[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 23 2010

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 05N09W 03N27W CROSSING THE EQUATOR
NEAR 45W THEN OVER NE BRAZIL NEAR 01S48W. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 03S TO 04N BETWEEN 24W-39W...AND
FROM 02S TO 07N BETWEEN 39W-47W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES MAINLY ZONAL WESTERLY UPPER LEVEL
FLOW DOMINATES OVER THE GULF THIS EVENING WITH RELATIVELY DRY
AIR AND SUBSIDENCE NOTED IN THE MIDDLE TO UPPER LEVELS.
HOWEVER...NEAR THE SURFACE AS OF 23/2100 UTC...A WEAK COLD FRONT
ENTERS THE SE GULF THROUGH THE FLORIDA STRAITS AND TRANSITIONS
TO A STATIONARY FRONT MEANDERING ALONG 24N83W 26N90W TO INLAND
OVER SOUTH TEXAS NEAR 28N97W. THIS VERY WEAK BOUNDARY BRIDGES
STRONGER SURFACE RIDGING TO THE NORTH OVER THE SE CONUS AND
WEAKER RIDGING OVER THE SW GULF AND PORTIONS OF EAST-CENTRAL
MEXICO. MOSTLY CLEAR SKIES AND FAIR CONDITIONS ACCOMPANY THE
RIDGING WHILE ISOLATED SHOWERS ARE POSSIBLE WITHIN 30 NM EITHER
SIDE OF THE FRONTAL BOUNDARY. THIS FRONT WILL CONTINUE TO BECOME
MORE DIFFUSE THROUGH THE NEXT 24 HOURS. LOOKING AHEAD TO THE
WEEKEND...A VIGOROUS UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING
EASTWARD ACROSS THE DESERT SOUTHWEST WITH LOW PRESSURE FORECAST
TO DEVELOP ALONG THE FRONT AND DEEPEN AS IT TRACKS EAST THROUGH
SUNDAY ALONG THE COASTAL PLAIN. A COLD FRONT DRAPED SW FROM THE
LOW CENTER WILL INTRODUCE STRONG NORTHERLY WINDS OVER MUCH OF
THE GULF BY EARLY SUNDAY.

CARIBBEAN SEA...
DRY AIR AND SUBSIDENCE ALOFT IS NOTED ON WATER VAPOR IMAGERY
OVER THE NW CARIBBEAN DUE TO ZONAL WESTERLY FLOW N OF 16N W OF
75W. SURFACE RIDGING ALSO EXTENDS FROM THE SOUTH-CENTRAL GULF OF
MEXICO ACROSS THE YUCATAN PENINSULA AND INTO THE NW CARIBBEAN
FURTHER ENHANCING FAIR CONDITIONS THIS EVENING. FARTHER EAST
HOWEVER...MOIST SOUTHWESTERLY FLOW ALOFT IS LOCATED ON THE
WESTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTERED IN THE TROPICAL NORTH ATLC NEAR 10N50W. THIS GENERAL
UPPER LEVEL DIFFLUENT ENVIRONMENT IS ENHANCING CONVECTION
FOCUSED ALONG A SET OF SURFACE TROUGHS ANALYZED OVER THE SW AND
EASTERN CARIBBEAN. THE FIRST SURFACE TROUGH EXTENDS FROM 15N80W
TO A 1011 MB LOW NEAR 11N80W THEN TO THE COAST OF NORTHERN
COLOMBIA NEAR 09N77W. OVERALL CLIMATOLOGICAL CYCLONIC SURFACE
FLOW ACROSS THE SW CARIBBEAN AND CONVERGENT TRADE WINDS ARE
GENERATING ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF A LINE
FROM 14N72W TO 13N80W...AND POSSIBLE ISOLATED SHOWERS S OF 16N W
OF 80W. THE OTHER TWO SURFACE TROUGHS ARE POSITIONED OVER THE
EASTERN CARIBBEAN...ONE ANALYZED FROM 16N64W TO 12N70W AND THE
OTHER EXTENDS FROM A WEAK 1011 MB LOW NEAR 17N55W ACROSS
DOMINICA TO NEAR 13N63W. WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS ARE OCCURRING S OF 17N E OF 69W IN ASSOCIATION WITH THESE
TWO BOUNDARIES.

ATLANTIC OCEAN...
A RATHER LARGE AND BROAD DEEP LAYER TROUGH REMAINS ANCHORED IN
THE WESTERN AND CENTRAL NORTH ATLC BY A 968 MB LOW CENTERED SE
OF NEWFOUNDLAND NEAR 45N48W THAT CONTINUES TO EXTEND INFLUENCE
OVER MUCH OF THE SW NORTH ATLC AND CENTRAL ATLC TO 22N W OF 35W.
IMPULSES OF MID-LEVEL ENERGY CONTINUE TO ROTATE AROUND THE MAIN
LOW COMPLEX WITH A PAIR OF COLD FRONTS ENTERING THE DISCUSSION
AREA. ONE COLD FRONT ENTERS THE SW NORTH ATLC NEAR 32N58W AND
EXTENDS SW ALONG 26N70W TO THE FLORIDA STRAITS NEAR 24N80W. THE
FRONT EXHIBITS A RELATIVE LACK OF ANY DEEP CONVECTION...HOWEVER
POSSIBLE ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE
FRONT BETWEEN 55W-72W...WHICH CLOSELY RELATES TO THE STRONGEST
MID-LEVEL FORCING. FARTHER EAST...THE SECOND COLD FRONT ENTERS
THE REGION NEAR 32N29W AND EXTENDS SW TO A WEAK 1011 MB LOW
CENTERED NEAR 17N55W. A SURFACE TROUGH THEN TRAILS SW FROM THE
LOW TO THE WINDWARD ISLANDS. ISOLATED SHOWERS ARE WITHIN 90 NM
EITHER SIDE OF THE FRONT. SOUTH OF THE WEAK LOW ALONG 55W...A
SURFACE TROUGH IS ANALYZED FROM 06N-12N ALONG 57W SUPPORTING
ISOLATED SHOWERS WITHIN 120 NM WEST OF THE TROUGH AXIS. THE
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1015 MB HIGH CENTERED NEAR 21N33W.

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

$$
HUFFMAN



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