Flash Flood Watch 4, NWS JSJ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
534 AM AST SAT MAY 9 2009

.DISCUSSION...LATEST SATELLITE IMAGES AND RADAR OBSERVATIONS EARLY
THIS MORNING SHOWED SCATTERED SHOWERS AND A FEW THUNDERSTORMS MAINLY
ACROSS THE COASTAL WATERS. FEW SHOWERS MOVED ACROSS EASTERN AND
SOUTHEASTERN PUERTO RICO AS WELL ACROSS VIEQUES...CULEBRA AND THE
U.S.V.I. FEW SHOWERS ALSO BRUSHED THE NORTHERN COASTAL
MUNICIPALITIES OF PUERTO RICO...BUT IN GENERAL THE TOTAL RAINFALL
AMOUNTS OVER LAND AREAS SO FAR THIS MORNING WERE MINIMAL. THE
RUNOFF FROM PREVIOUS AFTERNOON RAINFALL MAINTAINED THE RIO GRANDE
DE MANATI FROM CIALES TO THE ATLANTIC OCEAN ABOVE FLOOD STAGE
OVERNIGHT.

A MID TO UPPER LEVEL TROUGH WILL PERSIST JUST TO THE NORTH OF THE FA
THROUGH AT LEAST TONIGHT. THIS FEATURE IN COMBINATION WITH A WEAK
AND HUMID SOUTHEASTERLY WIND WILL INDUCE FAIRLY ABUNDANT LOW
LEVEL MOISTURE ACROSS THE REGION. DAYTIME HEATING AND LOCAL
EFFECTS WILL COMPLETE THE INGREDIENTS FOR A FAIRLY ACTIVE
AFTERNOON ESPECIALLY ACROSS NORTHWESTERN AND INTERIOR SECTIONS OF
PUERTO RICO. IN AGREEMENT WITH THIS REASONING...THE GFS MODEL
GUIDANCE INDICATED PWAT VALUES OF AROUND 2 INCHES FOR TODAY AND
UNTIL AT LEAST EARLY MONDAY...DECREASING TO AROUND 1.5 BY LATE MONDAY.
THEREFORE THE POTENTIAL FOR FLASH FLOODING DUE TO SATURATED SOILS
AND MUDSLIDES IN AREAS OF STEEP TERRAIN...REMAIN HIGH THROUGH THIS
EVENING AND POSSIBLE TOMORROW AFTERNOON AND EVENING. LESS
SHOWER ACTIVITY IS THEN EXPECTED BY MONDAY AND TUESDAY AS DRIER
AIR MOVES ACROSS THE FA.

LOOKING AHEAD...THE GFS MODEL GUIDANCE SUGGESTS A GENERAL INCREASE
IN MOISTURE BY THE END OF THE FORECAST PERIOD IN ASSOCIATION WITH
A COMPLEX WEATHER PATTERN...APPARENTLY A SURFACE REFLECTION OF AN
UPPER LEVEL TROUGH. BY THAT TIME THE PWAT VALUES WILL INCREASE
AGAIN TO MORE THAN 2.0 INCHES...GOOD INDICATIONS THAT THE
CONVECTIVE SEASON WILL CONTINUE WITH US FOR A WHILE. STAY TUNED.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED TO PREVAIL ACROSS ALL THE
LOCAL TAF SITES DURING THE EARLY MORNING HOURS...WITH SCT TO BKN
CIGS BETWEEN 5-100 KFT...LIGHT AND VARIABLE WINDS...AND A PASSING
SHRA POSSIBLE ENROUTE BETWEEN THE U.S.V.I AND EASTERN PUERTO RICO.
THE PASSING SHOWER ACTIVITY WILL RESULT IN INTERMITTENT PERIODS OF
MVFR AT AND AROUND...TISX...TIST...TJSJ...TNCM AND TKPK AT LEAST
THROUGH 12Z. THEREAFTER...EXPECT EASTERLY FLOW OF 10-15KTS AT ALL
TAF SITES...WITH A SHRA POSSIBLE ACROSS PR AND THE VI AFTER 16Z. IN
ADDITION...A TSRA WILL BE POSSIBLE OVER THE INTERIOR OF PR AS WELL
AS IN THE VCTY OF TJMZ AND TJPS FM 18-22Z.

&&

.MARINE...EXPECT WINDS OF 18 KNOTS OR LESS AND SEAS OF 6 FEET OR
LESS ACROSS THE REGIONAL WATERS THROUGH AT LEAST SUNDAY. THERE ARE
PRECAUTIONARY STATEMENTS FOR MOST OF THE LOCAL COASTAL WATERS.

&&

.PRELIMINARY POINT TEMPS/POPS...
SJU  84  75  85  75 /  70  40  40  40
STT  84  73  84  73 /  70  40  40  40

&&

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
&&

09/72

HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN
ISLANDS
NATIONAL WEATHER SERVICE SAN JUAN PR
558 AM AST SAT MAY 9 2009

AMZ710>745-PRZ001>013-101000-
SAN JUAN AND VICINITY-NORTHEAST-SOUTHEAST-EASTERN INTERIOR-
NORTH CENTRAL-CENTRAL INTERIOR-PONCE AND VICINITY-NORTHWEST-
WESTERN INTERIOR-MAYAGUEZ AND VICINITY-SOUTHWEST-CULEBRA-VIEQUES-
THE NEARSHORE AND OFF SHORE ATLANTIC AND CARIBBEAN COASTAL WATERS-
558 AM AST SAT MAY 9 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE
ADJACENT COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT
ABUNDANT TROPICAL MOISTURE SPREAD ACROSS THE REGION WILL COMBINE
WITH DIURNAL AND LOCAL EFFECTS...TO PRODUCE MODERATE TO LOCALLY
HEAVY RAINFALL AND ISOLATED THUNDERSTORMS ACROSS PARTS OF PUERTO
RICO...ESPECIALLY OVER THE NORTH CENTRAL AND WEST SECTIONS OF THE
ISLAND. THEREFORE THE POTENTIAL FOR FLASH FLOODING AND MUDSLIDES
REMAIN HIGH THROUGH THE EVENING HOURS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
SUNDAY THROUGH AT LEAST MONDAY...SHOWER DEVELOPMENT WILL CONCENTRATE
MAINLY ACROSS THE WESTERN INTERIOR SECTIONS OF THE ISLAND...WHERE
MINOR FLOODING MAY OCCUR ESPECIALLY ACROSS LOW LYING AND POOR DRAINAGE
AREAS...URBAN LOCATIONS AND LOCAL STREET AND HIGHWAYS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION NOT REQUIRED AT THE MOMENT.HOWEVER...REPORTS
OF RAINFALL AMOUNTS AND FLOODING WOULD BE GREATLY APPRECIATED.

AMZ715-725-VIZ001-002-101000-
ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX-
NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS-
558 AM AST SAT MAY 9 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS AND
THE ADJACENT COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT
TROPICAL MOISTURE SPREAD ACROSS THE REGION BY THE PREVAILING EAST
SOUTHEAST WIND FLOW...WILL BRING BRIEF PERIODS OF MODERATE TO LOCALLY
HEAVY RAINFALL ACROSS PARTS OF THE ISLANDS DURING THE DAY. THIS WILL
LEAD TO MINOR PONDING OF WATER ON STREETS AND ROADWAYS AND POORLY DRAINED
AREAS. NO OTHER HAZARDOUS WEATHER CONDITIONS EXPECTED THEREAFTER.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
NO WEATHER HAZARDOUS CONDITIONS EXPECTED FOR THIS PERIOD.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.