000
AXNT20 KNHC 181803
TWDAT 

TROPICAL WEATHER DISCUSSION   
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE NOV 18 2008

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 38W/39W SOUTH OF
17N MOVING WEST 10 TO 15 KT. A MOISTURE SURGE IS NOTED ON
THE CIMSS MIMIC DIAGRAM. THE WAVE SHOWS UP WELL IN THE LATEST 
VISIBLE SATELLITE IMAGERY. SHOWERS AND THUNDERSTORMS ARE
IN ONE PRECIPITATION CELL WITHIN A 15 TO 20 NM RADIUS OF
14N37W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ELSEWHERE FROM 8N TO 14N BETWEEN 35W AND 40W.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 71W SOUTH OF 17N
MOVING WEST 10 TO 15 KT. WE HAVE BEEN FOLLOWING THIS WAVE
FOR THE LAST FEW DAYS. IT SHOWS UP WELL IN THE LATEST VISIBLE
SATELLITE IMAGERY. STRONG SHOWERS AND THUNDERSTORMS WERE ARE
FROM 11N TO 13N BETWEEN 67W AND 68W...MOSTLY NEAR ISLAS LOS 
ROQUES VENEZUELA. ISOLATED MODERATE SHOWERS ARE ELSEWHERE
FROM THE COAST OF VENEZUELA TO 16N BETWEEN 66W AND 73W.
SHOWERS ARE POSSIBLE IN LOW CLOUDS FROM 16N TO 17N BETWEEN
69W AND 73W.

...THE ITCZ...
8N11W 6N22W 7N36W 8N42W 8N60W. SCATTERED STRONG SHOWERS AND 
THUNDERSTORMS ARE WITHIN A 30 NM RADIUS OF 8N47W...FROM 9N TO 
10N BETWEEN 45W AND 46W...AND FROM 10N TO 11N BETWEEN 45W AND 
47W. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE FROM 9N TO
10N BETWEEN 52W AND 54W...AND FROM 11N TO 12N BETWEEN 58W AND 
59W. ISOLATED MODERATE SHOWERS AND OTHER POSSIBLE THUNDERSTORMS 
ARE ELSEWHERE FROM 3N TO 6N BETWEEN 10W AND 30W...AND SOUTH OF
13N BETWEEN 40W AND 60W.

...DISCUSSION...

THE GULF OF MEXICO...
BROAD CYCLONIC FLOW AND DRY AIR IN SUBSIDENCE COVER THE AREA.
UPPER LEVEL ANTICYCLONIC FLOW IS MOVING FROM THE EASTERN PACIFIC 
OCEAN ACROSS MEXICO INTO THE GULF OF MEXICO SOUTH OF 25N.
A SHORTWAVE TROUGH THAT NOW IS MOVING THROUGH THE SOUTHEASTERN 
U.S.A. IS SUPPORTING A SECOND SHOT OF COLD AIR IN THE FORM
OF A COLD FRONT THAT PASSES THROUGH 32N76W TO 30N80W TO 
SOUTHEASTERN LOUISIANA AND EAST TEXAS. 

THE CARIBBEAN SEA...
THE STATIONARY FRONT PASSES THROUGH CUBA NEAR 20N77W TO 17N80W
TO THE SOUTHEASTERN COAST OF NICARAGUA NEAR 12N84W...AND IT 
CONTINUES INLAND TO NORTHWESTERN COSTA RICA. UPPER LEVEL 
ANTICYCLONIC FLOW MOVES FROM THE EASTERN PACIFIC OCEAN...
AND IT CROSSES OVER CENTRAL AMERICA...ON TOP OF THE STATIONARY
FRONT AND THROUGH THE NORTHWESTERN CORNER OF THE AREA. SCATTERED
MODERATE TO STRONG SHOWERS AND THUNDERSTORMS ARE FROM 10N TO 13N
BETWEEN 80W AND 83W. ISOLATED MODERATE SHOWERS AND POSSIBLE
THUNDERSTORMS ARE ELSEWHERE FROM 10N TO 19N BETWEEN 76W AND
84W...INCLUDING ON TOP OF JAMAICA. NORTHERLY WIND FLOW AT THE
SURFACE MOVES INTO THE NORTHWESTERN CORNER OF THE AREA TO THE 
NORTHWEST OF THE STATIONARY FRONT. SCATTERED MODERATE SHOWERS
TO ISOLATED STRONG THUNDERSTORMS ARE FROM 11N TO 13N BETWEEN
61W AND 64W...TO THE NORTH OF THE ITCZ AND NEAR A WEAK MIDDLE 
LEVEL TROUGH THAT EXTENDS FROM A CYCLONIC CIRCULATION CENTER 
NEAR 13N71W SOUTHEASTWARD.

THE ATLANTIC OCEAN...
THE STATIONARY FRONT PASSES THROUGH 32N62W TO 25N70W TO CUBA
NEAR 20N77W. SHOWERS ARE POSSIBLE WITHIN 60 TO 90 NM ON EITHER
SIDE OF THE LINE FROM 32N63W 25N70W 20N78W. A DEEP LAYER EASTERN 
ATLANTIC OCEAN TROUGH CONTINUES TO SUPPORT A SURFACE TROUGH THAT
IS ALONG 33N30W 27N31W 23N35W 20N40W. CYCLONIC FLOW ON WATER 
VAPOR IMAGERY COVERS THE AREA NORTH OF 20N BETWEEN 20W AND 50W.
SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS
ARE NORTH OF 22N BETWEEN 25W AND 41W. AN UPPER LEVEL RIDGE
IS ALONG 55W FROM 14N BEYOND 32N. A 1020 MB HIGH PRESSURE CENTER 
IS NEAR 28N58W. A 1007 MB LOW PRESSURE CENTER IS NEAR 32N41W. 
BROAD LOW PRESSURE IS NORTH OF 20N BETWEEN 30W AND 50W.
A SURFACE RIDGE IS TO THE EAST OF THE 33N30W 20N40W TROUGH
FROM THE CAPE VERDE ISLANDS TO 21N22W 26N21W BEYOND 32N21W.

$$
MT