[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211056
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU 21 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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 0600 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1045 UTC.

...TROPICAL WAVES...
CENTRAL ATLANTIC TROPICAL WAVE 55W SOUTH OF 20N MOVING WEST
10 KT. WAVE IS MOVING UNDER THE AREA OF A MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER NEAR 17N54W. ISOLATED MODERATE TO
LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 17N TO 20N BETWEEN
50W AND 60W. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR TROPICAL
CYCLONE FORMATION.

WESTERN CARIBBEAN SEA TROPICAL WAVE 78W SOUTH OF 20N MOVING
WEST 10 KT. THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH REACHES
TO 15N80W IN THE WEST CENTRAL CARIBBEAN SEA AS THE WAVE MOVES
TOWARD THAT SPOT. THERE IS NOT ANY ONE AREA OF SHOWERS AND/OR
THUNDERSTORMS WHICH IS DIRECTLY ATTRIBUTABLE TO THIS WAVE.
SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS FROM 9N
TO 11N BETWEEN 74W AND 78W IN COASTAL NORTHERN COLOMBIA...AND
FROM 5N TO 9N BETWEEN 77W AND 80W IN THE EASTERN PACIFIC OCEAN
WEST OF COLOMBIA AND SOUTH OF PANAMA...PROBABLY MORE RELATED
TO THE ITCZ THAN ANYTHING ELSE.

...ITCZ...
ITCZ 10N14W 8N30W 10N52W 10N56W 9N76W 9N79W 10N88W.
SHOWERS AND THUNDERSTORMS...SCATTERED MODERATE TO STRONG IN
COASTAL NORTHEASTERN VENEZUELA AND TRINIDAD FROM 9N TO 11.5N
BETWEEN 60W AND 62.5W...IN NORTHWESTERN VENEZUELA FROM 8N TO
11N BETWEEN 67W AND 72W...SCATTERED MODERATE TO STRONG FROM
9N TO 11N BETWEEN 74W AND 78W IN COASTAL NORTHERN COLOMBIA...
AND FROM 5N TO 9N BETWEEN 77W AND 80W IN THE EASTERN PACIFIC
OCEAN WEST OF COLOMBIA AND SOUTH OF PANAMA...WIDELY SCATTERED
MODERATE TO ISOLATED STRONG FROM 2N TO 10N BETWEEN 23W AND
40W...AND WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED
STRONG FROM 10N TO 20N BETWEEN 35W AND 50W...UNDER AN UPPER
LEVEL RIDGE AND TO THE EAST OF AN AREA OF UPPER LEVEL
DIFFLUENT FLOW.

...DISCUSSION...
THE GULF OF MEXICO...
BROAD UPPER LEVEL ANTICYCLONIC FLOW FROM A RIDGE IN CENTRAL
MEXICO COVERS THE AREA NORTH OF 13N BETWEEN 87W AND 110W.
MIDDLE TO UPPER LEVEL DRY AIR COVERS THIS SAME AREA...WITH
NO DEEP THUNDERSTORMS. A MIDDLE TO UPPER LEVEL TROUGH HAS BEEN
MOVING THROUGH AND NOW TO THE EAST OF FLORIDA DURING THE LAST
12 HOURS OR SO...WITH THE BASE NOW NEAR 80W IN THE STRAITS OF
FLORIDA. ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND
THUNDERSTORMS ARE ON THE EASTERN SIDE OF THE TROUGH...NORTH
OF 20N BETWEEN 70W AND 80W IN THE ATLANTIC WATERS. 1015 MB
SURFACE HIGH PRESSURE CENTER NEAR 27N88W. WEAK SURFACE PRESSURE
GRADIENT IN THE GULF OF MEXICO.

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW FROM THE MEXICO RIDGE COVERS THE
AREA WEST OF 80W. THE BASE OF AN ATLANTIC OCEAN-TO-WESTERN
CARIBBEAN SEA TROUGH REACHES 15N80W...FROM 27N67W IN THE
ATLANTIC WATERS. SCATTERED MODERATE TO STRONG SHOWERS AND
THUNDERSTORMS ARE IN THE NORTHEASTERN CORNER OF THE AREA FROM
16N TO 20N BETWEEN 63W AND 68W...AROUND PUERTO RICO.  MIDDLE
TO UPPER LEVEL DRY AIR IS WEST AND NORTHWEST OF 20N68W 14N77W
12N84W...MIDDLE TO UPPER LEVEL MOISTURE IS EAST OF THIS SAME
LINE UNDER UPPER LEVEL SOUTHWESTERLY FLOW.

THE SUBTROPICAL ATLANTIC...
THE MOIST MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW FROM THE
CARIBBEAN SEA IS BEING TRANSPORTED TO THE NORTHEAST...INTO THE
ATLANTIC OCEAN TO 28N59W...AND THEN PUSHED EASTWARD BY THE UPPER
LEVEL WESTERLIES. SURFACE RIDGE 25N70W 29N63W TO 1019 MB HIGH
PRESSURE CENTER NEAR 27N43W...AND CONTINUING ALONG 27N29W
30N16W. UPPER LEVEL WESTERLIES EVERYWHERE IN THE REST OF THE
SUBTROPICAL ATLANTIC OCEAN EAST OF 50W. THE MIDDLE TO UPPER
LEVEL FLOW IS MUCH MORE CYCLONIC NORTH OF 30N EAST OF 30W DUE
TO A TROUGH SWEEPING TOWARD WESTERN EUROPE AND NORTHWESTERN
AFRICA.

THE TROPICAL ATLANTIC...
THE 55W TROPICAL WAVE IS MOVING UNDER THE AREA OF A MIDDLE TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 17N54W. ISOLATED
MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 17N
TO 20N BETWEEN 50W AND 60W. UPPER-LEVEL WINDS ARE NOT FAVORABLE
FOR TROPICAL CYCLONE FORMATION. UPPER LEVEL ANTICYCLONIC FLOW
IN THE REST OF THE TROPICAL ATLANTIC EAST OF 50W.

$$
MT



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