Forecast Discussion for sju NWS Office
000
FXCA62 TJSJ 041537
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1137 AM AST SAT FEB 4 2012
.DISCUSSION...DRIED UP THE FORECAST A TAD FOR TODAY...EXCEPT FOR
THE SOUTHWEST OF PUERTO RICO WHERE WILL GO WITH PERSISTANCE SINCE
A FEW SHOWERS DID POP UP THERE YESTERDAY AFTERNOON. DROPPED
COVERAGE ACROSS MOST OF THE AREA FROM SCATTERED TO ISOLATED EXCEPT
FOR THE PREVIOUSLY MENTIONED SECTIONS. OTHEREWISE NO SIGNIFICANT
CHANGES TO FORECAST.
&&
.AVIATION...VFR CONDS WILL PREVAIL ACROSS THE LOCAL ISLANDS AND
AT ALL TAF SITES THROUGH 05/00Z. AFTERWORDS...MVFR CONDITIONS AND LOCAL
MOUNTAIN OBSCURATIONS ARE POSSIBLE IN SCATTERED PASSING SHOWERS IN
AND AROUND TJSJ/TIST/TISX AND TNCM. SURFACE WINDS WILL CONTINUE
EAST NORTHEAST AT 10 TO 15 KTS WITH SOME HIGHER GUSTS.
&&
.MARINE...HAVE NOT MAKE MANY CHANGES HERE FROM PREVIOUS
FORECASTER THOUGHTS. 12PLANET CHAT WITH TAFB_ATL INDICATED THAT
ECMWF IS IN THE 8-9 FOOT RANGE...AND IS IN LINE WITH ENSEMBLE
MEANS.
&&
.PREV DISCUSSION... /ISSUED 545 AM AST SAT FEB 4 2012/
SYNOPSIS...MID-UPPER LEVEL RIDGE WILL CONTINUE TO BE THE DOMINANT
WX FEATURE. A SFC TROF EAST OF THE LESSER ANTILLES IS EXPECTED TO
RETROGRESS WWD LATE TONIGHT AND SUN.
DISCUSSION...DRIER WX IS EXPECTED TODAY AS COMPARED TO PAST FEW
DAYS BUT A SFC TROF LOCATED EAST OF THE LEEWARD ISLANDS WILL MOVE
QUICKLY WWD THIS AFTERNOON WITH MOISTURE CONVERGENCE INCREASING
FIRST ACROSS ST. CROIX AND THEN WWD ACROSS ERN PR AND THE ATLC
AND CARIBBEAN COASTAL THIS EVENING. SFC TROF THEN MOVES INTO THE
MONA PASSAGE BY SUN AFTERNOON BUT MOISTURE LINGERS THROUGH THE
DAY. THIS IN COMBINATION WITH WEAKENING HIGH PRES TO THE NORTH
SHOULD LOOSEN THE PRES GRADIENT SIGNIFICANTLY TO ALLOW SEA BREEZE
DEVELOPMENT AND BETTER CHANCES OF PRECIP. LOW-LVL WINDS TURN MORE
SOUTHEAST FOR A CHANGE ALLOWING SCT-NMRS SHRAS AND EVEN POSSIBLE
TSTMS TO DEVELOP ACROSS NW PR. DID NOT INTRODUCE THUNDER AT THIS
TIME GIVEN TIME OF THE YEAR BUT THUNDER POTENTIAL SHOULD BE
REEVALUATED AS K INDICES CLIMB TO NEAR 30.
NEXT WEEK...MID-UPPER LEVEL RIDGE PREVAILS BUT WEAKER PRES GRADIENT
AND ENOUGH LOW LEVEL MOISTURE SHOULD RESULT IN AT LEAST ISOLD TO
SCT SHRAS WITH WRN AND NW PR THE MOST PREFERED LOCATION DUE TO A
MORE SOUTHEASTERLY LOW LEVEL STEERING FLOW WHICH IS QUITE A
CONTRAST FROM THE PAST FEW WEEKS.
AVIATION...VFR CONDS WILL PREVAIL ACROSS THE LOCAL ISLANDS AND
AT ALL TAF SITES THROUGHOUT THE DAY. AFT 05/00Z...MVFR CONDITIONS
AND LOCAL MOUNTAIN OBSCURATIONS ARE POSSIBLE IN SCATTERED PASSING
SHOWERS IN AND AROUND TJSJ/TIST/TISX AND TNCM. SURFACE WINDS WILL
CONTINUE EAST NORTHEAST AT 10 TO 15 KTS WITH SOME HIGHER GUSTS.
MARINE...INTENSE LOW PRES ACROSS THE NW ATLC IS GENERATING
A LARGE AREA OF STORM FORCE WINDS AND EVEN A SMALL AREA OF
HURRICANE FORCE WINDS AS INDICATED BY SEVERAL 50+KT VECTORS BY A
0105Z ASCAT PASS. THIS INSTRUMENT HAS A SIG LOW BIAS FOR WINDS AT
THIS MAGNITUDE AS COMPARED TO THE OLD QUIKSCAT SATELLITE WITH
RESEARCH STUDIES DONE INDICATING THAT WINDS OF 50+KT INDICATED BY
THE ASCAT SHOULD BE INCREASED TO A LEAST ONE CATEGORY. SO IT IS
ASSUMED THAT A SMALL AREA OF HURRICANE FORCE WINDS IS BEING
GENERATED BY THIS INTENSE LOW PRES AREA. ANYTIME HURRICANE FORCE
WINDS OCCUR ACROSS THE NW ATLC DURING THE WINTER SEASON THIS
TYPICALLY YIELDS HIGH SURF WITH BREAKING WAVES GREATER THAN 10 FT
ON THE ATLC COAST OF PR. SEAS WILL REMAIN 3-6 FT BUT INCREASE UP
TO 9 FT BY MON IN NORTH SWELLS. SCA AND HIGH SURF ADVISORIES WILL
BE REQUIRED BUT TOO EARLY ATTM TO ISSUE THEM.
FIRE WEATHER...DRIER TODAY THAN PAST COUPLE OF DAYS WITH LESS
CLOUD COVER THAN YDAY. WHILE MIN_RH MAY DROP INTO THE 40-45%...WINDS
WILL BE LIGHTER UP TO ABOUT 15KT. FIRE DANGER WILL CONTINUE TO BE
DRIVEN BY FUELS WHICH REMAIN VERY DRY ACROSS THE SOUTH COASTAL
PLAINS OF COAMO...SANTA ISABEL..SALINAS AND GUAYAMA.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 81 73 83 73 / 20 40 50 10
STT 84 74 84 74 / 20 50 50 20
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...NONE.
&&
$$
07/25
NWS sju Office Area Forecast Discussion
