Area Forecast Discussion
Issued by NWS San Juan, PR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXCA62 TJSJ 300753
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
353 AM AST SAT MAY 30 2015

.DISCUSSION...SHOWERS/THUNDERSTORMS HAVE BEEN RE-DEVELOPING OVER
USVI SINCE MIDNIGHT. THEY EXTEND WELL TO THE NORTH AND SOUTH AND
MOVING WEST ABOUT 12 KNOTS...HAVING REACHED VIEQUES. THERE IS
APPARENTLY A SMALL LOW LEVEL WAVE AND A WIND SURGE FOLLOWING THE
STORMS. 00Z WRF AND 18Z ARW MODELS APPEAR TO HAVE CAUGHT SOME
SEMBLENCE OF THIS BUT WRF WAS ABOUT 6 HOURS SLOW AND ARW ONLY
PUSHED THE STORMS TO THE NORTH OF ST. THOMAS. EXTRAPOLATION OF
THE LINE FROM RADAR...WHICH IS WEAKENING A LITTLE...WOULD PUSH
SHOWERS/STORMS ACROSS EASTERN PR EARLY THIS MORNING SO RAISED
PROBABILITY OF PRECIPITATION THERE SOMEWHAT.

LOTS OF CIRRUS PASSING OVER ISLANDS BUT BELIEVE IT IS THIN ENOUGH
TO ALLOW GOOD HEATING FOR AFTERNOON CONVECTION TO OCCUR MOST OF
ISLAND...ESPECIALLY NORTHWEST QUARTER OF MAIN ISLAND OF PR. NO
UPPER JET LEVEL DIVERGENCE TO HELP GENERATE THIS BUT THE LOW LEVEL
WAVE MIGHT INITIALIZE SOME BY LATE THIS MORNING OVER THE CENTRAL
PART OF THE ISLAND. THIS TROPICAL WAVE IS TOO WEAK TO CAUSE MUCH
CONVECTION WITHOUT HEATING OF ISLANDS EVEN THOUGH PRECIPITABLE
WATER WILL HOVE NEAR 2 INCHES EVEN INTO NEXT WEEK. GFS INDICATES
NO SIGNIFICANT DROP OFF IN MOISTURE UNTIL ABOUT THU.

&&

.AVIATION...VFR TO MVFR CONDS EXPECTED TO PREVAIL THROUGH THE
EARLY PART OF THE FCST PERIOD...SPREADING FROM THE LEEWARD ISLANDS
TO THE USVI AND EASTERN PR TERMINALS. THEN AS SHOWERS AND
THUNDERSTORMS RE-DEVELOP OVER THE LOCAL FLYING AREA MVFR/BRIEF IFR
CONDS POSSIBLE ACROSS ISX/JBQ/JMZ/JSJ AND THE VCNTY OF JPS...WITH
MULTIPLE SCT/BKN LAYERS AND MAX TOPS NEAR 40 KFT. WIDESPREAD MTN
OBSCURATIONS STILL LIKELY ACROSS THE CORDILLERA CENTRAL AND EASTERN
PR. SE WINDS AT 10-15 KT EXPECTED BELOW 10 KFT WITH SEA BREEZE
VARIATIONS AFTER 14Z. HIGHER GUSTS NEAR TSRA.

&&

.MARINE...WEAK TROPICAL WAVE WITH DEEP MOISTURE WILL GRADUALLY
MOVE OUT OF THE AREA BY MON WITH HIGH PRESSURE TRYING TO RE-
ESTABLISH TRADE WINDS. BUT THE HIGH PRESSURE WILL BE TOO WEAK AND
TOO FAR AWAY TO STRENGTHEN TRADES VERY MUCH BEFORE WEAKENING AGAIN
BY TUE.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  87  77  87  77 /  70  50  40  30
STT  87  80  87  78 /  60  60  30  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...NONE.
&&

$$

13/54



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.