000
AXNT20 KNHC 252348
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT SUN OCT 25 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE REMAINS TILTED FROM 18N48W TO 10N50W MOVING NW 
10-15 KT. WAVE REMAINS EMBEDDED WITHIN A MAXIMUM IN TOTAL 
PRECIPITABLE WATER. ISOLATED SHOWERS ARE FROM 16N18N BETWEEN 
47W-51W. 

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 15N15W 10N27W 10N46W 7N60W. A 
SHORT SURFACE TROUGH EXTENDS ALONG 55W FROM 11N-14N WITH 
ISOLATED SHOWERS FROM 11N-14N BETWEEN 52W-57W. SCATTERED 
MODERATE/STRONG CONVECTION IS WITHIN 250 NM S OF THE ITCZ FROM 
23W-30W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION ARE FROM 4N-13N BETWEEN 37W-47W.

...DISCUSSION...

GULF OF MEXICO...
THE FRONTAL BOUNDARY IS BEGINNING TO MOVE N OVER THE SE GULF 
EXTENDING ACROSS FLORIDA NEAR MIAMI JUST N OF THE FLORIDA KEYS 
TO 23N86W WITH ISOLATED SHOWERS WITHIN 45 NM N OF THE FRONT. A 
DEEP LAYERED TROUGH IS MOVING ACROSS THE CENTRAL PLAIN STATES TO 
OVER THE UPPER MISSISSIPPI VALLEY WITH THE COLD FRONT WELL 
INLAND OVER OKLAHOMA AND TEXAS. TROPICAL MOISTURE CONTINUES TO 
BE DRAWN NE ACROSS MEXICO AND THE GULF WITH SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS OVER THE W GULF N OF 20N W OF 90W. THE 
NEXT COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST MON 
NIGHT. 

CARIBBEAN SEA...
A SERIES OF SURFACE TROUGHS ARE PLAGUING THE W CARIBBEAN...ONE 
ALONG THE COAST OF THE YUCATAN PENINSULA S OF 20N TO JUST INLAND 
OVER HONDURAS...A SECOND FROM JUST OFF THE COAST OF COSTA RICA 
TO ALONG THE COAST OF NICARAGUA...AND A THIRD FROM JUST SW OF 
THE CAYMAN ISLANDS TO 14N80W. ALL OF THE TROUGHS ARE WEAK WITH 
NO SIGNIFICANT ACTIVITY ASSOCIATED WITH THEM. THE ELONGATED 
UPPER LOW IS CENTERED OVER CUBA NEAR 22N78W WITH THE UPPER 
TROUGH EXTENDING SW TO NEAR 15N74W GENERATING SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM 14N77W TO 
OVER CUBA NEAR 23N81W. AN UPPER TROUGH OVER THE TROPICAL ATLC 
EXTENDS W OVER THE E CARIBBEAN WITH DRY AIR AND MODERATE/STRONG 
SUBSIDENCE COVERING THE E CARIBBEAN AND THUS CLEAR SKIES FOR 
THAT AREA. 

ATLANTIC OCEAN...
THE REMNANT STATIONARY FRONTAL BOUNDARY ENTERS THE FAR W ATLC 
NEAR 32N79W S ALONG 29N79W TO OVER FLORIDA NEAR MIAMI GENERATING 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM EITHER 
SIDE OF THE FRONT N OF 28N. THE ELONGATED UPPER LOW CENTERED 
OVER CUBA NEAR 22N78W EXTENDS N TO 27N78W. AN UPPER HIGH IS JUST 
TO THE E ANCHORED NEAR BERMUDA PROVIDING DIFFLUENCE ALOFT TO 
ENHANCE THE ACTIVITY ASSOCIATED WITH THE FRONT AND GENERATE 
SCATTERED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS S OF 24N 
FROM 72W-78W. LARGE AREA OF STRONG SUBSIDENCE AND DRY STABLE AIR 
IS ACROSS MOST OF THE CENTRAL ATLC THUS LIMITING SHOWER ACTIVITY.
A SURFACE RIDGE IS BUILDING S OVER THE REMAINDER OF THE W AND 
INTO THE CENTRAL ATLC W OF 50W ANCHORED BY A 1027 MB HIGH WELL N 
OF THE REGION. BROAD UPPER TROUGH IS OVER THE E/CENTRAL ATLC N 
OF 25N FROM 25W-50W SUPPORTING A COLD FRONT ENTERING THE REGION 
NEAR 32N30W EXTENDING SW ALONG 28N40W TO 28N49W WITH ISOLATED 
SHOWERS WITHIN 60 NM SE OF THE COLD FRONT. A PREFRONTAL SURFACE 
TROUGH EXTENDS FROM 31N25W SW TO 26N31W WITH SCATTERED SHOWERS N 
OF 29N FROM 25W-27W. 

$$
WALLACE