Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 170245
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1045 PM AST WED APR 16 2014

.UPDATE...NO CHANGE TO PREVIOUS PACKAGE...FORECAST ON TRACK.

STRENGTHENING HIGH PRESSURE TO THE NORTH OF THE LOCAL AREA WILL
CONTINUE TO TIGHTEN THE LOCAL PRES GRADIENT THROUGH AT LEAST
SATURDAY. UNDER THIS ENE WIND FLOW...EXPECT THE CONTINUED TREND
OF PASSING SHOWERS ACROSS THE NORTH AND EAST COASTAL SECTIONS OF
THE ISLANDS OVERNIGHT AND THURSDAY...WITH AFTERNOON CONVECTION
DEVELOPING ACROSS WEST AND SOUTHWEST PUERTO RICO THURSDAY
AFTERNOON.

&&

.AVIATION...AN AREA OF MOISTURE ACROSS THE LEEWARD ISLANDS THIS
EVENING IS EXPECTED TO TRACK WESTWARD OVERNIGHT AND EARLY IN THE
MORNING. THIS FEATURE WILL BRING FEW PASSING SHOWERS AND BRIEF
PERIODS OF MVFR CONDITIONS ACROSS TKPK AND TNCM AFTER 17/03Z AND
ACROSS THE U.S. VIRGIN ISLANDS AND EASTERN PR AFTER 17/04Z.

AFTER 17/16Z...SHOWERS WILL DEVELOP ONCE AGAIN ACROSS WESTERN PR
AND MAY AFFECT TJMZ RESULTING IN BRIEF MVFR CONDITIONS AND
MOUNTAIN OBSCURATIONS. LATEST TJSJ SOUNDING INDICATED AN EAST
NORTHEAST WIND FLOW ALL THE WAY FROM THE SURFACE TO 10K FEET...
BECOMING FROM THE NORTH AND THEN NORTHWEST AND STRONGER ALOFT.

&&

.MARINE...WINDS WILL STRENGTHEN OVERNIGHT THROUGH FRIDAY MORNING
AND GENERATE ROUGH SEAS ACROSS MOST OF THE COASTAL WATERS. EXPECT
SEAS BUILDING 5 TO 7 FEET TOMORROW AND 6 TO 8 FEET BY FRIDAY-SATURDAY.
WINDS AND SEAS WILL BEGIN TO SUBSIDE SUNDAY.

&&

.PREV DISCUSSION... /ISSUED 301 PM AST WED APR 16 2014/

SYNOPSIS...UPPER LEVEL RIDGE WILL BUILD THROUGH THURSDAY THEN HOLD
THROUGH THE END OF THE WEEK. RIDGE WILL FLATTEN EARLY NEXT WEEK
AS SRN STREAM PERTURBATIONS STREAM NORTH OF THE AREA. STRONG WINDS
AND ROUGH SEAS EXPECTED THU THROUGH SAT.

DISCUSSION...STRENGTHENING HIGH PRESSURE TO THE NORTH WILL
TIGHTEN THE LOCAL PRES GRADIENT TONIGHT THROUGH SAT WITH WINDY
CONDITIONS EXPECTED. MODELS INDICATE A MOIST SURGE TONIGHT LIKELY
RELATED TO THE STRENGTHENING WINDS AS UPPER LEVELS WILL BE
DOMINATED BY UPPER RIDGE. EXPECT A CLOUDY SHOWERY DAY THU. DRYING
INDICATED ON FRI BUT THE STRONG WINDS COULD CARRY CLOUD CLUSTERS
AND BRIEF SHOWERS INLAND.

EARLY NEXT WEEK...MODELS CONTINUE TO INDICATE UPPER LEVEL RIDGE
ERODING AS SRN STREAM PERTURBATIONS TRACK EWD FROM THE BAHAMAS INTO
THE NORTHEAST CARIBBEAN. THIS WILL SUSTAIN GRADUAL EROSION OF MID
LEVEL RIDGE PATTERN PROMOTING MOISTURE TRANSPORT AND ENHANCING MID
LEVEL INSTABILITY. BY MID NEXT WEEK CONDITIONS BECOME MORE
FAVORABLE FOR HEAVY RAIN AND DEEP THUNDERSTORMS BRINGING THE BEST
CHANCE FOR HEAVY RAINS SO FAR THIS YEAR.

AVIATION...MVFR CIGS AT JMZ AND JPS THRU 23Z. CLOUDY AND SHOWERY
THU WITH MVFR CIGS AT ALL TAF SITES. WINDS WILL BE STRONG CLOSE TO
20 KT AT ALL TAF SITES XCPT AT JMZ WHERE A WEST WIND WILL BLOW
AGAINST THE PREVAILING EASTERLIES.

MARINE...WINDS STRENGTHEN TONIGHT THROUGH SAT WITH ROUGH SEAS
EXPECTED THROUGH SAT. WINDS AND SEAS BEGIN TO SUBSIDE SUN.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  76  85  76  85 /  30  30  40  40
STT  77  85  77  85 /  50  50  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...



VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY FROM 3 PM THURSDAY TO 6 AM AST SUNDAY FOR
     ANEGADA PASSAGE SOUTHWARD TO 17N-ATLC WATERS OF PUERTO RICO
     AND USVI FROM 10NM TO 19.5N-CARIBBEAN WATERS OF PUERTO RICO
     FROM 10 NM TO 17N-COASTAL WATERS OF NORTHERN USVI AND
     CULEBRA OUT 10 NM-COASTAL WATERS OF SOUTHERN USVI VIEQUES
     AND EASTERN PUERTO RICO OUT 10 NM.

     SMALL CRAFT ADVISORY FROM 9 PM THURSDAY TO 6 AM AST SUNDAY FOR
     COASTAL WATERS OF NORTHERN PUERTO RICO OUT 10 NM-MONA
     PASSAGE SOUTHWARD TO 17N.

&&

$$

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