000
AXNT20 KNHC 171047
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI APR 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 1015 UTC. 

...THE ITCZ...
FROM 4N7W AT THE LIBERIA/IVORY COAST BORDER...CROSSING THE 
EQUATOR ALONG 12W TO 3S20W 3S37W...AND GOING INTO NORTHEASTERN 
BRAZIL NEAR 3S43W. STRONG SHOWERS AND THUNDERSTORMS ARE FROM
1S TO 3N BETWEEN 9W AND 11W. WARMING CLOUD TOP TEMPERATURES AND 
DISSIPATING PRECIPITATION ARE ELSEWHERE FROM 1S TO 4N BETWEEN
9W AND 20W. STRONG SHOWERS REMAIN IN THE COASTAL WATERS OFF THE
EXTREME NORTHEASTERN BRAZIL COAST FROM THE EQUATOR TO 3N BETWEEN
BETWEEN 49W AND 51W.

...DISCUSSION...

THE GULF OF MEXICO...
A MIDDLE LEVEL TO UPPER LEVEL SHORTWAVE TROUGH RUNS THROUGH 
CENTRAL/EAST TEXAS TO 25N94W...ABOUT 200 NM TO THE EAST OF
THE LOWER TEXAS COAST. A FEW CLUSTERS OF STRONG SHOWERS AND 
THUNDERSTORMS ARE IN THE GULF WATERS...ONE WITHIN A 30 NM
TO 60 NM RADIUS OF 28.5N92W AND THE OTHER ONE NEAR 25N87W.
THIS PRECIPITATION IS OCCURRING IN AN AREA OF UPWARD VERTICAL 
MOTION IN THE ATMOSPHERE...THAT ALSO HAPPENS TO BE IN
A FAVORABLE SPOT FOR THE DEVELOPMENT OF CONVECTIVE
PRECIPITATION IN BETWEEN TWO JET STREAMS.

THE CARIBBEAN SEA...
MIDDLE LEVEL TO UPPER LEVEL WESTERLY WIND FLOW MOVES FROM THE 
EASTERN PACIFIC OCEAN ACROSS CENTRAL AMERICA...FROM NICARAGUA
TO BELIZE...INTO THE WESTERN CARIBBEAN SEA AND BEYOND. UPPER
LEVEL SOUTHWESTERLY WIND FLOW MOVES INTO THE CARIBBEAN SEA 
ACROSS COSTA RICA AND PANAMA...AND FROM NORTHERN SOUTH AMERICA. 
BROAD LOW LEVEL CYCLONIC FLOW SPANS THE AREA.
 
THE ATLANTIC OCEAN...
A WESTERN ATLANTIC OCEAN DEEP LAYER TROUGH SUPPORTS THE COLD 
FRONT THAT PASSES THROUGH 32N58W TO 26N67W TO 23N77W...BETWEEN
ANDROS ISLAND AND CUBA. ISOLATED MODERATE SHOWERS ARE WITHIN
30 NM ON EITHER SIDE OF 24N71W 28N62W BEYOND 32N56W.
A SURFACE RIDGE EXTENDS FROM 32N25W TO A 1024 MB HIGH PRESSURE 
CENTER NEAR 29N31W TO 25N47W 22N57W TO 21N66W. A MIDDLE LEVEL 
CYCLONIC CIRCULATION CENTER IS NEAR 18N33W. A TROUGH IS ALONG 
20N30W 18N33W 12N37W. BROAD LARGE SCALE UPPER LEVEL ANTICYCLONIC 
FLOW COVERS THE AREA TO THE EAST OF 50W.

$$
MT