Flash Flood Warning 53, NWS JSJ

PUERTO RICO AND U.S. VIRGIN ISLANDS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
100 AM AST WED SEP 15 2004

.UPDATE...

TROPICAL STORM JEANNE CONTINUES ON WEST NORTHWEST TRACK...WITH
OFFICIAL FORECAST INDICATING IT MAY ATTAIN HURRICANE INTENSITY AT
00Z THURSDAY. THE PROPAGATION SPEED WAS SLOWED DOWN TO 7 KNOTS
HOWEVER. THAT CONTINUES TO MAKE THE POTENTIAL FOR RAINFALL AMOUNTS
NEAR 8 TO 10 INCHES VERY POSSIBLE...WITH AMOUNTS IN SOME LOCALS EVEN
HIGHER. THEREFORE...A FLASH FLOOD WATCH IS IN EFFECT FOR ALL THE
U.S. VIRGIN ISLANDS AND PUERTO RICO.

THE MARINE FORECAST WAS UPDATED DUE TO A CHANGE IN THE TRACK AT 21Z
TUESDAY AFTERNOON. THAT TRACK...AND THE SLIGHT CHANGE IN THE CURRENT
TRACK...WOULD LIKELY BRING 12 FOOT SEAS INTO THE CARIBBEAN COASTAL
WATERS AND APPROACH THE COASTAL WATERS JUST OFF THE COASTS OF PUERTO
RICO LATER THIS MORNING AND THIS AFTERNOON. THE RAPIDLY CHANGING
CONDITIONS AS JEANNE CONTINUES ACROSS THE REGION PROMPTED A HIGH
SURF ADVISORY AND COASTAL FLOOD WATCH FOR ALL COASTLINES OF THE
LOCAL ISLANDS...I.E. ALL OF PUERTO RICO AND THE U.S VIRGIN ISLANDS.

DIEHL

...PREVIOUS DISCUSSION...

.SYNOPSIS...
AT 4 PM...TROPICAL STORM JEANNE WAS LOCATED ACROSS THE OPEN
NORTHEAST CARIBBEAN...WSW OF ST KITTS AND NEVIS...MOVING WNW NEAR 10
KT. DEEP CONVECTION HAS FIRED DURING THE PAST HOURS NEAR THIS
CENTER...WITH STLT SUGGESTING THE CENTER NEAR 16.95N 63.6W.
HOWEVER...SAN JUAN DOPPLER RADAR WAS SUGGESTING THE CENTER NEAR
16.8N 63.6W AT THIS SAME TIME...20Z...MOVING 285 AT 7 KNOTS.
RAINBANDS ON THE NW PERIPHERY OF JEANNE HAVE MOVED SW ACROSS THE
LOCAL ATLANTIC WATERS THIS AFTERNOON AND ACROSS PUERTO RICO...WHILE
THE VIRGIN ISLANDS HAVE REMAINED IN A DRY SLOT ON THE W SIDE OF
JEANNE DURING THE LAST FEW HOURS. AN UPPER LEVEL LOW AND
ACCOMPANYING TROUGH HAVE BEGUN TO DIG SSW...FROM THE ATLANTIC TO THE
NORTH OF THE MONA PASSAGE...WHICH IS HELPING TO CREATE A BETTER
ANTICYCLONIC FLOW PATTERN OVER JEANNE. LATEST RECON FLIGHT
DATA...AND BOTH STLT AND RADAR SIGNATURES SUGGEST THAT JEANNE IS
SLOWLY INTENSIFYING.

