weather.gov     
National Weather Service

Area Forecast Discussion
NWS Homepage
This page is being discontinued on March 12, 2014.
The same data is available at this site. Please update your bookmarks.
Thank you, and we apologize for the inconvenience.
Please send an email to SR-SRH.Webmaster@noaa.gov with any concerns.


Current Version
Previous Version:    01  02  03  04  05  06  07  08  09  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  
[Printable]
712
FXCA62 TJSJ 201854
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
254 PM AST SUN APR 20 2014

.SYNOPSIS...MID TO UPPER LEVEL RIDGE WILL WILL CONTINUE TO FLATTEN/ERODE
ACROSS THE REGION...AS TUTT EAST AND NORTHEAST OF THE LESSER ANTILLES
PULLS FARTHER NORTH AND WEAKENS...WHILE ANOTHER SHORT WAVE MOVES
EASTWARD ACROSS THE WESTERN ATLANTIC. THIS WILL LEAVE A CONVERGENT
AND HIGH ZONAL/WESTERLY WIND FLOW ALOFT THROUGH AT LEAST WEDNESDAY.
AT THE SURFACE AND LOW LEVELS...STRONG HIGH PRESSURE RIDGE THAT
HAS BEEN EXTENDING ACROSS THE REGION IN RECENT DAYS WILL CONTINUE
TO WEAKEN AND RELAX THE LOCAL PRESSURE GRADIENT...AS IT PULLS
FARTHER NORTH INTO THE ATLANTIC AND A POLAR TROUGH AND ASSOCIATED
COLD FRONT MOVES EASTWARD ACROSS THE WESTERN ATLANTIC THROUGH
WEDNESDAY.

&&

.DISCUSSION...EROSION OF THE RIDGE ALOFT WILL CONTINUE THROUGH
THE EARLY PART OF THE WEEK. SURFACE HIGH PRESSURE PULLING FATHER
NORTH OF REGION WILL ALLOW FOR LIGHTER TRADE WINDS AND LESSER
UPPER LEVEL SUPPORT TO ENHANCE THE LOW LEVEL MOISTURE CONVERGENCE
AND PASSING TRADE WIND SHOWER THAT HAS BEEN AFFECTING THE REGION IN
RECENT DAYS. EXPECT LESSER ACTIVITY OVERNIGHT THROUGH TUESDAY AND
WEDNESDAY...WITH MOSTLY ISOLATED PASSING SHOWERS TO AFFECT PARTS
OF THE EAST COASTAL SECTIONS OF THE ISLANDS....FOLLOWED BY ISOLATED
TO SCATTERED AFTERNOON CONVECTION DURING THE DAY...OVER PARTS OF
THE ISLANDS.

BY MID WEEK...PREVIOUSLY MENTIONED POLAR TROUGH/WEAKENING COLD FRONT
IS TO MOVE ACROSS THE WEST ATLANTIC AND CREATE AN AREA OF LOW LEVEL
CONVERGENCE ALONG WITH AN INDUCED PREFRONTAL TROUGH. THIS FEATURE IS
EXPECTED TO AFFECT THE AREA ON WEDNESDAY AND THURSDAY AND SHOULD
BRING AN EAST SOUTHEAST WIND FLOW AND MODERATE AMOUNTS OF MOISTURE
TRANSPORT. THIS IN TURN WILL ALLOW FOR BETTER FORMATION OF EARLY
MORNING SHOWERS ALONG WITH SOME ENHANCED AFTERNOON CONVECTION
WHICH WILL BE MAINLY FORCED BY LOCAL/DIURNAL EFFECTS AND SEA AND
LAND BREEZE CONVERGENCE. IN ADDITION...RECENT GALVEZ-DAVISON INDEX
AS WELL AS LATEST GFS MODEL GUIDANCE ALL SUGGEST BEST POTENTIAL FOR
INCREASING MOISTURE AND MORE UNSTABLE CONDITIONS...SHOULD BE DURING
THE LATTER PART OF THE UPCOMING WEEK. WILL CONTINUE TO MONITOR AND
SEE HOW THIS PATTERN UNFOLDS.

&&

.AVIATION...SHRA DECR MOST OF REGION. BUT SHRA WI MVFR CIGS TO
PERSIST THIS AFT NR TJSJ/TJBQ AND PSBL TJMZ...FEW OBSCD MTNS. OTHW
VFR XCP SHRA REACHING TNCM/TKPK AGAIN TONITE. WIND ESE 12-18 KT BCMG
SE 10-15 ON MON. FL100-FL200 TO BE VRBL/LESS THAN 10 KT.

&&

.MARINE...WINDS AND SEA HEIGHTS CONTINUED TO DECLINE ACROSS THE AS
EXPECTED WITH CONTINUED DIMINISHING WINDS EXPECTED ACROSS THE REGION
OVER THE NEXT FEW DAYS. RECENT BUOY DATA FROM 41043 SUGGESTS SEAS
AROUND 7 FT OR SO WITH A SLOW BUT STEADY DECLINE NOTED IN RECENT
HOURS. THE NEAR SHORE BUOY 41052 SUGGEST SEAS OF 5 TO 6 FEET AND SLOW
DECLINE. SEAS ARE NO LONGER EXPECTED TO BE AT SMALL CRAFT ADVISORY
CRITERIA WITHIN THE REGIONAL WATERS...THEREFORE SMALL CRAFT
ADVISORIES HAVE BEEN CANCELLED OR ALLOWED TO EXPIRE. HOWEVER DUE TO
MODERATE TO LOCALLY FRESH TRADE WINDS SMALL CRAFT OPERATORS SHOULD
EXERCISE CAUTION FOR MOST OF THE LOCAL WATERS. PLEASE REFER TO THE
LATEST COASTAL WATERS FORECAST ISSUED BY THE WFO NATIONAL WEATHER
SERVICE SAN JUAN.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  77  88  75  87 /  20  20  10  40
STT  76  86  77  87 /  30  20  20  50

&&

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

$$

54/09






U.S. Dept. of Commerce
NOAA National Weather Service
1325 East West Highway
Silver Spring, MD 20910
E-mail: w-nws.webmaster@noaa.gov
Page last modified: May 16, 2007
NATIONAL WEATHER SERVICE: for Safety, for Work, for Fun - FOR LIFE