[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU OCT 15 2009

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.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 67W S OF 15N MOVING W NEAR 15 KT. THE
WAVE IS LOCATED WITHIN AN AREA OF DEEP LAYER MOISTURE ACROSS THE
SE CARIBBEAN AS INDICATED IN THE TOTAL PRECIPITABLE WATER
IMAGERY. CIMSS WAVETRAK MODEL GUIDANCE ALSO DEPICTS A BROAD AREA
OF 850 MB RELATIVE VORTICITY ACROSS THE SRN HALF OF THE
CARIBBEAN. ISOLATED SHOWERS ARE OCCURRING FROM 12N-15N BETWEEN
65W-69W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 9N35W 8N38W 10N53W 10N56W
10N66W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
9N-13N BETWEEN 17W-22W. A SURFACE TROUGH IS EMBEDDED WITHIN THE
ITCZ ALONG 36W FROM 6N-11N THAT IS GENERATING ISOLATED MODERATE
CONVECTION FROM 7N-11N BETWEEN 32W-40W. A SECOND SURFACE
TROUGH...ALSO EMBEDDED WITHIN THE ITCZ...IS ALONG 55W FROM
7N-15N. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
7N-13N BETWEEN 53W-61W IN THE VICINITY OF THE SURFACE TROUGH.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE ANCHORED OVER NRN MEXICO NEAR 25N103W
EXTENDS A UPPER LEVEL RIDGE AXIS EWD ACROSS THE GULF ALONG 23N
AND OVER THE STRAITS OF FLORIDA AND WRN CUBA. MOSTLY DRY AND
STABLE AIR DOMINATES THE WRN AND SE GULF UNDER GENERALLY LIGHT
E-SE SURFACE FLOW. WEAK UPPER LEVEL TROUGHING IS OVER THE NE
GULF N OF 26N E OF 90W. THIS TROUGHING IS INCREASING LOW TO
MIDDLE LEVEL MOISTURE AND GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS N OF 28N E OF 86W IN THE VICINITY OF A STATIONARY
FRONT DRAPED ACROSS NE FLORIDA FROM GAINESVILLE TO DOTHAN
ALABAMA. THE NEXT COLD FRONT IS FORECAST TO ENTER THE NW GULF
EARLY FRIDAY WITH INCREASING SLY WINDS AHEAD OF THE FRONT UP TO
20 KT OVER PORTIONS OF THE EXTREME WRN GULF.

CARIBBEAN SEA...
THE BROAD UPPER RIDGE THAT COVERS THE GULF OF MEXICO AND W ATLC
WITH RIDGE AXIS ALONG 23N IS PROVIDING THE WRN CARIBBEAN W OF
80W WITH ELY UPPER LEVEL WINDS. WATER VAPOR IMAGERY SHOWS STRONG
SUBSIDENCE WITH GENERALLY A STABLE AND DRY ATMOSPHERE EXTENDING
TO THE SURFACE. E OF 80W ACROSS THE REMAINDER OF THE BASIN...
UPPER LEVEL TROUGHING IS PRESENT WITH A SHEAR AXIS EXTENDING
FROM THE LEEWARD ISLANDS ALONG 14N70W TO 12N80W. THE UPPER LEVEL
TROUGHING CONTINUES TO ENHANCE THE CONVECTION ASSOCIATED WITH
THE TROPICAL WAVE ALONG 67W AS WELL AS GENERATING SCATTERED
SHOWERS N OF 16N BETWEEN THE LEEWARD ISLANDS AND JAMAICA. A
PORTION OF THE ITCZ AXIS EXTENDS ACROSS SRN COSTA RICA AND
PANAMA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE IN THE VICINITY
OF THE AXIS ACROSS THE SW CARIBBEAN S OF 12N BETWEEN 75W-79W.

ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING EWD ACROSS THE W
ATLC WITH TROUGH AXIS ALONG 32N68W TO THE NW BAHAMAS NEAR
26N77W. THIS UPPER LEVEL TROUGH SUPPORTS A 1005 MB LOW CENTERED
NEAR 33N76W WITH A COLD FRONT DRAPING SW ALONG 30N79W TO DAYTONA
BEACH FLORIDA. LOW-LEVEL CONVERGENCE COUPLED WITH UPPER LEVEL
DIFFLUENCE E OF THE TROUGH AXIS ACROSS THE W ATLC IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS FROM 25N-30N BETWEEN
67W-78W. FARTHER TO THE E...A COLD FRONT ENTERS THE DISCUSSION
AREA NEAR 32N48W AND EXTENDS SW ALONG 30N50W 27N60W TO 27N64W
WHERE THE FRONT TRANSITIONS STATIONARY TO THE NW AND INTO THE
1005 MB LOW PREVIOUSLY MENTIONED ABOVE. SCATTERED SHOWERS WITH
POSSIBLE EMBEDDED ISOLATED TSTMS ARE WITHIN 120 NM EITHER SIDE
OF THE FRONTAL BOUNDARY ACROSS THE CENTRAL ATLC. WITH AN UPPER
LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 23N66W AND AN UPPER
LEVEL RIDGE EXTENDING NE TO 27N50W...A QUASI-STATIONARY 1016 MB
HIGH RESULTS AT THE SURFACE AND IS ANCHORED OVER THE CENTRAL
ATLC NEAR 25N46W. ACROSS THE ERN ATLC...UPPER LEVEL TROUGHING IS
LOCATED N OF 15N E OF 37W AND SUPPORTS A SURFACE TROUGH
EXTENDING THROUGH 32N20W 29N21W THEN SW TO 25N27W. ISOLATED
SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH.

$$
HUFFMAN





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