&&

.DISCUSSION...
UPPER LEVEL TROUGH HAS ONLY A WEAK AND BROAD REFLECTION AT MID
LEVELS AND IS NOT EXPECTED TO IMPACT SIGNIFICANTLY HE MOTION OF
JEANNE...AND IS FORECAST TO CONTINUE TO DIG SW AND TO THE WEST OF
JEANNE. DESPITE THE ENTRAINMENT OF DRY AIR INTO THE W THEN S THEN SE
SIDE OF JEANNE DURING THE DAY TODAY...IT HAS GENERATED A NEARLY
CLOSED BANDING EYE LIKE FEATURE...AND THIS SMALL CENTRAL CIRCULATION
MAY END UP BECOMING ISOLATED FROM THE REST OF THE BROADER
CIRCULATION OF THE SYSTEM...AND INTENSIFY TO HURRICANE FORCE DURING
THE NEXT 12 TO 24 HOURS. MIDDLE LEVEL HIGH PRESSURE PERSISTING TO
THE NORTH OF THE LOCAL REGION IS EXPECTED TO KEEP JEANNE ON A WEST
NORTHWEST TRACK DURING THE NEXT 24 HOURS THEN IT COULD MOVE MORE NW
ACROSS THE MONA PASSAGE. GFS DEPICTION OF JEANNE PAST SEVERAL RUNS
HAS SHOWN THE STORM BECOMING CAPTURED WITHIN THE LINGERING UPPER
LEVEL TROUGH NOW ACROSS THE SW ATLANTIC...AND MEANDERS JEANNE VERY
SLOWLY ACROSS THE SW ATLANTIC FOR THE NEXT WEEK OR SO. TOO...THE
LATEST GFS INCHES JEANNE AWAY FROM THE NORTH COAST OF HISPANOLA ON
THURSDAY AT ONLY 3 TO 5 KNOTS. ALL THIS IS VERY BAD NEWS FOR THE
LOCAL ISLANDS...AS A SLOW MOVING SYSTEM SUCH AS THIS THAT EXITS THE
AREA VERY SLOWLY TO OUR NW...COULD LEAVE EXTREME RAIN ACCUMULATIONS
ACROSS THE LOCAL ISLANDS...POSSIBLY IN EXCESS OF 15 INCHES BY
THURSDAY EVENING.

TROPICAL STORM FORCE WINDS WILL BEGIN TO MOVE IN ACROSS THE VIRGIN
ISLANDS THIS EVENING...THEN INTO VIEQUES...E AND SE SECTIONS OF
PUERTO RICO BY MIDNIGHT. STORM FORCE WINDS WILL AFFECT ALL THE LOCAL
ISLANDS...WITH POSSIBLE HURRICANE WINDS IMPACTING A SMALL AREA NEAR
THE CENTER OF JEANNES PATH. THE LATEST FORECAST FROM NHC HAS
SHIFTED TO THE LEFT...AND MOVES JEANNE ACROSS THE SOUTHWEST COAST OF
PUERTO RICO BY 18Z ON WEDNESDAY. LOCAL INTERESTS SHOULD PREPARE FOR
STRONG AND DAMAGING WINDS...HIGH SEAS AND COASTAL FLOODING...BUT THE
MAIN IMPACT WILL BE COPIOUS RAINFALL AS JEANNE MOVES SLOWLY ACROSS
THE AREA. THIS EVOLVING SCENARIO IS BEGINNING TO REMIND US OF
HURRICANE HORTENSE IN 1996...WHICH LEFT OVER 20 INCHES OF RAIN
ACROSS INTERIOR PUERTO RICO.

&&

.MARINE...
THE MORE WESTWARD MOTION ALONG THE SOUTH COAST OF PUERTO RICO WILL
GENERATE THE HIGHEST SEAS ACROSS THE SE AND E COASTAL WATERS TONIGHT
AND THEN THE REMAINING CARIB WATERS ON WEDNESDAY. WIND GENERATED
WAVES OF THIS SLOW SYSTEM WILL CAUSE SIGNIFICANT RUNUP OF WAVE
ACTION ALONG THE E AND S COASTLINES OF PUERTO RICO...ST CROIX...AND
VIEQUES...WHERE COASTAL FLOODING WILL LIKELY OCCUR...AS WELL AS HIGH
SURF OF 10 TO 15 FEET. ATLANTIC SEAS WILL LIKELY NOT EXCEED 8 OR 9
FEET BEFORE JEANNE REACHES THE MONA PASSAGE ON WEDNESDAY AFTERNOON.

