Flash Flooding and Debris Flows in Puerto Rico, December 10 to 12, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1018 AM AST MON DEC 10 2007

.UPDATE...EXPECT THE APPROACHING SUBTROPICAL
DISTURBANCE...PRESENTLY ABOUT 250 MILES EAST OF PUERTO RICO...TO
INCREASE THE PRESSURE GRADIENT ACROSS THE LOCAL ISLANDS
TODAY...RESULTING IN WINDY CONDITIONS LATER TODAY AND PERSISTING
THROUGH MIDDAY TUESDAY. ALREADY HAD A REPORT OF A WIND GUST OF 42
KNOTS AT STT THIS MORNING...AND SUSTAINED WINDS OF 25 TO 35 MPH
WITH GUSTS THIS HIGH CAN BE EXPECTED ACROSS THE ENTIRE FORECAST
AREA AS THIS DISTURBANCE GETS CLOSER TO THE LOCAL ISLANDS. AS A
RESULT...DECIDED TO EXTEND AND EXPAND THE WIND ADVISORY TO INCLUDE
ALL OF THE LOCAL ISLANDS THROUGH 4 PM AST TUESDAY AFTERNOON. IN
ADDITION...MODELS CONTINUE TO GENERATE SIGNIFICANT PRECIPITATION
AS THIS DISTURBANCE TRACKS OVER PUERTO RICO TONIGHT THROUGH EARLY
TUESDAY...SO ALSO DECIDED TO ISSUE A FLOOD WATCH FOR THE ENTIRE
FORECAST AREA THROUGH 4 PM AST TUESDAY AFTERNOON AS WELL.

&&

.PREV DISCUSSION... /ISSUED 648 AM AST MON DEC 10 2007/

SYNOPSIS...BROAD TUTT LOW EXTENDING WSW TO ENE ACROSS THE LOCAL
REGION THIS MORNING...WITH THREE EMBEDDED MID TO UPPER
VORTS...WITH A DOMINANT UPPER LOW TO THE S OF THE MONA
PASSAGE...AND TWO VIGOROUS MORE MID LEVEL VORTS E TO W ALONG ABOUT
19.5N AND JUST NE OF THE LOCAL AREA. THIS VIGOROUS MID LEVEL LOW
MOVING ACROSS 60W THIS MORNING HAS INDUCED A LLVL TROUGH THE PAST
FEW DAYS THAT HAS BECOME PROGRESSIVELY SHARPER AND WAS ALONG 61.5W
THIS MORNING...WITH GALE FORCE WINDS ACROSS THE NRN SEMICIRCLE PER
RECENT SCATTEROMETER PASSES AND SHIP REPORTS. HIGH PRESSURE IN THE
W ATLC AND THIS APPROACHING SURFACE TROUGH...MOVING W AT 15
KT...CONTINUES TO INDUCE A STRONG NELY FLOW ACROSS THE NE CARIB.

