[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181204
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU 18 NOV 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC 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 1115 UTC.

...ITCZ...

ITCZ 8N10W 6N20W 5N30W 4N40W 6N50W 7N60W...7N76W 7N83W SOUTH OF
THE COSTA RICA/PANAMA BORDER. SCATTERED MODERATE TO STRONG
SHOWERS AND THUNDERSTORMS FROM PANAMA TO 10N BETWEEN 76W AND
79W. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND
THUNDERSTORMS FROM 4N TO 8N BETWEEN 20W AND 27W...AND
FROM 1N TO 4N BETWEEN 29W AND 32W.

...DISCUSSION...

THE GULF OF MEXICO...
HIGH LEVEL MOISTURE FROM THE EASTERN PACIFIC OCEAN IS MOVING
ACROSS MEXICO WITH FLOW FROM AN UPPER LEVEL RIDGE ALONG
109W/110W. MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
NOW IS IN NORTHWESTERN OKLAHOMA...WITH A TROUGH FROM THIS CENTER
TO THE MIDDLE TEXAS COASTAL WATERS NEAR 28N93W. UPPER LEVEL
MOISTURE AT THE TAIL END OF THE CYCLONIC FLOW OF THIS CENTER IS
CAUGHT UP IN THE UPPER LEVEL NORTHWESTERLY WIND FLOW OVER THE
OPEN GULF WATERS...NORTH OF 27N BETWEEN FLORIDA AND 94W. MIDDLE
TO UPPER LEVEL DRY AIR SOUTH ELSEWHERE.SURFACE FRONTAL BOUNDARY
IN TEXAS AND MEXICO FROM 25N BEYOND 32N BETWEEN 91W AND 99W...IS
SLOW TO DEVELOP. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS
AND THUNDERSTORMS FROM 27.5N TO 29N BETWEEN 90W AND 92W.
ISOLATED MODERATE SHOWERS AND THUNDERSTORMS ALSO NORTH OF 25N
WEST OF 90W. BROAD SURFACE ANTICYCLONIC FLOW ELSEWHERE.

THE CARIBBEAN SEA...
UPPER LEVEL SOUTHWESTERLY WIND FLOW CONTINUES FROM NORTHERN
PARTS OF SOUTH AMERICA ACROSS THE OPEN CARIBBEAN WATERS. THIS
FLOW REGIME IS EAST AND SOUTHEAST OF A LINE FROM THE WINDWARD
PASSAGE TO THE EASTERN HONDURAS/NORTHEASTERN NICARAGUA BORDER.
HIGH LEVEL MOISTURE IS MOVING OVER/CUTTING INTO THE MIDDLE TO
UPPER LEVEL DRY AIR WHICH HAS BEEN IN PLACE IN THE NORTH CENTRAL
SECTION FOR THE LAST FEW DAYS. THE SHOWERS AND THUNDERSTORMS
SOUTH AND SOUTHEAST OF 16N60W 13N80W MAY BE MORE RELATED TO THE
ITCZ THAN ANYTHING ELSE...AND IN GENERAL...TO THE LEFT-OVER
BROAD LOW PRESSURE OF THE ATLANTIC-TO-CARIBBEAN SEA SURFACE
TROUGH. MIDDLE TO UPPER LEVEL TROUGH GOES FROM THE CENTRAL
ATLANTIC OCEAN TO JUST WEST OF JAMAICA...AND TO THE EASTERN
HONDURAS/NORTHEASTERN NICARAGUA BORDER. THIS TROUGH SUPPORTS
THE SURFACE COLD FRONT THROUGH 18N60W TO 17N67W. SURFACE TROUGH
16N50W 12N60W TO NORTHWESTERN VENEZUELA 11N70W. SHOWERS AND
THUNDERSTORMS SOUTH AND SOUTHEAST OF 16N60W 13N80W IN GENERAL.
SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS IN
PARTICULAR FROM 11N TO 13.5N BETWEEN 64W AND 70W. ISOLATED
MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS ELSEWHERE.

THE SUBTROPICAL ATLANTIC OCEAN...
BROAD AREA OF CYCLONIC FLOW COVERS THE ATLANTIC WATERS WEST OF
40W. ONE DEEP LAYER TROUGH IN THIS BROAD AREA OF CYCLONIC FLOW
HAS MOVED TO THE EASTERNMOST PART OF THIS AREA OF CYCLONIC FLOW
AND IT IS THE ONE WHICH HAS BEEN SUPPORTING THE SURFACE COLD
FRONT THROUGH 32N40W TO 23N50W TO THE CARIBBEAN SEA NEAR
18N60W...AND 17N67W. A SURFACE TROUGH...TO THE EAST OF THIS
FRONT...IS ALONG 31N35W 22N40W 16N50W 12N60W TO NORTHWESTERN
VENEZUELA 11N70W. THE NEXT MIDDLE TO UPPER LEVEL TROUGH PASSES
THROUGH 33N56W TO 26N61W...THE SOUTHERN BAHAMAS...EVENTUALLY
WORKING ITS WAY INTO THE CARIBBEAN SEA JUST WEST OF JAMAICA...
AND TO THE EASTERN HONDURAS/NORTHEASTERN NICARAGUA BORDER. THIS
TROUGH SUPPORTS A SECOND SURFACE COLD FRONT...WHICH JUST IS
MAKING ITS WAY INTO THE AREA...THROUGH 32N54W TO 30N62W BEYOND
32N72W. MIDDLE TO UPPER LEVEL DRY AIR NORTH OF 20N WEST OF 40W.
ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS
WITHIN 60 TO 120 NM ON EITHER SIDE OF 32N34W 27N34W 20N37W...
AND WITHIN 60 TO 120 NM ON EITHER SIDE OF 22N40W 18N50W 14N60W
11N72W. NO DEEP CONVECTIVE ACTIVITY YET WITH THE 32N54W 32N72W
COLD FRONT.

THE TROPICAL ATLANTIC OCEAN...
SURFACE RIDGE 10N52W 18N34W 26N28W BEYOND 32N25W. UPPER LEVEL
ANTICYCLONIC FLOW IMMEDIATELY EAST OF THE 40W CYCLONIC FLOW
REACHES THE CAPE VERDE ISLANDS...ANTICYCLONIC CENTER NEAR
18N42W. MIDDLE TO UPPER LEVEL TROUGH FROM 18N20W...OVER THE
CANARY ISLANDS...TO THE MADEIRA ISLANDS. UPPER LEVEL
ANTICYCLONIC FLOW IS OVER AFRICA EAST OF THIS 19N21W-TO-
CANARY ISLANDS TROUGH.

$$
MT



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