TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT THU OCT 13 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS IN THE ERN TRPCL ATLC ALONG 11N27W TO 5N32W 
MOVING W 10-15 KT. THE WAVE REMAINS LOW AMPLITUDE...BUT DOES 
COINCIDE WITH A SLIGHT SURGE OF DEEP LAYER MOISTURE EVIDENT IN 
TOTAL PRECIPITABLE WATER. SCATTERED MODERATE/STRONG CONVECTION 
IS FROM 6N-11N BETWEEN 25W-32W.

TROPICAL WAVE IS IN THE CENTRAL TRPCL ATLC ALONG 13N43W TO 6N48W 
MOVING W NEAR 15 KT. THE WAVE IS EMBEDDED WITHIN A RIDGE OF 
ENHANCED DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER 
IMAGERY. THE WAVE ALSO IS WELL-DEFINED IN MODEL STREAMLINE 
ANALYSIS. CURRENTLY THE WAVE IS UNDER THE INFLUENCE OF AN UPPER 
LEVEL TROUGH WHICH IS SHEARING CONVECTION TO THE NE. CURRENTLY 
SCATTERED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF 
THE AXIS AS WELL AS NE OF THE AXIS FROM 14N-19N BETWEEN 38W-44W. 


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

THE MONSOON TROUGH EXTENDS JUST SLIGHTLY OFF THE AFRICAN COAST 
ALONG 16N16W TO 14N19W. THE ITCZ PICKS UP ON THE W SIDE OF THE 
ERN-MOST TROPICAL WAVE ALONG 7N34W 8N45W CONTINUING ON THE OTHER 
SIDE OF THE WRN-MOST TROPICAL WAVE ALONG 8N49W 7N60W. ALL DEEP 
CONVECTION IS DESCRIBED IN ASSOCIATION WITH THE TROPICAL WAVES. 
ALTHOUGH...SCATTERED MODERATE/STRONG CONVECTION IS NEAR THE END 
OF THE ITCZ INLAND OVER VENEZUELA.

...DISCUSSION...

THE GULF OF MEXICO...
MAINLY WLY-NWLY FLOW ALOFT COVERS THE GULF OF MEXICO BETWEEN AN 
UPPER LEVEL RIDGE TO THE S OVER THE NW CARIBBEAN AND AN UPPER 
LEVEL TROUGH TO THE N OVER THE ERN CONUS. THIS UPPER TROUGH 
SUPPORTS A COLD FRONT EXTENDING FROM NEAR MOBILE ALABAMA TO 
BROWNSVILLE TEXAS ALONG 30N88W TO 26N98W. MOSTLY DRY AIR ALOFT 
COVERS THE BASIN WHICH IS LIMITING MOST OF THE 
SHOWER/THUNDERSTORM ACTIVITY ALONG THE FRONTAL BOUNDARY. 
ISOLATED SHOWERS ARE NOTED ALONG THE AXIS WITH MORE SCATTERED 
ACTIVITY S OF BROWNSVILLE AND AHEAD OF THE FRONT OVER THE 
FLORIDA PANHANDLE AND GEORGIA. A SURFACE TROUGH IS AHEAD OF THE 
FRONT EXTENDING FROM NE FLORIDA NEAR 31N81W TO 25N86W. A FEW 
ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. THE SE GULF IS LADEN 
WITH DEEP LAYER MOISTURE ASSOCIATED WITH THE MONSOON TROUGH 
WHICH HAS BEEN SITUATED N OF ITS TYPICAL POSITION. IT CURRENTLY 
EXTENDS ACROSS SRN MEXICO AND NRN CENTRAL AMERICA INTO THE WRN 
CARIBBEAN. WIDESPREAD SHOWERS/THUNDERSTORMS ARE ACROSS THIS AREA 
INCLUDING THE YUCATAN PENINSULA...CUBA AND REACHING THE FLORIDA 
STRAITS. THIS LARGE AREA OF MOISTURE IS EXPECTED TO REMAIN 
MOSTLY STATIONARY AND GRADUALLY LIFT N AND COVER THE SRN GULF. 
THE COLD FRONT IS EXPECTED TO CONTINUE TO PUSH SE AS HIGH 
PRESSURE WILL BUILD OVER THE NW GULF. THIS WILL INCREASE THE 
PRESSURE GRADIENT AND WINDS OVER THE BASIN. 

