[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 090548
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 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 0000 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 8N13W CONTINUING
ALONG 5N22W 7N37W TO 4N47W. CLUSTERS OF SCATTERED MODERATE/
STRONG CONVECTION ARE WITHIN 150/180 NM EITHER SIDE OF THE ITCZ
AXIS BETWEEN 14W-43W.

...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 THE
BIG BEND AREA OF FLORIDA TO TAMPICO MEXICO. A SURFACE RIDGE
COVERS THE GULF ANCHORED BY A 1026 MB HIGH OVER CENTRAL
TENNESSEE AND A 1028 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 FRI THROUGH SUN ALLOWING SOME INCREASE
IN WINDS AND SEAS ACROSS THE REGION.

CARIBBEAN SEA...
A DISSIPATING STATIONARY FRONT ENTERS THE W CARIBBEAN FROM THE W
ATLC ACROSS CUBA NEAR COLON INTO THE GULF OF HONDURAS AND THE
COAST NEAR GUATEMALA/HONDURAS. ISOLATED SHOWERS ARE W OF THE
FRONT TO 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 15N75W TO NICARAGUA NEAR 13N84W. HOWEVER...
EASTERLY SURFACE FLOW IS USHERING IN LOW LEVEL MOISTURE TO
GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S
OF 19N BETWEEN 73W-85W. BAND OF SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS CONTINUE TO STREAM EASTWARD WITHIN 90/120
NM OF LINE FROM 14N70W ACROSS THE LESSER ANTILLES NEAR 15N61W.
THE FRONT WILL DISSIPATE FROM W CUBA TO THE GULF OF HONDURAS
OVERNIGHT. THE SURFACE TROUGH E OF THE LESSER ANTILLES WILL
PIVOT WEST AND DISSIPATE THROUGH EARLY FRI. A SECOND TROUGH WILL
MOVE W THROUGH THE LEEWARD ISLANDS SUN AND MON.

ATLANTIC OCEAN...
A COLD FRONT EXTENDS ACROSS THE NW ATLC TO 31N69W WHERE IT
BECOMES STATIONARY ACROSS THE DISCUSSION AREA ALONG 26N75W TO
OVER THE N BAHAMA ISLANDS WHERE IT BEGINS TO DISSIPATE AS IT
CROSSED CUBA NEAR COLON INTO THE W CARIBBEAN. BROKEN/OVERCAST
LOW/MID CLOUDS WITH ISOLATED SHOWERS ARE W OF THE FRONT. AN E/W
ELONGATED UPPER LOW IS IN THE SW ATLC ROUGHLY CENTERED NEAR
22N64W COVERING THE AREA FROM 18N-15N BETWEEN 53W-75W AND
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 19N-22N
BETWEEN 57W-64W. A SECOND MORE SYMMETRICAL UPPER LOW IS IN THE
CENTRAL ATLC NEAR 26N46W SUPPORTING A SURFACE TROUGH THAT
EXTENDS FROM 32N45W ALONG 28N42W 22N45W INTO THE TROPICS NEAR
20N52W 17N58W TO E OF THE LESSER ANTILLES NEAR 15N60W. AN UPPER
TROUGH IS IN THE E ATLC N OF 27N E OF 30W. A VERY BROAD LOW
AMPLITUDE UPPER RIDGE COVERS THE TROPICS S OF 20N BETWEEN
30W-80W AND FROM 20N-25N BETWEEN THE CENTRAL ATLC UPPER LOW AND
E ATLC UPPER TROUGH GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 200 NM E OF THE CENTRAL ATLC SURFACE TROUGH
AND FROM 22N-27N BETWEEN 30W-38W. A SURFACE RIDGE DOMINATES THE
E ATLC ANCHORED BY A SERIES OF HIGHS N OF THE DISCUSSION AREA.
THE STATIONARY FRONT WILL WEAKEN AND START TO SHIFT W FRI
STALLING FROM 31N75W TO 23N81W BY LATE FRI. A COLD FRONT MOVING
OFF THE GEORGIA COAST SAT WILL OVERTAKE THE CURRENT FRONT THEN
WILL STALL FROM 31N72W TO CENTRAL FLORIDA BY LATE SAT. A SURFACE
TROUGH WILL MOVE W FROM THE CENTRAL ATLC TO BETWEEN PUERTO RICO
AND BERMUDA LATE SUN AND MON.

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

$$
PAW




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