[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT 16 APR 2005

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 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1715 UTC.

...THE ITCZ...

ITCZ 7N10W 5N20W 3N30W 3N40W TO THE EQUATOR AT 50W AND THE
EQUATOR AT 53W. WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED
STRONG SHOWERS AND THUNDERSTORMS FROM 1N TO 3N BETWEEN 5W AND
8W...FROM 2N TO 4N BETWEEN 17W AND 20W...SOUTH OF 5N BETWEEN
30W AND 47W...AND FROM 3N TO 6N BETWEEN 47W AND 54W.

...DISCUSSION...

FROM THE EASTERN PACIFIC OCEAN INTO THE GULF OF MEXICO...
MIDDLE LEVEL TROUGH RUNS FROM A CYCLONIC CIRCULATION CENTER IN
NORTHWESTERN ARIZONA TO NORTHWESTERN BAJA CALIFORNIA TO 30N118W.
THE SOUTHWESTERLY FLOW ON THE SOUTHEASTERN SIDE OF THIS TROUGH
IS MERGING WITH THE BROAD MOSTLY UPPER LEVEL SOUTHWESTERLY-TO-
WESTERLY WIND FLOW IN THE EASTERN PACIFIC OCEAN WHICH IS MOVING
TOWARD MEXICO. AN UPPER LEVEL RIDGE GOES FROM JUST SOUTH OF THE
SOUTHERN TIP OF BAJA CALIFORNIA NEAR 20N110W ACROSS NORTHWESTERN
INTERIOR MEXICO BEYOND THE TEXAS PANHANDLE. UPPER LEVEL
NORTHWESTERLY WIND FLOW ON THE EASTERN SIDE OF THIS RIDGE COVERS
THE REST OF INTERIOR MEXICO LEADING INTO THE GULF OF MEXICO.
ONE SURFACE RIDGE EXTENDS THROUGH CENTRAL LOUISIANA TO THE
NORTHWESTERN GULF OF MEXICO TO THE SOUTHWESTERN CORNER OF THE
AREA. ANOTHER SURFACE RIDGE EXTENDS THROUGH SOUTH CENTRAL
GEORGIA TO SOUTH FLORIDA TOWARD THE BAHAMAS. THE MIDDLE TO UPPER
LEVEL WIND FLOW ON TOP OF THE SURFACE RIDGES IS CYCLONIC OWING
TO THE INFLUENCE OF A DEEP LAYER TROUGH IN THE WESTERN ATLANTIC
OCEAN. THE TROUGH PASSES THROUGH WESTERN GEORGIA AND DISAPPEARS
IN THE NORTH CENTRAL GULF WATERS.

THE CARIBBEAN SEA...
A DEEP LAYER TROUGH RUNS FROM THE WESTERN ATLANTIC OCEAN TO
WESTERN GEORGIA TO THE NORTH CENTRAL GULF OF MEXICO. BROAD
MIDDLE TO UPPER LEVEL CYCLONIC WIND FLOW COVERS THE GULF OF
MEXICO. THIS TROUGH SUPPORTS THE SURFACE STATIONARY FRONT
WHICH CROSSES THROUGH 20N70W TO THE DOMINICAN REPUBLIC AND
HAITI...TO 18N75W. A SURFACE TROUGH CONTINUES FROM 18N75W...
IN THE WATERS BETWEEN HAITI AND JAMAICA...GRAZING THE EASTERN
COAST OF JAMAICA TO 17N80W...TO NORTHEASTERN NICARAGUA...TO
NORTHWESTERN NICARAGUA. LARGE SCALE UPPER LEVEL ANTICYCLONIC
FLOW IS OVER THE CARIBBEAN SEA...ON THE PERIPHERY OF AN UPPER
LEVEL RIDGE FROM SOUTH AMERICA NORTH OF 10N. HIGH CLOUDS CURVE
ANTICYCLONICALLY FROM THE SOUTHWESTERN CORNER TO THE NORTH
CENTRAL TO THE EASTERN CARIBBEAN ISLANDS...WITHIN 30 TO 40 NM
ON EITHER SIDE OF 15N82W 17N77W 18N70W 16N63W BEYOND 16N60W.
BROKEN LOW TO MIDDLE LEVEL CLOUDS AND POSSIBLE PRECIPITATION
ARE SOUTH OF 20N AND TO THE RIGHT OF THE LINE 20N65W 18N71W
16N81W 19N80W 21N78W. EARLIER SHOWERS AND THUNDERSTORMS...
WHICH WERE SOUTH OF 11N BETWEEN 80W AND 84W...HAVE WEAKENED
SINCE THEN...AND NOW ONLY SHOWERS AND THUNDERSTORMS ARE SEEN
FROM 9N TO 10N BETWEEN 80W AND 81W. REMNANT CLOUDINESS FROM
THE WEAKENED AREA OF SHOWERS FROM 4 HOURS AGO IS SOUTH OF 13N
WEST OF 80W.

THE ATLANTIC OCEAN...
A DEEP LAYER TROUGH...ORIGINATING FROM ONE DEEP LAYER CYCLONIC
CIRCULATION CENTER NEAR 36N66W TO A SECOND ONE NEAR 33N70W TO
32N77W TO WESTERN GEORGIA AND INTO THE GULF OF MEXICO. DEEP
LAYER CYCLONIC FLOW COVERS THE ATLANTIC WATERS WEST AND NORTHWEST
OF 32N61W 23N65W 22N72W. MIDDLE TO UPPER LEVEL DRY AIR IS SOUTH
OF 31N WEST OF THE 32N61W 22N72W LINE...AND THE SAME DRY AIR HAS
MADE IT NORTH OF 31N BETWEEN 61W AND 70W...WORKING ITS WAY AROUND
THE EASTERN SIDE OF THE CIRCULATION CENTERS. THIS DEEP LAYER
TROUGH SUPPORTS THE 1008 MB STORM CENTER NEAR 32N71W AND
STATIONARY FRONT THROUGH 32N62W 25N65W TO 20N70W...ACROSS THE
DOMINICAN REPUBLIC AND HAITI...TO 18N75W. A SURFACE TROUGH
CONTINUES FROM 18N75W...IN THE WATERS BETWEEN HAITI AND
JAMAICA...GRAZING THE EASTERN COAST OF JAMAICA TO 17N80W...TO
NORTHEASTERN NICARAGUA...TO NORTHWESTERN NICARAGUA. AN UPPER
LEVEL RIDGE IS JUST EAST OF THE DEEP LAYER TROUGH FROM 21N63W
TO 28N59W BEYOND 32N58W. MIDDLE LEVEL CYCLONIC FLOW IN A CENTRAL
ATLANTIC OCEAN TROUGH SHOWS UP IN THE 16/1500 UTC CIMSS
SATELLITE DERIVED WIND DATA FROM 23N30W TO 19N40W TO 14N46W.
A MIDDLE TO UPPER LEVEL TROUGH EXTENDS THROUGH 30N10W TO 27N14W
TO 24N20W. A SURFACE RIDGE RUNS FROM AN 1033 MB HIGH PRESSURE
CENTER NEAR 35N30W 32N37W 29N44W 27N50W 22N55W INTO THE EASTERN
CARIBBEAN SEA NEAR 16N64W. UPPER LEVEL NORTHWESTERLY TO WESTERLY
WIND FLOW IN THE TROPICS IS BLOWING RIGHT ON TOP OF THE ITCZ
WEST OF 37W...BECOMING SOUTHEASTERLY UPPER LEVEL WIND FLOW EAST
OF 37W IN THE TROPICS.

$$
MT

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