&&

.AVIATION...
OBVIOUSLY...IFR CONDITIONS WITH WINDS IN EXCESS OF 30 KNOTS SHOULD
BE EXPECTED AS JEANNE MOVES THROUGH THE AREA TONIGHT AND WEDNESDAY...
WITH PONCE AND ST CROIX AIRPORTS EXPECTED TO RECEIVE THE STRONGEST
IMPACTS...BASED ON THE LATEST FORECAST TRACK FROM NHC.

&&

.HYDROLOGY...
EVENING RAINFALL AMOUNTS ACROSS PUERTO RICO AREA EXPECTED TO BE ONE
QUARTER TO ONE INCH WITH ISOLATED HIGHER AMOUNTS...WHILE THE VIRGIN
ISLANDS WILL SEE LITTLE MORE RAIN THROUGH SUNSET. HOWEVER...AS
JEANNE IMPACTS THE LOCAL ISLANDS TONIGHT AND WEDNESDAY...RAINFALL
AMOUNTS OF 6 TO 10 INCHES ARE TO BE EXPECTED...THEN COULD INCREASE
FURTHER TO 8 TO 12 INCHES BY THURSDAY. LOCALLY HIGHER AMOUNTS WILL
BE POSSIBLE ACROSS THE INTERIOR OF PUERTO RICO...AND ALONG THE EAST
AND SOUTHEAST SLOPES OF THE LOCAL MOUNTAINS. SHOULD JEANNE MEANDER
NORTH OF HISPANIOLA ON THURSDAY...AN ADDITIONAL SEVERAL INCHES COULD
ACCUMULATE. THIS HAS THE POTENTIAL TO BECOME A MAJOR AND EXTENDED
FLASH FLOODING EVENT FOR ALL THE LOCAL ISLANDS...INCLUDING
HISPANIOLA...AND IT WILL LIKELY TAKE UNTIL THE WEEKEND FOR LOCAL
RIVERS AND STREAMS TO RETURN TO NORMAL WATER LEVELS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  78  88  78  90 /  90  90  80  50
STT  78  89  78  91 /  90  90  80  50

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...HURRICANE WARNING PRZALL AND AMZALL. CFW PRZ002-003-012-013.
     FFA PRZALL.
VI...HURRICANE WARNING VIZALL AND AMZ 710>730. CFW AND FFA VIZALL.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JUAN PR
630 AM AST TUE SEP 14 2004

PRZ001>013-AMZ710>750-151000-
630 AM AST TUE SEP 14 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.TODAY AND TONIGHT...
MOISTURE LEFT BEHIND RECENT DAYS TROPICAL WAVE IN COMBINATION WITH
THE INFLUX OF ADDITIONAL MOISTURE IN ADVANCE OF THE NEWLY FORMED
TROPICAL DEPRESSION ELEVEN...ALONG WITH LOCAL DIURNAL EFFECTS WILL
BE MORE THAN SUFFICIENT TO AID IN PRODUCING SCATTERED TO NUMEROUS
SHOWERS WITH ISOLATED TO SCATTERED THUNDERSTORMS ACROSS THE AREA.
THE AMOUNT OF MOISTURE AND SLOW MOVEMENT OF CONVECTION THAT FORMS
TODAY ESPECIALLY DURING THE AFTERNOON WILL CAUSE URBAN AND SMALL
STREAM FLOODING IN SOME AREAS...AND POSSIBLY FLASH FLOODING IN SOME
PARTS OF THE ISLAND. INCREASING WINDS LATER TODAY WITH PERIODS OF
STRONG GUSTY WINDS...SOME LATER REACHING TROPICAL STORM FORCE...WITH
FREQUENT SHOWERS AND SQUALLS...AND SCATTERED THUNDERSTORMS CAN ALSO
BE EXPECTED ACROSS THE LOCAL REGION ESPECIALLY LATER THIS EVENING.

A COASTAL FLOOD WATCH IS IN EFFECT FOR THE EAST AND SOUTHEAST FACING
COASTS FROM RIO JUEYES (SALINAS) TO CABEZAS SAN JUAN (FAJARDO)
INCLUDING ALL OF VIEQUES AND CULEBRA.

