[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED DEC 19 2012

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 06N10W TO
05N11W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
05N11W TO 01N26W TO 01N48W. ISOLATED MODERATE CONVECTION IS FROM
THE EQUATOR TO 06N BETWEEN 15W-33W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES A VERY DRY AND SUBSIDENT AIRMASS
IS IN CONTROL OVER THE GULF BASIN THIS EVENING...HOWEVER A WEAK
MID-LEVEL SHORTWAVE TROUGH IS NOTED IN THE VICINITY OF 25N90W.
AS A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED OVER NE
FLORIDA NEAR 30N82W CONTINUES TO DOMINATE STABLE WEATHER
CONDITIONS AT THE SURFACE...THIS AREA OF MID-LEVEL ENERGY IS
GENERATING AN AREA OF SCATTERED TO BROKEN CLOUDINESS AND
POSSIBLE ISOLATED SHOWERS FROM 24N-30N BETWEEN 89W-93W. THIS
AREA IS LOCATED ON THE WESTERN PERIPHERY OF THE SURFACE RIDGE
WHERE SOUTHERLY FLOW CONTINUES TO STREAM INTO A DEVELOPING AREA
OF LOW PRESSURE OVER THE CENTRAL PLAINS THIS EVENING. WITH THE
SURFACE HIGH EXPECTED TO SHIFT EASTWARD AND INTO THE SW NORTH
ATLC OVERNIGHT....S-SE WINDS WILL VEER S-SW BY EARLY THURSDAY
MORNING AS THE NEXT COLD FRONT EMERGES OFF THE TEXAS AND
LOUISIANA COAST. THIS FRONT WILL PACK A PUNCH OF NORTHERLY WINDS
EXPECTED TO SPREAD ACROSS THE ENTIRE BASIN BY EARLY FRIDAY. GALE
FORCE CONDITIONS ARE FORECAST TO BEGIN WITHIN 24 HOURS ACROSS
PORTIONS OF THE SOUTHWESTERN GULF WATERS.

CARIBBEAN SEA...
CONDITIONS ACROSS THE CARIBBEAN SEA BASIN REMAIN FAIRLY TRANQUIL
THIS EVENING AS WATER VAPOR IMAGERY INDICATES VERY DRY AIR AND
SUBSIDENCE PREVAILING ALOFT WITH MOSTLY NORTHWEST TO WESTERLY
FLOW DOMINATING. THIS PATTERN IS EXPECTED TO KEEP THE CARIBBEAN
STABLE OVER THE NEXT 24 TO 36 HOURS. AT THE SURFACE...A FAIRLY
WEAK PRESSURE GRADIENT CONTINUES TO SLOWLY TIGHTEN AS HIGH
PRESSURE SLIDES OFF THE SE CONUS AND INTO THE SW NORTH ATLC
WATERS. TRADE WINDS REMAIN IN THE RANGE OF 10 TO 20 KT WITH
SLIGHTLY STRONGER E-NE WINDS EXPECTED BETWEEN 70W-80W THROUGH
THE OVERNIGHT HOURS INTO THURSDAY. ISOLATED LOW-TOPPED SHOWERS
ARE OCCURRING OVER PORTIONS OF THE CENTRAL AND SW CARIBBEAN FROM
13N-17N BETWEEN 68W-82W...AND S OF 12N BETWEEN 76W-83W. THE
TRADES ARE EXPECTED TO PERSIST THROUGH LATE FRIDAY AS A COLD
FRONT WILL BEGIN TO IMPACT THE NW CARIBBEAN LATE FRIDAY INTO THE
WEEKEND WITH STRONG NE WINDS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH COUPLED WITH A MID-LEVEL LOW IS CENTERED
OFF THE NEW ENGLAND COAST NEAR 41N65W THAT SUPPORTS A COLD FRONT
ANALYZED FROM 32N55W SW TO 26N65W TO THE CENTRAL BAHAMAS NEAR
25N76W. THE FRONT REMAINS FREE OF PRECIPITATION W OF
64W...HOWEVER ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER
SIDE OF THE BOUNDARY E OF 64W. OTHERWISE...THE REMAINDER OF THE
SW NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED
BY A 1020 MB HIGH CENTERED OVER NE FLORIDA NEAR 30N82W. FARTHER
EAST...AN UPPER LEVEL TROUGH IS OVER THE EASTERN ATLC WITH AXIS
EXTENDING FROM 30N26W TO A BASE NEAR 12N40W. THIS TROUGHING
SUPPORTS A STATIONARY FRONT ANALYZED INTO THE DISCUSSION AREA
NEAR 32N23W EXTENDING SW TO 26N35W. A WEAK SURFACE TROUGH TAILS
OFF TO THE WEST FROM THE FRONT ALONG 27N39W TO 22N52W. THE
STATIONARY FRONT CONTINUES TO BRIDGE BETWEEN A PAIR OF 1020 MB
HIGHS...ONE CENTERED NEAR 33N27W AND THE OTHER CENTERED NEAR
29N23W. POSSIBLE ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM
EITHER SIDE OF THE FRONT...AND WITHIN 45 NM NORTH OF THE SURFACE
TROUGH AXIS.

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

$$
HUFFMAN




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