000
AXNT20 KNHC 181100
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON MAY 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1045 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 10N43W 6N45W 1N46W MOVING WEST ABOUT
10 KT. THIS WAVE IS EMBEDDED WITHIN A BROAD INVERTED-V SHAPE
IN THE LOW-LEVEL CLOUD FIELD. IT IS IN A MAXIMUM IN DEEP LAYER
MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM
CIMSS. COMPUTER MODEL GUIDANCE SHOWS THE WAVE COINCIDING WITH
AN AREA OF LOW LEVEL CYCLONIC CIRCULATION. ISOLATED AND 
DISORGANIZED SHOWERS ARE FROM THE EQUATOR TO 5N BETWEEN
43W AND 50W.

...THE ITCZ...

FROM THE LIBERIA COAST NEAR 6N11W TO 2N20W...CROSSING THE
EQUATOR ALONG 26W...TO 1S30W 2S40W...INTO NORTHEASTERN BRAZIL 
NEAR 3S49W. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE FROM 
THE EQUATOR TO 3N BETWEEN 19W AND 22W...AND WITHIN A 30 NM 
RADIUS OF 5N11.5W. ISOLATED AND DISORGANIZED MODERATE SHOWERS 
ARE ELSEWHERE TO THE SOUTH OF 6N TO THE EAST OF 50W.

...DISCUSSION...

THE GULF OF MEXICO...
A DEEP LAYER TROUGH THAT CUTS THROUGH LOUISIANA INTO THE WEST 
CENTRAL GULF WATERS SUPPORTS THE CURRENT COLD FRONT THAT IS 
PUSHING THROUGH THE AREA. THE COLD FRONT PASSES THROUGH NORTH
CENTRAL FLORIDA INTO THE NORTH CENTRAL GULF OF MEXICO...
DISSIPATING AFTER CROSSING 90W AND CONTINUING INTO THE 
SOUTHWESTERN CORNER OF THE AREA. THE TROUGH THAT HAD BEEN MOVING 
WESTWARD 16 HOURS AGO NOW HAS BEEN CAUGHT UP IN THE ENVIRONMENT 
AROUND THE COLD FRONT. IT EXTENDS FROM NORTHEASTERN FLORIDA TO 
THE EAST CENTRAL GULF TO THE NORTHERN YUCATAN PENINSULA. 
ISOLATED MODERATE SHOWERS ARE TO THE NORTH OF 25N BETWEEN 
FLORIDA AND THE COLD FRONT.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW MOVES ACROSS THE SOUTHWESTERN 
CORNER OF THE GULF OF MEXICO...INTO THE CARIBBEAN SEA TO THE 
WEST OF 80W. THIS FLOW CONTINUES INTO THE MIDDLE LEVEL TO UPPER 
LEVEL TROUGH THAT SPANS THE AREA FROM THE WATERS BETWEEN THE 
SOUTHEASTERN BAHAMA ISLANDS AND EASTERN CUBA INTO THE 
SOUTHWESTERN CORNER OF THE AREA. ISOLATED MODERATE SHOWERS ARE 
FROM 15N TO 23N BETWEEN 70W AND 80W. A SURFACE TROUGH UNDER THE 
MIDDLE LEVEL TO UPPER LEVEL FEATURE IS ALONG 75W FROM 17N TO 
22N. ISOLATED MODERATE SHOWERS ARE IN BROAD LOW LEVEL CYCLONIC 
FLOW FROM 16N TO 18N BETWEEN 60W AND 70W.

THE ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC OUTFLOW PUSHES HIGH CLOUDS TO CURVE
AWAY FROM THE AREA OF THE BAHAMA ISLANDS/CUBA MIDDLE LEVEL TO 
UPPER LEVEL TROUGH AS FAR AS 65W AND 29N. SHOWERS ARE POSSIBLE
FROM THE BAHAMA ISLANDS TO 29N BETWEEN THE BAHAMAS AND 70W.
A DEEP LAYER TROUGH EXTENDS FROM A 32N52W CYCLONIC CIRCULATION 
CENTER TO 19N54W. THIS TROUGH SUPPORTS A STATIONARY FRONT THAT 
EXTENDS FROM 31N46W TO 22N50W TO GUADELOUPE IN THE EASTERN 
CARIBBEAN ISLANDS. A POST-FRONTAL TROUGH IS WITHIN 120 NM TO THE 
NORTHWEST OF THE FRONT TO THE NORTH OF 25N...AND WITHIN 240 NM
TO THE WEST OF THE FRONT FROM 23N TO 25N. ISOLATED SHOWERS ARE 
FROM 16N TO 20N BETWEEN 53W AND 61W. ISOLATED MODERATE SHOWERS 
AND THUNDERSTORMS ARE FROM 23N BEYOND 32N BETWEEN 40W AND 53W.
A SURFACE TROUGH IS ALONG 75W FROM 17N TO 22N. BROAD LARGE-SCALE 
UPPER LEVEL ANTICYCLONIC FLOW MOVES ACROSS COLOMBIA AND 
VENEZUELA INTO THE CARIBBEAN SEA TO THE EAST OF 70W...ACROSS
THE EASTERN CARIBBEAN SEA ISLANDS AND INTO THE ATLANTIC 
OCEAN...STAYING TO THE SOUTH OF 24N AS IT EVENTUALLY CROSSES
30W AND BEYOND. 

$$
MT