Flood in Puerto Rico, May 11, 2004

PUERTO RICO AND U.S. VIRGIN ISLANDS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
230 PM AST TUE MAY 11 2004

.SYNOPSIS...MID TO UPPER LEVEL HIGH PRESSURE RIDGE AXIS EXTENDS FROM
THE CENTRAL CARIBBEAN NORTHWARD ACROSS THE WINDWARD PASSAGE AND INTO
THE WEST ATLANTIC. MEANWHILE...A BROAD LONG WAVE TROUGH EXTENDS FROM
THE NORTH CENTRAL ATLANTIC SOUTH SOUTHWEST ACROSS THE LEEWARD
ISLANDS AND INTO THE EASTERN CARIBBEAN. AT THE SURFACE... HIGH
PRESSURE DOMINATES THE WEST ATLANTIC AND CONTINUES TO BUILD EASTWARD
INTO THE LOCAL REGION. THE REMNANTS OF A COLD FRONT/FRONTAL BOUNDARY
EXTENDS FROM A LOW IN THE NORTH CENTRAL ATLANTIC SOUTH SOUTHWEST TO
NEAR 20 NORTH 53 WEST WHERE IT BECOMES MORE DIFFUSE THEN EXTENDS
ACROSS PORTIONS OF THE LEEWARD ISLANDS INTO THE EASTERN CARIBBEAN.
HIGH PRESSURE REMAINS ANCHORED ACROSS THE EASTERN ATLANTIC WITH THE
RIDGE AXIS EXTENDING SOUTH INTO THE TROPICAL ATLANTIC AND THUS
MAINTAINING A PREDOMINANT EASTERLY WIND FLOW ACROSS THESE AREAS.

&&

.DISCUSSION...MID TO UPPER LEVEL CLOUDINESS ACROSS PUERTO RICO
CONTINUED TO DECREASE DURING THE DAY WHILE SHIFTING EAST OVER THE
U.S. VIRGIN ISLANDS. IN THE MEANTIME CONSIDERABLE AMOUNTS OF LOW
LEVEL MOISTURE CONTINUED MOVE WEST ACROSS THE LOCAL REGION IN A
MODERATE TO FRESH EASTERLY TRADE WIND FLOW. BASED ON THE LATEST 12Z
SOUNDINGS AND GFS MODEL GUIDANCE...CONDITIONS ACROSS THE REGION
REMAIN MARGINALLY UNSTABLE AND WET IN THE LOW LEVELS. THEREFORE
EXPECT SHOWERS AND ISOLATED THUNDERSTORMS TO DEVELOP THIS AFTERNOON
DUE TO THE COMBINATION OF A WEAK SHORT WAVE TROUGH MOVING ACROSS THE
REGION...ABUNDANT LOW LEVEL MOISTURE AND DIURNAL HEATING. THESE
SHOWERS WILL QUICKLY MOVE WEST SOUTHWEST ACROSS THE LOCAL ISLANDS.
THE ACTIVITY WILL BE MORE NUMEROUS ACROSS THE SOUTHEAST LOCAL
CARIBBEAN WATERS...IN AND AROUND THE ISLAND OF SAINT CROIX...AND
ALSO ACROSS THE INTERIOR...WEST AND SOUTHWEST SECTIONS OF PUERTO
RICO. THE STRONG NORTHEAST LOW LEVEL WIND FLOW OVER THE REGION WILL
ASSIST IN MOVING THESE PATCHES OF CLOUDS AND SHOWERS RAPIDLY ACROSS
THE LOCAL ISLANDS. AS A RESULT...STILL EXPECT SOME LOCALIZED SMALL
STREAM AND URBAN FLOODING WITH PONDING OF WATER ON ROADWAYS DUE TO
OCCASIONAL MODERATE TO HEAVY DOWNPOURS IN ISOLATED AREAS ESPECIALLY
ACROSS PUERTO RICO.

&&

.MARINE...STRONG TO FRESH EAST NORTHEAST WIND FLOW WILL CONTINUE TO
DOMINATE THE REGION AND THEREFORE MAINTAIN ROUGH AND CHOPPY SEAS
ACROSS MUCH OF THE REGIONAL WATERS. AS A RESULT...A SMALL CRAFT
ADVISORY IS IN EFFECT FOR THE OFFSHORE ATLANTIC WATERS AND ALSO THE
SOUTHEAST CARIBBEAN WATERS. QUIKSCAT AND SATELLITE DERIVED WINDS
CONTINUE TO SHOW WINDS OF 20 KNOTS OR GREATER ACROSS THE REGIONAL
WATERS. MODEL GUIDANCE SHOWS NO CHANGES IN THESE CURRENT CONDITIONS
AS A STRONG HIGH PRESSURE GRADIENT WILL BE MAINTAINED ACROSS THE
REGION THROUGH THE UPCOMING WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  73  84  73  84 /  30  30  40  50
STT  73  83  73  83 /  40  40  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...SCA...AMZ710
VI...SCA...AMZ730.

