Area Forecast Discussion
Issued by NWS San Juan, PR

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FXCA62 TJSJ 051458
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1058 AM AST TUE MAY 5 2015

.UPDATE...DOPPLER WEATHER RADAR DETECTED ONLY LIGHT ISOLATED
SHOWERS OVER THE WATERS BETWEEN THE U.S. VIRGIN ISLANDS AND
EASTERN PUERTO RICO THIS MORNING...BUT NOT PRECIPITATION WAS
DETECTED OVER LAND AREAS. A GENERALLY FAIR...MAINLY STABLE AND
HAZY WEATHER PATTERN WILL CONTINUE TO PREVAIL ACROSS THE REGION
FOR THE NEXT SEVERAL DAYS. FOR THIS AFTERNOON THE LIMITED LOW
LEVEL MOISTURE ACROSS THE REGION IS EXPECTED TO COMBINE WITH
DAYTIME HEATING AND LOCAL EFFECTS TO INDUCE SOME POSSIBLE SHOWERS
ACROSS WESTERN AND INTERIOR SECTIONS OF PUERTO RICO. HAZY SKIES
WILL CONTINUE ACROSS THE LOCAL ISLANDS FOR THE NEXT SEVERAL DAYS
AS AN AREA OF SAHARAN DUST CONTINUES OVER THE REGION. LOOKING
AHEAD...COMPUTER MODELS INDICATED THAT AN UPPER LEVEL TROUGH
IS EXPECTED TO APPROACH TO THE REGION BY THE END OF THE WEEK...
INCREASING THE MOISTURE TRANSPORT ACROSS THE REGION BY THE
UPCOMING WEEKEND AND EARLY NEXT WEEK.

&&

.AVIATION...MOSTLY VFR CONDITIONS EXPECTED AT ALL TAF SITES THE
NEXT 24 HOURS WITH ONLY FEW CLOUDS AND ISOLATED SHOWERS POSSIBLE
AFTER 05/18Z IN THE VICINITY OF TJBQ AND TJMZ. A SAHARAN AIR MASS
WILL REMAIN ACROSS THE LOCAL FLYING AREA...PRODUCING HAZY SKIES
FOR THE NEXT 24 HOURS. EAST SOUTHEAST WINDS OF 15 TO 20 KT ARE
EXPECTED THIS AFTERNOON WITH GUSTS UP TO 25 KT.

&&

.MARINE...BORDERLINE SMALL CRAFT ADVISORY CONDITIONS WILL PREVAIL
THROUGH TONIGHT ACROSS THE ATLANTIC AND CARIBBEAN WATERS. THIS IS
DUE TO THE COMBINATION OF 4 TO 5 FEET NORTHERLY SWELL AND FRESH
WINDS ACROSS THE LOCAL WATERS. SOUTHEAST WINDS WILL CONTINUE TO
GENERATE CHOPPY CONDITIONS ACROSS THE CARIBBEAN WATERS.

&&

.PREV DISCUSSION... /ISSUED 414 AM AST TUE MAY 5 2015/

SYNOPSIS...
AS THE SURFACE HIGH WILL CONTINUE TO PREVAIL ACROSS THE LOCAL AREA
LIMITING THE SHOWER GENERATION ACROSS THE LOCAL ISLANDS. THIS
FEATURE LOCATED OVER THE THE WESTERN ATLANTIC IS FORECAST TO
SHIFTS EASTWARD INTO THE CENTRAL ATLANTIC...THIS WILL TIGHT THE
LOCAL PRESSURE GRADIENT ACROSS THE REGION INCREASING LOCAL WINDS.

DISCUSSION...A DRYING WEATHER PATTERN IS EXPECTED THROUGH
WEDNESDAY WITH A VERY MINIMAL INCREASE IN LOW LEVEL MOISTURE
THEREAFTER. THEREFORE SHOWER DEVELOPMENT IF ANY WILL BE VERY
LIMITED AND SHORT LIVE FOR THE NEXT SEVERAL DAYS. THIS DRY
PATTERN AND BREEZY CONDITIONS WILL ALSO GENERATE A HEALTHY
ENVIRONMENT FOR THE DEVELOPMENT AND SPREADING OF WILD FIRES.

MODELS ARE SUGGESTING A RELIEF ON THIS DRY AND HOT WEATHER PATTERN
AS AN UPPER LEVEL TROUGH APPROACH FROM THE WEST ON TUESDAY. THIS
FEATURE WILL BEGIN TO INCREASE RELATIVE HUMIDITIES AFTER SUNDAY AS
THE UPPER LEVEL TROUGH APPROACHES. WE ARE TO FAR AWAY TO KNOW HOW
MUCH RAIN THIS FEATURE WILL GENERATE THEREFORE WILL CONTINUE TO
MONITOR THE DEVELOPMENT OF THIS CHANGING WEATHER PATTERN THAT IS
MOST NEEDED.

AVIATION...VFR CONDITIONS EXPECTED AT ALL TAF SITES THE NEXT 24
HOURS. A SAHARAN AIR MASS IS EXPECTED TO MOVE IN...PRODUCING HAZY
SKIES TODAY. ESE WINDS 15 TO 20 KT WITH GUSTS UP TO 25 KT.

MARINE...ALTHOUGH BORDERLINE SMALL CRAFT ADVISORY CONDITIONS WILL
PREVAIL THROUGH TONIGHT ACROSS THE ATLANTIC WATERS AND WEDNESDAY
OVER THE CARIBBEAN WATERS. THIS IS DUE TO THE COMBINATION OF 4 TO
5 FEET NORTHERLY SWELL AND FRESH WINDS ACROSS THE LOCAL WATERS.
AS SWELL SUBSIDE TODAY ATLANTIC WATERS CONDITIONS WILL REACH BELOW
SCA CONDITIONS LATER TODAY BUT SOUTHEAST WINDS WILL CONTINUE TO
GENERATE CHOPPY CONDITIONS ACROSS THE CARIBBEAN WATERS. NORTH
NORTHWEST SWELL WILL REACH OUR LOCAL WATERS SATURDAY MORNING.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  89  78  90  78 /  10   0  10  10
STT  87  78  88  78 /  10  20  20  20

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 8 PM AST THIS EVENING FOR ATLC WATERS
     OF PUERTO RICO AND USVI FROM 10NM TO 19.5N.

     SMALL CRAFT ADVISORY UNTIL 8 PM AST WEDNESDAY FOR CARIBBEAN
     WATERS OF PUERTO RICO FROM 10 NM TO 17N-MONA PASSAGE
     SOUTHWARD TO 17N.

&&

$$

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