000
FXCA62 TJSJ 181518
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1118 AM AST FRI APR 18 2014

.UPDATE...NO CHANGES MADE TO INHERITED SHORT TERM FORECAST AT THIS
TIME. QUICK PASSING SHOWERS DRIVEN BY THE STRONG EASTERLY TRADES
CONTINUED TO MOVE ACROSS THE REGION THIS MORNING PRODUCING PERIODS
OF MOSTLY LIGHT TO MODERATE RAINFALL WITH SO FAR NO SIGNIFICANT
RAINFALL ACCUMULATIONS. HOWEVER...SOME AREAS OF ISOLATED LOCALLY
HEAVY DOWNPOURS LEAD TO PONDING OF WATER ON ROADWAYS AND HAZARDOUS
DRIVING CONDITIONS. EXPECT THESE CONDITIONS TO CONTINUE INTO THE
AFTERNOON HOURS...FOLLOWED BY DEVELOPMENT OF SCATTERED SHOWERS AND
SLIGHT POSSIBILITY OF A THUNDERSTORM MAINLY ACROSS THE WEST
INTERIOR SECTION OF PUERTO RICO. MOSTLY PASSING SHOWERS EXPECTED
FOR THE REST OF THE DAY IN AND AROUND THE VIRGIN ISLANDS. ALL IN
ALL...OVERALL DECREASING CLOUDINESS AND MORE SUNSHINE/CLEARING IS
EXPECTED DURING THE AFTERNOON AND EVENING HOURS ACROSS THE
ISLANDS...AS SOMEWHAT DRIER AIR WILL BEGIN TO FILTER IN FROM THE
EAST... AND THE STRONG EASTERLY TRADE WINDS STILL FORECAST TO
GRADUALLY DIMINISH OVERNIGHT AND THROUGH SUNDAY AND MONDAY.

&&

.AVIATION UPDATE...SCT-BKN LOW TO MID LVL CLD LYRS MOVG QUICKLY
ACROSS RGN WITH EMBEDDED ISOLD-SCT -SHRA/SHRA AND FEW TCU NOW
MAINLY ACROSS OFFSHORE AND NORTH AND SOUTH OF THE LOCAL ISLANDS.
MOST OF CLOUDINESS BLO FL150 WITH PREVAILING WNDS FM E AT 15-25
KTS...BCMG FM N-NW AND INCR W/HT TO MAX WND NR 60 KTS AROUND FL450.
BREEZY CONDS AND OCNL SFC WND GUSTS UP TO 27 KNOTS OR SO WILL
REMAIN PSBL AT ALL LCL TAF SITES TIL AT LEAST 18/22Z...ESPECIALLY
ACCOMPANYING PASSING SHOWER ACTIVITY. BRIEF MTN TOP OBSCR ALSO
LIKELY W/PASSING SHRA IN AND AROUND CENTRAL MTN RANGE OR PR. NO
OTHER SIG OPERATIONAL WX IMPACTS AT THIS TIME.

&&

.MARINE UPDATE...HAZARDOUS SEAS CONTINUED ACROSS THE REGIONAL
WATERS THIS MORNING DUE TO FRESH TO STRONG EASTERLY TRADE WINDS
AND OCCASIONAL WINDS GUSTS UP TO AS MUCH AS 27 KNOTS OBSERVED
ACROSS THE LOCAL WATERS ACCOMPANYING PASSING TRADE WIND SHOWERS.
SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR ALL OF THE LOCAL
WATERS AND PASSAGES EXCEPT FOR THE NEAR SHORE COASTAL WATERS OF
SOUTHWEST PUERTO RICO WHERE SMALL CRAFT OPERATORS SHOULD STILL
EXERCISE CAUTION DUE TO MODERATE TO LOCALLY FRESH TRADE WINDS.

&&

.PREV DISCUSSION... /ISSUED 544 AM AST FRI APR 18 2014/

SYNOPSIS...AT UPPER LEVELS...A WEAK TROUGH WILL MOVE THROUGH THE
NORTHWESTERLY FLOW AHEAD OF THE RIDGE OVER THE CENTRAL CARIBBEAN.
THE RIDGE WILL WEAKEN AND PASS OVER THE AREA SUNDAY NIGHT. ANOTHER
TROUGH WILL MOVE THROUGH THE AREA ON THURSDAY.

AT MID LEVELS...A TROUGH EXTENDS INTO THE EASTERN CARIBBEAN FROM A
STRONG LOW PRESSURE 2600 MILES NORTHEAST OF SAN JUAN. HIGH
PRESSURE SITS NORTH OF HISPANIOLA OVER THE BAHAMA ISLANDS. THE
TROUGH WILL WEAKEN AND PULL BACK INTO THE TROPICAL ATLANTIC AND
THE HIGH WILL WEAKEN BUT REMAIN OVER MOST OF THE CARIBBEAN THROUGH
MONDAY. A BROAD TROUGH WILL MOVE INTO THE AREA ON THURSDAY FROM A
STRONG LOW NORTH OF THE AREA AT 40 DEGREES NORTH.

AT LOWER LEVELS...HIGH PRESSURE SAGS SOUTH AND THEN SOUTHEAST INTO
THE EASTERN ATLANTIC DURING THE NEXT 5 DAYS. A LOW IN THE GULF OF
MEXICO WILL MOVE ACROSS NORTHERN FLORIDA AND INTO THE WESTERN
ATLANTIC BY SATURDAY AND THEN MOVE NORTHEAST. THE INTERACTION
BETWEEN THE HIGH AND THE LOW WILL CAUSE WINDS TO DIMINISH GREATLY
AND TURN FROM EASTERLY TO SOUTHEASTERLY BY MID WEEK NEXT WEEK.
THIS WILL BRING BETTER MOISTURE OUT OF THE TROPICS.

