FXCA62 TJSJ 100211
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1011 PM AST SAT MAY 9 2009
.DISCUSSION...ABUNDANT TROPICAL MOISTURE ACROSS THE REGION WILL
CONTINUE TO BRING SIGNIFICANT CLOUD COVER AS WELL AS PERIODS OF
MODERATE TO HEAVY SHOWER ACTIVITY ACROSS PUERTO RICO AND THE
U.S. VIRGIN ISLANDS FOR THE NEXT SEVERAL DAYS. WHILE THERE WILL BE
A SLIGHT DECREASE IN OVERALL LOW LEVEL MOISTURE ACROSS THE REGION
TO START OFF THE WEEK...STILL EXPECT AMPLE MOISTURE AND
INSTABILITY AVAILABLE TO INDUCE SIGNIFICANT AFTERNOON AND EVENING
SHOWER ACTIVITY...ESPECIALLY OVER THE INTERIOR AND WESTERN
SECTIONS OF PUERTO RICO. MADE SOME MINOR CHANGES TO THE FORECAST
TO KEEP IN LINE WITH LATEST GUIDANCE...BUT OVERALL...IT LOOKS
LIKE ANOTHER FAIRLY ACTIVE WEATHER WEEK IS IN STORE FOR THE LOCAL
ISLANDS.
&&
.AVIATION...A LINE OF MODERATE TO HEAVY SHOWERS WILL MOVE ACROSS THE 
VICINITY ZONE OF SJU BETWEEN 02-03Z...OTHERWISE CONDITIONS SHOULD 
REMAIN VFR AT ALL TAF SITES OVERNIGHT. SHOWERS WILL REDEVELOP OVER 
MAINLAND PUERTO RICO AND PLACE SHOWERS VICINITY OF ALL TAF SITES 
BETWEEN 10/16-22Z. MOUNTAIN OBSCURATIONS ARE LIKELY...BUT ONLY TJMZ 
AND TJBQ HAVE A GOOD CHANCE OF MVFR CONDS IN THAT TIME PERIOD. WINDS 
WERE LIGHT AND VARIABLE 4-16 KFT...AND SHOULD PERSIST THIS WAY 
THROUGH THE WEEKEND BUT TRADEWINDS OF UP TO 17 KTS HELD AT THE 
LOWEST LEVELS.
&&
.PREV DISCUSSION... /ISSUED 345 PM AST SAT MAY 9 2009/ 
SYNOPSIS...HIGH PRESSURE WILL CONTINUE NORTHEAST OF THE LOCAL
AREA. A DRY SLOT WILL MOVE MONDAY AND TUESDAY OVER THE LOCAL AREA.
DEEP TROPICAL MOIST WILL MOVE FROM THE SOUTHEAST STARTING WEDNESDAY. 
DISCUSSION...ANOTHER ACTIVE DAY ACROSS MOST OF PUERTO RICO. HIGH
RELATIVE HUMIDITY VALUES...COMBINED WITH DAYTIME
HEATING...PRODUCED NUMEROUS SHOWERS ACROSS THE LOCAL AREA...MAINLY
NORTH OF THE CORDILLERA CENTRAL. THIS WEATHER PATTERN IS EXPECTED
TO PREVAIL AT LEAST THROUGH MONDAY...WHEN A DRY SLOT WILL MOVE
FROM THE EAST NORTHEAST EARLY MONDAY...CONTINUING UNTIL TUESDAY.
THIS AREA OF DRIER WEATHER...WILL DECREASE SOMEWHAT THE CHANCES OF
PRECIPITATION ACROSS THE LOCAL AREA. HOWEVER...NAM12 AS WELL AS
SJU-GFS COMPUTER MODELS AGREE IN A SIGNIFICANT INCREASE IN
MOISTURE WILL OCCUR STARTING ON WEDNESDAY AND CONTINUING TO AT
LEAST NEXT WEEKEND. GFS PROG SOUNDINGS INDICATED THAT PRECIPITABLE
WATER VALUES WILL INCREASE FROM 1.56 INCHES TUESDAY UP TO 2.17 INCHES
SATURDAY. THEREFORE...DIDN'T MAKE ANY CHANGES TO LONG TERM GRIDS
WHICH ARE IN GOOD SHAPE...WHICH ARE IN TRACK ON EXPECTED WEATHER.
IN THE MEANTIME...HIGH PRESSURE WILL STAY NORTHEAST OF THE LOCAL
AREA...BUT WILL MOVE SLOWLY NORTHEAST..LEAVING THE LOCAL AREA
UNDER A WEAKER TRADE WIND FLOW STARTING TUESDAY.
AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS MOST OF THE
LOCAL ISLANDS AND TAF SITES...EXCEPT MVFR OR EVEN BRIEF IFR
CONDITIONS AND MOUNTAIN OBSCURATIONS WILL CONTINUE
LOCALLY...ESPECIALLY OVER PARTS OF PUERTO RICO THROUGH AT LEAST
22Z OR 23Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU  75  85  75  85 /  40  40  40  40 
STT  73  84  73  84 /  50  40  40  40 
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
&&
$$
12/04