000
AXNT20 KNHC 200520
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 AM EDT THU OCT 20 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL 
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0445 UTC.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 17N36W 13N41W 7N46W.
SCATTERED MODERATE TO ISOLATED STRONG RAINSHOWERS ARE FROM 14N
TO 20N BETWEEN 30W AND 40W. SCATTERED STRONG RAINSHOWERS ARE
FROM 11N TO 13N BETWEEN 38W AND 43W. NUMEROUS STRONG RAINSHOWERS 
ARE FROM 8N TO 11N BETWEEN 45W AND 48W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 54W/55W FROM 6N TO 14N.
ISOLATED MODERATE CONVECTIVE PRECIPITATION THAT IS SURROUNDED BY
BROKEN TO OVERCAST MULTILAYERED CLOUDS IS IN THE WATERS THAT ARE
TO THE SOUTH OF 13N BETWEEN 50W AND 60W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH HAS BEEN DISRUPTED IN THE ATLANTIC OCEAN DUE 
TO THE LARGE CYCLONIC WIND FIELD THAT IS ASSOCIATED WITH THE 
TROPICAL WAVES. THE MONSOON TROUGH REACHES COASTAL SENEGAL NEAR
15N17W. STRONG RAINSHOWERS ARE IN THE COASTAL WATERS OF SIERRA 
LEONE. WIDELY SCATTERED TO SCATTERED STRONG RAINSHOWERS ARE FROM
4N TO 8N BETWEEN 17W AND 25W. SCATTERED MODERATE TO ISOLATED 
STRONG CONVECTIVE PRECIPITATION IS ELSEWHERE FROM 9N TO 13N
BETWEEN 25W AND 30W.
 
...DISCUSSION...

THE GULF OF MEXICO AND THE ATLANTIC OCEAN TO THE WEST OF 70W...
INCLUDING THE NORTHWESTERN CARIBBEAN SEA...

A DEEP LAYER UPPER LEVEL TROUGH IS SWEEPING THROUGH THE EASTERN 
HALF OF THE CONTINENTAL U.S.A. AND STRAIGHT INTO THE GULF OF 
MEXICO. THE TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH
32N77W IN THE ATLANTIC OCEAN...THROUGH THE WATERS THAT ARE 
BETWEEN THE NORTHERN BAHAMAS AND FLORIDA...TO CUBA ALONG 81W...
INTO THE NORTHWESTERN CARIBBEAN SEA...THROUGH NORTHERN BELIZE
AND NORTHERN GUATEMALA...TO SOUTHERN MEXICO BETWEEN THE ISTHMUS
OF TEHUANTEPEC AND SOUTHWESTERN GUATEMALA. A SURFACE TROUGH IS
IN THE CARIBBEAN SEA FROM CUBA NEAR 22N/23N ALONG 80W TO 14N81W.
NUMEROUS STRONG RAINSHOWERS ARE FROM 14N TO 18N BETWEEN 79W AND
83W NEAR THE COASTS OF CENTRAL AMERICAN COUNTRIES FROM NICARAGUA
TO BELIZE AND THE SOUTHEASTERN YUCATAN PENINSULA OF MEXICO.
THE 24-HOUR RAINFALL TOTAL FOR THE PERIOD ENDING 20/0000 UTC
FOR HAVANA CUBA WAS 1.24 INCHES AND THE TOTAL FOR TEGUCIGALPA WAS
0.51 INCHES. OTHER RAINFALL IS POSSIBLE OVER THE WATERS THAT ARE 
TO THE WEST OF 83W. ISOLATED MODERATE TO STRONG RAINSHOWERS ARE 
WITHIN 15 TO 30 NM ON EITHER SIDE OF 23N79W OFF THE COAST OF CUBA
TO ANDROS ISLAND AND ABACO ISLAND IN THE BAHAMAS...TO 28N75W...
AND 32N74W. COMPARATIVELY DRIER AIR IN WATER VAPOR IMAGERY IS TO 
THE NORTHWEST OF THE LINE THAT PASSES THROUGH 32N77W IN THE 
ATLANTIC OCEAN...TO FLORIDA TO THE NORTH OF 27N...TO THE NORTH 
CENTRAL COAST OF THE YUCATAN PENINSULA. 

THE REST OF THE CARIBBEAN SEA...
BROAD UPPER LEVEL NORTHEASTERLY-TO-EASTERLY WIND FLOW... THAT IS 
ASSOCIATED WITH ANTICYCLONIC FLOW...COVERS THE AREA. UPPER LEVEL 
SOUTHERLY WIND FLOW IS LIMITED TO THE SOUTHEASTERN CORNER OF THE 
CARIBBEAN SEA. STRONG RAINSHOWERS ARE WITHIN A 30 NM RADIUS OF 
12N76W. ISOLATED MODERATE RAINSHOWERS ARE ELSEWHERE TO THE SOUTH 
OF 13N TO THE WEST OF 72W. ALL THIS PRECIPITATION IS IN THE AREA 
OF A MIDDLE LEVEL TO UPPER LEVEL TROUGH. RAINSHOWERS ARE
POSSIBLE ELSEWHERE TO THE NORTH OF 13N TO THE EAST OF 78W
IN CLUSTERS OF LOW CLOUDS.

THE REST OF THE ATLANTIC OCEAN...
AN UPPER LEVEL CENTRAL ATLANTIC OCEAN TROUGH PASSES THROUGH 
32N45W TO A CYCLONIC CIRCULATION CENTER THAT IS NEAR 26N46W...
TO 19N52W AND 16N56W. AN UPPER LEVEL CYCLONIC CIRCULATION CENTER 
THAT IS NEAR 20N43W APPEARS TO BE SHRINKING IN SIZE...AS IT IS
ABOUT 400 NM TO THE SOUTH-SOUTHEAST OF THE 26N46W CYCLONIC
CENTER. WIDELY SCATTERED MODERATE CONVECTIVE PRECIPITATION
COVERS THE WATERS FROM 25N TO 32N BETWEEN 40W AND 52W. ISOLATED
MODERATE RAINFALL IS FROM 18N TO 22N BETWEEN 48W AND 54W.
BROAD UPPER LEVEL CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN 
TO THE NORTH AND NORTHEAST OF THE LINE THAT PASSES THROUGH 32N41W
27N30W 26N20W...BEYOND AFRICA ALONG 26N. RAINSHOWERS ARE 
POSSIBLE TO THE NORTH OF 29N BETWEEN AFRICA AND 34W. A SURFACE 
RIDGE IS ALONG 23N68W 28N63W BEYOND 32N59W. 

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
MT