[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091132
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST FRI DEC 09 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS A PORTION OF AFRICA WITH THE
ITCZ AXIS ENTERING THE E TROPICAL ATLC NEAR 8N12W CONTINUING
ALONG 8N15W 6N21W TO 6N41W. SCATTERED MODERATE/STRONG CONVECTION
IS WITHIN 150 NM N OF THE ITCZ AXIS BETWEEN 21W-42W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120/150 NM S OF
THE ITCZ AXIS BETWEEN 16W-36W.

...DISCUSSION...

GULF OF MEXICO...
ZONAL SW FLOW ALOFT DOMINATES THE GULF WITH STRONG SUBSIDENCE
AND DRY STABLE AIR ALOFT COVERING THE GULF SE OF A LINE FROM
CEDAR KEY FLORIDA TO TAMPICO MEXICO. A SURFACE RIDGE COVERS THE
GULF ANCHORED BY A 1026 MB HIGH OVER CENTRAL MISSISSIPPI AND A
1029 MB HIGH OVER E MARYLAND. IN SPITE OF THE DRY AIR ALOFT...
MOSTLY OVERCAST LOW STRATOCUMULUS CLOUDS COVER THE GULF WITH
POSSIBLE ISOLATED SHOWERS. SURFACE RIDGE WILL BUILD OVER THE US
CONUS THROUGH THE WEEKEND RESULTING IN INCREASING WINDS AND
SEAS. THE RIDGE WILL THEN WEAKEN MON AND TUE ALLOWING FOR WINDS
TO DIMINISH AND SEAS TO SUBSIDE.

CARIBBEAN SEA...
A DISSIPATING STATIONARY FRONT ENTERS THE W CARIBBEAN FROM THE W
ATLC ACROSS CUBA NEAR CIEGO DE AVILA ALONG 19N84W TO THE COAST
OF HONDURAS NEAR 16N86W. SCATTERED SHOWERS ARE WITHIN 120 NM E
OF THE FRONT WITH ISOLATED SHOWERS S OF 18N W OF THE FRONT TO
INLAND OVER CENTRAL AMERICA AND THE YUCATAN PENINSULA. A VERY
BROAD LOW AMPLITUDE UPPER RIDGE COVERS CARIBBEAN INTO THE
TROPICAL ATLC GIVING THE CARIBBEAN SW TO W FLOW ALOFT. STRONG
SUBSIDENCE AND DRY STABLE AIR COVERS THE CARIBBEAN N OF LINE
FROM THE N LEEWARD ISLANDS NEAR 17N63W ALONG 16N77W TO NICARAGUA
NEAR 13N83W. HOWEVER...EASTERLY SURFACE FLOW IS USHERING IN LOW
LEVEL MOISTURE TO GENERATE CLUSTERS OF ISOLATED SHOWERS DOTTING
THE CENTRAL CARIBBEAN S OF 19N BETWEEN 71W-84W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM ALONG THE COAST
OF VENEZUELA AND COLOMBIA W OF 66W TO THE COAST OF PANAMA. BAND
OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
CONTINUES TO STREAM EASTWARD WITHIN 90 NM OF LINE FROM 14N69W
ACROSS THE LESSER ANTILLES NEAR 15N61W. FRONT WILL DISSIPATE
LATER TODAY. THE SURFACE TROUGH E OF THE LESSER ANTILLES WILL
LIFT N SUN THROUGH EARLY NEXT WEEK.

ATLANTIC OCEAN...
A STATIONARY FRONT ENTERS THE W ATLC NEAR 32N67W ALONG 27N74W TO
ACROSS THE BAHAMA ISLANDS NEAR 24N76W WHERE IT BEGINS TO
DISSIPATE AS IT CROSSES CUBA NEAR CIEGO DE AVILA INTO THE W
CARIBBEAN. BROKEN/OVERCAST LOW/MID CLOUDS WITH ISOLATED SHOWERS
ARE WITHIN 200 NM W OF THE FRONT N OF THE BAHAMA ISLANDS. AN E/W
ELONGATED UPPER LOW IS IN THE SW ATLC ROUGHLY CENTERED NEAR
22N64W COVERING THE AREA FROM 18N-24N BETWEEN 56W-71W GENERATING
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN
60/75 NM OF LINE FROM 20N66W TO 23N75W. A SECOND MORE
SYMMETRICAL UPPER LOW IS IN THE CENTRAL ATLC NEAR 26N46W
SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 29N45W THROUGH A
1012 MB LOW NEAR 24N43W CONTINUING ALONG 20N48W INTO THE TROPICS
ALONG 19N56W TO GUADELOUPE IN THE LEEWARD ISLANDS. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 18N-21N BETWEEN 59W-64W.
AN UPPER TROUGH IS IN THE E ATLC N OF 26N E OF 30W. A VERY BROAD
LOW AMPLITUDE UPPER RIDGE COVERS THE TROPICS S OF 20N BETWEEN
25W-80W AND FROM 20N-30N BETWEEN THE CENTRAL ATLC UPPER LOW AND
E ATLC UPPER TROUGH GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 20N-26N BETWEEN 30W-43W AND FROM 26N-29N
BETWEEN 36W AND THE SURFACE TROUGH. A SURFACE RIDGE DOMINATES
THE E ATLC ANCHORED BY A SERIES OF HIGHS N OF THE DISCUSSION
AREA. THE STATIONARY FRONT WILL LIFT NW AS A WARM FRONT TODAY. A
COLD FRONT WILL MOVE OFF THE GEORGIA COAST SAT OVERTAKING THE
CURRENT FRONT THEN WILL STALL FROM 31N72W TO CENTRAL FLORIDA BY
LATE SAT NIGHT. A SURFACE TROUGH WILL MOVE W FROM THE CENTRAL
ATLC TO BETWEEN PUERTO RICO AND BERMUDA LATE SUN AND MON.  A
REINFORCING FRONT WILL MERGE WITH THIS OLD FRONTAL BOUNDARY MON
AND TUE THEN WILL MERGE WITH THE TROUGH AND WILL SHIFT E BY LATE
TUE.

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

$$
PAW






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