[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED APR 18 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...THE ITCZ...
7N7W 3N20W...CROSSING THE EQUATOR AT 27W...TO 3S36W AND FINALLY
TO 4S44W IN NORTHEASTERN BRAZIL. STRONG SHOWERS AND THUNDERSTORMS
IN INDIVIDUAL CELLS WITHIN 30 NM RADIUS OF 1N6W AND 1N10W. OTHER
ISOLATED MODERATE SHOWERS ARE FROM 3N TO 5N BETWEEN 6W AND 12W.
ISOLATED MODERATE SHOWERS FROM THE EQUATOR TO 6N BETWEEN 13W AND
40W.

...DISCUSSION...

THE GULF OF MEXICO...
GRADUAL AND EVER-SO-SLIGHT UPPER LEVEL ANTICYCLONIC WIND FLOW
COVERS THE GULF WATERS...AS THE LATEST MIDDLE TO UPPER LEVEL
TROUGH MOVES ARKANSAS/LOUISIANA/MISSISSIPPI. THE COLD FRONT
BEING SUPPORTED BY THE MIDDLE TO UPPER LEVEL TROUGH WAS STILL
INLAND AT 18/0600 UTC...AND IT HAS REACHED THE NORTHWESTERN GULF
OF MEXICO WATERS AT 18/0900 UTC. VIRTUALLY NO SURFACE PRESSURE
GRADIENT EXISTS IN THE GULF AT THIS TIME AS NO ISOBAR WAS DRAWN
THERE ON THE SURFACE MAP ANALYSIS. A 1012 MB HIGH PRESSURE
CENTER IS NEAR 22N82W BETWEEN CUBA AND THE ISLE OF YOUTH.

THE CARIBBEAN SEA...
MIDDLE TO UPPER LEVEL DRY AIR ALREADY IS IN PLACE IN THE
CARIBBEAN SEA. BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
THE AREA. MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE IS
EVERYWHERE. THE SOUTHERNMOST POINT OF THE ATLANTIC OCEAN COLD
FRONT PASSES THROUGH 22N60W TO THE VIRGIN ISLANDS TO
17N73W...BECOMING A TROUGH FROM 17N73W TO 17N80W...TO THE
NORTHERN HONDURAS COAST NEAR 16N86W TO SOUTHERN GUATEMALA NEAR
15N91W. THIS TROUGH WAS NOT INCLUDED IN THE 18/0900 UTC SURFACE
MAP ANALYSIS. BROKEN TO OVERCAST LOW TO MIDDLE LEVEL CLOUDS AND
POSSIBLE PRECIPITATION ARE WITHIN 60 TO 90 NM ON EITHER SIDE OF
23N56W 20N61W...AND FROM THE VIRGIN ISLANDS TO PUERTO RICO
WESTWARD TO HISPANIOLA.

THE ATLANTIC OCEAN...
DEEP LAYER CYCLONIC FLOW COVERS THE AREA NORTH OF 20N WEST OF 50W
WITH THE DEEP LAYER CYCLONIC CIRCULATION CENTER AND TROUGH THAT
HAVE BEEN BRINGING STORMY WEATHER FROM THE U.S.A. EAST COAST
INTO THE ATLANTIC OCEAN. THE WESTERN ATLANTIC OCEAN CYCLONIC
CENTER AND TROUGH ARE SUPPORTING THE COLD FRONT THAT PASSES
THROUGH 32N52W TO 22N60W TO THE VIRGIN ISLANDS...SOUTHEASTERN
PUERTO RICO...AND EVENTUALLY 17N73W. ISOLATED MODERATE SHOWERS
AND POSSIBLE THUNDERSTORMS ARE WITHIN 30 TO 60 NM ON EITHER SIDE
OF 23N56W 27N51W...AND WITHIN 60 TO 90 NM ON EITHER SIDE OF
27N51W BEYOND 32N47W. BROKEN TO OVERCAST LOW TO MIDDLE LEVEL
CLOUDS AND POSSIBLE PRECIPITATION ARE WITHIN 60 TO 90 NM ON
EITHER SIDE OF 23N56W 20N61W...AND FROM THE VIRGIN ISLANDS TO
PUERTO RICO WESTWARD TO HISPANIOLA. A SHORTWAVE MIDDLE TO UPPER
LEVEL TROUGH GOES FROM A 33N28W CYCLONIC CIRCULATION CENTER TO
28N30W. THE DEEP LAYER CYCLONIC CIRCULATION CENTER AND TROUGH
FROM 24 HOURS AGO HAVE MOVED EASTWARD QUITE A BIT AND NOW ARE IN
NORTHERN AFRICA. AN UPPER LEVEL TROUGH IS IN THE TROPICAL JET
STREAM. BROAD WESTERLY FLOW FROM VENEZUELA AND GUYANA/SURINAME/
AND FRENCH GUIANA TO 2N43W 5N39W 20N30W BEYOND 24N20W. MIDDLE TO
UPPER LEVEL DRY AIR/SUBSIDENCE IS WITHIN 120 TO 240 NM NORTHWEST
OF THE JET STREAM EAST OF 33W...AND WITHIN 180 TO 240 NM WEST OF
THE JET STREAM BETWEEN 33W AND 44W.

$$
MT





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