[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041758
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON 04 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 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1715 UTC.

...SPECIAL FEATURES...
NONE.

...TROPICAL WAVES...
THE TROPICAL WAVE WHICH WAS ALONG 40W/43W AT 04/0600 UTC HAS
BEEN DROPPED FROM THE 04/1200 SURFACE MAP ANALYSIS AS IT WAS
NOT DISCERNIBLE AT THE TIME. IT WAS REPLACED BY A SURFACE
TROUGH...WHICH SHOWED UP WELL IN THE VISIBLE SATELLITE
IMAGERY...ALONG 26N41W 22N44W 17N48W. A MIDDLE TO UPPER LEVEL
TROUGH RUNS FROM A SMALL SIZED CYCLONIC CIRCULATION CENTER NEAR
32N55W TO A SECOND SIMILAR CYCLONIC CENTER NEAR 25N59W...THROUGH
THE MONA PASSAGE...INTO THE CARIBBEAN SEA NEAR 13N71W. AN UPPER
LEVEL RIDGE IS TO THE EAST OF THIS TROUGH...AND IT IS THIS UPPER
LEVEL RIDGE WHICH IS ON TOP OF THE AREA OF THE 26N41W 17N48W
SURFACE TROUGH. THE UPPER LEVEL FLOW IS SHEARING THE HIGHEST
CLOUD TOPS...WHICH ARE PRODUCING ISOLATED MODERATE TO LOCALLY
STRONG SHOWERS AND THUNDERSTORMS FROM 16N TO 18N BETWEEN 40W AND
50W...AND ISOLATED MODERATE SHOWERS FROM 20N TO 26N BETWEEN 38W
AND 47W.

TROPICAL WAVE ALONG 51W/52W SOUTH OF 18N MOVING WEST 10 KT. THIS
WAVE IS ASSOCIATED WITH A WEAK AREA OF LOW PRESSURE...A CYCLONIC
SWIRL OF CLOUDS IN THE VISIBLE IMAGERY...NEAR 13N51W. ISOLATED
TO WIDELY SCATTERED MODERATE/LOCALLY STRONG SHOWERS AND
THUNDERSTORMS FROM 10N TO 16N BETWEEN 46W AND 56W. THE CYCLONIC
SWIRL IN VISIBLE IMAGERY HAS BEEN FOLLOWED FOR AT LEAST THE
LAST 24 HOURS.

TROPICAL WAVE 76W/77W SOUTH OF 20N MOVING WEST 10 TO 15 KT.
THIS WAVE SPENT THE LAST 24 TO 48 HOURS MOVING THROUGH THE BASE
OF A MIDDLE TO UPPER LEVEL TROUGH FROM 32N55W TO 25N59W 13N71W.
UPPER LEVEL NORTHWESTERLY WINDS STILL CUT ACROSS THE WAVE AT
THIS TIME. THE TOPS OF THE CLOUDS PRODUCING THE ISOLATED MODERATE
SHOWERS AND THUNDERSTORMS...NOW FROM 14N TO 17N BETWEEN 76W AND
82W...ARE BEING SHEARED BY THIS UPPER LEVEL FLOW.

TROPICAL WAVE 95W/96W SOUTH OF 22N MOVING WEST 10 TO 15 KT.
MOST OF THE DEEP LAYER FLOW IN THIS PART OF EASTERN MEXICO IS
FROM THE NORTHEAST TO EAST...UP TO AT LEAST 300 MB. THE FLOW
HIGHER THAN 300 MB IS WESTERLY. A SMALL BIT OF A RIDGE HAS
DEVELOPED IN THE SOUTHWESTERN CORNER OF THE GULF OF CAMPECHE.
SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS
HAVE DEVELOPED FROM 23N/24N SOUTHWARD TO LAND BETWEEN 92W AND
THE MEXICO COAST NEAR 98W. THIS SYSTEM IS EXPECTED TO MOVE OVER
EASTERN MEXICO DURING THE NEXT DAY OR SO WITHOUT SIGNIFICANT
DEVELOPMENT.

...ITCZ...
ITCZ 13N16W 6N27W 6N49W...6N53W 10N63W...AND IN THE SOUTHWESTERN
CARIBBEAN SEA FROM 11N75W TO 10N80W TO 10N85W. THE CLOUD TOP
TEMPERATURES OF THE CLOUDS FOR THE NUMEROUS STRONG SHOWERS AND
THUNDERSTORMS FROM 7N TO 11N BETWEEN 77W AND 81W AT 04/1215 UTC
HAVE BEEN WARMING SIGNIFICANTLY DURING THE LAST SEVERAL HOURS.
RESIDUAL SHOWERS AND THUNDERSTORMS ARE IN THAT AREA. NEWER STRONG
SHOWERS AND THUNDERSTORMS IN THE EASTERN PACIFIC OCEAN HAVE
DEVELOPED RECENTLY WITHIN 50 NM RADIUS OF 7N82.5W...AND IN
PACIFIC COASTAL SECTIONS OF PANAMA AND COSTA RICA FROM 8N TO 9N.
SHOWERS AND THUNDERSTORMS IN SOUTHEASTERN NICARAGUA COASTAL
SECTIONS HAVE WEAKENED...AND OTHERS HAVE RE-DEVELOPED IN
NICARAGUA COASTAL SECTIONS FROM 12N TO 14N.

