[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 220543
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU OCT 22 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 32W S OF 18N MOVING W NEAR 10 KT. THE
WAVE COINCIDES WITH A MAXIMUM IN TOTAL PRECIPITABLE WATER AS
WELL AS AN AREA OF MAXIMUM 850 MB RELATIVE VORTICITY IN GLOBAL
MODEL FIELDS IN THE VICINITY OF THE WAVE AXIS. CYCLONIC
CURVATURE OF THE LOW LEVEL CLOUD FIELD IS NOTED ON SATELLITE
IMAGERY WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM
13N-18N BETWEEN 25W-31W. THE CONVECTION IS CONTINUING TO BE
ENHANCED BY AN UPPER RIDGE OVER THE TROPICAL EASTERN ATLC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 10N29W 10N34W 10N62W.
CLUSTERS OF SCATTERED SHOWERS AND ISOLATED MODERATE CONVECTION
ARE FROM 3N-9N BETWEEN 18W-35W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF IS DOMINATED BY A SURFACE RIDGE ANCHORED IN THE W ATLC
LOCATED EAST OF THE NORTH CAROLINA COAST. SELY RETURN FLOW
ASSOCIATED WITH THE SURFACE RIDGE AND THE RESULTING INCREASED
PRESSURE GRADIENT CONTINUES TO IMPACT THE GULF WITH WINDS UP TO
25 KT ACROSS MUCH OF THE GULF. LOW-LEVEL CONVERGENCE AHEAD OF
THE NEXT COLD FRONT CURRENTLY POSITIONED ACROSS WESTERN TEXAS IS
GENERATING ISOLATED SHOWERS OVER THE NORTHERN GULF WATERS N OF
25N W OF 88W. SIMILAR ACTIVITY IS MOVING WESTWARD OVER THE SE
GULF AND PORTIONS OF THE FLORIDA PENINSULA. AN AMPLIFIED UPPER
LEVEL RIDGE EXTENDS FROM SOUTHERN MEXICO OVER THE BAY OF
CAMPECHE TO THE SE CONUS. THIS UPPER RIDGE IS ENHANCING MUCH OF
THE CURRENT SHOWERS AND TSTM ACTIVITY OBSERVED INLAND OVER TEXAS
THIS EVENING. AS THE SURFACE RIDGE SLIDES EASTWARD...THE NEXT
COLD FRONT IS FORECAST TO ENTER THE NW GULF WATERS LATE
THURSDAY.

CARIBBEAN SEA...
A 1007 MB LOW IS IN THE SW CARIBBEAN OFF THE COAST OF NICARAGUA
NEAR 12N83W. SCATTERER SHOWERS AND ISOLATED TSTMS ARE OCCURRING
OVER THE SW CARIBBEAN AND PORTIONS OF CENTRAL AMERICA FROM
9N-16N BETWEEN 76W-87W. THIS AREA IS UNDER THE INFLUENCE OF THE
BASE OF AN UPPER TROUGH THAT DIPS SOUTHWARD FROM CUBA TO EASTERN
HONDURAS. UPPER LEVEL DIFFLUENCE E OF THE TROUGH AXIS IS
ENHANCING THE CONVECTION ASSOCIATED WITH THE SURFACE LOW.
FARTHER EAST...AN UPPER LEVEL RIDGE IS ANCHORED OVER NW
VENEZUELA WITH RIDGE AXIS ALONG 70W WHILE UPPER LEVEL TROUGHING
COVERS THE REMAINDER OF THE EASTERN CARIBBEAN E OF 65W PROVIDING
A DRY STABLE AIRMASS AND GIVING GENERALLY CLEAR SKIES. A FEW
ISOLATED LOW-LEVEL SHOWERS HOWEVER ARE PRIMARILY N OF 16N AND E
OF 68W.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH COVERS THE WESTERN AND CENTRAL ATLC N
OF 30N WITH A NARROW AMPLIFIED TROUGH AXIS EXTENDING S OVER THE
SW NORTH ATLC THROUGH 30N75W ACROSS CUBA INTO THE NW CARIBBEAN
SEA. THIS AMPLIFIED UPPER LEVEL TROUGH IS PROVIDING STRONG
SUBSIDENCE AND MOSTLY DRY STABLE AIR W OF 76W WITH ONLY A FEW
ISOLATED SHOWERS MOVING WESTWARD OVER THE NW BAHAMAS AND FLORIDA
PENINSULA. THE BROAD UPPER LEVEL TROUGH IS SUPPORTING A
DISSIPATING COLD FRONT THAT ENTERS THE CENTRAL ATLC NEAR 32N49W
EXTENDING SW TO 28N56W. WEST OF THE COLD FRONT...A SURFACE RIDGE
ANCHORED BY A 1024 MB HIGH OFF THE COAST OF NORTH CAROLINA
CONTINUES TO PROVIDE NE TO ELY FLOW W OF 56W. AN UPPER LEVEL
RIDGE EXTENDS FROM NEAR 20N65W TO 28N60W PROVIDING DIFFLUENCE
ALOFT TO GENERATE AN AREA OF SCATTERED SHOWERS AND ISOLATED
TSTMS S OF 28N TO OVER HISPANIOLA AND EASTERN CUBA BETWEEN
67W-76W. A SURFACE TROUGH EXTENDS FROM 28N48W TO 22N60W.
LOW-LEVEL CONVERGENCE LOCATED TO THE EAST OF THE SURFACE TROUGH
ALONG WITH A MID-LEVEL SHORTWAVE TROUGH WITH AXIS ALONG 45W N OF
20N IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN
120 NM OF A LINE FROM 21N45W TO BEYOND 32N39W. A WEAK SURFACE
RIDGE DOMINATES THE REMAINDER OF THE EASTERN ATLC ANCHORED BY A
1018 MB HIGH CENTERED NEAR 29N26W. IN THE TROPICAL ATLC...A 1010
MB LOW IS N OF THE ITCZ NEAR 14N42W WITH SCATTERED SHOWERS AND
ISOLATED TSTMS E OF THE LOW FROM 12N-16N BETWEEN 37W-42W.

$$
HUFFMAN





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