THE CARIBBEAN SEA...
DEEP LAYER MOISTURE COVERS THE NW CARIBBEAN ASSOCIATED WITH THE 
MONSOON TROUGH THAT CONTINUES TO SIT N OF ITS USUAL LOCATION. IT 
CURRENTLY RUNS THROUGH SRN MEXICO ACROSS NRN GUATEMALA AND 
BELIZE TO A 1007 MB LOW NEAR 17N87W CONTINUING ESE TO NEAR 
14N73W. WIDESPREAD SHOWERS/THUNDERSTORMS ARE ACROSS THIS AREA 
FROM 16N-22N BETWEEN 81W-87W...AS WELL AS OVER LAND INCLUDING 
NRN NICARAGUA...HONDURAS...GUATEMALA...BELIZE...THE YUCATAN 
PENINSULA...CUBA...AND JAMAICA. MANY OF THESE AREAS HAVE ALREADY 
RECEIVED SIGNIFICANT RAINFALL OVER THE PAST COUPLE OF DAYS AND 
FLOODING IS POSSIBLE. A LARGE CLUSTER OF STRONG 
SHOWERS/THUNDERSTORMS IS ALSO OVER THE SW CARIBBEAN FROM 9N-13N 
BETWEEN 78W-82W...AS WELL AS ACROSS COSTA RICA AND PANAMA. 
ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM HONDURAS ACROSS WRN 
CUBA. TO THE E...A NARROW UPPER LEVEL TROUGH IS ALONG 75W. UPPER 
LEVEL DIFFLUENCE AROUND THE ERN SIDE OF THE TROUGH IS SUPPORTING 
A FEW CLUSTERS OF SHOWERS/THUNDERSTORMS OVER HISPANIOLA WITH 
SCATTERED SHOWERS BETWEEN 64W-75W. FAIR CONDITIONS ARE ACROSS 
THE FAR ERN CARIBBEAN INCLUDING THE LESSER ANTILLES DUE TO DRY 
AIR ALOFT SINKING INTO THE BASIN AROUND AN UPPER LEVEL RIDGE 
ALONG 66W. EXPECT MOIST CONDITIONS TO REMAIN ACROSS THE WRN 
CARIBBEAN BRINGING CONTINUED STRONG SHOWERS AND THUNDERSTORMS TO 
THAT AREA.

THE ATLANTIC OCEAN...

A BROAD UPPER LEVEL TROUGH OVER THE ERN CONUS EXTENDS OVER THE 
FAR WRN ATLC. AN UPPER LEVEL RIDGE IS TO THE E ALONG 66W. AT THE 
SURFACE...A 1007 MB LOW LIES UNDERNEATH THE AREA OF DIFFLUENCE 
ALOFT CENTERED NE OF THE BAHAMAS NEAR 27N73W. THE SWLY FLOW 
ALOFT IS SHEARING THE SHOWERS/THUNDERSTORMS AWAY FROM THE LOW 
CENTER FROM 24N-30N BETWEEN 66W-72W. A FEW SHOWERS/THUNDERSTORMS 
ARE ALSO N OF HISPANIOLA AND PUERTO RICO. THE LOW IS EXPECTED TO 
MOVE NNE AT AROUND 15 KTS OVER THE NEXT COUPLE OF DAYS. THE 
UPPER RIDGE SUPPORTS A SURFACE RIDGE AROUND A 1029 MB HIGH WELL 
N OF THE DISCUSSION AREA. A NARROW UPPER LEVEL TROUGH IS ALONG 
33N40W TO E OF THE WINDWARD ISLANDS NEAR 11N58W. THIS UPPER 
TROUGH SUPPORTS A STATIONARY FRONT THAT ENTERS THE AREA ALONG 
31N38W TO 29N46W. ISOLATED SHOWERS ARE ALONG THE BOUNDARY. A 
SURFACE TROUGH IS TO THE S ALONG 28N41W TO 21N47W. SCATTERED 
SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE AXIS. THE UPPER 
TROUGH IS ALSO SHEARING MOISTURE FROM THE ITCZ AND A TROPICAL 
WAVE TOWARDS THE NE WHICH IS SUPPORTING UPPER LEVEL CLOUDS AND 
POSSIBLE ISOLATED SHOWERS WITHIN A LARGE SWATH FROM NEAR 14N43W 
TO 32N30W. AN UPPER LEVEL RIDGE COVERS THE FAR ERN ATLC CENTERED 
NEAR 10N29W SUPPORTING A SURFACE RIDGE AROUND A 1021 MB HIGH 
NEAR 35N20W PROVIDING FAIR WEATHER ACROSS THIS PORTION OF THE 
BASIN.