DISCUSSION...BROAD TUTT CIRCULATION REMAINS CUT OFF AND IS
FORECAST TO SHIFT EVER SO SLIGHTLY W AND NW NEXT SEVERAL
DAYS...AND WILL LIKELY ATTEMPT TO MERGE INTO ONE CIRCULATION.
MEANWHILE SURFACE TROUGH WILL CONTINUE TO MOVE W 15 KT ACROSS THE
LOCAL AREA NEXT 24 HOURS AND ACCOMPANIED BY ABUNDANT MOISTURE AND
A VIGOROUS MID LEVEL CIRCULATION...WILL SPREAD STRONG NELY WINDS
AND OCCASIONAL SQUALLS AND ISOLATED TSTORMS ACROSS THE LOCAL AREA
THIS MORNING THROUGH TONIGHT. GLOBAL MODELS MOVE THIS LLVL TROUGH
WESTWARD ACROSS THE AREA NEXT 24-36 HOURS...AND THE DEEP CNVTN
SEEN ON STLT IMAGERY THIS MORNING WILL LIKELY REMAIN OVER THE ATLC
WATERS AND NOT MOVE EN MASS ACROSS THE LOCAL ISLANDS. HOWEVER...
STLT IMAGERY IS SUGGESTING A LLVL CIRCULATION ATTEMPTING TO FORM
JUST NE OF BARBUDA...IN THE COL BETWEEN THE TWO MAIN TUTT
LOWS...AND ALSO IN BETWEEN THE MID LEVEL CIRCULATION AND SURFACE
REFLECTION TO ITS SSE. IF A CLOSED SURFACE CIRCULATION IS TO
DEVELOP...ISOLATED DEEP CNVTN WILL LIKELY FORM AROUND PERIPHERY
AND AFFECT THE LOCAL ISLANDS...AND FURTHER ENHANCE HEAVY PRECIP
POTENTIAL. OCCASIONAL SQUALLS AND ISOLATED TSTORMS EMBEDDED IN THE
NE FLOW EXPECTED TO MOVE INTO THE AREA TODAY AND TONIGHT WILL
LEAVE SIGNIFICANT RAINS ACROSS THE N SLOPES AND COASTS OF PR...AND
WILL LIKELY LEAD TO RIVER FLOODING TONIGHT OR TUESDAY...AS WELL AS
URBAN AND STREAM FLOODING. HOWEVER...ANYTHING MORE THAN A FEW DEEP
CNVTV CELLS ACROSS THE N SLOPES COULD PRODUCE ADDITIONAL VERY
HEAVY RAINS...AND WITH MOIST SOILS CURRENTLY...FLOOD POTENTIAL
DOES EXIST. WIND ADVISORIES ARE CURRENTLY IN EFFECT FOR PR FOR
ELEVATIONS ABOVE 1000 FT...AND HIGH SURF ADVISORIES ALONG N AND NE
COASTS. HAVE YET TO ISSUE ANY FLASH FLOOD WATCH ATTM...BUT MAY
BECOME NECESSARY LATER TODAY.

MOST WIDESPREAD RAIN AND STRONGEST FORCING DUE TO STRONG NE LLVL
WINDS AGAINST THE N SLOPES OF PR WILL OCCUR TODAY THROUGH
TONIGHT...WITH RAIN TOTALS OF ONE TO THREE INCHES LIKELY...AND 3
TO 5 INCHES POSSIBLE IN ISOLATED AREAS. AFTER THE TROUGH EXITS
THE AREA TUESDAY...HIGH PRESSURE WILL SHIFT INTO THE W CENTRAL
ATLC DUE NORTH OF THE LOCAL AREA AND MAINTAIN A TIGHT PRESSURE
GRADIENT AND STRONG LLVL FLOW...AND TRAILING LLVL MOISTURE WILL
MAINTAIN HIGH SHOWER CHANCES THROUGH THURSDAY.

AVIATION...SHOWERS AND THUNDERSTORMS WILL BEGIN TO AFFECT THE U.S
VIRGIN ISLANDS TAF SITES FROM 12Z-16Z. RADAR IS ALREADY DETECTING
TOPS OF 40 THOUSAND FEET. THEREFORE...MVFR AND OCCASIONALLY IFR
CONDITIONS COULD BE SEEN THIS MORNING ACROSS THESE AIRPORTS.
THEN...BY EARLY AFTERNOON...TJSJ AND TJBQ ARE EXPECTED TO BE
AFFECTED BY SHOWERS AND THUNDERSTORMS...WHICH WILL RESULT IN
VISIBILITY REDUCTION AND CLOUDS BASES COMING DOWN TO LESS THAN
1000 FEET DURING HEAVY RAIN. FOR THIS AFTERNOON THROUGH THIS
EVENING...ALL LOCAL TAF SITES COULD EXPERIENCE MVFR CONDITIONS
THROUGH THIS PERIOD. WINDS WILL BE AVERAGING AT THE SURFACE FROM
15 TO 20 MPH WITH HIGHER GUSTS UP TO 40 MPH.

