[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 010535
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON 01 NOV 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED OVER THE E CARIBBEAN IS ALONG 65W S OF 20N
MOVING W 10 KT. THE WAVE IS ENTANGLED WITHIN A BROAD FRONTAL
ZONE WHICH STRETCHES ACROSS AND JUST TO THE N OF THE EASTERN
GREATER ANTILLES...MAKING ITS EXACT LOCATION RATHER UNCERTAIN.
THE AREA ALSO LIES UNDER THE ENTRANCE REGION OF A 50-70 KT UPPER
LEVEL JET WHICH EXTENDS NE OF PUERTO RICO AND THIS HAS HELPED TO
INDUCE CONVECTIVE ACTIVITY OVER A LARGE AREA SURROUNDING THE
WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
17N-22N BETWEEN 61W-67W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS COVER THE AREA FROM 10N-20N BETWEEN 56W-68W
INCLUDING THE THE LESSER ANTILLES.

TROPICAL WAVE LOCATED OVER THE W CARIBBEAN AND CENTRAL AMERICA
IS ALONG 85W/86W S OF 20N MOVING W 5-10 KT. THE BROAD WAVE AXIS
EXTENDS FROM THE YUCATAN CHANNEL S ACROSS CENTRAL HONDURAS AND
NICARAGUA WITH A LINE OF SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 14N-22N BETWEEN 82W-86W.

...ITCZ...

ITCZ AXIS IS ALONG 12N10W 8N20W 8N40W 5N31W 9N44W 12N63W.
SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 45 NM OF LINE
11N59W-12N63W INCLUDING PORTIONS OF TRINIDAD AND THE WINDWARD
ISLANDS. CLUSTERS OF SIMILAR CONVECTION ARE FROM 2N-10N BETWEEN
20W-35W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
75/90 NM OF LINE 9N38W-10N47W. CLUSTERS OF SIMILAR CONVECTION
ARE FROM 2N-10N BETWEEN 35W-45W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 2N-11N BETWEEN 5W-18W INCLUDING THE COASTAL
REGIONS OF W AFRICA.

...DISCUSSION...

GULF OF MEXICO AND W ATLANTIC...
BROAD MID/UPPER LEVEL HIGH COVERS THE AREA N OF 22N FROM
70W-100W AND CENTERED OFF THE W COAST OF FLORIDA EXTENDING N TO
OVER THE E UNITED STATES. ABUNDANT DRY AIR AND STRONG SUBSIDENCE
COVERS THE AREA WITH ONLY LOW LEVEL ISOLATED SHOWERS OVER THE NW
GULF MOVING INLAND OVER LOUISIANA AND E TEXAS. THE STATIONARY
FRONT REMAINS INLAND OVER CENTRAL TEXAS AND A COLD FRONT IS
FORECAST TO MOVE OFF THE TEXAS COAST EARLY TUESDAY...BUT
SHOWERS/THUNDERSTORMS WILL BEGIN TO MOVE OFF THE COAST BEGINNING
LATER TODAY...SPREADING E TO FLORIDA THROUGH WEDNESDAY AND
THURSDAY. HIGH PRESSURE IS OVER THE W ATLC ANCHORED BY A 1023 MB
HIGH SE OF BERMUDA NEAR 30N61W AND PRESSURES OVER THE GULF ARE
BEGINNING TO DROP AS THE FRONTAL SYSTEM OVER THE CENTRAL UNITED
STATES WILL BEGIN TO SHIFT EAST.

CARIBBEAN...
UNSETTLED WEATHER SPANS MOST OF THE CARIBBEAN SEA TONIGHT AS A
THE TWO TROPICAL WAVES MOVE ACROSS THE AREA AMONG A DISSIPATING
FRONTAL BOUNDARY N OF PUERTO RICO AND THE NORTHERN LEEWARD
ISLANDS. WATER VAPOR IMAGERY INDICATES MOIST UPPER LEVEL
WESTERLY FLOW COVERING MUCH OF THE AREA WITH MID/UPPER LEVEL
TROUGH EXTENDING FROM N OF THE LEEWARD ISLANDS TO AN UPPER LOW
NOW ALONG THE S COAST OF THE DOMINICAN REPUBLIC AS DRY AIR
SURGES S ACROSS THE CENTRAL CARIBBEAN. THIS CIRCULATION/TROUGH
IS STRENGTHENING VERTICAL LIFT OVER THE E CARIBBEAN AND
PRODUCING AN ENVIRONMENT FAVORABLE FOR WIDESPREAD CONVECTION. IN
ADDITION...A 50-70 KT WESTERLY JET EXTENDS NE OF PUERTO RICO AND
BROAD SCALE LIFTING WITHIN THE RIGHT FRONT QUADRANT IS ENHANCING
CONVECTION NEAR PUERTO RICO AND THE VIRGIN ISLANDS. IT IS ALSO
INTERESTING TO NOTE THAT STRONG VERTICAL SHEAR EXTENDS ACROSS
THE ENTIRE LENGTH OF THE BASIN SINCE THE UPPER LEVEL WESTERLY
FLOW LIES ABOVE DEEPER LOW/MID-LEVEL EASTERLY FLOW.

CENTRAL/EASTERN ATLANTIC...
DEEP LAYERED TROUGH COVERS THE CENTRAL ATLC N OF 22N FROM
35W-70W USHERING IN DRIER AIR AND MODERATE SUBSIDENCE FROM
23N-30N BETWEEN 43W-70W. DISSIPATING COLD FRONT EXTENDS THROUGH
32N35W SW TO 25N50W WHERE IT CONTINUES AS A DISSIPATING
STATIONARY FRONT W ALONG 23N65W TO THE N COAST OF HISPANIOLA. A
SECOND SURGE IN THE FORM OF A COLD FRONT EXTENDS THROUGH 32N41W
SW TO 26N52W THEN AS A SURFACE TROUGH TO 26N65W. OVER THE E ATLC
STRONG UPPER LEVEL RIDGING IS CENTERED ALONG 22W AND TRANSITIONS
TO A DEEP TROUGH OVER NW AFRICA. AT THE SURFACE...A RIDGE
EXTENDS FROM A 1022 MB HIGH NEAR MADEIRA ISLANDS SW ALONG 26N30W
TO A 1021 MB HIGH NEAR 24N43W. DRY UPPER LEVEL AIR WITH STRONG
SUBSIDENCE COVERS THE FAR E ATLC N FROM 10N-30N E OF 27W TO
INLAND OVER AFRICA WITH SCATTERED LOW CLOUDS AND POSSIBLE
ISOLATED SHOWERS.

TROPICAL ATLANTIC...
BROAD UPPER LEVEL WESTERLIES ARE EXTENDING FROM OVER THE E
CARIBBEAN OVER THE TROPICAL ATLC WATERS WITH ABUNDANT MOISTURE
SPREADING AS FAR E AS 26W. FARTHER E...A WEAKENING NW/SE TILTED
SHORTWAVE TROUGH ALONG 22N30W 13N25W IS BEING UNDERCUT BY THE
WESTERLY FLOW TO THE W AND IS LIFTING TO THE N. THIS FEATURE IS
MOVING INTO THE DRIER AIR HENCE CONVECTIVE ACTIVITY ALONG THE
ITCZ IN THIS AREA HAS BEEN MORE LIMITED.

$$
WALLACE


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