS WITH ISOLD-SCT SHRA/PSBL TSRA DVLPMNT...
ESPECIALLY VCNTY TJMZ AND TJBQ FM 09/16Z-09/22Z. MTN TOP OBSCR ALSO
PSBL OVR PARTS OF CORDILLERA CENTRAL OF PR. OVERNIGHT LCL SFC WINDS
WILL BE LIGHT BUT MAINLY FM EAST...INCRG AFT 09/12Z TO 10-15 KTS
FROM THE EAST WITH OCNL HIGHER WIND GUSTS. HIGHER WIND GUSTS ALSO
PSBL WITH PASSING SHRA ACTIVITY DURG OVERNIGHT HOURS.

&&

.PREV DISCUSSION... /ISSUED 256 PM AST FRI JUL 8 2011/

SYNOPSIS...TROPICAL WAVE WEST OF PUERTO RICO INTERACTING WITH
WEAK UPPER TROUGH NORTHWEST OF PUERTO RICO. DRIER WEATHER IN STORE
FOR TONIGHT AND SATURDAY. MODERATE EAST SOUTHEAST SURFACE WIND
FLOW BEHIND IN WAKE OF WAVE.

DISCUSSION...AFTER AN ACTIVE MORNING ACROSS THE USVI MOST OF THE
CONVECTION DIED OUT AND ONLY UPPER LEVEL CLOUDS REMAIN. TROPICAL
WAVE HAS MOVED WEST OF PR BUT WEAK UPPER TROUGH REMAINS TO THE
NORTHWEST OF PUERTO RICO. UPDATED PARTS OF THE FORECAST FOR THE
NEXT 36 HOURS. LATEST GFS BRINGS DRIER WEATHER FOR LOCAL AREA BY
SATURDAY MORNING WITH PW VALUES PER GFS DOWN TO 1.7 FOR BOTH USVI
AND PUERTO RICO ALTHOUGH OVER THE NORTHERN AND SOUTHERN WATERS PW
VALUES REMAIN HIGH. WOULD EXPECT NORMAL CONVECTIVE PATTERN ON
SATURDAY AFTERNOON ALTHOUGH LATE SATURDAY PW VALUES INCREASE AGAIN
MAINLY ACROSS THE USVI AND ON MONDAY ACROSS EAST PUERTO RICO.

AVIATION...PREVAILING VFR CONDITIONS ARE EXPECTED ACROSS MOST
TAF SITES THROUGH AT LEAST 09/16Z. AFTER 09/16Z MOISTURE WILL
INCREASE WITH MVFR OR EVEN IFR CONDITIONS AND LOCAL MOUNTAIN
OBSCURATIONS POSSIBLE OVER THE TJMZ AND TJBQ IN TSRA. OVERNIGHT
WINDS ARE EXPECTED TO BE LIGHT AND MAINLY EASTERLY. AFT
09/12Z...SFC WINDS WILL INCREASE TO 10-15 KTS FROM THE EAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  88  79  89 /  30  20  20  20
STT  76  86  80  89 /  40  20  20  20

&&

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

$$