&&

MITCHELL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JUAN PR
610 AM AST TUE MAY 11 2004

PRZ001>013-AMZ710>750-121000-
610 AM AST TUE MAY 11 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.TODAY...MODERATE AND GUSTY NORTHEAST LOW LEVEL WINDS TODAY WILL
COMBINE WITH THE MOISTURE REMAINING FROM THE WEAK FRONTAL TROUGH
THAT LIES TO THE EAST AND SOUTH OF THE VIRGIN ISLANDS. THIS TROUGH
WILL CONTINUE TO HAVE EFFECTS ACROSS THE LOCAL AREA BUT NOT AS
MARKED AS DURING THE PREVIOUS DAYS. A DENSE AND OVERCAST LAYER OF
HIGH CLOUDS WILL ALSO COVER THE AREA. SCATTERED MORNING SHOWERS
ALONG THE NORTHERN SLOPES WILL CAUSE LIGHT RAINFALL ACCUMULATIONS.
HOWEVER...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP
THIS AFTERNOON AND MAY BECOME NUMEROUS AS AN UPPER LEVEL DISTURBANCE
ARRIVES TO THE LOCAL AREA FROM THE CENTRAL CARIBBEAN. THIS UPPER
DISTURBANCE WILL HELP WITH HELP TO TRIGGER LOCALLY HEAVY
PRECIPITATION ALONG THE SOUTHWEST AND THE INTERIOR AND NORTH
CENTRAL..WHERE RIVER LEVELS COULD RAPIDLY RISE AND OVERFLOW THEIR
BANKS DUE TO THE SATURATED GROUND CONDITIONS ESPECIALLY ALONG THE
NORTH CENTRAL.

MARINE CONDITIONS WILL REMAIN UNSETTLED ALONG OFF SHORE ATLANTIC
WATERS. ELSEWHERE SMALL CRAFT SHOULD EXERCISE CAUTION ELSEWHERE
EXCEPT THE WEST WATERS.

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

.DAYS TWO THROUGH SEVEN...

SERIES OF UPPER LEVEL DISTURBANCES WILL TRAVEL AROUND THE BASE OF AN
UPPER LEVEL TROUGH THAT WILL GRADUALLY SETTLE JUST WEST OF PUERTO
RICO TO PROVIDE UNSTABLE CONDITIONS FROM WEDNESDAY THROUGH FRIDAY.
THIS UPPER TROUGH WILL INTERACT WITH THE MOISTURE LEFT OVER BY THE
WEAK FRONTAL BOUNDARY TO THE EAST AND SOUTH TO PRODUCE SCATTERED TO
NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS MAINLY DURING THE
AFTERNOON HOURS. LOCALIZED FLASH FLOODING AND SMALL STREAM FLOODING
IS LIKELY.

A MODERATE TO FRESH WIND FLOW AND CHOPPY SEAS WILL PREVAIL ACROSS
THE LOCAL WATERS UNTIL FRIDAY.

VIZ001-002-AMZ710>730-121000-
610 AM AST TUE MAY 11 2004

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

.TODAY...SCATTERED SHOWERS TO NUMEROUS SHOWERS WILL MOVE WEST
SOUTHWEST ACROSS THE TERRITORIAL WATERS. SOME OF THESE WILL MOVE
OVERLAND CAUSING LIGHT TO MODERATE RAINFALL ACCUMULATIONS THAT COULD
COULD RESULT IN SOME URBAN AND GUT FLOODING. MODERATE TO STRONG AND
GUSTY NORTHEAST WINDS WILL MAINTAIN CHOPPY MARINE CONDITIONS.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED.

.DAYS TWO THROUGH SEVEN...

SCATTERED SHOWERS WILL CONTINUE ACROSS THE U.S. VIRGIN ISLANDS
BECOMING NUMEROUS AT TIMES DUE TO THE APPROACH OF AN UPPER LEVEL
TROUGH FROM THE WEST. RISK OF URBAN AND GUT FLOODING WILL REMAIN
DURING THE REMAINDER OF THIS WEEK AND POSSIBLY INTO EARLY PART OF
NEXT ONE.

A MODERATE TO FRESH WIND FLOW AND CHOPPY SEAS WILL PREVAIL ACROSS
THE LOCAL WATERS THROUGH FRIDAY.

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.

RM