000
AXNT20 KNHC 170605
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN MAY 17 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 0515 UTC.

...THE ITCZ...

FROM THE LIBERIA COAST NEAR 6N10W TO 2N20W 1N30W...FROM THE 
EQUATOR TO 1N BETWEEN 30W AND 42W...CROSSING THE EQUATOR ALONG 
42W...INTO NORTHEASTERN BRAZIL NEAR 2S48W. ISOLATED AND 
DISORGANIZED MODERATE SHOWERS AND LOCALLY STRONG THUNDERSTORMS
ARE TO THE SOUTH OF 5N TO THE EAST OF 50W.

...DISCUSSION...

THE GULF OF MEXICO...
LARGE SCALE UPPER LEVEL ANTICYCLONIC FLOW MOVES FROM THE EASTERN 
PACIFIC OCEAN NEAR 16N119W ACROSS MEXICO INTO THE GULF OF 
MEXICO. SOME OF THE CYCLONIC FLOW THAT HAS BEEN ASSOCIATED WITH 
THE BAHAMAS-TO-CUBA-SOUTHWESTERN CARIBBEAN SEA TROUGH OF 
YESTERDAY HAS MOVED INTO THE SOUTHEASTERN CORNER OF THE GULF OF 
MEXICO. MOST OF THE UPPER LEVEL NORTHWESTERLY WIND FLOW THAT IS 
ON THE EASTERN SIDE OF THE RIDGE REACHES 85W. ANOTHER PART OF 
THAT FLOW MOVES TOWARD THE SMALL CYCLONIC CIRCULATION CENTER 
THAT IS IN THE STRAITS OF FLORIDA. A COLD FRONT IS MOVING
THROUGH EASTERN AND SOUTH CENTRAL TEXAS. THE WESTERNMOST PART
OF THE FRONT EXTENDS FROM SOUTH CENTRAL TEXAS TO THE TEXAS BIG
BEND AND INTO NORTH CENTRAL MEXICO. AN OUTFLOW BOUNDARY IS ALONG 
THE TEXAS COAST FROM THE MIDDLE TEXAS COAST SOUTHWARD. STRONG
SHOWERS AND THUNDERSTORMS IN EXTREME NORTHEASTERN MEXICO HAVE 
BEEN MOVING SOUTHWARD AND WEAKENING IN INTENSITY DURING THE LAST 
SIX HOURS. ISOLATED MODERATE SHOWERS ARE ALONG A SOUTHEAST-TO-
NORTHWEST ORIENTED LINE...ALONG A CENTRAL MEXICO SURFACE TROUGH.
A SURFACE TROUGH IS ALONG 88W FROM THE YUCATAN PENINSULA TO 27N
NOT ACCOMPANIED BY ANY DEEP CONVECTIVE PRECIPITATION.

THE CARIBBEAN SEA...
A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM THE STRAITS OF 
FLORIDA...ACROSS CUBA AND JAMAICA...INTO THE SOUTHWESTERN CORNER 
OF THE AREA. THIS TROUGH HAS PERSISTED IN MORE OR LESS THE SAME 
AREA FOR AT LEAST THE LAST 72 HOURS OR SO. MOIST UPPER LEVEL 
SOUTHWESTERLY WIND FLOW IS ON THE EASTERN SIDE OF THE TROUGH 
ACROSS THE REMAINDER OF THE CARIBBEAN SEA TO THE EAST OF 70W. 
THE CYCLONIC FLOW AROUND THE TROUGH COVERS THE AREA ROUGHLY FROM 
THE MONA PASSAGE TO THE COAST OF NORTHERN COLOMBIA. SCATTERED 
MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE IN THE 
AREA TO THE NORTH OF THE LINE FROM THE WESTERN TIP OF CUBA TO 
16N78W TO THE WATERS OF THE JAMAICA CHANNEL. 

THE ATLANTIC OCEAN...
A DEEP LAYER TROUGH EXTENDS FROM A 32N53W CYCLONIC CIRCULATION 
CENTER TO 26N53W TO 22N60W. THIS TROUGH SUPPORTS A SURFACE COLD 
FRONT THAT EXTENDS FROM A 1007 MB LOW PRESSURE CENTER NEAR 
33N53W. AN OCCLUDED FRONT PASSES THROUGH 32N48W TO 31N48W.
A COLD FRONT CONTINUES FROM 31N48W TO 26N50W 21N57W 21N63W.
ISOLATED MODERATE SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF 
21N51W 16N59W. A SURFACE TROUGH IS ALONG 21N54W 18N57W 16N59W.
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 23N AS IT EVENTUALLY 
CROSSES 30W AND BEYOND. THE REMNANTS OF AN EARLIER MIDDLE LEVEL 
TO UPPER LEVEL TROUGH ARE ALONG THE LINE FROM THE MADEIRA 
ARCHIPELAGO TO 21N22W.

$$
MT