[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 290008
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI APR 28 2006

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...WEATHER OBSERVATIONS...
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 4N5W 1N23W 1N32W 1N41W EQ50W.
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 60 NM OF THE
AXIS BETWEEN 9W-16W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 30 NM OF THE AXIS BETWEEN 30W-34W.
SCATTERED MODERATE CONVECTION IS NOTED FROM EQ-1N BETWEEN
35W-41W.

...DISCUSSION...
GULF OF MEXICO...
AN UPPER ANTICYCLONE IS CENTERED OVER THE E PAC NEAR 12N106W. A
RIDGE EXTENDS N ACROSS OLD MEXICO ALONG 22N102W...THEN SHARPENS
AS IT CRESTS NORTHEAST ACROSS CENTRAL TEXAS WITH MEAN RIDGE AXIS
FROM 32N96W TO 25N98W. THE UPPER FLOWS DIVES SOUTHEASTWARD ACROSS
THE EASTERN GULF TO ACROSS THE FLORIDA PENINSULA...CUBA...AND
THE YUCATAN PENINSULA. A MOISTURE PLUME...ORIGINATING FROM ITCZ
CONVECTION OVER THE E PACIFIC BETWEEN 108W-125W IS BEING EJECTED
NORTHEASTWARD AHEAD OF A MID/UPPER LEVEL TROUGH OVER THE EASTERN
PACIFIC ALONG THE PERIPHERY OF THE RIDGE...OR ROUGHLY WITHIN 250
NM EITHER SIDE OF LINE 21N110W TO 27N100W TO 32N91W TO 29N84W
WHERE IT EVAPORATES. MODERATE SUBSIDENCE AND ASSOCIATED DRY IS
INHIBITING ANY CONVECTION FROM DEVELOPING OVER THE GULF AT THIS
TIME. ONLY SCATTERED LOW CLOUDS MOVING QUICKLY NORTH AND
NORTHWEST IN RETURN SOUTHERLY FLOW ARE NOTED ON THE LAST FEW
FRAMES OF VISIBLE IMAGERY OVER THE CENTRAL AND WESTERN GULF. AT
THE SURFACE..HIGH PRESSURE RIDGING IS BUILDING SOUTHWARD THROUGH
21N83W TO 23N82W.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONE IS ESTIMATED NEAR 6N45W BASED ON
WATER VAPOR IMAGERY. BROAD MID/UPPER LEVEL RIDGING EXTENDS FROM
THE ANTICYCLONE NORTHWEST THROUGH 6N52W TO ACROSS VENEZUELA.
NORTH OF THE UPPER RIDGE...A SHORTWAVE TROUGH IS NOTED WITH ITS
MEAN AXIS EXTENDING SOUTHWEST FROM THE DOMINICAN REPUBLIC TO
16N74W TO 14N80W. A JET STREAM BRANCH WITH MAXIMUM WINDS 70-90 KT
ROUNDS THE BASE OF THIS TROUGH FROM 12N75W THROUGH 15N65W AND
NORTHEAST ACROSS THE LEEWARD ISLANDS. CONFLUENT FLOW ON THE BACK
SIDE OF THE TROUGH IS USHERING IN MODERATE TO STRONG SUBSIDENCE
AND ASSOCIATED DRY AIR ACROSS ALMOST THE ENTIRE WESTERN AND
CENTRAL PORTION OF THE CARIBBEAN SEA. ONLY SIGNIFICANT CONVECTION
OVER SEA ALREADY OCCURRED...AND THAT WAS OVER THE ISLANDS OF
HISPANIOLA...JAMAICA AND PUERTO RICO AND EASTERN CUBA. THIS
ACTIVITY IS FADING OUT QUICKLY NOW THAT DAYTIME HEATING HAS
BEEN LOST. RESULTANT DEBRIS MOISTURE IS SEEN MOVING QUICKLY
SOUTHEASTWARD AWAY FROM THESE ISLANDS. WIDELY SCATTERED SHOWERS
ARE SEEN PRIMARILY NORTH OF 16.5N AND EAST OF 66W. ELSEWHERE
...ONLY SCATTERED LOW CLOUDS WITH SOME ISOLATED SHOWERS ARE
MOVING WESTWARD IN LIGHT TRADE WIND FLOW ACROSS THE SEA.

ATLANTIC OCEAN...
THE WESTERN SW N ATLC IS UNDER UPPER LEVEL NORTHWESTERLY FLOW
WHICH MARKS THE WESTERN EXTENT OF BROAD CYCLONIC FLOW DUE TO A
RATHER VIGOROUS SHORTWAVE TROUGH WITH ITS MEAN AXIS EXTENDING
ROUGHLY FROM 32N70W TO 20N74W. THE CYCLONIC FLOW EXTENDS
EASTWARD TO 60W. DIFFLUENCE INDICATED EAST OF THE TROUGH
CONTINUES TO ENHANCE CONVECTION WELL EAST OF A SURFACE COLD
FRONT THAT EXTENDS FROM A GALE CENTER NEAR 32N70W 1007 MB
THROUGH 27N70W TO EASTERN CUBA WHERE IT IS BECOMING ILL-DEFINED.
THIS CONVECTION CONSISTS OF THE SCATTERED MODERATE/ISOLATED
STRONG TYPE AND IS FOUND GENERALLY WITHIN AN AREA BOUNDED FROM
24N-30N BETWEEN 60W-67W. WIDELY SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE SEEN SOUTH OF 24N BETWEEN 60W-65W. ONLY
ISOLATED SHOWERS AND THUNDERSTORMS ARE ALONG AND WITHIN ABOUT 60
NM EAST OF THE COLD FRONT FROM 23N-26N. SCATTERED TO BROKEN LOW
CLOUDS WITH ISOLATED SHOWERS MOVING SOUTH-SOUTHEAST IN CYCLONIC
FLOW DUE TO THE GALE CENTER ARE PRESENT WEST OF THE COLD FRONT
NORTH OF 23N.

TO THE EAST OF THE SHORTWAVE TROUGH...A RATHER COMPACT MID/UPPER
LEVEL RIDGING IS SEEN NORTH OF 19N BETWEEN 53W-60W. EAST OF THIS
RIDGE...A LONGWAVE TROUGH CONTINUES TO DOMINATE THE CENTRAL NORTH
ATLANTIC. AN EMBEDDED CYCLONE MOVING WESTWARD 15 KT IS NOTED
NEAR 25N45W. MODERATE SUBSIDENCE AND DRY AIR IS NOTED NORTH OF
20N BETWEEN 50W-60W. AT THE SURFACE...HIGH PRESSURE RIDGING
EXTENDS THROUGH 32N52W TO 27N63W. HIGH PRESSURE COVERS THE AREA
NORTH OF 20N EAST OF 62W.

OVER THE FAR EASTERN ATLANTIC...AN UPPER LEVEL ANTICYCLONE IS
ESTIMATED OVER AFRICA NEAR 9N7W WITH A RIDGE EXTENDING WESTWARD
THROUGH 8N25W TO 8N38W. DEBRIS MOISTURE FROM CONVECTION OF SOUTH
AMERICA...AND THE ITCZ BETWEEN 24W AND 35W...IS STREAMING
NORTHEAST ACROSS THE TROPICAL ATLC WATERS SOUTH OF 19N EAST OF
36W.

$$
AGUIRRE


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