MARINE...MARINE CONDITIONS HAVE BEEN ROUGH PAST SEVERAL DAYS...
AND WITH INCREASING WINDS OVERNIGHT THROUGH TONIGHT...SEAS WILL
BUILD FURTHER...IN A MIX OF NE SWELL AND LARGE STEEP WIND WAVES.
WWIII IS FORECASTING 16 FT SEAS FOR THE OUTER ATLC WATERS THIS
EVENING AND TONIGHT...BUT HAVE CAPPED OFF SEAS AT 14 FEET UNTIL WE SEE
BUOY 41043 REACHING 15 FT OR GREATER. A FEW REGIONAL SHIP OBS
OVERNIGHT HAVE REPORTED 30-38 KT WINDS...BUT THESE ARE LIKELY
LARGE VESSELS WITH WINDS WELL ABOVE 10M. BASED ON RECENT
SCATTEROMETER PASSES AND A CONSENSUS OF WIND GUIDANCE HAVE DECIDED
TO ISSUE A GALE WARNING FOR THE OUTER ATLC COASTAL WATERS THIS
AFTERNOON AND TONIGHT...WITH SEAS SUBSIDING SLOWLY TUESDAY THROUGH
WEDNESDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  83  73  83  73 /  70  70  70  50
STT  83  76  83  76 /  70  70  70  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR CENTRAL INTERIOR-
     CULEBRA-EASTERN INTERIOR-MAYAGUEZ AND VICINITY-NORTH
     CENTRAL-NORTHEAST-NORTHWEST-PONCE AND VICINITY-SAN JUAN AND
     VICINITY-SOUTHEAST-SOUTHWEST-VIEQUES-WESTERN INTERIOR.

     HIGH SURF ADVISORY UNTIL 11 AM AST TUESDAY FOR CULEBRA-NORTH
     CENTRAL-NORTHEAST-NORTHWEST-SAN JUAN AND VICINITY-VIEQUES.

     WIND ADVISORY UNTIL 4 PM AST TUESDAY FOR CENTRAL INTERIOR-
     CULEBRA-EASTERN INTERIOR-MAYAGUEZ AND VICINITY-NORTH
     CENTRAL-NORTHEAST-NORTHWEST-PONCE AND VICINITY-SAN JUAN AND
     VICINITY-SOUTHEAST-SOUTHWEST-VIEQUES-WESTERN INTERIOR.

VI...FLOOD WATCH THROUGH TUESDAY AFTERNOON FOR ST. THOMAS ST. JOHN
     AND ADJACENT ISLANDS.

     HIGH SURF ADVISORY UNTIL 11 AM AST TUESDAY FOR ST CROIX-ST.
     THOMAS ST. JOHN AND ADJACENT ISLANDS.

     WIND ADVISORY UNTIL 4 PM AST TUESDAY FOR ST CROIX-ST. THOMAS ST.
     JOHN AND ADJACENT ISLANDS.

&&

04/10

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN JUAN PR
630 AM AST MON DEC 10 2007

PRZ001>013-AMZ710>750-111000-
630 AM AST MON DEC 10 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO.

.TODAY AND TONIGHT...TROPICAL DISTURBANCE LOCATED THIS MORNING TO
THE NORTHEAST OF THE NORTHERN LEEWARD ISLANDS IS FORECAST TO MOVE
ACROSS THE LOCAL AREA THIS AFTERNOON THROUGH TUESDAY MORNING. THIS
FEATURE IS EXPECTED TO BRING SIGNIFICANT SHOWER ACTIVITY ACCOMPANIED
WITH THUNDERSTORMS AND WINDY CONDITIONS WITH GUSTS UP TO 40 MPH OVER
LAND AREAS AND EVEN HIGHER OVER THE LOCAL COASTAL WATERS.

BETWEEN THIS AFTERNOON AND EVENING...THE MAIN AREA OF SHOWERS AND
THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS SYSTEM WILL BE VERY CLOSE
TO THE AREA. EXPECT NUMEROUS SHOWERS WITH VERY HEAVY RAIN AND
THUNDERSTORMS FOR MOST OF THE NORTHERN COASTS AND CENTRAL INTERIOR
SECTIONS OF THE ISLANDS. RESIDENTS AND VISITORS OF THE LOCAL ISLANDS
SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM AS IT MOVES
CLOSER TO THE AREA WITHIN THE NEXT SEVERAL HOURS.

A WIND ADVISORY IS IN EFFECT FOR LOCATIONS IN PUERTO RICO OF 1000
THOUSAND FEET AND HIGHER THROUGH 2 PM AST THIS AFTERNOON.
HOWEVER...MOST LIKELY...THIS ONE WILL BE EXTENDED THIS AFTERNOON FOR
A LONGER TIME PERIOD.

MARINE...THIS WIND WILL CAUSE AN INCREASING TREND IN COASTAL
SEAS...AND SMALL CRAFT ADVISORIES ARE IN EFFECT FOR ALL LOCAL
WATERS...MODERATE NORTHEASTERLY SWELLS WILL PRODUCE MODERATE SIZED
BREAKING WAVE ALONG THE NORTH AND NORTHEAST COASTS OF THE LOCAL
ISLANDS...GENERATING RIP CURRENTS. ALSO...A GALE WARNING IS NOW IN
EFFECT FROM 11 AM AST THIS MORNING THROUGH LATE TONIGHT.

HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 AM AST THIS
MORNING...HOWEVER...THIS ONE ALSO IS EXPECTED TO BE EXTENDED FOR A
LONGER TIME PERIOD LATER IN THE DAY.

NO OTHER HAZARDOUS WEATHER CONDITIONS ARE EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...NORTHEASTERLY WINDS WILL CONTINUE TO
PRODUCE HIGH AND VERY ROUGH SEAS...AND MAINTAIN RIP CURRENTS IN THE
SURF ZONE. EXPECT FREQUENCY OF SHOWERS TUESDAY AND WEDNESDAY THAT
COULD LEAD TO URBAN FLOODING...AND WILL CAUSE RIVER RISES. MUDSLIDES
WILL REMAIN POSSIBLE IN AREAS OF STEEP TERRAIN THROUGH AT LEAST
WEDNESDAY ACROSS THE LOCAL ISLANDS.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY TODAY.

VIZ001-002-AMZ710>730-111000-
630 AM AST MON DEC 10 2007

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

.TODAY AND TONIGHT....TROPICAL DISTURBANCE LOCATED THIS MORNING TO
THE NORTHEAST OF THE NORTHERN LEEWARD ISLANDS IS FORECAST TO MOVE
ACROSS THE LOCAL AREA THIS AFTERNOON THROUGH TUESDAY MORNING. THIS
FEATURE IS EXPECTED TO BRING SIGNIFICANT SHOWER ACTIVITY ACCOMPANIED
WITH THUNDERSTORMS AND WINDY CONDITIONS WITH GUSTS UP TO 40 MPH OVER
LAND AREAS AND EVEN HIGHER OVER THE LOCAL COASTAL WATERS.

BETWEEN THIS AFTERNOON AND EVENING...THE MAIN AREA OF SHOWERS AND
THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS SYSTEM WILL BE VERY CLOSE
TO THE AREA. EXPECT NUMEROUS SHOWERS WITH VERY HEAVY RAIN AND
THUNDERSTORMS FOR MOST OF THE NORTHERN COASTS AND CENTRAL INTERIOR
SECTIONS OF THE ISLANDS. RESIDENTS AND VISITORS OF THE LOCAL ISLANDS
SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM AS IT MOVES
CLOSER TO THE AREA WITHIN THE NEXT SEVERAL HOURS.

A WIND ADVISORY MAY BE NECESSARY FOR ST. THOMAS AND ST. CROIX MORE
AREAS ABOVE 500 FEET LATER TODAY.

MARINE...THIS WIND WILL CAUSE AN INCREASING TREND IN COASTAL
SEAS...AND SMALL CRAFT ADVISORIES ARE IN EFFECT FOR ALL LOCAL
WATERS...MODERATE NORTHEASTERLY SWELLS WILL PRODUCE MODERATE SIZED
BREAKING WAVE ALONG THE NORTH AND NORTHEAST COASTS OF THE LOCAL
ISLANDS...GENERATING RIP CURRENTS. ALSO...A GALE WARNING IS NOW IN
EFFECT FROM 11 AM AST THIS MORNING THROUGH LATE TONIGHT.

HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 AM AST THIS
MORNING...HOWEVER...THIS ONE ALSO IS EXPECTED TO BE EXTENDED FOR A
LONGER TIME PERIOD LATER IN THE DAY.

.DAYS TWO THROUGH SEVEN...NORTHEASTERLY WINDS WILL CONTINUE TO
PRODUCE HIGH AND VERY ROUGH SEAS...AND MAINTAIN RIP CURRENTS IN THE
SURF ZONE. EXPECT FREQUENCY OF SHOWERS TUESDAY AND WEDNESDAY THAT
COULD LEAD TO URBAN AND STREAM FLOODING...AND WILL CAUSE RIVER RISES
ALONG NORTH COASTAL RIVER SYSTEMS. MUDSLIDES WILL REMAIN POSSIBLE IN
AREAS OF STEEP TERRAIN THROUGH AT LEAST WEDNESDAY ACROSS THE LOCAL
ISLANDS

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY TODAY.

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

FROM YOUR PDA/PHONE: HTTP://MOBILE.SRH.NOAA.GOV OR
WWW.SRH.NOAA.GOV/WML