[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 231236
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI SEP 23 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...SPECIAL FEATURES...

HURRICANE RITA IS CENTERED NEAR 27.1N 91.5W OR ABOUT 225 NM
SE OF GALVESTON TEXAS AND 190 NM SSE OF CAMERON LOUISIANA AT
23/1200 UTC MOVING NW AT 8 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 930 MB. MAXIMUM SUSTAINED WIND SPEED IS 120 KT
WITH GUSTS TO 145 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY
UNDER HEADERS MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. RITA
REMAINS A DANGEROUS CATEGORY 4 HURRICANE ON THE SAFFIR-SIMPSON
SCALE WITH A 30 NM EYE. POSSIBILITY OF UPPER SHEAR STILL EXISTS.
SCATTERED MODERATE/STRONG CONVECTION COVERS THE AREA FROM
25N-30N BETWEEN 87W-94W. OUTER RAINBANDS OF SCATTERED
SHOWERS/THUNDERSTORMS EXTEND EVEN FURTHER OUT N OF 23N TO INLAND
OVER THE N GULF COAST PENSACOLA FLORIDA TO CENTRAL LOUISIANA.

TROPICAL STORM PHILIPPE IS CENTERED NEAR 30.5N 60.3W OR 260 NM
ESE OF BERMUDA AT 23/0900 UTC MOVING WNW AT 16 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND
SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE
DETAILS. BROAD...ELONGATED UPPER LEVEL LOW IS CENTERED TO THE SW
NEAR 26N63W AND CONTINUES TO DOMINATE THE AREA. THIS IS
PRODUCING STRONG S TO SW SHEAR OVER PHILIPPE AS IT BEGINS TO
DISPLAY MORE SUBTROPICAL CHARACTERISTICS RATHER THAN TROPICAL.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF
LINE 33N58W-31N62W AND 30N62W-27N65W.

...TROPICAL WAVES...

A 1008 MB LOW IS CENTERED NEAR 10N26W MOVING W 10 KT. VERY SMALL
LOW LEVEL SWIRL WITHIN A BROAD AREA OF LOW PRESSURE IS OBSERVED
ON VISIBLE SATELLITE IMAGERY. ASSOCIATED SCATTERED MODERATE/
STRONG CONVECTION IS N AND W OF THE LOW SWIRL WITHIN 90 NM OF
LINE 14N25W-13N28W-10N27W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM OF LINE
12N18W-14N25W.

CENTRAL ATLC TROPICAL WAVE IS ALONG 50W/51W S OF 20N MOVING W
10-15 KT. WELL-DEFINED SIGNATURE CURVATURE IS OBSERVED ON
INFRARED SATELLITE IMAGERY. WAVE IS BENEATH AN UPPER RIDGE IN NE
FLOW WITH WEAKENING DIFFLUENCE BUT GENERATING AN AREA OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 10-18N BETWEEN
46W-50W.

W ATLC TROPICAL WAVE IS ALONG 58W/59W S OF 14N MOVING W 10-15
KT. WEAK WAVE IS BENEATH A BROAD UPPER RIDGE WITH PREDOMINANTLY
E FLOW PARTIALLY MASKING ANY SIGNATURE ON SATELLITE IMAGERY. NO
ASSOCIATED DEEP CONVECTION.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 16N16W 8N34W 9N56W 10N64W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF THE ITCZ
AXIS FROM 38W-42W.

...DISCUSSION...

GULF OF MEXICO...
RITA CONTINUES TO DOMINATE THE WEATHER PICTURE THIS MORNING AS A
CAT 4 HURRICANE OVER THE NW GULF. RITA MAY CONTINUE TO FLUCTUATE
BUT IS STILL EXPECTED TO BE A MAJOR HURRICANE AT LANDFALL. AT
THE UPPER LEVELS...AN UPPER HIGH IS CENTERED NEAR HURRICANE RITA
AND DOMINATES THE NW GULF. A DEVELOPING UPPER HIGH IS IN THE
STRAITS OF FLORIDA WITH A RIDGE EXTENDING SW INTO THE CARIBBEAN.
THE UPPER LEVEL INVERTED TROUGH HAS MOVED SW OVER MEXICO. THE
DRY AIR REMAINS OVER THE SW GULF AS RITA CONTINUES MOVING TOWARD
THE TEXAS COAST MAKING LANDFALL DURING LATE TONIGHT INTO SAT
MORNING.

CARIBBEAN...
THE DEVELOPING UPPER HIGH OVER THE STRAITS OF FLORIDA EXTENDS A
RIDGE AXIS SW ACROSS THE CARIBBEAN THROUGH CUBA NEAR 22N80W TO
VENEZUELA NEAR LAKE MARACAIBO. BROAD UPPER LOW/TROUGH OVER THE
CENTRAL ATLC EXTENDS S OVER THE E CARIBBEAN TO 14N E OF 70W
ACROSS THE LEEWARD ISLANDS. ABUNDANCE OF TROPICAL MOISTURE
COVERS MOST OF THE CARIBBEAN BUT IS ONLY GENERATING CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS EXCEPT N OF A LINE FROM
HISPANIOLA NEAR 18N72W 15N77W TO CUBA NEAR 22N83W. THE STRONGEST
AND MOST CONDENSE AREA IS OVER NW VENEZUELA.

ATLANTIC...
UPPER HIGH IN ASSOCIATED WITH HURRICANE RITA IS GIVING THE W
ATLC OUTFLOW FROM THE STORM WITH BROAD ANTICYCLONIC FLOW W OF
73W. WIDELY SCATTERED SHOWERS ARE N OF 25N W OF 78W ACROSS THE
FLORIDA PENINSULA. BROAD UPPER LOW IS IN THE CENTRAL ATLC NEAR
26N63W WITH A TROUGH AXIS EXTENDING S INTO THE E CARIBBEAN
ACROSS PUERTO RICO. THIS UPPER LOW/TROUGH IS PROVIDING SW SHEAR
AND DRY UPPER AIR INTO T.S. PHILIPPE. AN UPPER HIGH IS OVER THE
W TROPICAL ATLC NEAR 20N55W EXTENDING A RIDGE NE TO BEYOND
32N50W PRODUCING BROAD AREA OF DIFFLUENCE AND ABLE TO GENERATE
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER
THE AREA WITHIN 200/225 NM OF LINE FROM THE LESSER ANTILLES NEAR
17N63W ALONG 24N55W TO 33N58W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE CLOSER TO THE UPPER LOW FROM 23N-30N BETWEEN
62W-68W. THE SUBTROPICAL RIDGE OVER THE E ATLC IS N OF 20N
BETWEEN AFRICA AND 50W WITH A 1028 MB HIGH ABOUT 550 NM SW OF
THE AZORES. OVER THE E ATLC...AN UPPER TROUGH OVER THE NE ATLC
EXTENDS FROM AN UPPER LOW MOVING S PORTUGAL ACROSS THE MADEIRA
ISLANDS THEN SW ALONG 24N32W TO 10N39W. THIS IS RESPONSIBLE FOR
A WEAK JET WITH WINDS TO 70 KT ON THE W SIDE TO THE BASE OF
THE UPPER TROUGH. AN UPPER HIGH IS LOCATED OVER W AFRICA WITH A
RIDGE EXTENDING W ACROSS THE CAPE VERDE ISLANDS TO 30W.

$$
WALLACE






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