000
AXNT20 KNHC 160542
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
205 AM EDT FRI OCT 16 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 
0345 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 69W S OF 15N MOVING W NEAR 15 KT. WAVE IS 
EMBEDDED WITHIN AN AREA OF DEEP MOISTURE AS INDICATED IN THE 
TOTAL PRECIPITABLE WATER IMAGERY REMAINING AT A LOW AMPLITUDE. 
ISOLATED SHOWERS ARE S OF 13N TO INLAND OVER VENEZUELA BETWEEN 
67W-71W INCLUDING THE ABC ISLANDS. 

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N11W 6N25W 8N40W 7N48W 10N57W. 
A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ ALONG 39W FROM 
6N-11N WITH A SECOND SURFACE TROUGH ALSO EMBEDDED WITHIN THE 
ITCZ ALONG 57W FROM 8N-14N. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS WITHIN 75 NM OF THE ITCZ FROM 40W-44W. CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-13N E 
OF 35W TO JUST INLAND OVER THE COAST OF W AFRICA. SCATTERED 
MODERATE CONVECTION IS FROM 12N-15N BETWEEN 58W-61W INCLUDING 
THE WINDWARD ISLANDS. 

...DISCUSSION...

GULF OF MEXICO...
THE PATTERN OF THE PAST FEW DAYS HAS FINALLY BROKEN DOWN AS THE 
BROAD UPPER RIDGE THAT HAD DOMINATED THE GULF AND MOST OF THE 
ATLC HAS RETREATED TO OVER MEXICO AND THE FAR W GULF. A BROAD 
UPPER TROUGH IS OVER THE E HALF OF THE US COVERING THE N GULF TO 
25N WITH THE ACCOMPANYING FRONTAL BOUNDARY INLAND OVER THE GULF 
COAST STATES GENERATING SCATTERED TO HEAVY SHOWERS WITH 
SCATTERED TO NUMEROUS THUNDERSTORMS FROM OVER S GEORGIA TO 
LOUISIANA INCLUDING THE W FLORIDA PANHANDLE WITH ISOLATED 
SHOWERS OVER THE N GULF WATERS N OF 26N E OF 92W. EASTERLY UPPER 
FLOW OVER THE CARIBBEAN IS GENERATING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS OVER W CUBA MOVING OVER THE SE GULF WITHIN 60 NM 
OF THE COAST OF CUBA W OF 82W. THE REMAINDER OF THE GULF IS 
DOMINATED BY DRY STABLE AIR GIVING THE AREA CLEAR SKIES TONIGHT. 
THE COLD FRONT IS EXPECTED TO ENTER THE GULF OFF THE COAST OF 
TEXAS BY LATER THIS MORNING.  

CARIBBEAN SEA...
AN UPPER RIDGE IS ANCHORED OVER THE SW CARIBBEAN NEAR 13N81W 
WITH AN AXIS EXTENDING NE ALONG 16N70W TO OVER THE LEEWARD 
ISLANDS NEAR 17N62W. THIS IS CONTINUING TO GIVE THE N CARIBBEAN 
EASTERLY UPPER FLOW GENERATING SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS OVER HAITI AND THE IMMEDIATE COASTAL WATERS AND W 
GULF WITH THE ACTIVITY MOVING INTO THE SE GULF OF MEXICO. THIS 
UPPER RIDGE IS DRAWING UPPER LEVEL TROPICAL MOISTURE OVER THE SE 
CARIBBEAN AND COUPLED WITH A SURFACE TROUGH IN THE W TROPICAL 
ATLC IS GIVING THE AREA S OF 16N E OF THE TROPICAL WAVE ACROSS 
THE WINDWARD ISLANDS SCATTERED SHOWERS AND POSSIBLE ISOLATED 
THUNDERSTORMS. A SMALL AREA OF SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ARE IN THE SW CARIBBEAN S OF 12N TO THE COAST OF 
PANAMA BETWEEN 79W-81W. THE REMAINDER OF THE CARIBBEAN IS UNDER 
A VERY DRY AND STABLE AIRMASS GIVING THE AREA CLEAR SKIES AGAIN 
TONIGHT. 

ATLANTIC OCEAN...
BROAD UPPER TROUGH OVER THE E US AND N GULF OF MEXICO COVERS THE 
W ATLC N OF 26N W OF 62W WITH THE ASSOCIATED FRONTAL SYSTEM N OF 
THE REGION BUT GENERATING SCATTERED SHOWERS/THUNDERSTORMS N OF 
26N FROM 77W-80W. A BROAD UPPER RIDGE REMAINS OVER THE W ATLC 
ANCHORED NEAR 25N58W EXTENDING AN AXIS NE TO BEYOND 32N40W. A 
BROAD UPPER LEVEL TROUGH IS N OF 30N FROM 40W-50W SUPPORTING A 
COLD FRONT THAT DRAPES INTO THE REGION NEAR 32N44W EXTENDING 
ALONG 28N52W WITH THE FRONTAL BOUNDARY CONTINUING ALONG 27N59W 
THE NW  TO BEYOND 32N66W. ISOLATED SHOWERS ARE WITHIN 120 NM OF 
FRONT N OF 30N. A WEAK 1018 MB HIGH IS LOCATED NEAR 25N54W AND A 
EQUALLY WEAK 1017 MB HIGH IS LOCATED NEAR 27N44W. BROAD COMPLEX 
UPPER LEVEL TROUGH COVERS THE E ATLC N OF 16N E OF 40W 
SUPPORTING A COMPLEX TROUGH SYSTEM WITH A 1012 MB LOW CENTERED 
NEAR 29N28W. SCATTERED SHOWERS WITH POSSIBLE ISOLATED 
THUNDERSTORMS ARE N OF 23N FROM 24W-30W. 
 
$$
WALLACE