Area Forecast Discussion
Issued by NWS San Juan, PR

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000
FXCA62 TJSJ 290913
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
513 AM AST SUN MAR 29 2015

.SYNOPSIS...BROAD MID TO UPPER LEVEL RIDGE WILL CONTINUE TO ERODE
TODAY THROUGH MID WEEK IN RESPONSE TO A DEEP/AMPLIFYING LONG WAVE
TROUGH MOVING ACROSS THE WESTERN ATLANTIC. WEAKENING FRONTAL
BOUNDARY WILL STALL ACROSS THE ATLANTIC WATERS BY THE MIDDLE OF THE
WEEK.

&&

.DISCUSSION...DOPPLER WEATHER RADAR DETECTED ISOLATED TO SCATTERED
TRADE WIND SHOWERS OVER THE SURROUNDING WATERS OVERNIGHT AND EARLY
THIS MORNING. UNDER AN EAST SOUTHEAST LOW LEVEL WIND FLOW...SOME OF
THESE SHOWERS AFFECTED THE EASTERN AND SOUTHEASTERN SECTIONS OF
PUERTO RICO AS WELL AS ST CROIX IN THE U.S. VIRGIN ISLANDS.
HOWEVER...MOST OF THE AREA REMAINED MOSTLY DRY. THE NORTHEAST
CARIBBEAN REMAINS UNDER THE INFLUENCE OF A WEAKENING MID TO UPPER
LEVEL RIDGE. THIS FEATURE IS EXPECTED TO PROVIDE SUBSIDENCE
INVERSION OVER THE REGION...LIMITING THE SHOWER ACTIVITY. THUS...FOR
TODAY THE TYPICAL TRADE WIND SHOWERS ARE EXPECTED OVER THE U.S.
VIRGIN ISLANDS...VIEQUES...CULEBRA AND EASTERN PUERTO RICO EARLY IN
THE MORNINGS WITH SOME CONVECTION DEVELOPING ACROSS WESTERN AND
INTERIOR SECTIONS OF PUERTO RICO THIS AFTERNOON. BY LATE MONDAY INTO
THE MIDDLE OF THE WEEK...LATEST GFS MODEL GUIDANCE CONTINUED TO
SUGGEST THE DISSIPATING FRONTAL BOUNDARY/SHEAR LINE TO STALL JUST
NORTH OF THE REGION. EXPECT SOME LOW LEVEL MOISTURE TRANSPORT AND
CONVERGENCE ACROSS THE FORECAST AREA TO INCREASE THE CHANCES FOR
SHOWER DEVELOPMENT ACROSS THE COASTAL WATERS AND PARTS OF THE
ISLANDS. IN ADDITION...THE EROSION OF THE UPPER LEVEL RIDGE...WILL
ALSO INCREASE THE POTENTIAL FOR ISOLATED THUNDERSTORMS IN RESPONSE
TO WEAKENING CAP INVERSION.

&&

.AVIATION...VFR CONDS EXPECTED AT ALL TAF SITES THRU THE FORECAST
PERIOD. ISOLD SHRA PSBL FM 29/18-29/22Z OVR AND VCTY TJMZ/TJBQ...
WITH SLIGHT CHC OF FEW VCSH AT TJNR AND OVR E INTERIOR OF PR TIL
29/21Z. SFC WND LGT AND VARIABLE TIL 29/14Z...WITH LCL SEA BREEZE
VARIATIONS THEREAFTER. L/LVL WND BLO FL100 FM SE AT 5-15 KNOTS...
BCMG LGT/VRB ABV AND UP TO FL250. NO SIG OPERATIONAL WX IMPACTS
ATTM.

&&

.MARINE...SEAS UP TO 6 FFET AND WINDS UP TO 20 KNOTS ARE EXPECTED
TODAY AND TONIGHT. SMALL CRAFT ARE URGED TO EXERCISE CAUTION
ACROSS PART OF THE LOCAL COASTAL WATETRS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  88  75  86  75 /  10  10  10  10
STT  86  73  84  73 /  20  10  10  10

&&

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

$$

09/72




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