000
AXNT20 KNHC 151751
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 PM EST WED DEC 15 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 
1745 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 7N12W 
EXTENDING WESTWARD ALONG 7N20W 5N30W 7N40W...AND ALONG 6N46W TO 
4N54W. WIDELY SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS 
WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 12W-29W. A CLUSTER 
OF MODERATE CONVECTION IS FROM 4N-6N BETWEEN 13W-18W. A WEAK 
SURFACE TROUGH IS EMBEDDED WITHIN THE AXIS ANALYZED FROM 05N44W 
TO 10N41W. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED WITH THE 
SURFACE TROUGH. 

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY CONTINUES TO SHOW STRONG SUBSIDENCE AND DRY 
STABLE AIR ALOFT DOMINATING THE GULF WATERS THIS AFTERNOON. 
AT SURFACE...ANTI-CYCLONIC FLOW OF 10-20 KT IS OBSERVED ACROSS 
THE REGION CAUSED BY A 1023 MB HIGH OVER SW GEORGIA WITH LOW 
LEVEL STRATOCUMULUS CLOUDS MOVING ALONG THIS FLOW. AN UPPER 
LEVEL RIDGE IS ANCHORED OVER THE CENTRAL PLAIN STATES CONTINUING 
TO USHER IN A VERY COOL AND DRY CONTINENTAL POLAR AIRMASS TO THE 
BASIN. THE RIDGE IS FORECAST TO SLIDE E-SE AND INTO THE W ATLC 
BY THURSDAY. INCREASED S-SE WINDS AND SOUTHERLY RETURN FLOW IS 
EXPECTED TO PERSIST THROUGHOUT TODAY AHEAD OF THE NEXT FRONTAL 
BOUNDARY EXPECTED TO EMERGE OFF THE TEXAS COAST EARLY FRIDAY 
WITH SHOWERS.

CARIBBEAN SEA...
VERY STRONG SUBSIDENCE AND DRY AIR ALOFT IS NOTED ACROSS THE NW 
CARIBBEAN THAT CONTINUES TO SUPPORT A SURFACE RIDGE THAT EXTENDS 
FROM THE SE CONUS AND GULF OF MEXICO OVER MUCH OF THE WESTERN 
CARIBBEAN W OF 76W. OVER THE EASTERN AND CENTRAL CARIBBEAN...A 
STATIONARY FRONT ENTERS THE CARIBBEAN FROM THE CENTRAL ATLANTIC 
ACROSS THE ANEGADA PASSAGE NEAR 18N65W TO 16N69W TO 15N73W 
BECOMING A SHEAR AXIS TO THE COAST OF COLOMBIA NEAR 10N75W. 
LOW-LEVEL CONVERGENCE IN VICINITY OF THIS BOUNDARY CONTINUES TO 
PROVIDE FOCUS FOR ISOLATED SHOWERS WITHIN 30-60 NM ON EITHER 
SIDE OF THE BOUNDARY. THE REMAINDER OF THE EASTERN CARIBBEAN 
CONTINUES UNDER FAIR WEATHER CONDITIONS WITH A FEW ISOLATE 
SHOWERS EMBEDDED IN THE LIGHT TRADEWINDS. A SURFACE TROUGH IS 
ANALYZED EAST OF TRINIDAD AND TOBAGO ALONG 60W/61W THAT IS 
PROVIDING SCATTERED SHOWERS S OF 13N BETWEEN 57W AND 63W.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH IS OVER THE NW ATLANTIC WITH TROUGHING 
DIPPING SOUTH TO W ATLC WATERS. WATER VAPOR IMAGERY INDICATES 
THAT MOSTLY DRY AIR AND W-SW FLOW ALOFT DOMINATES W OF 55W 
PROVIDING FAIR WEATHER ACROSS THE AREA. THIS TROUGHING SUPPORTS 
A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N53W AND 
EXTENDS SW ALONG 24N58W BECOMING STNRY ALONG THE ANEGADA PASSAGE 
INTO THE CARIBBEAN SEA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE 
WITHIN 200 NM EAST OF THE FRONT N OF 22N AND LIKELY ENHANCED DUE 
TO DIFFLUENCE BETWEEN THE TROUGH AND AN UPPER LEVEL RIDGE OVER 
THE CENTRAL ATLC. FARTHER EAST...AN UPPER LEVEL TROUGH CONTINUES 
TO IMPACT MUCH OF THE EASTERN ATLC E OF 33W SUPPORTING A BROAD 
AREA OF LOWER PRESSURES NORTH OF THE DISCUSSION AREA. THIS 
SCENARIO EXTENDS A COLD FRONT INTO OUR AREA ALONG 32N20W 24N21W 
TO THE CAPE VERDE ISLANDS NEAR 17N23W. SCATTERED SHOWERS ARE 
WITHIN 50 NM EAST OF THE FRONT N OF 27N. ISOLATED SHOWERS ARE 
BEHIND THE FRONT N OF 28N BETWEEN 26W AND 32W IN ASSOCIATION 
WITH THE UPPER LEVEL TROUGHING.

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

$$

MONTALVO/GARCIA