[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 242350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 24 2011

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 INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N11W TO
07N14W TO 04N29W TO 06N41W. A SURFACE TROUGH IS ANALYZED ON THE
WESTERN EXTENT OF THE ITCZ AXIS FROM 07N44W TO 14N42W LARGELY AS
A REFLECTION OF AN UPPER LEVEL LOW CENTERED NEAR 23N44W AND THE
ASSOCIATED TROUGH AXIS WHICH EXTENDS SOUTHWARD TO 12N50W.
LOW-LEVEL CONVERGENCE EAST OF THE SURFACE TROUGH AND ENHANCEMENT
DUE TO STRONG UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL
TROUGH AXIS IS GENERATING A LARGE AREA OF SCATTERED MODERATE
CONVECTION NORTH OF THE ITCZ FROM 05N-22N BETWEEN 27W-43W.

...DISCUSSION...

GULF OF MEXICO...
SOUTHWESTERLY UPPER LEVEL FLOW IS NOTED ACROSS THE ENTIRE GULF
THIS EVENING ON THE WESTERN PERIPHERY OF AN UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED OVER THE BAHAMAS NEAR 25N77W.
THE INFLUENCE OF THE UPPER LEVEL RIDGE EXTENDS WESTWARD TO 92W
WHERE UPPER LEVEL MOISTURE INCREASES TO THE WEST OVER THE NW
GULF AND MOST OF TEXAS AND LOUISIANA. THIS MOISTURE IS LOCATED
EAST OF AN UPPER LEVEL LOW CENTERED OVER NEW MEXICO WITH THE
ASSOCIATED HEIGHT FALLS SUPPORTING CYCLOGENESIS OVER THE NW
GULF. AS OF 24/2100 UTC...A 1017 MB LOW IS CENTERED NEAR 27N96W
WITH A STATIONARY FRONT EXTENDING ALONG 27N TO THE EAST...AND A
STATIONARY FRONT EXTENDING SOUTHWARD TO SOUTHERN MEXICO NEAR
20N93W. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE
NUMEROUS SHOWERS N OF 26N W OF 93W AND ISOLATED SHOWERS AND
TSTMS WITHIN 90 NM EITHER SIDE OF THE FRONT S OF 27N. ASIDE FROM
PRECIPITATION IMPACTS...WINDS IN THE VICINITY OF THE SURFACE LOW
REMAIN STRONG IN THE RANGE OF 20 TO 30 KT AS THE PRESSURE
GRADIENT CONTINUES TO STRENGTHEN AS THE UPPER LEVEL FEATURE
APPROACHES FROM THE WEST. THESE WINDS ARE EXPECTED TO REACH GALE
FORCE W OF 95W THROUGH THE OVERNIGHT HOURS INTO SUNDAY AS STRONG
HIGH PRESSURE BUILDS IN ACROSS THE SOUTHERN PLAINS AND NE MEXICO.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE EXTENDS ACROSS THE CARIBBEAN SEA WITH AXIS
FROM THE SE CARIBBEAN NEAR 10N66W N-NW TO EASTERN CUBA THEN TO
AN ANTICYCLONIC CIRCULATION CENTERED OVER THE BAHAMAS NEAR
25N77W. WATER VAPOR IMAGERY INDICATES DRY AIR AND SUBSIDENCE
OVER MUCH OF THE BASIN E OF 82W THIS EVENING IN THE MIDDLE AND
UPPER LEVELS. HOWEVER...AT THE SURFACE A STRONG PRESSURE
GRADIENT CONTINUES ACROSS THE CENTRAL CARIBBEAN AND A PORTION OF
THE WESTERN CARIBBEAN AS A 1024 MB HIGH IS CENTERED IN THE SW
NORTH ATLC NEAR 28N65W AND LOWER PRESSURE LOCATED OVER NORTHERN
SOUTH AMERICA. AS A RESULT...EAST-NORTHEAST TRADES REMAIN STRONG
IN THE RANGE OF 20 TO 30 KT AS DEPICTED BY AN EARLIER ASCAT PASS
AROUND 24/1438 UTC. ELSEWHERE...MOST LOW-LEVEL MOISTURE IS NOTED
ALONG THE CENTRAL AMERICA COAST WITH CONVERGENCE OF THE TRADES
GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS WEST OF A
LINE FROM 10N76W TO 20N87W. THE SURFACE HIGH OVER THE SW NORTH
ATLC IS FORECAST TO DISSIPATE SLIGHTLY THROUGH THE OVERNIGHT
HOURS AND RE-ESTABLISH ITSELF THROUGH MONDAY WITH FRESH TO
STRONG E-NE TRADES EXPECTED TO PERSIST BETWEEN 65W-82W THROUGH
TUESDAY.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH LOCATED WELL NORTH OF THE DISCUSSION AREA
OFF THE NEW ENGLAND COAST EXTENDS A COLD FRONT S OF 32N ALONG
32N70W TO THE FLORIDA PENINSULA NEAR 28N81W. THE ENERGY
ASSOCIATED WITH THE FRONT CONTINUES TO BECOME MORE DIFFUSE AS AN
UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
BAHAMAS NEAR 25N77W AND INFLUENCES MUCH OF THE SW NORTH ATLC.
LOW-LEVEL MOISTURE ASSOCIATED WITH THE FRONT CONTINUES TO
GENERATE ISOLATED SHOWERS WITHIN 75 NM EITHER SIDE OF THE
BOUNDARY. TO THE SE OF THE FRONT...THE UPPER LEVEL RIDGING
SUPPORTS A 1024 MB HIGH CENTERED NEAR 28N65W WHICH IS EXPECTED
TO DISSIPATE SLIGHTLY THROUGH THE OVERNIGHT HOURS AND
RE-ESTABLISH ITSELF THROUGH MONDAY. FARTHER EAST...AN UPPER
LEVEL LOW CENTERED NEAR 23N44W AND ASSOCIATED TROUGHING WITH
AXIS ALONG 45W SUPPORTS A SURFACE TROUGH ANALYZED FROM 23N45W TO
30N44W. LOW-LEVEL CONVERGENCE EAST OF THE SURFACE TROUGH AXIS
AND MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL LOW
IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM
22N-29N BETWEEN 36W-45W. THE REMAINDER OF THE EASTERN ATLC IS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1038 MB
HIGH CENTERED NE OF THE AZORES NEAR 43N15W.

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

$$
HUFFMAN




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