Flash Flood Warning 26, NWS JSJ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
330 PM AST WED APR 20 2005

.DISCUSSION...ACTIVE WEATHER OCCURRED ACROSS PUERTO RICO AGAIN ON
WEDNESDAY AS NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS DEVELOPED
OVER THE INTERIOR SINCE MID TO LATE MORNING AND SLOWLY DRIFTED NORTH
NORTHEAST UNDER THE INFLUENCE OF MID TO UPPER SOUTHWESTERLY FLOW.
EVEN VIEQUES RECEIVED A SHARE OF THE WEATHER. WEATHER CONDITIONS
WILL NOT CHANGE MUCH OVER THE NEXT SEVERAL DAYS AND IN FACT THEY
WILL FURTHER DETERIORATE.

IN THE SHORT TERM WILL EXPECT SHOWERS AND SCATTERED THUNDERSTORMS TO
LINGER THROUGH THE EVENING HOURS AND SOME OF THEM TO PERSIST
OVERNIGHT INTO THURSDAY ESPECIALLY ALONG THE COASTAL AREAS OF THE
SOUTH AND EAST. POTENTIAL FOR FLOODING REMAINS HIGH ADDITIONAL RAIN
CELLS KEEP DEVELOPING OVER THE INTERIOR.  THURSDAY PROMISES TO BE
ANOTHER ACTIVE DAY WITH FRONTAL BOUNDARY REMAINING ALMOST STATIONARY
TO THE NORTHWEST OF PUERTO RICO. I DONT THINK WE WILL SEE THAT MUCH
RETROGRESSION OF THE FRONT THROUGH FRIDAY.

LONGER TERM BEGINNING ON FRIDAY WE WILL EXPERIENCE A SIGNIFICANT
INCREASE IN LOW LEVEL MOISTURE ADVECTING FROM THE SOUTH...AS MOIST
AND EXPLOSIVELY CHARGED TROPICAL AIR FROM SOUTH AMERICA INTRUDES
INTO THE REGION. SHOWERS AND THUNDERSTORMS SHOULD BECOME MORE
NUMEROUS AND PERSIST THROUGH THE WEEKEND WITH A HIGH POTENTIAL FOR
WIDESPREAD AND SIGNIFICANT FLASH FLOODING NOT ONLY OVER PUERTO RICO
BUT ALSO ACROSS THE U.S. VIRGIN ISLANDS.

&&

.SYNOPSIS...A BROAD FRONTAL BOUNDARY EXTENDS FROM THE EAST COAST OF
THE DOMINICAN REPUBLIC...TO JUST NORTH OF THE MONA PASSAGE AND INTO
THE LOCAL OFFSHORE ATLANTIC WATERS. THIS FRONTAL BOUNDARY WILL
REMAIN ALMOST STATIONARY TOP THE NORTHWEST OF PUERTO RICO THROUGH
FRIDAY. BANDS AND LINES OF HEAVY SHOWERS...SOME WITH THUNDERSTORMS
WILL CONTINUE TO IMPACT THE REGIONAL WATERS THROUGH MONDAY AND
PRODUCE HAZARDOUS FLOODING CONDITIONS ACROSS THE REGION.

&&

.MARINE...MODERATE NORTHERLY SWELLS WILL PERSIST ACROSS THE LOCAL
WATERS THROUGH THURSDAY. EARLY THIS EVENING AND TONIGHT...DANGEROUS
THUNDERSTORMS WILL AFFECT MAINLY THE LOCAL NORTHERN WATERS
...PRODUCING LOW VISIBILITIES...STRONG GUSTY WINDS  AND CLOUD TO
WATER LIGHTNING.

&&

.HYDROLOGY...FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE ENTIRE
ISLAND OF PUERTO RICO THROUGH THURSDAY MORNING ALTHOUGH IT IS VERY
LIKELY TO BE EXTENDED THROUGH THE WEEKEND. RAINFALL ACCUMULATIONS OF
BETWEEN 2 TO 5 INCHES PER DAY ARE LIKELY OVER THE NEXT FEW DAYS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  70  83  70  83 /  70  70  70  70
STT  72  82  71  83 /  60  80  70  70

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
.PR...FLASH FLOOD WATCH PRZ001>011-211300.
.VI...NONE.

