[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181128
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN DEC 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ/MONSOON TROUGH...

THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N12W TO
05N24W TO 07N50W TO 06N57W. SCATTERED MODERATE CONVECTION IS
FROM 06N-10N BETWEEN 30W-39W.

...DISCUSSION...

GULF OF MEXICO...
UPPER LEVEL CONFLUENCE IS NOTED ACROSS THE GULF THIS MORNING AS
AN UPPER LEVEL LONGWAVE TROUGH REMAINS TO THE NORTH OVER THE SE
CONUS AND EASTERN SEABOARD AND AN UPPER LEVEL RIDGE REMAINS
ANCHORED OVER THE WESTERN CARIBBEAN SEA. WITH THE UPPER LEVEL
TROUGHING CONTINUING TO SLIDE E-SE INTO NORTHERN PORTIONS OF THE
SW NORTH ATLC...A DISSIPATING COLD FRONT IS ANALYZED FROM THE
FLORIDA PENINSULA NEAR 27N83W TO 26N92W AND BECOMES STATIONARY
ALONG 25N95W TO 19N96W. LOW-LEVEL MOISTURE REMAINS LIMITED ALONG
THE COLD FRONT...HOWEVER...ISOLATED SHOWERS ARE POSSIBLE S OF
27N W OF 94W. THE FRONT IS EXPECTED TO CONTINUE DISSIPATING AS
SURFACE TROUGHING SETS UP OVER THE WESTERN GULF AND A 1031 MB
SURFACE HIGH PRESSURE CURRENTLY ANCHORED OVER NW LOUISIANA
BUILDS EASTWARD ACROSS THE SE CONUS THROUGH LATE SUNDAY. THE
HIGH IS EXPECTED TO PROVIDE MOSTLY EAST TO NORTHEAST WINDS
ACROSS MUCH OF THE GULF THROUGHOUT THE DAY ON SUNDAY. BY
MONDAY...SOUTHERLY RETURN FLOW IS EXPECTED TO RE-ESTABLISH OVER
PORTIONS OF THE WESTERN GULF AS AN AREA OF LOW PRESSURE DEVELOPS
OVER NORTH TEXAS AND OKLAHOMA. THE NEXT COLD FRONT IS THEN
FORECAST TO ENTER THE NW GULF WATERS EARLY TUESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF THE
WESTERN CARIBBEAN CENTERED NEAR 15N72W WITH AXIS EXTENDING NW TO
NEAR 23N83W. ON THE WESTERN PERIPHERY OF THE RIDGE...SOUTHERLY
DIFFLUENT FLOW ALOFT CONTINUES TO ENHANCE SCATTERED SHOWERS AND
ISOLATED TSTMS S OF 19N BETWEEN 77W-84W...INCLUDING PORTIONS OF
PANAMA...COSTA RICA...AND EASTERN NICARAGUA. MOST OF THIS
CONVECTIVE ACTIVITY IS FOCUSED IN THE VICINITY AND NORTH OF THE
MONSOON TROUGH AXIS EXTENDING FROM THE E PACIFIC ALONG 09N TO
NORTHERN COLOMBIA. OTHERWISE THE REMAINDER OF THE WESTERN
CARIBBEAN W OF 72W IS UNDER STRONG NE TRADES DUE TO AN INCREASED
PRESSURE GRADIENT FROM A HIGH PRESSURE CENTER OVER THE SW NORTH
ATLC. FARTHER EAST...A VERY DRY AND STABLE ATMOSPHERE IS NOTED
UNDER NW FLOW ALOFT ON THE EASTERN PERIPHERY OF THE PREVIOUSLY
MENTIONED UPPER LEVEL RIDGE. NE TRADES PREVAIL E OF 72W AS
WELL...HOWEVER REMAIN GENERALLY FROM 10 TO 15 KT. TWO AREAS OF
ISOLATED SHOWERS ARE ALSO NOTED ON SATELLITE IMAGERY...ONE N OF
16N E OF 71W...AND THE OTHER S OF 13N E OF 71W. WITH INCREASED
POSSIBILITY OF PRECIPITATION CONTINUING ALONG THE NORTHERN
SHORES OF THE GREATER ANTILLES...NAMELY HISPANIOLA...POTENTIAL
LOCALIZED FLOODING REMAINS AN IMPACT FOR THE NEXT 24-36 HOURS.
HIGH PRESSURE IS FORECAST TO REMAIN ANCHORED EAST OF THE BAHAMAS
THROUGH LATE SUNDAY MAINTAINING THE AREA OF INCREASED E-NE
TRADES.

ATLANTIC OCEAN...
AN UPPER LEVEL LONGWAVE TROUGH IS PROGRESSING OVER THE EASTERN
CONUS AND SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION
AREA NEAR 32N70W THAT EXTENDS SW TO THE CENTRAL FLORIDA
PENINSULA NEAR 28N80W. POSSIBLE ISOLATED SHOWERS ARE OCCURRING
WITHIN 90 NM EITHER SIDE OF THE FRONT. TO THE SE OF THE COLD
FRONT...AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE WESTERN
CARIBBEAN SEA ALONG 15N72W NE TO BEYOND 32N57W AND SUPPORTS A
WEAKENING 1020 MB SURFACE HIGH CENTERED NEAR 26N67W. MOSTLY NE
WINDS ARE NOTED WITHIN THE SOUTHEASTERN PERIPHERY OF THE HIGH AS
A RECENT ASCAT PASS AROUND 18/0052 UTC DEPICTED WINDS IN THE
RANGE OF 10 TO 15 KT. OVER THE CENTRAL ATLC...AN UPPER LEVEL LOW
IS CENTERED NEAR 26N48W AND EXTENDS TROUGHING SOUTHWARD TO 09N
BETWEEN 40W-62W. THE UPPER LEVEL LOW SUPPORTS A COLLOCATED
SURFACE LOW WITH A SET OF FRONTAL BOUNDARIES ASSOCIATED WITH THE
SYSTEM. A STATIONARY FRONT EXTENDS FROM EAST OF THE LOW CENTER
ALONG 27N46W TO 20N47W TO 17N48W THEN AS SURFACE TROUGH TO
10N50W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 240 NM
EAST OF THE BOUNDARY N OF 16N. CLOSER TO THE LOW CENTER...A
STATIONARY FRONT EXTENDS NORTHWARD FROM THE LOW CENTER TO BEYOND
32N50W AND A SURFACE TROUGH IS ANALYZED FROM THE LOW TO 25N49W
TO 19N56W. SCATTERED SHOWERS ARE OCCURRING WITHIN 330 NM EAST OF
THE STATIONARY FRONT. BOTH OF THESE CONVECTIVELY ACTIVE AREAS
ARE ENHANCED EAST OF THE UPPER LEVEL TROUGH AXIS DUE TO STRONG
UPPER LEVEL DIFFLUENCE. THE REMAINDER OF THE EASTERN ATLC IS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1033 MB
HIGH CENTERED SE OF THE AZORES NEAR 37N26W. THE INFLUENCE OF THE
RIDGE EXTENDS SOUTHWARD TO 16N REMAINING E OF 40W.

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

$$
HUFFMAN




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