DISCUSSION...SHOWERS VISITED MOST OF THE U.S. VIRGIN
ISLANDS...VIEQUES AND THE SOUTHEAST QUADRANT OF PUERTO RICO
OVERNIGHT AS WELL AS THE NORTH COAST FROM LUQUILLO TO
BARCELONETA. AMOUNTS WERE GENERALLY LIGHT BUT 12-HOUR RAINFALL
REACHED 1.13 INCHES AT THE LUIS MUNOZ MARIN AIRPORT OVERNIGHT AND
THE EASTERN FLANKS OF EL YUNQUE AND RIDGES OF MAUNABO LIKELY HAD
MORE THAN THAT ACCORDING TO NWS DOPPLER RADAR. INFRA RED IMAGERY
SHOWS THAT THE MOISTURE IS BANDED AND WILL PERSIST THROUGH MUCH OF
THE DAY TODAY...EVEN WHILE GENERALLY DECREASING. OPERATIONAL
MODELS SHOW SHOWERS DIMINISHING AREA-WIDE DURING THE DAY AS
PRECIPITABLE WATER DROPS FROM 1.6 INCHES TO AS LITTLE AS 1.2
INCHES BY MIDNIGHT FRIDAY NIGHT. NEVERTHELESS ENOUGH MOISTURE IS
EXPECTED TO BE PRESENT TO HAVE INTERMITTENT SHOWERS IN MOST AREAS
TODAY WITH SCATTERED SHOWERS IN EASTERN PUERTO RICO TONIGHT.

AS THE HIGH PRESSURE RECEDES INTO THE EASTERN ATLANTIC AND FLOW
OVER THE AREA TURNS MORE SOUTHERLY BEGINNING MONDAY...MORE AND MORE
MOISTURE WILL BE ABLE TO REACH THE AREA WITH AS MUCH AS 1.8 INCHES
OF PRECIPITABLE WATER EXPECTED ON TUESDAY AND NEARLY 2 INCHES ON
THURSDAY. CONSEQUENTLY SHOWER ACTIVITY IS EXPECTED TO INCREASE
OVER THE WEEKEND SOMEWHAT...BUT MORE SO ON TUESDAY AND THURSDAY.
IN SOME AREAS THIS RAINFALL COULD BE LOCALLY HEAVY. MOISTURE
DIMINISHES AFTER THURSDAY.

ISOLATED THUNDERSTORMS ARE POSSIBLE TODAY AND FRIDAY...BUT MID
LEVEL MOISTURE IS VERY WEAK. MOISTURE DEPTH IMPROVES OVER THE
WEEKEND AND THE CHANCE OF THUNDERSTORMS IMPROVES SOMEWHAT.

WITH SOUTHERLY WINDS THERE WILL BE SOME WARMING ON THE NORTH
COAST. HAVE ADJUSTED TEMPERATURES SOMEWHAT NEXT WEEK...BUT
CLOUDINESS AND SHOWERS WILL LIMIT THE USUAL DOWN-SLOPE WARMING THAT
THE NORTH COAST EXPERIENCES WITH SOUTHERLY WIND FLOW.

AVIATION...CLOUDS AND PASSING SHOWERS WILL CONTINUE TO AFFECT
PORTIONS OF THE ISLANDS TODAY. AS A RESULT...BRIEF MVFR CONDS ARE
POSSIBLE NEAR TJSJ...TIST...TISX...TNCM AND TKPK TIL AT LEAST
18/14Z. IN ADDITION...MOUNTAIN OBSCURATION WILL ARE EXPECTED ACROSS
THE INTERIOR PORTIONS OF PR. EAST WINDS OF 15-25 KT GUSTING TO
25-30KT ARE EXPECT TODAY.

MARINE...SMALL CRAFT ADVISORIES HAVE BEEN POSTED FOR NEARLY ALL
ZONES TODAY. WINDS IN SOME AREAS WILL REACH UP TO 24 KNOTS AND
SEAS OF 6 TO 8 FEET WILL PREVAIL WITH PERIODS AROUND 10 SECONDS.
WINDS AND SEAS SUBSIDE SUNDAY AND MONDAY AND WE ARE LOOKING FOR
SEAS TO BE LESS THAN 6 FEET EVERYWHERE BY TUESDAY. HIGH SEAS ARE
NOT EXPECTED TO RETURN UNTIL VERY LATE IN THE MONTH.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  84  75  86  76 /  60  40  60  40
STT  85  76  86  77 /  50  50  50  50

&&

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

VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 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 PUERTO RICO OUT 10 NM-
     COASTAL WATERS OF NORTHERN USVI AND CULEBRA OUT 10 NM-
     COASTAL WATERS OF NORTHWESTERN PUERTO RICO OUT 10 NM-
     COASTAL WATERS OF SOUTHERN USVI VIEQUES AND EASTERN PUERTO
     RICO OUT 10 NM-MONA PASSAGE SOUTHWARD TO 17N.

     SMALL CRAFT ADVISORY UNTIL 11 PM AST THIS EVENING FOR COASTAL
     WATERS OF SOUTHERN PUERTO RICO OUT 10 NM.

&&

$$

09/71