000
AXNT20 KNHC 131039
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 91W/92W S OF 20N MOVING W NEAR 15 KT. 
WAVE IS MOSTLY INLAND OVER THE YUCATAN PENINSULA/S MEXICO AND 
INTO THE E PACIFIC REGION GENERATING SCATTERED SHOWERS AND 
POSSIBLE ISOLATED THUNDERSTORMS IN THE BAY OF CAMPECHE S OF 21N 
E OF 93W TO INLAND OVER THE YUCATAN.  

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 16N16W THROUGH A 1012 MB LOW 
NEAR 12N22W THEN ALONG 8N39W 12N53W 10N62W. CLUSTERS OF 
SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 90 NM OF LINE 
FROM 20N26W ACROSS THE CAPE VERDE ISLANDS TO 13N22W. CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM N 
OF THE ITCZ FROM 37W-44W AND WITHIN 90 NM EITHER SIDE OF THE 
ITCZ FROM 57W-61W.  

...DISCUSSION...

GULF OF MEXICO...
A QUASI-STATIONARY BOUNDARY EXTENDS ACROSS THE N GULF FROM A 
1011 MB LOW OFF THE COAST OF GEORGIA THROUGH APALACHICOLA 
FLORIDA THEN OVER NEW ORLEANS LOUISIANA ALONG THE NE COAST OF 
TEXAS TO 29N95W THEN S TO A 1005 MB LOW NEAR 28N95W WITH A 
SURFACE TROUGH EXTENDING SW ACROSS S TEXAS TO 26N100W. A STRONG 
UPPER LOW IS INLAND OVER E TEXAS WITH THE UPPER TROUGH EXTENDING 
S TO 20N COVERING THE GULF W OF 90W WHILE AN UPPER RIDGE COVERS 
THE REMAINDER OF THE GULF ANCHORED NEAR 26N84W EXTENDING ACROSS 
FLORIDA INTO THE W ATLC. THIS SCENARIO COUPLED WITH THE 
ABUNDANCE OF DEEP LAYER MOISTURE IS GENERATING SCATTERED SHOWERS 
AND SCATTERED/NUMEROUS THUNDERSTORMS ACROSS THE NW GULF WITHIN 
90 NM OF LINE FROM 22N93W TO THE N GULF COAST NEAR THE TEXAS/ 
LOUISIANA BORDER. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE 
IN THE BAY OF CAMPECHE S OF 21N W OF 93W. SCATTERED/NUMEROUS 
SHOWERS ARE OVER THE SE GULF S OF 26N TO CUBA BETWEEN 80W-83W 
INCLUDING S FLORIDA AND THE FLORIDA KEYS. ISOLATED SHOWERS DOT 
THE REMAINDER OF THE GULF THIS MORNING. 

CARIBBEAN SEA...
THE UPPER RIDGE ANCHORED IN THE GULF OF MEXICO COVERS THE W 
CARIBBEAN N OF 14N W OF 75W WHILE AN UPPER TROUGH COVERS THE NE 
CARIBBEAN EXTENDING FROM AN UPPER LOW N OF PUERTO RICO/VIRGIN 
ISLANDS. DIFFLUENCE ALOFT IS GENERATING CLUSTERS OF SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS FROM 18N-22N BETWEEN 74W-84W. THE 
ITCZ EXTENDS FROM COLOMBIA ACROSS PANAMA INTO THE E PACIFIC 
REGION GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 
12N TO INLAND OVER COLOMBIA AND PANAMA FROM 75W-82W. OTHERWISE 
THE REMAINDER OF THE CARIBBEAN IS REMARKABLY CLEAR AGAIN THIS 
MORNING. 

ATLANTIC OCEAN...
A 1011 MB LOW IS OFF THE GEORGIA COAST NEAR 31N79W WITH A QUASI- 
STATIONARY BOUNDARY EXTENDING W ACROSS NE FLORIDA INTO THE GULF 
OF MEXICO. THE UPPER RIDGE ANCHORED IN THE GULF OF MEXICO 
EXTENDS OVER THE W ATLC W OF 68W PROVIDING DIFFLUENCE ALOFT TO 
GENERATE LARGE CLUSTERS OF SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS N OF 24N W OF 68W. AN UPPER LOW IS N OF PUERTO 
RICO/VIRGIN ISLANDS NEAR 21N65W WITH THE UPPER TROUGH DIPPING S 
OVER THE NE CARIBBEAN. A BROAD UPPER TROUGH COVERS THE CENTRAL 
ATLC N OF 17N BETWEEN 35W-55W WITH THE ASSOCIATED FRONTAL 
BOUNDARY ENTERING THE REGION NEAR 32N35W EXTENDING SW ALONG 30N 
FROM 41W TO A 1013 MB LOW NEAR 30N56W THEN NW TO BEYOND 32N58W. 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 28N-31N 
BETWEEN 53W-56W WITH ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE 
OF THE REMAINDER OF THE FRONTAL BOUNDARY. A REMNANT SURFACE 
TROUGH REMAINS IN THE TROPICAL ATLC EXTENDING FROM 17N54W TO 
11N54W WITH NO SIGNIFICANT WEATHER. A BROAD UPPER RIDGE COVERS 
THE E ATLC FROM THE TROPICS TO 30N ANCHORED NEAR 19N21W AND 
PROVIDING THE SLY SHEAR OVER A 1008 MB LOW...THE REMNANTS OF 
FRED...CENTERED NEAR 17N34W AND ENHANCING THE CONVECTION OVER 
THE CAPE VERDE ISLANDS.   

$$
WALLACE