000
FXCA62 TJSJ 220213
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1013 PM AST TUE MAY 21 2013

.UPDATE...VERY ACTIVE DAY ACROSS THE LOCAL AREA. SEVERAL FLOOD
ADVISORIES WERE ISSUED...WITH EVEN A FLASH FLOOD WARNING ISSUED
FOR THE SAN JUAN METRO AREA. FORTUNATELY...ALL THIS ACTIVITY
DISSIPATED JUST AFTER SUNSET. PARTLY CLOUDY SKIES WILL PREVAIL
ACROSS PUERTO RICO OVERNIGHT. SOME PASSING SHOWERS ARE EXPECTED
OVER THE U.S. VIRGIN ISLANDS. LITTLE CHANGES WERE MADE TO SHORT
TERM GRIDS TO ADJUST FORECAST WITH ONGOING WEATHER SITUATION.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES
THROUGH AT LEAST 22/12Z. SOME PASSING SHOWERS EXPECTED OVER
TNCM...TKPK...AND TIST.

&&

.MARINE...SEAS WILL INCREASE TOMORROW AT 7 FEET ACROSS THE
OFFSHORE ATLANTIC WATERS. SEAS OF 6 FEET OT LESS AND WINDS OF 20
KNOTS OR LESS ARE EXPECTED.


&&

.PREV DISCUSSION... /ISSUED 834 PM AST TUE MAY 21 2013/

UPDATE...MOST OF THE SHOWERS AND THUNDERSTORMS HAVE DISSIPATED OR
MOVED AWAY. AT THIS MOMENT THE DOPPLER RADAR IS SHOWING SHOWERS
AND THUNDERSTORMS OVER THE EXTREME SOUTHERN WATERS OF OUR CWA.
ISOLATED TO LOCALLY SCATTERED SHOWERS WILL CONTINUE TO MOVE OVER
THE EASTERN PORTIONS OF PUERTO RICO AND LOCAL ISLANDS THROUGH THE
OVERNIGHT HOURS.

AVIATION...ALTHOUGH BRIEFED PERIODS OF MVFR COULD OCCUR OVER THE
TIST AND TISX...MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES
THROUGH AT LEAST 22/12Z.

MARINE...MOST OF THE SHOWERS AND THUNDERSTORMS ASSOCIATED TO A
WEAK TROPICAL WAVE ARE AFFECTING THE OFF SHORE CARIBBEAN LOCAL
WATERS.

PREV DISCUSSION... /ISSUED 300 PM AST TUE MAY 21 2013/

SYNOPSIS...A MODERATE TO FRESH TRADE WIND FLOW WILL CONTINUE TO
PREVAIL ACROSS THE LOCAL ISLANDS AND REGIONAL WATERS AS SURFACE
HIGH PRESSURE DOMINATES THE CENTRAL ATLANTIC. WEAK TROPICAL WAVE
WILL CONTINUE TO MOVE WEST...AND AWAY FROM THE LOCAL AREA TONIGHT.
UPPER LEVEL PERTURBATIONS ARE EXPECTED TO STREAM ACROSS THE
FORECAST AREA OVER THE NEXT FEW DAYS.

DISCUSSION...CLOUDINESS AND SHOWERS WITH ISOLATED THUNDERSTORMS
HAVE BEEN DETECTED THROUGHOUT THE DAY. THESE SHOWERS AND
THUNDERSTORMS WERE FAST MOVERS...AND THEREFORE NO MAJOR FLOOD
PROBLEMS HAVE BEEN REPORTED. HOWEVER...A COUPLE OF FLS`S HAVE
BEEN ISSUED.

WEAK TROPICAL WAVE...NOW LOCATED SOUTH OF THE LOCAL AREA...WILL
CONTINUE TO MOVE WEST AT AROUND 10-15 KNOTS...AND AWAY FROM THE
FORECAST AREA TONIGHT. THE NORTHERN PERIPHERY OF AFOREMENTIONED
TROPICAL WAVE WILL CONTINUE TO LEAD TO SCATTERED/LOCALLY NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE FORECAST AREA...
ESPECIALLY OVER THE EAST AND SOUTHEAST COASTAL AREAS OF PUERTO
RICO...SAINT CROIX AND THE CARIBBEAN WATERS THIS EVENING AND
TONIGHT.

AS UPPER LEVEL PERTURBATIONS STREAM ACROSS THE AREA...WET AND
UNSTABLE CONDITIONS WILL CONTINUE WITH A GOOD CHANCE OF SHOWER
AND THUNDERSTORM ACTIVITY AT LEAST THROUGH WEDNESDAY. AT THIS
TIME...A SHORT BREAK IS EXPECTED BY THE END OF THE WORK WEEK...
AS LOW LEVEL MOISTURE DECREASE. HOWEVER...THERE IS ENOUGH MOISTURE
TO COMBINE WITH LOCAL AFFECTS AND DIURNAL HEATING TO RESULT IN
SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON ACROSS WESTERN PUERTO
RICO. MODEL GUIDANCE CONTINUED TO INDICATE AN INCREASE IN LOW
LEVEL MOISTURE AND FAVORABLE UPPER LEVEL DYNAMICS BY THE WEEKEND
INTO THE UPCOMING WEEK AS AN EASTERLY WAVE MOVES ACROSS THE AREA.

AVIATION...VFR ARE EXPECTED TO PREVAIL ACROSS ALL THE TERMINAL
EXCEPT IN SHRA/TSRA NEAR TJMZ ALONG WITH SOME OBSC MTNS ACROSS
INTERIOR OF PR. VFR CONDS EXPECTED EVERYWHERE AFT 21/22Z. LLVL
WIND FM E TO ESE AT 10-20 KT...HIGHER GUSTS UP TO 30 KT NEAR
SHRA/TSRA.

MARINE...MODERATE TO FRESH WINDS AND SEAS OF 6 FEET EXPECTED
THROUGH THE FORECAST PERIOD. THE MAIN HAZARD FOR THE MARINERS IS
CLOUD TO WATER LIGHTNING PRODUCING BY THUNDERSTORMS OVER THE
REGIONAL WATERS...ESPECIALLY THE CARIBBEAN LOCAL WATERS. SEAS WILL
INCREASE TO 7 FEET OVER MUCH OF THE ATLANTIC WATERS ON WEDNESDAY
AND THEREFORE SMALL CRAFT ADVISORIES WILL BE REQUIRED.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  86  78  86 /  20  30  30  30
STT  77  87  77  87 /  50  50  30  30

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
COASTAL WATERS...SMALL CRAFT ADVISORY FROM 3 PM WEDNESDAY TO 6 AM AST SATURDAY
     FOR ANEGADA PASSAGE SOUTHWARD TO 17N-CARIBBEAN WATERS OF
     PUERTO RICO FROM 10 NM TO 17N.

     SMALL CRAFT ADVISORY FROM 9 AM WEDNESDAY TO 6 AM AST SATURDAY
     FOR ATLC WATERS OF PUERTO RICO AND USVI FROM 10NM TO 19.5N.

&&

$$

10/71