000
AXNT20 KNHC 180605
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0545 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 10N42W 6N44W 2N45W MOVING WEST ABOUT
10 KT. THIS WAVE IS EMBEDDED WITHIN A BROAD INVERTED-V SHAPE
IN THE LOW-LEVEL CLOUD FIELD. IT IS ASSOCIATED WITH A MAXIMUM
IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER
PRODUCT FROM CIMSS. COMPUTER MODEL GUIDANCE INDICATES THAT THE 
WAVE COINCIDES WITH AN AREA OF LOW LEVEL CYCLONIC CIRCULATION. 
ISOLATED MODERATE SHOWERS ARE FROM THE EQUATOR TO 5N BETWEEN
41W AND 48W.

...THE ITCZ...

FROM THE LIBERIA COAST NEAR 6N11W TO 2N20W...CROSSING THE
EQUATOR ALONG 25W...TO 1S30W 1S40W...INTO NORTHEASTERN BRAZIL
NEAR 3S49W. STRONG SHOWERS AND THUNDERSTORMS ARE FROM THE
EQUATOR TO 3N BETWEEN 18W AND 22W. 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 TEXAS INTO THE 
NORTHWESTERN GULF COASTAL WATERS SUPPORTS THE CURRENT COLD
FRONT THAT IS PUSHING THROUGH THE AREA. THE COLD FRONT PASSES
THROUGH THE FLORIDA PANHANDLE 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 JUST TO THE 
SOUTH OF THE FLORIDA BIG BEND TO THE NORTHERN YUCATAN PENINSULA.
ISOLATED MODERATE SHOWERS ARE TO THE NORTH OF 22N WITHIN 60 NM
ON EITHER SIDE OF THE TROUGH. ISOLATED MODERATE SHOWERS ARE
WITHIN 15 NM TO 30 NM ON EITHER SIDE OF THE FRONT TO THE EAST
OF 93W.

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 TO STRONG 
SHOWERS ARE IN GUATEMALA TO THE NORTH OF 14N IN BROAD SURFACE 
LOW PRESSURE UNDER THE UPPER LEVEL ANTICYCLONIC FLOW. ISOLATED 
MODERATE SHOWERS ARE FROM 15N TO 21N BETWEEN 72W AND 77W.
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 14N TO 17N 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 32N53W CYCLONIC CIRCULATION 
CENTER TO 19N55W. 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 14N TO 17N BETWEEN 58W AND 61W. ISOLATED MODERATE SHOWERS
ARE FROM 21N 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