Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 301902
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
302 PM AST THU JUL 30 2015

.SYNOPSIS...TROPICAL WAVE AXIS IS NOW WEST OF PUERTO RICO WITH
TRAILING MOISTURE EXPECTED TO START MOVING IN LATER TONIGHT INTO
FRIDAY. TUTT WILL CONTINUE TO SLOWLY MOVE TO THE WEST
NORTHWEST...SLIGHTLY INCREASING INSTABILITY OVER THE LOCAL AREA
TONIGHT AND ON FRIDAY. STARTING ON SATURDAY...ANOTHER ROUND OF DRY
AIR AND SAHARAN DUST WILL MOVE INTO THE LOCAL AREA...THEN A
TROPICAL WAVE MOVES IN ON MONDAY.


&&

.DISCUSSION...SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPED ACROSS
THE NORTHWESTERN QUADRANT OF PUERTO RICO IN THE AFTERNOON HOURS.
THE REST OF THE AREA REMAINED MOSTLY DRY WITH ONLY A FEW LIGHT AND
BRIEF SHOWERS THAT PRODUCED TRACE AMOUNTS OF RAIN. ISOLATED
SHOWERS ARE EXPECTED TONIGHT ACROSS THE WATERS...USVI...AND
EASTERN PR...BECOMING SCATTERED LATE TONIGHT INTO VERY EARLY
FRIDAY...ISOLATED THUNDERSTORMS ARE POSSIBLE OVER THE WATERS.

LATEST GUIDANCE AND OBSERVATIONS SUGGEST THAT MOISTURE WILL
INCREASE TONIGHT INTO FRIDAY...WHICH WHEN COMBINED WITH THE TUTT
AND THE INCREASED STABILITY...COULD HELP DEVELOP SOME SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE LOCAL AREA ON FRIDAY.

THIS INCREASE IN MOISTURE WILL BE SHORT LIVED AS DRY AIR AND
SAHARAN DUST WILL QUICKLY MOVE IN ON SATURDAY INTO SUNDAY. THE
NEXT CHANCE OF RAIN WILL BE ON MONDAY AS ANOTHER TROPICAL WAVE
MOVES IN...AND AT THAT TIME THERE IS ALSO A BROAD LOW ALOFT.
THERE WILL BE SOME INSTABILITY ON MONDAY SO SHOWERS AND ISOLATED
THUNDERSTORMS ARE ONCE AGAIN EXPECTED. MUCH DRIER AIR IS EXPECTED
TO MOVE IN ONCE AGAIN ON TUESDAY WITH ONLY PATCHES OF MOISTURE
MOVING IN FOR THE REST OF THE WEEK.


&&

.AVIATION...SCT SHRA/ISOLD TSRA WILL REMAIN PSBL OVR W PR AND IN
AND AROUND TJMZ/TJBQ AND INTERIOR PR UNTIL 30/22Z. AS RESULT
BRIEF MTN TOP OBSCR WITH CONVECTIVE DVLPMNT. LOW LVL EASTERLY
WINDS AROUND 15-20 KNOTS WILL PREVAIL. SFC WND MAINLY FM E-NE AT
10 TO 15 KNOTS...OCNL HIGHER GUSTS UP TO 25 KTS PSBL TIL 30/23Z.NO
OTHER CHG TO PREV DISCUSSION. WINDS WILL DECREASE AFTER 31/00Z TO
ABOUT 05-10KT WITH SCT SHRA MOVING IN LATE TONIGHT.


&&

.MARINE...SEAS WILL BE UP TO 5 FEET AND WINDS UP TO 20 KNOTS
TONIGHT AND FRIDAY. SMALL CRAFT OPERATORS ARE URGED TO EXERCISE
CAUTION.


&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  79  90  79  91 /  20  40  40  20
STT  79  87  79  89 /  30  30  30  20

&&

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

$$

09/25



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