[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 230546
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.

...SPECIAL FEATURES...

HURRICANE RITA IS CENTERED NEAR 26.4N 90.6W OR ABOUT 380 NM SE
OF GALVESTON TEXAS AND 250 NM SE OF CAMERON LOUISIANA AT 23/0600
UTC MOVING WNW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
921 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. RITA REMAINS AN IMPRESSIVE SYSTEM AND HAS RECENTLY WENT
THROUGH A CONCENTRIC EYEWALL CYCLE. FLUCTUATIONS IN INTENSITY
ARE EXPECTED OVER THE NEXT SEVERAL HOURS AS THE EYEWALL
CONSTRICTS...POSSIBILITY OF INCREASE IN UPPER SHEAR...AND
INCREASE IN SST ALONG THE PATH OF THE STORM WILL ALL HAVE AN
EFFECT RITA. SCATTERED STRONG CONVECTION IS WITHIN 75 NM FROM
THE CENTER ON ALL QUADRANTS. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERS THE AREA FROM 24N-30N BETWEEN 86W-93W. OUTER
RAINBANDS OF SCATTERED SHOWERS/THUNDERSTORMS EXTEND EVEN FURTHER
OUT BETWEEN THE N COAST OF THE YUCATAN PENINSULA TO JUST INLAND
OVER THE N GULF COAST FROM LOUISIANA TO OVER THE FLORIDA
PENINSULA.

TROPICAL STORM PHILIPPE IS CENTERED NEAR 28.8N 58.3W OR 390 NM
ESE OF BERMUDA AT 23/0300 UTC MOVING NNW AT 15 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1004 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 UPPER LEVEL LOW IS CENTERED TO THE SW NEAR 25N63W
AND CONTINUES TO DOMINATE THE AREA. THIS IS PRODUCING STRONG S
TO SW SHEAR OVER PHILIPPE AND IT IS BEGINNING TO DISPLAY
SUBTROPICAL CHARACTERISTICS. SCATTERED MODERATE/STRONG
CONVECTION IS FROM 29N-32N BETWEEN 56W-62W.

...TROPICAL WAVES...

A 1008 MB LOW IS CENTERED NEAR 11N25W MOVING W 10 KT. BROAD LOW
LEVEL CIRCULATION IS OBSERVED ON INFRARED SATELLITE IMAGERY.
CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE FROM
11N-15N BETWEEN 22W-28W.

CENTRAL ATLC TROPICAL WAVE IS ALONG 49W S OF 19N MOVING W 15 KT.
WELL-DEFINED SIGNATURE CURVATURE IS OBSERVED ON INFRARED
SATELLITE IMAGERY. WAVE IS BENEATH AN UPPER RIDGE IN N TO NE
FLOW WITH ENOUGH DIFFLUENCE TO GENERATE AN AREA OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 8N-13N BETWEEN
46W-52W.

W ATLC TROPICAL WAVE IS ALONG 57W S OF 16N MOVING W 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 7N33W 8N53W 10N62W. CLUSTERS
OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE N OF THE
ITCZ AXIS WITHIN 45 NM OF LINE 6N32W-11N41W.

...DISCUSSION...

GULF OF MEXICO...
RITA CONTINUES TO DOMINATE THE WEATHER PICTURE TONIGHT AS A CAT
4 HURRICANE MOVING INTO 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 GULF EXCEPT IN THE SW WHERE A
INVERTED UPPER TROUGH IN THE BAY OF CAMPECHE WHICH IS INCREASING
THE UPPER SHEAR ON THE SW SIDE OF RITA. AREA OF DRY AIR REMAINS
OVER THE SW GULF AS RITA CONTINUES MOVING TOWARD THE TEXAS COAST
MAKING LANDFALL DURING THE NIGHT FRI/SAT.

CARIBBEAN...
THE UPPER HIGH ASSOCIATED WITH RITA EXTENDS A RIDGE AXIS SW
ACROSS THE CARIBBEAN THROUGH CUBA NEAR 22N83W TO VENEZUELA NEAR
LAKE MARACAIBO. BROAD UPPER LOW/TROUGH OVER THE CENTRAL ATLC
EXTENDS S OVER THE E CARIBBEAN TO 14N E OF 68W ACROSS THE
LEEWARD ISLANDS. ABUNDANCE OF TROPICAL MOISTURE COVERS THE
ENTIRE CARIBBEAN GENERATING CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ACROSS THE AREA. THE STRONGEST AND MOST
CONDENSE AREAS ARE OVER HONDURAS AND COLOMBIA/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
71W. CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N
OF 24N W OF 77W ACROSS THE FLORIDA PENINSULA. BROAD UPPER LOW IS
IN THE CENTRAL ATLC NEAR 25N63W 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 18N53W EXTENDING A
RIDGE NNE TO BEYOND 32N50W PRODUCING BROAD AREA OF DIFFLUENCE
WITH SCATTERED MODERATE AND EMBEDDED CLUSTERS OF SCATTERED
STRONG CONVECTION OVER THE AREA WITHIN 200/225 NM OF LINE FROM
THE LESSER ANTILLES NEAR 16N62W ALONG 23N55W TO 29N53W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE CLOSER TO THE UPPER
LOW FROM 23N-29N BETWEEN 63W-66W. THIS SCENARIO HAS BROKEN DOWN
THE SUBTROPICAL RIDGE WITH THE LARGEST PORTION OVER THE E ATLC N
OF 20N BETWEEN AFRICA AND 50W WITH A 1029 MB HIGH 500 NM SW OF
THE AZORES. OVER THE E ATLC...AN UPPER TROUGH OVER THE NE ATLC
EXTENDS FROM AN UPPER LOW MOVING OVER S PORTUGAL ACROSS THE
MADEIRA ISLANDS THEN SW TO 10N39W. THIS IS RESPONSIBLE FOR A
WEAKENING 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 28W.

$$
WALLACE





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