[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 142345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI NOV 14 2008

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 9N12W 7N22W 7N36W 9N49W 8N61W.
A SURFACE TROUGH...WHICH EXTENDS FROM 13N55W TO 11N55W TO
8N56W...IS EMBEDDED WITHIN THE ITCZ. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 8N-13N BETWEEN 41W-57W...WHICH IS
BEING ENHANCED BY THE COMBINATION OF ENHANCED LOW LEVEL
CONVERGENCE NEAR THE SURFACE TROUGH AND UPPER LEVEL DIFFLUENCE.
ELSEWHERE...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 4N-27N BETWEEN BETWEEN 16W-33W.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS UPPER-LEVEL SHORTWAVE TROUGH IS QUICKLY PROGRESSING
EASTWARD ACROSS THE N GULF...WITH AN ASSOCIATED MID/UPPER-LEVEL
WIND SPEED MAXIMUM E OF THE THE TROUGH AXIS. STRONG UPPER LEVEL
DIVERGENCE TO THE NW OF THIS WIND SPEED MAXIMUM IS SUPPORTING A
1007 MB SURFACE LOW OVER S LOUISIANA NEAR 31N92W...AND A SURFACE
TROUGH THAT EXTENDS TO THE S OF THIS LOW FROM 31N92W TO 28N93W
TO 26N95W. THE COMBINATION OF THE LOW LEVEL CONVERGENCE IN THE
VICINITY OF THE SURFACE LOW AND SURFACE TROUGH...AS WELL AS THE
UPPER LEVEL DIVERGENCE...IS SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE NORTH CENTRAL GULF N OF 27N BETWEEN
88W-93W. IN THE WAKE OF THE SURFACE TROUGH...A 1010 MB SURFACE
HIGH IS OVER SE TEXAS NEAR 29N95W...WITH DEEP LAYER SUBSIDENCE
IN NORTHWESTERLY FLOW ALOFT AND DEEP LAYER DRY AIR BRINGING FAIR
WEATHER CONDITIONS OVER THE NW GULF. ALSO...DEEP LAYER DRY AIR
IS LIMITING DEEP CONVECTION ACROSS MUCH OF THE SE GULF. OVER THE
NEXT DAY...A DEEP LAYER TROUGH AND ASSOCIATED STRONG SURFACE
COLD FRONT...CURRENTLY OVER THE PLAINS OF THE CONUS...WILL MOVE
ACROSS THE NW GULF...WITH STRONG SURFACE HIGH PRESSURE BUILDING
IN THE WAKE OF THE FRONT. AT THE SAME TIME...PARTICULARLY STRONG
MID/UPPER-LEVEL FLOW ACCOMPANYING THE DEEP LAYER TROUGH WILL
ALSO MOVE ACROSS THE NW GULF OVER THE NEXT DAY. THESE FACTORS
ARE FORECAST TO RESULT IN STRONG NORTHERLY WINDS TO GALE FORCE
FOR LOCATIONS W OF THE COLD FRONT IN THE W GULF IN 24 HOURS.
ALSO OF NOTE...THE INTERACTION OF UPPER LEVEL DIVERGENCE
ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE TROUGH OVER THE N
GULF...AND LOW LEVEL CONVERGENCE ASSOCIATED WITH BOTH A FRONT
OVER THE SE CONUS AND THE REMNANT LOW LEVEL CIRCULATION OF
PALOMA...RESULTED IN SHOWERS AND THUNDERSTORMS WITH HEAVY
RAINFALL OVER THE FLORIDA PANHANDLE EARLIER TODAY. IN FACT...A
TOTAL OF 9 INCHES OF RAIN ARE REPORTED TO HAVE FALLEN THIS
MORNING ABOUT 15 NM W OF TALLAHASSEE FLORIDA.

CARIBBEAN SEA...
AN UPPER RIDGE IS AFFECTING THE W CARIBBEAN...WITH THE UPPER
RIDGE AXIS EXTENDING FROM CENTRAL CUBA NEAR 22N79W TO N HONDURAS
NEAR 15N86W. SUBSIDENCE AND DEEP LAYER DRY AIR IN THE VICINITY
OF THIS UPPER RIDGE ARE BRINGING FAIR WEATHER CONDITIONS TO MUCH
OF THE W CARIBBEAN. OVER THE E CARIBBEAN...AN UPPER LEVEL TROUGH
IS PRESENT...WHICH EXTENDS FROM AN UPPER LOW NEAR 13N71W TO
PUERTO RICO NEAR 18N67W NORTHEASTWARD INTO THE SW ATLC. WEAK
INSTABILITY...COMBINED WITH GREATER DEEP MOISTURE OVER THE E
CARIBBEAN...IS SUPPORTING ISOLATED SHOWERS E OF 71W...INCLUDING
PORTIONS OF THE LESSER ANTILLES...PUERTO RICO...AND HISPANIOLA.
THIS ACTIVITY IS FURTHER BEING ENHANCED BY A SURFACE TROUGH THAT
EXTENDS FROM NE OF THE DOMINICAN REPUBLIC NEAR 19N68W FURTHER
NORTHEAST INTO THE SW ATLC. ALSO...SCATTERED SHOWERS AND
THUNDERSTORMS ARE OCCURRING OVER PORTIONS OF NE COLOMBIA...AS
WELL AS THE ADJACENT CARIBBEAN SEA. THIS ACTIVITY IS BEING
ENHANCED BY GREATER INSTABILITY OVER HIGHER TERRAIN.

ATLANTIC OCEAN...
AN UPPER RIDGE AXIS IS OVER THE W ATLC EXTENDING FROM CENTRAL
CUBA NEAR 22N79W TO 28N72W TO 32N67W TO NE OF THE DISCUSSION
AREA. DEEP LAYER DRY AIR IS INHIBITING DEEP CONVECTION ACROSS
MUCH OF THE W ATLC. FARTHER TO THE E...THE AXIS OF A DEEP LAYER
TROUGH EXTENDS FROM PUERTO RICO NEAR 18N67W TO 22N60W TO 26N53W.
THIS DEEP LAYER TROUGH IS ACCOMPANIED BY A SURFACE TROUGH THAT
EXTENDS FROM NE OF THE DOMINICAN REPUBLIC NEAR 19N68W TO 23N68W
TO 25N67W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE TROUGH IS
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM 19N-25N
BETWEEN 63W-71W...INCLUDING PORTIONS OF THE LESSER
ANTILLES...PUERTO RICO...AND HISPANIOLA. ALSO...AN UPPER LEVEL
TROUGH IS N OF 21N BETWEEN 30W-45W...WITH A COLD FRONT EXTENDING
FROM 31N41W TO NE OF THE DISCUSSION AREA AND A SURFACE TROUGH
EXTENDING FROM 31N37W TO 27N38W TO 24N38W. ATMOSPHERIC LIFT
ASSOCIATED WITH THESE FEATURES IS SUPPORTING ISOLATED SHOWERS
AND THUNDERSTORMS N OF 27N BETWEEN 32W-46W. OVER THE TROPICAL
ATLC...AN UPPER HIGH IS CENTERED NEAR 2N45W...AND AN UPPER RIDGE
IS S OF 10N BETWEEN 26W-39W. UPPER LEVEL DIFFLUENCE ASSOCIATED
WITH THESE FEATURES IS ENHANCING THE CONVECTION IN THE VICINITY
OF THE SURFACE TROUGH EMBEDDED WITHIN THE ITCZ.

$$
COHEN

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