Heavy Rain in Puerto Rico, August 25, 2003

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
252 PM AST MON AUG 25 2003

...POTENTIAL FOR HEAVY RAINS AND FLOODING EXISTS FOR EASTERN PUERTO
RICO AND LOCAL AREAS ELSEWHERE ON THE ISLAND...

THIS APPEARS TO BE THE BEST TROPICAL WAVE OF THE SEASON WITH RESPECT
TO EFFECTS OVER THE ISLAND OF PUERTO RICO.

THIS MORNINGS SOUNDING CONFIRMED WHAT WAS ALREADY WELL KNOWN...THE
AIR MASS ASSOCIATED WITH THE TROPICAL WAVE NOW AT 63 DEGREES WEST
LONGITUDE DUE TO PASS AROUND 06Z TONIGHT IS LOADED WITH MOISTURE AND
VERY UNSTABLE. MODELS CONTINUE TO SHOW VERY STRONG MOISTURE
CONTINUING UNTIL 12Z TUESDAY. IN ADDITION THE DIVERGENCE ALOFT AT
250 MB BUILDS OVER THE AREA BEGINNING AT 06Z TUESDAY...TONIGHT...AND
CONTINUES THROUGH 06Z WEDNESDAY...EVEN AFTER THE BEST MOISTURE HAS
PASSED. THIS SUGGESTS THAT RAIN AND THUNDERSTORMS WILL BUILD
OVERNIGHT TONIGHT CONTINUE THROUGH A GOOD PORTION OF THE MORNING AND
THEN CONTINUE DURING THE NIGHT ON TUESDAY UNTIL THE MOISTURE HAS
BEEN WRUNG FROM THE ATMOSPHERE. THE 06Z RUN OF THE GFS MODEL SHOWS
STRONG CYCLONIC CURVATURE IN THE 850 MB WIND FIELD BEGINNING AT 06Z
TONIGHT ACCOMPANIED BY AN EXCELLENT MOISTURE FIELD THAT MAXES OUT AT
ABOUT 09Z. A SECOND BAND OF MOISTURE FOLLOWS THIS IN THE BACK PART
OF THE SAME WAVE AND SPREADS OVER THE ISLAND BETWEEN 00Z AND 06Z
WEDNESDAY...EXACTLY THE TIME OF THE BEST DIVERGENCE OF THE WHOLE
PERIOD.  MODELS ARE BULLISH WITH REGARDS TO RAINFALL AMOUNTS AS
WELL.  THE GFS GIVES PUERTO RICO OVER ONE INCH JUST FROM 12Z TUESDAY
UNTIL 00Z WEDNESDAY WITH HALF AN INCH IN THE PREVIOUS 12 HOURS.
LOCAL RAINS COULD BE MUCH HEAVIER.

THIS IS ALL POINTING TO A RATHER SERIOUS SITUATION. EMERGENCY
MANAGERS...ESPECIALLY IN EASTERN PUERTO RICO SHOULD MAKE
PREPARATIONS FOR SIGNIFICANT HEAVY RAINS...ESPECIALLY OVER THE
EASTERN AND SOUTHEASTERN INTERIOR PORTIONS OF PUERTO
RICO...BEGINNING THIS EVENING AND CONTINUING THROUGH MID MORNING ON
TUESDAY. LOCAL FLOODING IS LIKELY WITH THIS SYSTEM. AREAS PRONE TO
FLOODING WITH SOUTHERN AND SOUTHEASTERN EXPOSURES ARE MOST
VULNERABLE. SOME OF THE FLOODING WILL OCCUR BEFORE DAYLIGHT TOMORROW
COMPOUNDING THE HAZARD OF THIS SITUATION. AS THE EXACT AREA OF
FLOODING IS NOT CERTAIN AND SINCE THE FLOODING DEPENDS GREATLY ON
CONVECTION MOVING NORTHWEST AFTER THE WAVE HAS PASSED WILL HOLD OFF
ISSUING A WATCH FOR EASTERN PUERTO RICO THIS SHIFT.

ALTHOUGH THE WEATHER SHOULD IMPROVE DURING THE AFTERNOON
TUESDAY...CONTINUED SCATTERED SHOWERS OVERNIGHT ON WEDNESDAY AND
WINDS FROM THE SOUTHEAST COULD PRESENT SOME FLOODING HAZARDS FOR THE
SOUTHEAST AND EAST CENTRAL PORTION OF THE ISLAND OVERNIGHT TUESDAY
AS WELL.

