000
AXNT20 KNHC 162348
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAY 16 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 6N10W 3N15W 1N20W CROSSING THE 
EQUATOR NEAR 23W TO NE BRAZIL NEAR 3S39W. SCATTERED MODERATE 
CONVECTION IS WITHIN 30 NM OF THE AXIS BETWEEN 17W-20W. 

...DISCUSSION...

THE GULF OF MEXICO...
MUCH OF THE GULF WATERS IS EXPERIENCING QUITE CONDITIONS...BUT 
IT IS QUITE DIFFERENT JUST INLAND ALONG THE N GULF COAST. A COLD 
FRONT OVER THE SE CONUS COMBINED WITH A DIFFLUENT PATTERN ALOFT 
IS SUPPORTING WIDESPREAD SCATTERED SHOWERS AND TSTMS THERE. SOME 
OF THIS UNSETTLED WEATHER IS BEGINNING TO MOVE INTO THE FAR NW 
WATERS FROM 25N-27N W OF 96W JUST AHEAD OF THE FRONT. THIS FRONT 
IS FORECAST TO MOVE OFFSHORE INTO THE NW GULF LATE TONIGHT THEN 
TRACK SE AND WEAKEN SUN AND MON. BY MON...MANY OF THE GLOBAL 
MODELS ARE SHOWING LOW PRES DEVELOP OVER CUBA OR THE SE 
GULF...EITHER EXTRATROPICAL OR SUBTROPICAL...AND MOVING 
GENERALLY N. ITS DEVELOPMENT AND TRACK IS UNCERTAIN BUT MODELS 
ARE IN ENOUGH AGREEMENT TO WARRANT GALE HEADLINES OVER A PORTION 
OF THE E AND MIDDLE WATERS FOR EARLY NEXT WEEK.   

THE CARIBBEAN SEA...
A MID TO UPPER TROUGH OVER THE WRN CARIBBEAN IS PRODUCING 
SCATTERED SHOWERS AND TSTMS N OF 17N BETWEEN 75W-84W. LIGHTNING 
DATA SHOWS THE GREATEST CONCENTRATION OF STRIKES OVER CUBA...AS 
LOCAL SEABREEZE/TERRAIN EFFECTS ARE PROVIDING ENHANCED LIFT. 
LATEST VIS/SHORTWAVE IR IMAGES SHOW CYCLONIC ROTATION IN THE MID 
LEVEL CLOUDS ALONG 79W JUST S OF CUBA. THIS FEATURE MAY BUILD 
CLOSER TO THE SFC OVER THE NEXT COUPLE OF DAYS AND DRIFT 
GENERALLY NWD...CONTINUING THE THREAT FOR TSTMS OVER THIS AREA. 
STRONG SWLY UPPER FLOW ON THE E SIDE OF THE AFOREMENTIONED 
TROUGH IS ADVECTING MOISTURE ACROSS THE LESSER ANTILLES. THIS 
FLOW COMBINED WITH A LOW-LEVEL TROUGH A COUPLE HUNDRED NM E OF 
THE AREA IS GENERATING SCATTERED SHOWERS ACROSS MUCH OF THE E 
CARIBBEAN. MEANWHILE...HIGH PRES JUST NW OF BERMUDA IS 
MAINTAINING 15-20 KT TRADES ACROSS THE MUCH OF THE AREA E OF 
76W. THESE WINDS ARE EXPECTED TO REMAIN SIMILAR OR SLACKEN 
SLIGHTLY AS THE HIGH WEAKENS IN PLACE OVER THE NEXT DAY OR TWO.

THE ATLANTIC OCEAN...
AN OCCLUDED 1007 MB LOW IS QUASI-STATIONARY ALONG THE N BORDER 
OF THE DISCUSSION ZONE NEAR 32N53W. A COLD FRONT EXTENDS FROM 
31N48W TO 23N54W CONTINUING SW TO 21N62W. ASSOCIATED SCATTERED 
SHOWERS AND TSTMS ARE MAINLY CONFINED TO THE E SEMICIRCLE OF THE 
LOW N OF 30N BETWEEN 45W AND 51W. DEEP LAYER RIDGING W OF THE 
LOW IS PROVIDING MAINLY FAIR WEATHER ACROSS MUCH OF THE W ATLC. 
HOWEVER...THERE ARE SCATTERED SHOWERS AND TSTMS OVER CUBA AND 
NEARBY WATERS. SEE CARIBBEAN SECTION FOR MORE DETAILS. THE TIGHT 
PRESSURE GRADIENT BETWEEN THE LOW AND HIGH PRES NEAR BERMUDA IS 
GENERATING A SWATH OF NLY GALE FORCE WINDS JUST N OF THE 
ZONE...WHICH IS SPREADING NLY SWELL TO THE NE CARIBBEAN. A WEAK 
SFC TROUGH IS LOCATED JUST E OF THE FRONT FROM 23N52W TO 19N58W 
PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 240 NM OF 
THE AXIS. SFC HIGH PRES RIDGING AND MAINLY ZONAL FLOW ALOFT 
DOMINATES MUCH OF THE E ATLC...SUPPORTING MAINLY FAIR WEATHER. 

$$
CANGIALOSI