[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED OCT 21 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 TILTED FROM 8N29W TO 18N26W DRIFTING WESTWARD.
THE WAVE AXIS COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM AS
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY AS WELL AS A
MAXIMUM IN 850 MB RELATIVE VORTICITY IN THE CIMSS GLOBAL MODEL
GUIDANCE FIELDS. THE LOW-LEVEL CLOUD FIELD EXHIBITS CYCLONIC
TURNING IN THE VICINITY OF THE WAVE AXIS WITH ISOLATED SHOWERS
AND MODERATE CONVECTION FROM 12N-18N BETWEEN 22W-30W THAT
INCLUDES THE CAPE VERDE ISLANDS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N13W 6N30W 9N38W 9N61W. A 1010
MB SURFACE LOW IS LOCATED N OF THE AXIS ACROSS THE CENTRAL
TROPICAL ATLC CENTERED NEAR 13N38W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 120 NM OF LINE FROM 6N36W TO 16N39W
IN ASSOCIATION WITH THE LOW. ELSEWHERE...CLUSTERS OF ISOLATED
MODERATE CONVECTION COVER THE AREA FROM 3N-7N BETWEEN 16W-29W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD SURFACE RIDGE DOMINATES ACROSS FLORIDA AND THE GULF...
ANCHORED OVER THE CAROLINAS BY A 1025 MB HIGH. ALOFT...THE GULF
IS INFLUENCED BY W-NW ANTICYCLONIC FLOW AROUND AN UPPER LEVEL
RIDGE ACROSS MUCH OF THE GULF. STRONG SUBSIDENCE AND DRY STABLE
AIR IS NOTED ON WATER VAPOR IMAGERY PRIMARILY E OF 90W...WHILE
UPPER LEVEL CONVECTIVE DEBRIS CLOUDINESS FROM TROPICAL STORM
RICK IN THE EASTERN PACIFIC ADVECTS EASTWARD AND SPILLS OVER THE
TOP OF THE UPPER LEVEL RIDGE N OF 25N W OF 92W. AT THE SURFACE
HOWEVER...E TO SE SURFACE FLOW UP TO 20 KT IS FORECAST TO
CONTINUE THROUGH WEDNESDAY...TURNING MORE SOUTHERLY OVER THE
WESTERN GULF BY THURSDAY AHEAD OF THE NEXT COLD FRONT EXPECTED
TO ENTER THE NW GULF WATERS LATE THURSDAY.

CARIBBEAN SEA...
A DEEP LAYERED TROUGH IS OVER THE W ATLC AND FLORIDA PENINSULA
THAT DIPS DIPS S OVER THE NW CARIBBEAN AND WESTERN CUBA. A 1007
MB LOW IS CENTERED INLAND OVER SOUTHERN NICARAGUA NEAR 12N84W
AND EXTENDS SURFACE TROUGHING N-NW TO A 1009 MB LOW IN THE GULF
OF HONDURAS NEAR 17N87W. A NARROW UPPER LEVEL RIDGE IS LOCATED
TO THE E EXTENDING FROM NORTHERN COLOMBIA NEAR 11N75W TO ACROSS
EASTERN HISPANIOLA AND INTO THE W ATLC. THIS IS PROVIDING A
DIFFLUENT ENVIRONMENT ALOFT TO ENHANCE A BROAD AREA OF SCATTERED
SHOWERS AND ISOLATED TSTMS THAT COVERS THE WESTERN CARIBBEAN W
OF A LINE FROM PANAMA NEAR 9N78W TO HAITI NEAR 18N72W. A BROAD
UPPER LEVEL TROUGH COVERS THE EASTERN CARIBBEAN EXTENDING FROM
AN UPPER LOW IN THE CENTRAL ATLC PROVIDING STRONG SUBSIDENCE AND
DRY STABLE AIR E OF 70W.

ATLANTIC OCEAN...
A BROAD DEEP LAYERED UPPER LEVEL TROUGH COVERS MUCH OF THE SW
NORTH ATLC...FLORIDA PENINSULA AND STRAITS OF FLORIDA WITH THE
ASSOCIATED COLD FRONT ENTERING THE REGION NEAR 32N59W SW TO
24N70W WHERE IT BECOMES STATIONARY ACROSS THE SE BAHAMAS TO
EASTERN CUBA NEAR 21N76W. SCATTERED SHOWERS ARE OCCURRING WITHIN
200 NM BEHIND THE FRONT WITH LOW-LEVEL CONVERGENCE E OF THE
FRONT GENERATING ISOLATED SHOWERS WITHIN 150 NM E OF THE FRONT.
A NARROW UPPER RIDGE EXTENDS FROM THE WESTERN CARIBBEAN THROUGH
HISPANIOLA ALONG 25N62W TO 32N54W PROVIDING DIFFLUENCE ALOFT TO
ENHANCE THE ACTIVITY ASSOCIATED WITH THE FRONTAL BOUNDARY. A
WEAK PRE-FRONTAL SURFACE TROUGH IS TO THE E ALONG 67W FROM
22N-25N. FARTHER EAST...A BROAD UPPER LEVEL LOW IS CENTERED IN
THE CENTRAL ATLC NEAR 24N49W WITH UPPER LEVEL TROUGHING
EXTENDING SW TO THE LESSER ANTILLES AND EASTERN CARIBBEAN. THIS
SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM 21N53W TO 27N54W
WITH POSSIBLE ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE OF THE
SURFACE TROUGH. UPPER LEVEL DIFFLUENCE E OF THE UPPER LEVEL LOW
HOWEVER IS GENERATING A MUCH MORE ACTIVE AREA OF SCATTERED
SHOWERS AND ISOLATED TSTMS COVERING THE AREA FROM 20N-29N
BETWEEN 39W-50W. ACROSS THE REMAINDER OF THE ATLC...A BROAD
UPPER RIDGE IS LOCATED OVER THE TROPICAL ATLC ANCHORED NEAR
8N42W THAT EXTENDS A RIDGE AXIS N TO 25N27W.

$$
HUFFMAN



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