[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120537
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN DEC 12 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0500 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED FROM LIBERIA 6N11W ALONG 7N20W 9N27W
5N39W 3N52W. A SURFACE TROUGH EXTENDS FROM S OF THE CAPE VERDE
ISLANDS NEAR 13N23W TO 6N28W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 4N-8N BETWEEN 27W-35W...AND FROM 3N-7N
BETWEEN 38W-43W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0300 UTC...A COLD FRONT HAS PUSHED OFF THE COAST OF TEXAS
EXTENDING FROM NEAR ATCHAFALAYA BAY AT 29N92W TO BROWNSVILLE
TEXAS AT 26N98W. THE FRONT IS SUPPORTED BY A LONGWAVE UPPER
LEVEL TROUGH EXTENDING FROM THE UPPER MIDWEST TO SRN TEXAS AND
ACROSS NRN MEXICO. A LINE OF SHOWERS...SOME STRONG...EXTEND UP
TO 60 NM AHEAD OF THE FRONT. 20 KT NLY WINDS ARE NOTED BEHIND
THE FRONT. AS THE FRONT PUSHES FARTHER SE...GALE FORCE WINDS ARE
EXPECTED BEHIND IT WITHIN 24 HRS. THE REMAINDER OF THE BASIN IS
UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1017 MB
HIGH OFF THE SW COAST OF FLORIDA NEAR 25N84W. DRY AIR ALOFT IN
MAINLY ZONAL WLY FLOW COVERS THIS AREA MAINTAINING FAIR
CONDITIONS WITH PATCHES OF STRATOCUMULUS CLOUDS.  EXPECT THE
SURFACE RIDGE TO WEAKEN AS THE COLD FRONT RACES ACROSS THE BASIN
AND REACHES S FLORIDA BY 24 HRS.

CARIBBEAN SEA...
DRY AIR AND SUBSIDENCE AROUND AN UPPER LEVEL RIDGE CENTERED OVER
NW COLOMBIA IS KEEPING MUCH OF THE CARIBBEAN UNDER FAIR
CONDITIONS TONIGHT. A LINE OF SHOWERS/POSSIBLE THUNDERSTORMS
EXTENDS FROM HISPANIOLA TO PANAMA ALONG 19N72W 16N80W 9N80W
SUPPORTED BY SURFACE CONVERGENCE BETWEEN N-NE WINDS ACROSS THE
NW CARIBBEAN AND NE-E TRADE WINDS ACROSS THE REMAINDER OF THE
BASIN. SOME SHOWERS ACROSS THE MONA PASSAGE ARE ATTRIBUTED TO A
SURFACE TROUGH IN THE W ATLC THAT REACHES TO THE NW TIP OF
PUERTO RICO. EXPECT A LINE OF SHOWERS TO CONTINUE IN THE CENTRAL
CARIBBEAN AS NLY WINDS INCREASE IN THE NW PORTION OF THE AREA
AHEAD OF THE COLD FRONT THAT IS MOVING ACROSS THE GULF OF
MEXICO. THE FRONT SHOULD REACH THE NW CARIBBEAN EARLY MONDAY.

ATLANTIC OCEAN...
MAINLY ZONAL FLOW ALOFT COVERS THE W AND CENTRAL ATLC NO LONGER
PROVIDING EXTRA SUPPORT TO THE SURFACE FEATURES. HOWEVER...A
WEAKENING SURFACE TROUGH STILL REMAINS OFF THE ERN FLORIDA
COAST. THE TROUGH EXTENDS FROM A 1012 MB LOW NEAR 27N60W ALONG
25N69W 26N76W 30N77W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 30 NM
EITHER SIDE OF THE AXIS. A RECENT ASCAT SCATTEROMETER PASS
INDICATES WINDS UP TO 20 KTS N OF THE BOUNDARY WITH WEAKER WINDS
TO THE S. A SECOND SURFACE TROUGH EXTENDS SW FROM THE SAME LOW
PRESSURE CENTER TO WRN PUERTO RICO. POSSIBLE ISOLATED SHOWERS
ARE WITHIN 30 NM EITHER OF THIS BOUNDARY. A DISSIPATING
STATIONARY FRONT DRAPES ACROSS THE N CENTRAL ATLC ALONG 30N46W
TO 29N57W SUPPORTING SCATTERED SHOWERS N OF 27N BETWEEN 44W-60W.
TO THE S OF THIS BOUNDARY...STRONGER SHOWERS/POSSIBLE
THUNDERSTORMS ARE FROM 23N-27N BETWEEN 48W-57W ASSOCIATED WITH
AN UPPER LEVEL JET IN THE ZONAL WLY FLOW ALOFT. THE REMAINDER OF
THE E ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1020 MB
HIGH NEAR 26N39W. THE RIDGE IS SUPPORTED BY A BROAD UPPER LEVEL
RIDGE WITH AXIS FROM NRN S AMERICA TO THE AZORES ISLANDS. AN
UPPER LEVEL TROUGH IS TO THE E OF THIS RIDGE EXTENDING FROM THE
CANARY ISLANDS TO THE CAPE VERDE ISLANDS SUPPORTING A LOW
PRESSURE SYSTEM TO THE N OF THE DISCUSSION AREA WITH A SURFACE
TROUGH EXTENDING INTO THE AREA TO THE E OF THE CANARY ISLANDS.
THIS UPPER LEVEL TROUGH IS ALSO ENHANCING CONVECTION ALONG THE
ITCZ AND THE SURFACE TROUGH EMBEDDED WITHIN THE AXIS.

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

$$
WALTON





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