[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT NOV 17 2012

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO
05N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
05N17W TO 03N22W TO 06N33W THEN RESUMES NEAR 12N43W TO 11N50W TO
10N61W. A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 20N40W AND
CONTINUES TO PRODUCE A BROAD AREA OF UPPER LEVEL DIFFLUENCE
WHICH IS GENERATING WIDELY SCATTERED MODERATE CONVECTION FROM
07N-22N BETWEEN 243W-48W. THIS AREA IS FOCUSED ALONG A SURFACE
TROUGH ANALYZED FROM 11N42W TO 19N33W. ELSEWHERE...SCATTERED
MODERATE CONVECTION IS FROM 03N-07N BETWEEN 19W-25W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE CAROLINAS THIS
AFTERNOON NEAR 34N82W AND EXTENDS A TROUGH AXIS SOUTHWARD ALONG
82W TO AS FAR SOUTH AS 10N OVER CENTRAL AMERICA. WHILE MOST OF
THE ACTIVE WEATHER WITH THIS UPPER LEVEL FEATURE IS LOCATED IN
THE SW NORTH ATLC...THE BACK SIDE OF THE TROUGHING IS PROVIDING
MUCH OF THE GULF WITH NORTHWESTERLY UPPER LEVEL FLOW. WATER
VAPOR IMAGERY INDICATES MOSTLY DRY AIR AND SUBSIDENCE IS FOUND N
OF 23N BETWEEN 82W-93W. AT THE SURFACE...RIDGING PERSISTS OVER
MUCH OF THE EASTERN CONUS WITH THE RIDGE AXIS EXTENDING FROM
THE GREAT LAKES REGION S-SW ACROSS THE LOWER MISSISSIPPI RIVER
VALLEY THE ALONG THE TEXAS AND EASTERN MEXICO GULF COASTS.
NORTHEAST WINDS IN THE RANGE OF 10 TO 20 KT PREVAIL WITH
LOW-LEVEL MOISTURE CONVERGENCE NOTED ON SATELLITE IMAGERY OVER
THE SW GULF ALONG A SURFACE TROUGH ANALYZED FROM 18N94W TO
23N98W. ISOLATED SHOWERS ARE OCCURRING S OF 24N W OF 92W.
OTHERWISE...ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER
PORTIONS OF THE SE GULF AND PORTIONS OF THE FLORIDA STRAITS S OF
25N E OF 87W WHERE THE BASE OF THE AFOREMENTIONED UPPER LEVEL
TROUGH IS LOCATED.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH IS LOCATED OVER THE FLORIDA PENINSULA WITH
A TROUGH AXIS ALONG 82W DIPPING SOUTHWARD INTO THE WESTERN
CARIBBEAN AND OVER PORTIONS OF CENTRAL AMERICA. WATER VAPOR
IMAGERY INDICATES THAT WEST OF THE TROUGH AXIS MOSTLY FAIR
WEATHER IS NOTED OVER THE NW CARIBBEAN...WESTERN CUBA...AND
AREAS W OF 84W. NORTHERLY WINDS AT THE SURFACE PREVAIL AND THESE
ARE EXPECTED TO PERSIST THROUGH TUESDAY. EAST OF THE UPPER LEVEL
TROUGH AXIS...SOUTH-SOUTHWESTERLY MOISTURE-LADEN UPPER LEVEL
FLOW DOMINATES AND CONTINUES TO PROVIDE OVERALL CLOUDY SKIES
WITH SCATTERED SHOWERS AND ISOLATED TSTMS OVER MUCH OF THE AREA
BETWEEN 70W-80W. AN AREA OF SCATTERED SHOWERS AND TSTMS ARE
OCCURRING OVER THE SW CARIBBEAN WATERS FROM 10N-14N BETWEEN
79W-84W DUE LARGELY IN PART TO LOW-LEVEL MOISTURE CONVERGENCE OF
EASTERLY TRADES AND THE AFOREMENTIONED NORTHERLY FLOW OVER THE
NW CARIBBEAN. CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS
EXTENDING ALONG 09N FROM THE EASTERN PACIFIC REGION IS ALSO A
CONTRIBUTING FOCUS OF THE CONVECTION. ELSEWHERE OVER THE
REMAINDER OF THE EASTERN CARIBBEAN...EMBEDDED ISOLATED SHOWERS
WITHIN THE TRADE WIND FLOW CONTINUE TO MOVE EAST-NORTHEAST OVER
THE LESSER ANTILLES AND PUERTO RICO THIS AFTERNOON.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE CAROLINAS NEAR
34N83W AND SUPPORTS A STATIONARY FRONT THAT EXTENDS ALONG 32N75W
TO 26N79W. LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE
FRONT ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE
TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND TSTMS WITHIN 75
NM EITHER SIDE OF THE FRONT S OF 29N AND FROM 29N-34N BETWEEN
71W-81W. FARTHER EAST OVER THE REMAINDER OF THE SW NORTH ATLC...
MOIST SOUTHWESTERLY UPPER LEVEL FLOW DOMINATES BETWEEN THE
PREVIOUSLY MENTIONED LOW AND TROUGHING AND AN UPPER LEVEL RIDGE
AXIS THAT EXTENDS FROM THE EASTERN CARIBBEAN SEA NEAR 17N64W TO
BEYOND 32N54W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE
OCCURRING OVER A LARGE AREA FROM 20N-32N BETWEEN 58W-75W AND
REMAIN LARGELY FOCUSED ALONG A SURFACE TROUGH ANALYZED FROM
23N66W TO 30N63W TO 36N58W. ELSEWHERE OVER THE REMAINDER OF THE
CENTRAL AND EASTERN ATLC...A SURFACE RIDGE PREVAILS AND IS
ANCHORED BY A 1031 MB HIGH CENTERED SW OF THE AZORES NEAR
36N34W.

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

$$
HUFFMAN



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