[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261115
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON DEC 26 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
1100 UTC.

...ITCZ/MONSOON TROUGH...

MOST OF THE MONSOON TROUGH REMAINS INLAND OVER AFRICA. A SMALL
SECTION OF IT ENTERS THE ATLC THROUGH THE COAST OF SIERRA LEONE
ALONG 8N13W AND QUICKLY ENDS AT 7N17W. THE ITCZ AXIS EXTENDS WSW
FROM THIS POINT ALONG 3N30W TO 2N43W. SCATTERED WEAK TO MODERATE
CONVECTION IS WITHIN 70-100 NM ON EITHER SIDE OF THE ITCZ AXIS
BETWEEN 25W-37W.

...DISCUSSION...

GULF OF MEXICO...
SW FLOW ALOFT COVERS THE ENTIRE GULF THIS MORNING. THIS UPPER
LEVEL FLOW PATTERN IS MOVING MIDDLE TO UPPER LEVEL MOISTURE
NORTHEASTWARD ACROSS THE NRN AND ERN HALF OF THE GULF. WITHIN
THIS REGION OF MOISTURE ALOFT...A NEARLY STATIONARY SURFACE
TROUGH IS ANALYZED FROM 29N91W TO 24N93W THEN SOUTH TO THE COAST
OF MEXICO NEAR 18N93W. VISIBLE NIGHT CHANNEL AND IR WINDOW SHOW
A BROAD LAYER OF LOW LEVEL STRATOCUMULUS CLOUDS W OF THE TROUGH
TO THE MEXICO AND TEXAS COAST W OF 92W...WITH A FEW ISOLATED
SHOWERS OCCURRING WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS S
OF 26N92W. MOSAIC DOPPLER RADAR INDICATES SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS NE OF THE TROUGH N OF 28N BETWEEN 84W-90W
AFFECTING THE COASTAL WATERS OF LOUISIANA...MISSISSIPPI...
ALABAMA...AND THE FLORIDA PANHANDLE. AN EARLIER ASCAT PASS
REVEALED GUSTY N WINDS UP TO 20 KT W OF THE TROUGH AXIS. SURFACE
RIDGING WILL RETURN TO THE WRN GULF OVER THE NEXT FEW DAYS.

CARIBBEAN SEA...
VERY DRY AIR ALOFT AND STRONG SUBSIDENCE COVERS MOST OF THE
CARIBBEAN WATERS THIS MORNING. THIS AIRMASS IS SUPPRESSING DEEP
CONVECTION ACROSS THE DISCUSSION AREA. FRESH TO STRONG TRADE
WIND FLOW CONTINUES ACROSS MUCH OF THE BASIN...ESPECIALLY
BETWEEN 68W-80W...WITH A FEW SMALL CLUSTERS OF LOW-TOP WEAK
SHOWERS EMBEDDED IN THE FLOW. THESE CONDITIONS ARE EXPECTED TO
PERSIST THROUGH TUESDAY MORNING.

ATLANTIC OCEAN...
THE TAIL END OF A COLD FRONT IS ENTERING THE FAR WRN ATLC WITH
LIMITED CONVECTION AT THE MOMENT. HOWEVER...THIS FRONT WILL
CONTINUE TO TRACK EASTWARD WITH INCREASING CONVECTION AS THE DAY
PROGRESSES. IN THE MEAN TIME...AN UPPER LEVEL RIDGE IS ACROSS
MUCH OF THE WESTERN ATLC W OF 45W WITH VERY DRY AIR ALOFT AND
STRONG SUBSIDENCE NOTICED ON WATER VAPOR IMAGERY. THIS FEATURE
SUPPORTS A 1023 MB HIGH CENTERED NEAR 28N65W. SLICING THROUGH
THE SURFACE RIDGE IS A WEAK COLD FRONT ANALYZED FROM 32N48W TO
27N56W TO 26N64W WHERE LOW-LEVEL MOISTURE BECOMES MORE DIFFUSE
AND A DISSIPATING COLD FRONT EXTENDS TO 27N70W. THIS FRONT IS
GENERATING POSSIBLE ISOLATED SHOWERS WITHIN 30 NM EITHER SIDE OF
IT. TO THE EAST OF THE FRONT...AN EARLIER ASCAT PASS REVEALED AN
AREA OF LOW LEVEL CONFLUENCE OF LIGHT WINDS ANALYZED AS A WEAK
SURFACE TROUGH FROM 29N45W TO 23N48W WITHOUT ANY RAINSHOWER
ACTIVITY ASSOCIATED. A SIMILAR SURFACE TROUGH IS ALSO ANALYZED
FROM 17N46W TO 10N50W. FARTHER EAST...AN UPPER LEVEL LOW IS
CENTERED NEAR 21N38W. THIS UPPER LEVEL CIRCULATION IS GENERATING
A BROAD AREA OF DIFFLUENCE FLOW ALOFT THAT COVERS THE ERN ATLC S
OF 25N E OF 38W. SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE IN THIS REGION...WITH NE WINDS UP TO 25 KT.

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

$$

GARCIA




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