[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EDT FRI NOV 11 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.

...SPECIAL FEATURES...

TROPICAL STORM SEAN IS CENTERED NEAR 35.5N 61.3W AT 11/2100 UTC
OR ABOUT 260 NM NE OF BERMUDA MOVING NE AT 26 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 991 MB. MAXIMUM SUSTAINED WIND SPEED
IS 45 KT WITH GUSTS TO 55 KT. PLEASE SEE LATEST FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS. SEAN IS QUICKLY LOSING TROPICAL CHARACTERISTICS WITH
THE CONVECTION REMOVED TO THE NE OF THE LOW CENTER. SCATTERED
MODERATE CONVECTION IS WITHIN 60 NM OF LINE FROM 34N58W TO
37N61W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 12N16W TO 8N20W. THE ITCZ AXIS EXTENDS FROM 8N20W
ALONG 6N25W 7N31W TO 6N50W. CLUSTERS OF SCATTERED MODERATE/
STRONG CONVECTION ARE FROM 3N-10N BETWEEN 17W-40W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER TROUGH COVERS THE E CONUS INTO THE W ATLC AND S
OVER THE GULF WITH THE AXIS EXTENDING FROM NEAR MOBILE ALABAMA
TO VERACRUZ MEXICO SUPPORTING A STRONG COLD FRONT THAT HAS JUST
EXITED THE GULF. A SURFACE RIDGE HAS BUILT IN BEHIND THE FRONT
ANCHORED BY A 1027 MB HIGH ALONG THE COAST OF LOUISIANA NEAR
30N92W. THE STRONG NORTHERLY SURFACE WINDS ARE BANKING LOW
CLOUDS WITH POSSIBLE ISOLATED SHOWERS ALONG THE E SLOPES OF THE
SIERRA MADRE MOUNTAINS OF MEXICO AND WITHIN 90/120 NM ALONG THE
COAST S OF TAMPICO AND W OF CIUDAD DEL CARMEN. COLD AIR
STRATOCUMULUS CLOUDS COVER MOST OF THE GULF WITH THE EXCEPTION
OF THE NE GULF WHERE CLEAR SKIES PREVAIL. SURFACE RIDGE WILL
MOVE E ALONG THE N GULF COAST ALLOWING FOR SOUTHERLY RETURN FLOW
TO BECOME ESTABLISHED OVER THE W GULF THROUGH TUE AHEAD OF THE
NEXT COLD FRONT FORECAST TO ENTER THE GULF TUE EVENING.

CARIBBEAN SEA...
THE UPPER TROUGH OVER THE GULF OF MEXICO IS APPROACHING THE NW
CARIBBEAN. HOWEVER...THE ASSOCIATED FRONT HAS ALREADY ENTERED
THE AREA EXTENDING FROM THE W ATLC ACROSS W CUBA AND THE ISLE OF
YOUTH TO THE YUCATAN PENINSULA NEAR 20N87W TO INLAND OVER S
MEXICO. WATER VAPOR IMAGERY INDICATES DRY STABLE AIR AND STRONG
SUBSIDENCE OVER THE NW CARIBBEAN...THUS NO SHOWER ACTIVITY IS
ASSOCIATED WITH THE FRONT. A BROAD UPPER RIDGE COVERS THE
CARIBBEAN W OF 70W ANCHORED IN THE CENTRAL CARIBBEAN NEAR 15N75W
PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75/90 NM OF LINE FROM
17N72W TO 14N76W EXPANDING TO WITHIN 120 NM TO NEAR 11N81W. THE
BROAD UPPER TROUGH OVER THE CENTRAL ATLC EXTENDS S OVER THE
REMAINDER OF THE CARIBBEAN E OF 70W WITH A SURFACE TROUGH
EXTENDING FROM THE DOMINICAN REPUBLIC NEAR 19N69W TO INLAND OVER
SOUTH AMERICA NEAR 12N72W AND SCATTERED SHOWERS/THUNDERSTORMS
INLAND AND WITHIN 45 NM ALONG THE COAST OF COLOMBIA BETWEEN
72W-75W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE INLAND AND
WITHIN 60 NM ALONG THE COAST OF PUERTO RICO. THIS IS LEAVING THE
REMAINDER OF THE CARIBBEAN WITH FAIR CONDITIONS THIS EVENING.
COLD FRONT WILL REACH FROM E CUBA TO NE NICARAGUA LATE TONIGHT
THEN DISSIPATE SAT.

ATLANTIC OCEAN...
BROAD UPPER TROUGH COVERS THE E CONUS INTO THE W ATLC W OF 75W
SUPPORTING A STRONG COLD FRONT THAT EXTENDS INTO THE W ATLC
THROUGH 32N68W ACROSS THE N BAHAMA ISLANDS NEAR 25N77W TO OVER
CUBA INTO THE NW CARIBBEAN NEAR 23N80W. WATER VAPOR IMAGERY
INDICATES DRY STABLE AIR AND STRONG SUBSIDENCE W AND E OF THE
FRONT LIMITING SHOWER ACTIVITY WITH A NARROW SWATH OF MOISTURE
ALONG THE FRONT. A BROAD UPPER RIDGE AXIS EXTENDS FROM THE
CARIBBEAN ACROSS HAITI NEAR 20N71W TO BEYOND 32N62W WITH DRY
STABLE AIR W OF 60W. A NARROW UPPER TROUGH IS IN THE CENTRAL
ATLC WITH THE AXIS EXTENDING THROUGH 32N55W ALONG 24N58W INTO
THE E CARIBBEAN OVER THE LEEWARD ISLANDS NEAR 17N62W WITH
POSSIBLE ISOLATED SHOWERS WITHIN 200/250 NM OF THE TROUGH AXIS.
A SURFACE RIDGE IS BUILDING S OVER THE CENTRAL ATLC N OF 25N
BETWEEN 30W-55W. AN UPPER TROUGH COVERS THE E ATLC N OF 24N E OF
40W WITH A SURFACE TROUGH EXTENDING THROUGH 32N22W TO 24N28W. AN
AMPLIFIED UPPER RIDGE REMAINS IN THE TROPICS S OF 25N E OF 35W
TO THE COAST OF W AFRICA DRAWING TROPICAL MOISTURE N FROM THE
ITCZ WITH ISOLATED SHOWERS FROM 10N-26N BETWEEN 20W-35W. W ATLC
COLD FRONT WILL REACH FROM THE CENTRAL ATLC TO N HISPANIOLA SAT
NIGHT DISSIPATING OVER THE CENTRAL ATLC MON. SURFACE RIDGE WILL
BUILD BEHIND FRONT THROUGH TUE. A SECOND COLD FRONT WILL ENTER
NW ATLC EARLY WED.

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

$$
PAW








This weather bulletin was brought to you by:
www.nashvilleweather.net