000
AXNT20 KNHC 130604
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON APR 13 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 0315 UTC.

...THE ITCZ...
FROM 5N8W AT THE SOUTHERN COAST OF LIBERIA...CROSSING THE 
EQUATOR ALONG 22W...TO 1S37W AND GOING INTO NORTHEASTERN BRAZIL 
NEAR 4S44W. ISOLATED AND DISORGANIZED MODERATE SHOWERS ARE TO 
THE SOUTH OF 5N TO THE EAST OF 11W...AND TO THE SOUTH OF 4N
BETWEEN 25W AND THE COAST OF NORTHEASTERN SOUTH AMERICA.

...DISCUSSION...

THE GULF OF MEXICO...
A DEEP LAYER TROUGH FROM CENTRAL OKLAHOMA INTO CENTRAL TEXAS
IS DRIVING A COLD FRONT THAT IS IN THE NORTHWESTERN CORNER OF 
THE GULF OF MEXICO. THE FRONT STRETCHES FROM SOUTH CENTRAL 
LOUISIANA TO NORTHERN COASTAL MEXICO JUST TO THE SOUTH OF 
THE LOWER VALLEY OF TEXAS. THIS COLD FRONT IN THE NORTHWESTERN 
CORNER OF THE AREA IS CONNECTED TO A LOW PRESSURE CENTER IN
NORTHEASTERN LOUISIANA. A WARM FRONT EXTENDS FROM THE LOW CENTER 
INTO THE EAST-CENTRAL GULF OF MEXICO. THE COMPARATIVELY STRONGEST
SHOWERS AND THUNDERSTORMS ARE MOVING FROM MISSISSIPPI 
NORTHEASTWARD. AN UPPER LEVEL RIDGE IS ALONG 88W...IN BETWEEN
THE OKLAHOMA-TO-TEXAS TROUGH AND A WESTERN ATLANTIC OCEAN DEEP 
LAYER TROUGH. SHOWERS ARE POSSIBLE OVER LAND CLOSE TO THE 
SOUTHWESTERN CORNER OF THE AREA FROM 17N TO 21N BETWEEN 92W AND 
96W...TO THE NORTHWEST OF THE WESTERN ISTHMUS OF TEHUANTEPEC.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA TO THE WEST OF
66W THANKS TO THE UPPER LEVEL 88W RIDGE THAT ALSO SPANS THE
GULF OF MEXICO. DEEP LAYER CYCLONIC FLOW CUTS INTO THE EASTERN
CARIBBEAN SEA TO THE EAST OF 66W THANKS TO THE DEEP LAYER 
WESTERN ATLANTIC OCEAN TROUGH THAT REACHES AS FAR TO THE SOUTH 
AS DOMINICA. A WEAK SURFACE PRESSURE GRADIENT EXISTS ACROSS THE 
AREA. SHOWERS ARE POSSIBLE TO THE SOUTH OF 16N BETWEEN 58W AND 
62W IN CLUSTERS OF BROKEN LOW CLOUDS.
 
THE ATLANTIC OCEAN...
A WESTERN ATLANTIC OCEAN DEEP LAYER TROUGH SUPPORTS THE ATLANTIC 
OCEAN COLD FRONT THAT PASSES THROUGH THE AREA...THROUGH 32N62W
TO 27N67W TO 25N72W. ISOLATED MODERATE SHOWERS ARE IN A LINE IN 
FRONT OF THE COLD FRONT...TO THE NORTH OF 27N BETWEEN 60W AND 
65W. TO THE EAST OF 76W. BROAD SURFACE ANTICYCLONIC FLOW IS TO 
THE NORTH OF 15N BETWEEN AFRICA AND 60W. AN UPPER LEVEL RIDGE
IS ALONG 32N20W TO 32N54W. BROAD LARGE-SCALE UPPER LEVEL 
ANTICYCLONIC FLOW IS TO THE SOUTH OF 26N TO THE EAST OF 60W. 

$$
MT