RAINS WILL END EARLIER ON THE VIRGIN ISLANDS AND HEAVY AMOUNTS ARE
POSSIBLE...BUT THE LACK OF SIGNIFICANT OROGRAPHIC EFFECTS WILL
LIKELY MITIGATE THE WORST PART OF THE FLOOD POTENTIAL FOR THEM.

LATER IN THE WEEK THE MODELS CONTINUE TO SPIN UP A VERY STRONG LOW
PRESSURE SYSTEM...BUT THIS TURNS NORTHWEST AND CROSSES 20 NORTH
LATITUDE ON FRIDAY NIGHT BEFORE REACHING 50 WEST LONGITUDE. THIS
LEAVES US WITH MOSTLY CLIMATOLOGICAL SHOWERS FOR THE THE DURATION OF
THE MONTH.  SNELL

PRELIMINARY NUMBERS:
SJU TW 074/086 076/088 078 12976
    BBEBB 088/076 087/075 088/076 088/076 088 64444452422
STT TW 077/086 077/088 078 12976
    EBEBB 088/078 088/078 088/078 088/078 088 64444444422=

SJU...
.PR...NONE.
.VI...NONE.

EQUIPMENT...NO PROBLEMS AT THIS TIME.

SNELL

PRZ001>013-VIZ001-002-AMZ710>750-261000-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
1157 AM AST MON AUG 25 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.THIS AFTERNOON AND TONIGHT...A STRONG TROPICAL WAVE LOCATED NEAR 62
WEST THIS MORNING...WILL MOVE WEST ACROSS PUERTO RICO
TONIGHT...RESULTING IN SCATTERED TO NUMEROUS THUNDERSHOWERS TODAY
FOLLOWED BY WIDESPREAD THUNDERSTORMS TONIGHT WITH ACTIVITY MAINLY IN
THE EAST. THE POTENTIAL EXISTS FOR SIGNIFICANT FLOODING BEGINNING
LATE TONIGHT AND CONTINUING THROUGH MIDDAY TUESDAY...MAINLY IN THE
EASTERN HALF OF THE ISLAND. EMERGENCY MANAGERS SHOULD MAKE
PREPARATIONS FOR POSSIBLE FLOODING TONIGHT AND TOMORROW MORNING
ESPECIALLY IN MOUNTAINOUS AREAS WITH SOUTHERN AND SOUTHEASTERN
SLOPES.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION IS REQUESTED BEGINNING TONIGHT.

.TUESDAY THROUGH SUNDAY...THE TROPICAL WAVE AND LOW LEVEL MOISTURE
BEHIND THE WAVE WILL CONTINUE ACROSS THE LOCAL AREA THROUGH TUESDAY
WITH SIGNIFICANT FLOODING POSSIBLE ESPECIALLY OVER THE EASTERN HALF
OF THE ISLAND TUESDAY.  NO OTHER HAZARDOUS WEATHER IS EXPECTED AT
THIS TIME.

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

.THIS AFTERNOON AND TONIGHT...A STRONG TROPICAL WAVE LOCATED NEAR 62
WEST THIS MORNING...WILL MOVE WEST ACROSS THE U.S. VIRGIN ISLANDS
TODAY AND TONIGHT...TO PRODUCE NUMEROUS THUNDERSHOWERS . SOME
FLOODING IS POSSIBLE...AND A FEW LOCATIONS COULD RECEIVE ENOUGH
RAINFALL TO RESULT IN URBAN AND GUT FLOODING.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

.TUESDAY THROUGH SUNDAY...THE TROPICAL WAVE AND LOW LEVEL MOISTURE
BEHIND THE WAVE WILL CONTINUE ACROSS THE LOCAL AREA THROUGH TUESDAY.
THIS SYSTEM HAS THE POTENTIAL TO BRING AT LEAST SOME LOCALIZED HEAVY
RAINFALL AND MINOR FLOODING TO THE LOCAL AREA. NO OTHER HAZARDOUS
WEATHER IS EXPECTED AT THIS TIME.

SNELL

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.