[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 280548
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST WED DEC 28 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
0535 UTC.

...ITCZ/MONSOON TROUGH...

A GREAT PORTION OF THE MONSOON TROUGH REMAINS INLAND OVER
AFRICA. A SMALL SECTION OF IT ENTERS THE ATLC THROUGH THE COAST
OF SIERRA LEONE ALONG 8N10W AND QUICKLY ENDS AT 6N17W. THE ITCZ
AXIS EXTENDS WSW FROM THIS POINT ALONG 3N25W 2N35W TO THE COAST
OF BRAZIL NEAR 1S47W. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS WITHIN 200 NM ON THE NRN SIDE OF THE ITCZ AXIS
BETWEEN 18W-40W.

...DISCUSSION...

GULF OF MEXICO...
THE COLD FRONT THAT HAS BEEN MOVING ACROSS THE GULF THESE PAST
FEW DAYS IS NOW IN THE WRN ATLC BASIN. HOWEVER...SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE STILL MOVING
THROUGH THE STRAITS OF FLORIDA THIS LATE EVENING. SIMILAR
ACTIVITY LINGERS OVER THE BAY OF CAMPECHE S OF 20N. THE
REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF MOSTLY DRY WSW
FLOW ALOFT AND A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH
CENTERED OVER ERN TEXAS. NORTHERLY WINDS ARE EXPECTED TO PERSIST
WITH WEATHER CONDITIONS REMAINING FAIR THROUGH EARLY THURSDAY.

CARIBBEAN SEA...
VERY DRY AIR ALOFT AND STRONG SUBSIDENCE COVERS MOST OF THE
CARIBBEAN WATERS THIS LATE EVENING. THIS AIRMASS IS SUPPRESSING
DEEP CONVECTION ACROSS THE DISCUSSION AREA. HOWEVER...A FEW
SHOWERS ARE OVER THE FAR NW BASIN INCLUDING THE YUCATAN CHANNEL
IN THE VICINITY OF THE SRN EXTENSION OF THE WRN ATLC COLD FRONT.
FRESH TO STRONG TRADE WIND FLOW CONTINUES ACROSS MUCH OF THE
BASIN...ESPECIALLY BETWEEN 68W-80W AND NEAR THE COAST OF
COLOMBIA...WITH A FEW SMALL CLUSTERS OF LOW-TOP WEAK SHOWERS
EMBEDDED IN THE FLOW. THESE CONDITIONS ARE EXPECTED TO PERSIST
THROUGH FRIDAY AS A RIDGE WILL POSITION ITSELF IN THE SW NORTH
ATLC AND INCREASE THE TRADES DUE TO AN INCREASED PRESSURE
GRADIENT. THE TRADES WILL REMAIN STRONG BASIN-WIDE THROUGH THE
UPCOMING WEEKEND.

ATLANTIC OCEAN...
A LONGWAVE UPPER LEVEL TROUGH IS MOVING OFF THE CONUS SEABOARD
SUPPORTING A COLD FRONT ANALYZED INTO THE DISCUSSION AREA ALONG
32N75W TO THE SRN FLORIDA COAST NEAR 26N80W. SCATTERED SHOWERS
AND TSTMS ARE OCCURRING WITHIN 100 NM EAST OF THE FRONT. THE
REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A 1024
MB SURFACE HIGH CENTERED NEAR 28N62W. FARTHER EAST...AN UPPER
LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NORTH OF THE
DISCUSSION AREA NEAR 40N50W. THIS UPPER LEVEL FEATURE SUPPORTS
AN OCCLUDED BUT STRONG LOW PRESSURE SYSTEM THAT EXTENDS A COLD
FRONT INTO THE AREA ALONG 32N44W TO 25N50W TO 23N55W THEN IT
CONTINUES W AS A DISSIPATING COLD FRONT TO 25N68W. WITH MOISTURE
REMAINING LIMITED WITH THIS FRONT...ONLY POSSIBLE ISOLATED
SHOWERS ARE WITHIN 70 NM E OF THE BOUNDARY. THE MAIN IMPACT WITH
THIS FRONT IS GALE FORCE NW WINDS N OF 30N W OF FRONT GENERATING
SEAS BETWEEN 12-24 FT. THESE CONDITIONS ARE EXPECTED TO DECREASE
BELOW GALE WARNING CRITERIA OVER THE NEXT 6-9 HOURS. A WEAK AREA
OF LOW LEVEL CONFLUENCE OF LIGHT WINDS IS ANALYZED AS A WEAK
SURFACE TROUGH FROM 22N47W TO 14N50W WITHOUT ANY RAINSHOWER
ACTIVITY ASSOCIATED. THE REMAINDER OF THE EASTERN ATLC IS UNDER
THE INFLUENCE OF AN UPPER LEVEL LOW CENTERED NEAR 21N27W. MIDDLE
TO UPPER LEVEL MOISTURE CONTINUES TO BE DRAWN ACROSS THE FAR ERN
ATLC WITH ISOLATED SHOWERS OCCURRING FROM 10N-21N E OF 23W.

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

$$

GARCIA




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