[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EDT THU NOV 10 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM SEAN IS CENTERED NEAR 30.5N 70.0W AT 10/1800 UTC
OR ABOUT 290 NM W-SW OF BERMUDA MOVING NE AT 8 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 983 MB. MAXIMUM SUSTAINED WIND SPEED
IS 55 KT WITH GUSTS TO 65 KT. SEE LATEST NHC INTERMEDIATE PUBLIC
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC FOR MORE DETAILS. SMALL UPPER RIDGE ASSOCIATED WITH SEAN IS
WITHIN 120/150 NM OF 30N70W. SCATTERED MODERATE CONVECTION IS
FROM 29N-31N BETWEEN 69W-72W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 12N16W TO 9N19W. THE ITCZ AXIS EXTENDS FROM 9N19W
ALONG 6N32W TO 7N43W. A SURFACE TROUGH EXTENDS FROM 11N43W TO
4N45W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE FROM 3N-10N BETWEEN 15W-34W...FROM 4N-12N BETWEEN 34W-47W
AND FROM 9N-13N BETWEEN 48W-54W.

...DISCUSSION...

GULF OF MEXICO...
A RE-ENFORCING UPPER TROUGH IS PUSHING ACROSS THE MISSISSIPPI
VALLEY AND IS ABSORBING THE SHORTWAVE UPPER TROUGH MOVING
ACROSS THE GREAT LAKES REGION THAT IS SUPPORTING A COLD FRONT
THAT ENTERS THE GULF AT 10/1500 UTC ACROSS E GEORGIA AND FLORIDA
NEAR 30N83W EXTENDING ALONG 25N87W TO 20N93W THEN S TO OVER S
MEXICO NEAR 18N93W. THE REMNANTS OF A STATIONARY BOUNDARY REMAIN
OVER MEXICO W OF THE ISTHMUS OF TEHUANTEPEC. MOST OF THE ENERGY
ASSOCIATED WITH THE UPPER TROUGH IS LOCATED WELL N OF THE GULF
CONSEQUENTLY THE FRONT LACKS ANY SIGNIFICANT DEEP CONVECTION.
HOWEVER...SCATTERED SHOWERS ARE W OF THE FRONT AND E OF A LINE
FROM NEAR LAKE CHARLES LOUISIANA TO JUST N OF BROWNSVILLE TEXAS.
SKIES ARE CLEARING W OF THAT LINE. A SURFACE RIDGE IS BUILDING W
OF THE FRONT ANCHORED BY A 1035 MB HIGH OVER W TEXAS. THIS IS
LEAVING THE SE GULF UNDER MOSTLY CLEAR SKIES FOR THE MOMENT.
CONDITIONS WILL BE CHANGING LATER THIS AFTERNOON INTO THE
EVENING AS THE FRONT APPROACHES. THE COLD FRONT WILL REACH FROM
SW FLORIDA TO THE NE YUCATAN PENINSULA TONIGHT MOVING INTO THE
CARIBBEAN AND W ATLC BY FRI MORNING. SURFACE RIDGE WILL CONTINUE
TO BUILD BEHIND THE FRONT WITH WINDS AND SEAS CONTINUING TO
DIMINISH AND SUBSIDE THROUGH MON.

CARIBBEAN SEA...
AN UPPER RIDGE COVERS THE CARIBBEAN W OF 75W ANCHORED OVER
NICARAGUA COAST NEAR 13N84W WITH WATER VAPOR IMAGERY INDICATING
DRY STABLE AIR AND STRONG SUBSIDENCE OVER THE BASIN N OF 13N W
OF 70W. A BROAD UPPER TROUGH OVER THE W ATLC EXTENDS S OVER THE
REMAINDER OF THE CARIBBEAN E OF 75W WITH A SURFACE TROUGH
EXTENDING FROM THE E TIP OF THE DOMINICAN REPUBLIC ALONG 16N70W
TO 13N71W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN
120 NM E OF THE TROUGH N OF 16N INCLUDING PUERTO RICO AND FROM
12N-17N BETWEEN 61W-65W INCLUDING THE LESSER ANTILLES. THE
MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA
NEAR 10N74W ALONG 11N77W INTO THE E PACIFIC REGION ACROSS
PANAMA/COSTA RICA NEAR 9N83W WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF 13N BETWEEN 75W-82W. THIS IS LEAVING THE
REMAINDER OF THE CARIBBEAN WITH FAIR CONDITIONS THIS AFTERNOON.
THE COLD FRONT WILL MOVE INTO THE NW CARIBBEAN FRI MORNING
STALLING AND WEAKENING FROM E CUBA TO THE GULF OF HONDURAS SAT
MORNING.

ATLANTIC OCEAN...
THE PRIMARY CONCERN FOR BERMUDA IS TROPICAL STORM SEAN THAT IS
FORECASTED TO MOVE N OF THE AREA THIS EVENING WHILE
STRENGTHENING THEN PASSING NW OF THE ISLANDS BY FRI MORNING. AN
UPPER RIDGE AXIS EXTENDS FROM THE CARIBBEAN ACROSS CUBA NEAR
22N79W TO BEYOND 32N76W WITH DRY STABLE AIR WITHIN 200 NM EITHER
SIDE OF THE RIDGE AXIS. THIS DRY AIR IS BEGINNING TO BE DRAWN
INTO TROPICAL STORM SEAN. A BROAD UPPER TROUGH COVERS MOST OF
THE W ATLC INTO THE CENTRAL ATLC BETWEEN 58W-73W AND S TO OVER
THE E CARIBBEAN. TROPICAL STORM SEAN IS EMBEDDED WITHIN THIS
BROAD FEATURE. CLUSTERS OF SCATTERED SHOWERS/THUNDERSTORMS ARE
BEING DRAWN E OF SEAN FROM 18N-31N BETWEEN 55W-68W WITH THE
HIGHEST CONCENTRATION OF THUNDERSTORMS FROM 18N-20N BETWEEN
64W-67W INCLUDING THE PUERTO RICO...THE VIRGIN ISLANDS...AND THE
MONA PASSAGE. A VERY BROAD UPPER TROUGH COVERS THE E ATLC INTO
THE CENTRAL ATLC N OF 32N BUT IS EXTENDING A REMNANT COLD FRONT
FROM A WEAK 1016 MB LOW OVER MOROCCO NEAR 31N8W TO THE CANARY
ISLANDS NEAR 28N13W WHERE IT CONTINUES AS A STATIONARY FRONT
ALONG 27N27W 26N40W TO 28N53W WITH SCATTERED SHOWERS POSSIBLE
WITHIN 120 NM EITHER SIDE OF THE FRONT. AN UPPER LOW IS IN THE
TROPICS NEAR 17N38W WHICH IS AMPLIFYING THE UPPER RIDGE TO THE E
DRAWING TROPICAL MOISTURE N FROM THE ITCZ WITH SCATTERED SHOWERS
FROM 12N-20N BETWEEN 31W-37W. THE GULF OF MEXICO COLD FRONT WILL
MOVE INTO THE NW PORTION TONIGHT QUICKLY REACHING FROM 31N72W TO
THE STRAITS OF FLORIDA FRI MORNING THEN INTO THE CENTRAL ATLC
SAT WHERE IT WILL DISSIPATE. SURFACE RIDGE WILL BUILD BEHIND THE
FRONT THIS WEEKEND INTO EARLY NEXT WEEK.

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

$$
PAW





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