...DISCUSSION...
THE GULF OF MEXICO...
MIDDLE TO UPPER LEVEL WESTERLY WINDS FROM MEXICO NORTH OF
26N104W...ACROSS THE GULF WATERS NORTH OF 26N92W BEYOND 28N80W.
A SEPARATE UPPER LEVEL ANTICYCLONIC CIRCULATION HAS DEVELOPED
IN THE SOUTHWESTERN CORNER OF THE GULF OF MEXICO. UPPER LEVEL
NORTHWESTERLY WINDS FROM THIS ANTICYCLONE CONTINUE OVER THE
YUCATAN PENINSULA AND THE YUCATAN CHANNEL INTO THE CARIBBEAN
SEA...AND ULTIMATELY SOUTHEASTWARD TO THE BASE OF THE 32N55W
13N71W MIDDLE TO UPPER LEVEL TROUGH. SURFACE TROUGH FROM FLORIDA
NEAR 30N83W INTO THE GULF OF MEXICO NEAR 25N85W...ANALYZED IN
THE WIND AND PRESSURE FIELD AT 04/1200 UTC...WAS NOT APPARENT IN
THE 04/1500 UTC SURFACE MAP ANALYSIS. NO DEEP THUNDERSTORMS.

THE CARIBBEAN SEA...
UPPER LEVEL NORTHWESTERLY WIND FLOW IN THE NORTHWESTERN
CORNER...MOVING TOWARD THE BASE OF THE 32N55W 13N71W TROUGH.
UPPER LEVEL DIFFLUENT FLOW IN THE SOUTHWESTERN CORNER OF THE
CARIBBEAN SEA...AS UPPER LEVEL ANTICYCLONIC FLOW ORIGINATING
IN CENTRAL PANAMA MOVES INTO THE SOUTHERN CARIBBEAN WATERS.
SOME OF THIS FLOW CONTINUES EASTWARD...WHILE OTHER PARTS OF
THE FLOW MOVE TOWARD NICARAGUA AND HONDURAS. THE 76W/77W
TROPICAL WAVE IS SET TO MOVE INTO THIS AREA DURING THE NEXT
TWENTY FOUR HOURS. A MIDDLE TO UPPER LEVEL TROUGH RUNS FROM
A SMALL SIZED CYCLONIC CIRCULATION CENTER NEAR 32N55W TO
A SECOND SIMILAR CYCLONIC CENTER NEAR 25N59W...THROUGH THE
MONA PASSAGE...INTO THE CARIBBEAN SEA NEAR 13N71W. ISOLATED
MODERATE SHOWERS AND THUNDERSTORMS SOUTHEAST OF 16N72W 20N63W.

THE SUBTROPICAL ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH HAS MOVED OFF THE COAST OF THE
MIDDLE ATLANTIC STATES OF THE U.S.A...SUPPORTING A SURFACE COLD
FRONT WHICH RUNS THROUGH 32N69W 30N75W 29N81W. SHOWERS AND
THUNDERSTORMS...WHICH WERE MORE ABUNDANT SIX HOURS AGO FROM
29.5N TO 31N BETWEEN 71W AND 80W...HAVE BEEN DISSIPATING DURING
THAT TIME PERIOD. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS
AND THUNDERSTORMS ARE IN THE ATLANTIC OCEAN WITHIN 60 TO 90 NM
ON EITHER SIDE OF 15N60W 18N57W 22N55W 26N55W...AND FROM 25N TO
29N BETWEEN 50W AND 58W. OVERCAST HIGH LEVEL CLOUDS NORTH OF 30N
BETWEEN 47W AND 55W. A MIDDLE TO UPPER LEVEL TROUGH RUNS FROM
A SMALL SIZED CYCLONIC CIRCULATION CENTER NEAR 32N55W TO A
SECOND SIMILAR CYCLONIC CENTER NEAR 25N59W...THROUGH THE MONA
PASSAGE...INTO THE CARIBBEAN SEA NEAR 13N71W. TROUGH RUNS FROM
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR
30N17W...JUST NORTH OF THE CANARY ISLANDS...TO 24N28W TO 19N33W.
BROAD MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW IN BETWEEN THIS
TROUGH AND THE 32N55W 13N71W TROUGH.

THE TROPICAL ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC FLOW SOUTHEAST OF THE 30N17W 24N28W
19N33W TROUGH...EAST OF 30W.

$$
MT


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