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

.DAYS TWO THROUGH SEVEN...
TROPICAL DEPRESSION ELEVEN WILL CONTINUE ACROSS THE LOCAL REGION
THROUGH THURSDAY. THIS WILL MAINTAIN COPIOUS AMOUNTS OF MOISTURE AND
INSTABILITY ACROSS THE LOCAL REGION. FLASH FLOODING AND LANDSLIDES
ARE A HIGH PROBABILITY DURING THIS TIME PERIOD. SOME STRENGTHENING
IS EXPECTED WITHIN THE NEXT 24 HOURS AND SYSTEM COULD QUITE POSSIBLY
BE A TOPICAL STORM BY THE TIME IT ARRIVES THE U.S. VIRGIN ISLANDS.
THEREFORE OCCASIONAL PERIOD OF HEAVY SHOWERS AND THUNDERSTORMS WITH
A STRONG POTENTIAL FOR FLASH FLOODING CAN BE EXPECTED OVER MANY
PORTIONS OF THE ISLAND AT LEAST THROUGH THURSDAY. UNSTABLE
ATMOSPHERIC CONDITIONS AND AMPLE MOISTURE ACROSS THE REGION WILL
MAINTAIN HIGH RAIN CHANCES THROUGH SATURDAY.

VIZ001-002-AMZ710>730-151000-
630 AM AST TUE SEP 14 2004

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

.TODAY AND TONIGHT...
INCREASING MOISTURE ACROSS THE AREA DUE TO THE APPROACHING TROPICAL
DEPRESSION ELEVEN AND THE COMBINATION OF AN UPPER LEVEL TROUGH WILL
BE SUFFICIENT TO MAINTAIN A CLOUDY AND WET WEATHER PATTERN ACROSS
THE LOCAL ISLANDS TODAY. SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED
TO SCATTERED THUNDERSTORMS WILL GRADUALLY INCREASE ACROSS THE AREA
TODAY AS THE DEVELOPING TROPICAL DEPRESSION MOVES WEST NORTHWEST
TOWARDS THE LOCAL ISLANDS. OCCASIONAL TROPICAL FORCE WIND GUSTS CAN
BE EXPECTED LATER IN THE AFTERNOON THROUGH WEDNESDAY AS THE SYSTEM
PASSES ACROSS PORTIONS OF THE U.S. VIRGIN ISLANDS BASED ON THE
LATEST FORECAST TRACK. THE AMOUNT OF MOISTURE AND SLOW MOVEMENT OF
CONVECTION THAT FORMS THROUGHOUT THE DAY ESPECIALLY LATER IN THE
AFTERNOON MAY PRODUCE FLOODING OF LOW LYING AND POOR DRAINAGE
AREA...AS WELL AS GUTS AND GULLEYS. INCREASING WINDS WITH PERIODS OF
STRONG GUSTY WINDS...SOME LATER REACHING TROPICAL STORM
FORCE...FREQUENT SHOWERS AND SQUALLS...AND SCATTERED THUNDERSTORMS
CAN ALSO BE EXPECTED ACROSS THE LOCAL REGION.

A COASTAL FLOOD WATCH IS IN EFFECT FOR ALL OF THE U.S. VIRGIN
ISLANDS.

.SPOTTER CALL TO ACTION STATEMENT...
SPOTTER ACTIVATION IS REQUIRED.

.DAYS TWO THROUGH SEVEN...
THE DEVELOPING TROPICAL DEPRESSION WILL CONTINUE WEST NORTHWEST
ACROSS THE LOCAL REGION THROUGH WEDNESDAY TO PRODUCE PERIODS OF
STRONG GUSTY WINDS...FREQUENT SHOWERS AND SQUALLS...AND SCATTERED
THUNDERSTORMS. HEAVY RAINFALL IS LIKELY AT LEAST THROUGH
WEDNESDAY...WITH THE POTENTIAL FOR AREAS OF COPIOUS RAINFALL. FLASH
FLOODING AND LANDSLIDES ARE A HIGH PROBABILITY DURING THIS TIME
PERIOD. UNSTABLE ATMOSPHERIC CONDITIONS AND AMPLE MOISTURE ACROSS
THE REGION WILL MAINTAIN HIGH RAIN CHANCES THROUGH SATURDAY.

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.