[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 12 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 14N20W TO 8N24W
MOVING W NEAR 10 KT. THE WAVE REMAINS LOW AMPLITUDE...BUT DOES
COINCIDE WITH A SLIGHT SURGE OF DEEP LAYER MOISTURE EVIDENT IN
TOTAL PRECIPITABLE WATER. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 5N-10N BETWEEN 20W-27W.


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

ONLY A SMALL PORTION OF THE MONSOON TROUGH EXISTS W OF THE
TROPICAL WAVE AXIS ALONG 7N25W 8N32W. THE ITCZ CONTINUES FROM
8N32W ALONG 8N40W 5N52W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 60 NM S...AND 280 NM N OF THE AXIS BETWEEN
27W-48W. SIMILAR ACTIVITY IS ALSO FROM 2N-10N BETWEEN 51W-59W.

...DISCUSSION...

THE GULF OF MEXICO...

MAINLY WLY FLOW ALOFT COVERS THE GULF OF MEXICO BETWEEN AN UPPER
LEVEL RIDGE TO THE S CENTERED OVER THE YUCATAN PENINSULA AND AN
UPPER LEVEL TROUGH TO THE N OVER THE ERN CONUS.  MOSTLY DRY AIR
ALOFT COVERS THE NW AND SE PORTIONS MAINTAINING FAIR CONDITIONS
WITH A SWATCH OF MOISTURE EXTENDING FROM THE SW TO NE BEING
DRAWN FROM THE MOISTURE ASSOCIATED WITH WHAT IS NOW T.D. JOVA
WHICH IS INLAND OVER SW MEXICO. THIS UPPER LEVEL MOISTURE IS
SUPPORTING HIGH CLOUDS. A SURFACE TROUGH ALSO EXTENDS SW TO NE
ACROSS THE BASIN FROM A WEAK 1009 MB SURFACE LOW NEAR 24N93W TO
THE BIG BEND OF FLORIDA TO NEAR 31N83W. POSSIBLE ISOLATED
SHOWERS ARE ALONG THE TROUGH AXIS. A FEW STRONGER STORMS ARE
ALSO NOTED NEAR LAKE OKEECHOBEE FLORIDA. THE SURFACE LOW IS
EXPECTED TO CONTINUE TO WEAKEN AS A WEAK FRONT ENTERS THE NW
GULF THURSDAY.

THE CARIBBEAN SEA...
DRY AIR ALOFT IS BEING WRAPPED AROUND THE ERN SIDE OF AN UPPER
LEVEL RIDGE OVER THE YUCATAN PENINSULA WHICH IS HELPING MAINTAIN
FAIR CONDITIONS ACROSS THE FAR NW CARIBBEAN. HOWEVER...A NARROW
UPPER LEVEL TROUGH OVER THE BAHAMAS...ERN CUBA...AND JAMAICA IS
PLACING DIFFLUENT FLOW OVER THE CENTRAL CARIBBEAN. THIS IS
PRODUCING ISOLATED SHOWERS/THUNDERSTORMS N OF 14N BETWEEN
69W-75W WITH SIMILAR ACTIVITY ALSO OVER JAMAICA AND PUERTO RICO.
THE MONSOON TROUGH REMAINS N OF ITS USUAL LOCATION AND CURRENTLY
EXTENDS JUST E OF T.D. TWELVE-E ACROSS SE
MEXICO...GUATEMALA...NRN HONDURAS ALONG 16N AND CONTINUES SE TO
NRN COLOMBIA ALONG 15N83W TO 11N75W. STRONG
SHOWERS/THUNDERSTORMS ARE S OF THE AXIS CONCENTRATED OVER
HONDURAS...NRN NICARAGUA...COSTA RICA...PANAMA...AND OVER THE SW
CARIBBEAN FROM 9N-13N BETWEEN 78W-83W. ACROSS THE ERN
CARIBBEAN...A NARROW UPPER LEVEL RIDGE IS ALONG 67W WHICH IS
DRAWING DRY AIR ALOFT OVER THIS PORTION OF THE BASIN MAINTAINING
MOSTLY FAIR WEATHER BESIDES SOME ISOLATED SHOWERS ACROSS THE
WINDWARD ISLANDS ASSOCIATED WITH AN AREA OF LOW-LEVEL MOISTURE.

THE ATLANTIC OCEAN...

A NARROW UPPER LEVEL TROUGH EXTENDS FROM THE CENTRAL BAHAMAS SWD
ALONG 76W PLACING DIFFLUENT FLOW ALOFT ACROSS HISPANIOLA AND THE
SE BAHAMAS. THE UPPER TROUGH ALSO SUPPORTS A WEAK 1009 MB LOW
NEAR 23N75W WITH A SURFACE TROUGH EXTENDING THROUGH IT ALONG
26N76W TO 22N73W. THE COMBINATION OF SURFACE CONVERGENCE AND
DIFFLUENCE ALOFT IS SUPPORTING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 20N-25N BETWEEN 70W-74W. AN UPPER LEVEL RIDGE
IS TO THE E ALONG 67W SUPPORTING SURFACE RIDGING EXTENDING FROM
A 1028 MB HIGH CENTERED S OF NEWFOUNDLAND. A LONGWAVE UPPER
TROUGH EXTENDS ALONG 39N40W TO E OF THE LESSER ANTILLES NEAR
11N59W. A SHEARLINE...REMNANTS OF AN OLD FRONTAL BOUNDARY
EXTENDS ALONG 30N34W 22N48W 25N63W. ISOLATED SHOWERS ARE WITHIN
90 NM EITHER SIDE OF THE AXIS. AN UPPER LEVEL RIDGE COVERS THE
FAR ERN ATLC ALONG 13N33W TO 36N24W SUPPORTING SURFACE RIDGING
AROUND A 1026 MB HIGH NEAR 47N9W.

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

$$
WALTON




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