Area Forecast Discussion
Issued by NWS San Juan, PR

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000
FXCA62 TJSJ 280933
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
533 AM AST TUE JUL 28 2015

.SYNOPSIS...A MID TO UPPER LEVEL RIDGE CONTINUED IN PLACE ACROSS THE
ATLANTIC AND WILL DOMINATE THE LOCAL WEATHER PATTERN AT LEAST THROUGH
TUESDAY WHEN IT IS EXPECTED TO MOVE WESTWARD AWAY FROM THE LOCAL
REGION. AN UPPER LEVEL LOW/TUTT WILL RELOCATE NEAR PUERTO RICO BY
MID WEEK. A SAHARAN AIR LAYER WITH SUSPENDED DUST PARTICLES IS
EXPECTED TO CONTINUE OVER THE REGION AT LEAST UNTIL THURSDAY. A
SURFACE HIGH PRESSURE WILL REMAIN ANCHORED ACROSS THE SOUTHWEST
AND CENTRAL ATLANTIC FOR THE REST OF THE WEEK. A TROPICAL WAVE IS
FORECAST TO ENTER THE EASTERN CARIBBEAN BY MID WEEK...THEN MOVE
ACROSS THE REGIONAL WATERS ON THURSDAY. ANOTHER SAHARAN AIR LAYER
IS EXPECTED TO MOVE ACROSS THE REGION DURING THE WEEKEND.

&&

.DISCUSSION...MOSTLY CLEAR SKIES ACROSS THE WESTERN HALF OF PUERTO
RICO TO VARIABLY CLOUDY SKIES ACROSS THE EASTERN HALF AND THE US
VIRGIN ISLANDS PREVAILED OVERNIGHT. SATELLITE...AND RADAR IMAGERY
OBSERVED HAZY WEATHER CONDITIONS WITH PASSING SHOWERS MAINLY OVER
THE LOCAL WATERS OVERNIGHT. SOME SHOWERS AFFECTED THE WINDWARD
SECTIONS BUT THE ACTIVITY WAS BRIEF AND NO SIGNIFICANT RAINFALL
AMOUNTS WERE DETECTED OVER LAND.

HAZY AND DRY CONDITIONS ARE EXPECTED TO CONTINUE AT LEAST UNTIL
WEDNESDAY AS A SAHARAN AIR LAYER AND A MID LEVEL RIDGE ARE
EXPECTED TO DOMINATE THE LOCAL WEATHER FOR THE NEXT FEW DAYS.
MODEL GUIDANCE SUGGEST AN INCREASE IN INSTABILITY BY THURSDAY AND
FRIDAY...WHEN A TUTT LOW IS EXPECTED TO BE OF TO THE NORTHWEST OF
THE ISLAND OF PUERTO RICO. AS A RESULT DIFFLUENCE ALOFT COMBINED
WITH THE MOISTURE OF AN APPROACHING TROPICAL WAVE WILL INCREASE
THE CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL REGION.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THE BULK OF TROPICAL
MOISTURE TO THE SOUTH OF THE ISLANDS...OVER THE CARIBBEAN WATERS.
THE AMOUNT OF SHOWER AND THUNDERSTORM ACTIVITY WILL DEPEND ON THE
POSITION OF THE TUTT LOW WHICH COULD FAVOR THE DEVELOPMENT OF AN
INDUCE SURFACE TROUGH. DRIER CONDITIONS RETURN QUICKLY LATE FRIDAY
INTO SATURDAY AS SAL MOVES OVER THE REGION AND HOLDS THRU THE
WEEKEND.

&&

.AVIATION...VFR XPCTD THRU WED XCP MVFR IN SCT SHRA/ISOLD TSRA W TO
WCNTRL PR BOTH AFT...FEW OBSCD MTNS. ISOLD SHRA ELSEWHERE SHUD NOT
LWR CONDS. WIND BLW FL100 ESE 16-32 KT BCMG E 16-24 KT IN AFT THEN
ENE 12-20 KT TUE NITE-WED.

&&

.MARINE....MARINERS CAN EXPECT SEAS BETWEEN 2 AND 5 FEET WITH
OCCASIONAL SEAS UP TO 6 FEET AND WINDS BELOW 18 KNOTS. EXCEPT FOR
THE CARIBBEAN OFFSHORE WATERS AND MONA PASSAGE WERE THEY CAN
EXPECT SEAS BETWEEN 4 AND 6 FEET WITH OCCASIONAL SEAS UP TO 8
FEET. WINDS WILL GRADUALLY INCREASE UP TO 20 KNOTS LATE IN THE
MORNING HOURS AND INTO THE AFTERNOON. SMALL CRAFT SHOULD EXERCISE
CAUTION ACROSS MOST OF THE LOCAL WATERS.

&&

.FIRE WEATHER...ELEVATED FIRE WEATHER CONDITIONS EXPECTED
TODAY...MAINLY FOR PORTIONS OF SOUTHERN AND SOUTHWESTERN PUERTO
RICO. REFER TO THE FIRE DANGER STATEMENT FOR ADDITIONAL DETAILS
ABOUT THE CURRENT CONDITIONS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  90  79  91  79 /  10  20  20  10
STT  90  79  90  79 /  20  20  30  30

&&

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

$$

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