&&

RM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JUAN PR
600 AM AST WED APR 20 2005

PRZ001>013-AMZ710>750-211000-
600 AM AST WED APR 20 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.TODAY AND TONIGHT...THE COMBINATION OF LOW LEVEL MOISTURE
ASSOCIATED WITH A FRONTAL BOUNDARY AND AN UNSTABLE ATMOSPHERE WILL
RESULT IN THE DEVELOPMENT OF SHOWERS AND ISOLATED THUNDERSTORMS
ACROSS PORTIONS OF THE LOCAL ISLANDS. SOME OF THESE SHOWERS MAY
PRODUCE LOCALLY HEAVY RAINFALL AND THEREFORE CAUSE FLOODING OF
STREETS AND ROADWAYS...AND ALSO CAUSE LOCAL RIVERS AND CREEKS TO
RAPIDLY RISE IN THESE AREAS.

MODERATE NORTH NORTHEASTERLY SWELLS WILL PERSIST ACROSS THE LOCAL
WATERS THROUGH THURSDAY. MARINERS SHOULD REMAIN ALERT FOR INTENSE
SHOWERS AND THUNDERSTORMS THROUGH SUNDAY.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION MAY BE REQUIRED.

.DAYS TWO THROUGH SEVEN...
A MIDDLE TO UPPER TROUGH LOCATED FROM THE WESTERN ATLANTIC...
SOUTHWARD ACROSS THE BAHAMAS AND INTO THE NORTH CENTRAL CARIBBEAN IS
EXPECTED TO LINGER AT LEAST THROUGH SUNDAY...BRINGING THE CHANCE OF
HEAVY RAINFALL ACROSS PORTIONS OF THE LOCAL ISLANDS. THEREFORE...THE
POTENTIAL FOR FLASH FLOODING AND RIVER FLOODING WILL REMAIN HIGH.

VIZ001-002-AMZ710>730-211000-
600 AM AST WED APR 20 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS.

.TODAY AND TONIGHT...THE COMBINATION OF LOW LEVEL MOISTURE
ASSOCIATED WITH A FRONTAL BOUNDARY AND AN UNSTABLE ATMOSPHERE WILL
AID IN THE DEVELOPMENT OF SHOWERS AND ISOLATED THUNDERSTORMS ACROSS
PARTS OF THE ISLANDS. THERE MAY BE ENOUGH RAINFALL ACCUMULATION TO
RESULT IN MINOR URBAN AND GUT TYPE FLOODING...WITH LOCALLY HEAVY
RAINFALL POSSIBLE IN ISOLATED AREAS.

MODERATE NORTH NORTHEASTERLY SWELLS WILL PERSIST ACROSS THE LOCAL
WATERS THROUGH THURSDAY. MARINERS SHOULD REMAIN ALERT FOR INTENSE
SHOWERS AND THUNDERSTORMS THROUGH SUNDAY.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION MAY BE REQUIRED.

.DAYS TWO THROUGH SEVEN...
A MIDDLE TO UPPER TROUGH LOCATED FROM THE WESTERN ATLANTIC...
SOUTHWARD ACROSS THE BAHAMAS AND INTO THE NORTH CENTRAL CARIBBEAN IS
EXPECTED TO LINGER AT LEAST THROUGH SUNDAY...BRINGING THE CHANCE OF
HEAVY RAINFALL ACROSS PORTIONS OF THE LOCAL ISLANDS. THEREFORE THE
POTENTIAL FOR MINOR URBAN AND GUT TYPE FLOODING WILL REMAIN HIGH.

STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER
DETAILS OR UPDATES.

FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE WEB
SITE FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS AT (ALL LOWERCASE
LETTERS): HTTP://WWW.SRH.NOAA.GOV/SJU.