000
AXNT20 KNHC 171107
TWDAT 

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

...TROPICAL WAVES...
A TROPICAL WAVE HAS BECOME MORE PRONOUNCED IN SHORTWAVE INFRARED 
SATELLITE IMAGERY ALONG THE LINE FROM 11N40W TO 5N42W. IT IS 
POSSIBLE THAT THIS WAVE WAS INTRODUCED INTO THE ANALYSIS A FEW 
DAYS AGO AND THEN DROPPED BECAUSE IT WAS NOT ABLE TO BE DETECTED 
IN OBSERVATIONS AND SATELLITE IMAGERY AT THAT TIME ANY MORE. 
BROKEN TO OVERCAST MULTILAYERED CLOUDS ARE FROM 4N TO 12N 
BETWEEN 36W AND 43W...AND FROM 6N TO 10N BETWEEN 43W AND 50W. 
ITCZ PRECIPITATION IS FROM THE EQUATOR TO 3N BETWEEN 38W AND 46W.

...THE ITCZ...

FROM THE LIBERIA COAST NEAR 6N10W TO 2N20W 1N30W...FROM THE 
EQUATOR TO 1N BETWEEN 30W AND 41W...CROSSING THE EQUATOR ALONG 
41W...INTO NORTHEASTERN BRAZIL NEAR 2S49W. 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 16N111W ACROSS MEXICO INTO THE GULF OF 
MEXICO. A COLD FRONT IS APPROACHING THE TEXAS GULF COAST...
PASSING THROUGH SOUTH CENTRAL TEXAS INTO MEXICO JUST TO THE 
SOUTH OF THE TEXAS BIG BEND AND INTO NORTH CENTRAL MEXICO.
BROAD LOW PRESSURE IS ALONG THE TEXAS COASTAL WATERS TO THE
EAST OF THE COLD FRONT. ISOLATED MODERATE SHOWERS ARE ALONG
A SOUTHEAST-TO-NORTHWEST ORIENTED LINE...ALONG A CENTRAL
MEXICO SURFACE TROUGH. A SURFACE TROUGH IS ALONG 88W/89W FROM
THE YUCATAN PENINSULA TO 28N. MODERATE SHOWERS FROM 25N TO 28N
BETWEEN 86W AND 88W.

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. A SURFACE TROUGH HAS 
BECOME MORE PRONOUNCED IN SHORTWAVE INFRARED SATELLITE IMAGERY 
ALONG 79W/80W FROM 16N TO 21N. 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 TO THE EAST OF 
THE LINE FROM GUADELOUPE TO THE GUAJIRA PENINSULA OF 
NORTHEASTERN COLOMBIA. SCATTERED MODERATE SHOWERS TO ISOLATED 
STRONG THUNDERSTORMS ARE FROM 16N TO 20N BETWEEN THE JAMAICA
CHANNEL AND 78W.

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 1006 MB LOW PRESSURE CENTER NEAR 
33N53W. A COLD FRONT PASSES THROUGH 32N46W TO 25N50W TO 21N56W.
ISOLATED MODERATE SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF 
20N52W 16N60W...WITH COVERAGE INCREASING TO THE NORTH OF 26N
BETWEEN 44W AND 52W. A SURFACE TROUGH IS ALONG 20N54W 18N57W 
15N60W. 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