[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED DEC 22 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED FROM SIERRA LEONE NEAR 8N12W ALONG 4N31W
4N47W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ALONG
THE AXIS WITHIN 30 NM EITHER SIDE BETWEEN 27W-41W. AN EMBEDDED
SURFACE TROUGH EXTENDS ALONG 10N51W TO 3N50W ENHANCING NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION FROM 3N-10N BETWEEN
44W-54W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE EXTENDING FROM ERN MEXICO AND UP THE
CENTRAL CONUS COMBINED WITH DRY AND SUBSIDENT AIR ALOFT IS
PROVIDING MOSTLY FAIR CONDITIONS ACROSS THE GULF OF MEXICO
TODAY. THE UPPER RIDGE SUPPORTS A SURFACE RIDGE ANCHORED BY A
1021 MB HIGH OFF THE SW COAST OF FLORIDA NEAR 25N82W. LIGHT
ANTI-CYCLONIC FLOW IS AROUND THE RIDGE WITH STRONGER SLY WINDS
UP TO 15 KTS ALONG THE TEXAS COASTLINE. MAINLY CLEAR SKIES ARE
ACROSS THE BASIN WITH THE EXCEPTION OF AN AREA OF STRATOCUMULUS
CLOUDS IN THE N AND CENTRAL PORTIONS. CLOUD COVER ACROSS THE
GULF COAST IS DUE TO AN APPROACHING WEAK COLD FRONT WHICH IS
FORECAST TO MOVE OFF THE TEXAS COAST LATER TONIGHT FOLLOWED BY A
STRONGER FRONT MOVING OFF THE COAST LATE FRIDAY AND EARLY
SATURDAY.

CARIBBEAN SEA...
DRY AIR AND SUBSIDENCE ALOFT THAT COVERS THE GULF OF MEXICO IS
ALSO IMPACTING MUCH OF THE WRN CARIBBEAN KEEPING CONDITIONS
FAIR. A LONGWAVE UPPER TROUGH OVER THE W ATLC SUPPORTS A COLD
FRONT THAT REACHES THE LEEWARD ISLANDS AT GUADELOUPE NEAR 16N62W
WHERE IT CONTINUES AS A SHEAR LINE ALONG 14N66W 14N73W.
WIDESPREAD SHOWERS/THUNDERSTORMS ARE WITHIN 100 NM N OF THE
AXIS...AND WITHIN 45 NM S OF THE AXIS DUE TO THE SPEED
CONVERGENCE OF 25-30 KT WINDS TO THE N AND 10-15 KT WINDS TO THE
S. A SURFACE TROUGH IS IN THE CENTRAL CARIBBEAN ALONG 15N77W TO
THE COLOMBIA COAST AT 11N73W. SURFACE CONVERGENCE NEAR THE
TROUGH IS SUPPORTING SHOWERS/THUNDERSTORMS FROM 14N-16N BETWEEN
74W-78W. A SECOND SURFACE TROUGH IS IN THE SE CARIBBEAN
EXTENDING FROM THE TROPICAL ATLC NEAR ST LUCIA AT 13N61W AND
INTO VENEZUELA NEAR 9N65W. A 1011 MB LOW IS ANALYZED ALONG THE
TROUGH AXIS NEAR 11N64W. SURFACE CONVERGENCE NEAR THIS
LOW/TROUGH IS ENHANCING SHOWERS/THUNDERSTORMS NW OF THE SYSTEM
FROM 11N-15N BETWEEN 61W-66W. ALOFT...MAINLY SWLY FLOW COVERS
THE BASIN AROUND THE ERN HALF OF AN UPPER LEVEL RIDGE CENTERED N
OF ERN SOUTH AMERICA. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE
ACROSS THE ERN CARIBBEAN OVER THE NEXT 24 HRS.

ATLANTIC OCEAN...
SURFACE RIDGING CENTERED W OF SW FLORIDA EXTENDS OVER THE FAR SW
N ATLC KEEPING CONDITIONS FAIR. A DEEP LAYER TROUGH IS TO THE E
SUPPORTING A BROAD LOW PRESSURE SYSTEM CENTERED OFF THE NEW
ENGLAND COAST WITH AN ASSOCIATED COLD FRONT ENTERING THE
DISCUSSION AREA NEAR 32N41W CONTINUING TO THE LEEWARD ISLANDS
ALONG 23N50W 16N62W. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE
ALONG THE FRONT N OF 21N...AS WELL AS N OF 24N BETWEEN 36W-41W.
GALE FORCE WINDS ARE BEHIND THE FRONT N OF 28N TO 64W. A SURFACE
TROUGH IS S OF THE FRONT IN THE TROPICAL ATLC ALONG 18N51W TO
THE WINDWARD ISLANDS NEAR 13N61W. SCATTERED SHOWERS/POSSIBLE
THUNDERSTORMS ARE FROM 16N-19N BETWEEN 50W-55W. ACROSS THE ERN
ATLC...A BROAD UPPER LEVEL RIDGE EXTENDING FROM NE SOUTH AMERICA
TO THE AZORES ISLANDS SUPPORTS A SURFACE RIDGE ANCHORED BY A
1019 MB HIGH NEAR 25N32W PROVIDING GENERALLY FAIR WEATHER ACROSS
THIS PORTION OF THE BASIN. AN UPPER LEVEL TROUGH IS TO THE E
FROM PORTUGAL ACROSS THE CANARY ISLANDS TO THE CAPE VERDE
ISLANDS SUPPORTING A LOW PRESSURE SYSTEM N OF THE DISCUSSION
AREA THAT IS GENERATING CYCLONIC SURFACE FLOW N OF 25N E OF 23W.
A SURFACE TROUGH DEPICTS THE SHIFTING CYCLONIC WINDS ALONG
32N14W TO THE CAPE VERDE ISLANDS. THERE ARE NO ASSOCIATED
SHOWERS WITH THIS TROUGH.

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

$$
WALTON




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