[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241158
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 24 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
1115 UTC.

...SPECIAL FEATURES...

HURRICANE RITA IS CENTERED NEAR 30.4N 94.2W...MIDWAY BETWEEN
JASPER AND BEAUMONT TEXAS AT 24/1200 UTC MOVING NW 10 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 950 MB. MAXIMUM SUSTAINED
WIND SPEED IS 105 KT WITH GUSTS TO 130 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. THE EYE OF RITA FINALLY MOVED ONSHORE AROUND 0730
UTC NEAR THE TEXAS/LOUISIANA BORDER AND IS NOW CONTINUING NNW
ACROSS FAR E TEXAS. THE EYEWALL MOVED OVER BEAUMONT TEXAS AND
THE ASOS AMAZINGLY SURVIVED...AND REPORTED A WIND GUST TO 91 KT
AROUND 0900 UTC. CONVECTION SEEMED TO HAVE STRENGTHENED AT
LANDFALL WITH THE CLOUD TOPS HAVING COOLED TO -85C BUT ARE NOW
BEGINNING TO WARM AGAIN AS THE SYSTEM COMMENCES ITS INLAND
WEAKENING TREND. NUMEROUS MODERATE/STRONG CONVECTION IS FROM
29N-33N BETWEEN 90W-96W. UNFORTUNATELY THE WSR-88D AT LAKE
CHARLES FAILED AT 0742 UTC BUT OTHER RADAR SITES AROUND THE
REGION INDICATE THAT THE RAIN SHIELD HAS SPREAD NWD TO THE
LOUISIANA/ARKANSAS BORDER...AND EXTENDS FROM SE LOUISIANA/SW
MISSISSIPPI WWD TO 40 NM W OF HOUSTON. RITA IS EXPECTED TO STALL
OVER NE TEXAS IN THE NEXT FEW DAYS AND CONTINUOUS HEAVY RAINFALL
COULD PRODUCE LOCALLY AS MUCH AS 25 INCHES...WITH A LARGE THREAT
OF FLOODING IN THE ARKLATEX REGION.

A 1002 MB LOW...THE REMNANT OF T.D. PHILIPPE...IS CENTERED NEAR
29N62W AND IS NOW MOVING NE AROUND A MUCH LARGER CIRCULATION
WHICH HAS A COMMON CENTER NEAR 31N62W. THE ENTIRE SYSTEM IS
MOVING SLOWLY TO THE NE AND IS LOCATED ON THE E SIDE OF A LARGE
UPPER LOW WHICH IS CENTERED NEAR 27N72W. STRONG SOUTHERLY FLOW
HAS SHEARED THE TSTM ACTIVITY TO THE N AND E OF THE LOW...WITH
SCATTERED MODERATE CONVECTION ALIGNED WITHIN 60 NM OF A LINE
FROM BERMUDA TO 32N59W 30N58W 26N60W. ALTHOUGH THIS CONVECTION
IS FAR REMOVED FROM THE LOW-LEVEL CENTER...TROPICAL OR
SUBTROPICAL DEVELOPMENT IS POSSIBLE WITHIN THE NEXT 36 HRS IF
THE TSTM ACTIVITY CAN CONSOLIDATE AND PERSIST FOR A PROLONGED
PERIOD OF TIME.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 33W/34W S OF 20N MOVING
W 15 KT WITH AN ELONGATED 1011 MB LOW ALONG THE AXIS NEAR
11N34W. ALTHOUGH THE LOW HAD A WELL-DEFINED SIGNATURE
YESTERDAY...IT HAS SINCE BECOME MORE ELONGATED AND THE ENTIRE
FEATURE HAS A MORE WAVE-LIKE APPEARANCE. THE FIRST FEW VISIBLE
IMAGES FROM METEOSAT-8 SUPPORT THIS AND SHOW AT LEAST TWO
DISTINCT CIRCULATIONS WITH THE EASTERNMOST ONE NEAR 13N31W
ASSOCIATED WITH DEEPER CONVECTION. SCATTERED MODERATE CONVECTION
FROM 13N-17N BETWEEN 27W-35W.

TROPICAL WAVE LOCATED ABOUT 275 NM E OF THE LEEWARD/WINDWARD
ISLANDS ALONG 56W S OF 19N MOVING W 15 KT. A SLIGHT NE/SE WIND
SHIFT IS NOTED BETWEEN BUOYS 41100 AND 41040 WHICH SUGGESTS GOOD
PLACEMENT OF THE WAVE. DEEP CONVECTION WHICH DEVELOPED NEAR THE
WAVE AXIS EARLIER OVERNIGHT HAS WEAKENED JUST A BIT BUT
SCATTERED MODERATE IS FROM 9N-16N BETWEEN 51W-60W. SOME OF THIS
ACTIVITY IS LIKELY TO SPREAD ACROSS THE LEEWARD AND WINDWARD
ISLANDS LATER TODAY AND TONIGHT...POSSIBLY LINGERING OVER THE
AREA FOR A GOOD PART OF THE START OF NEXT WEEK.

E CARIBBEAN TROPICAL WAVE IS ALONG 65W/66W S OF 20N MOVING W 15
KT. UPPER AIR DATA FROM CAYENNE AND TRINIDAD BOTH INDICATE WAVE
PASSAGE OVER THE PAST 48 HRS. THE WAVE IS ESSENTIALLY DEVOID OF
ANY DEEP CONVECTION AND ALSO LACKS MUCH CLOUD COVER.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N10W 11N17W 15N30W...THEN ALONG
10N35W 7N43W 12N55W...THEN ALONG 9N70W 14N80W 16N90W. SCATTERED
MODERATE/STRONG CONVECTION OFF THE COAST OF GUINEA-BISSAU FROM
9N-13N BETWEEN 16W-19W. ISOLATED SHOWERS/TSTMS FROM 8N-12N
BETWEEN 33W-38W. SCATTERED MODERATE WITHIN 180 NM SW OF THE AXIS
BETWEEN 43W-53W. WIDELY SCATTERED MODERATE FROM 8N-14N BETWEEN
70W-85W INCLUDING FROM NW VENEZUELA WWD TO NICARAGUA AND COSTA
RICA.

...DISCUSSION...

GULF OF MEXICO...
THE CIRCULATION OF HURRICANE RITA TAKES UP A GOOD CHUNK OF THE
GULF OF MEXICO ALTHOUGH THE MOST INCLEMENT WEATHER IS LIMITED TO
PRIMARILY THE NW PART OF THE BASIN. DRY CONTINENTAL AIR HAS
WRAPPED AROUND THE W AND S SIDE OF THE HURRICANE AND IS
PRODUCING MAINLY FAIR WEATHER WITH SOME HIGH LEVEL CIRRUS S OF
27N W OF 90W TO THE BAY OF CAMPECHE. THE ATMOSPHERE IS A LITTLE
MORE MOIST E OF 90W DUE TO THE TROPICAL S/SE FLOW MOVING TOWARDS
RITA SO CLOUD COVER IS MORE ABUNDANT AND WIDELY SCATTERED
SHOWERS SPECKLE THE E GULF IN REMNANT SPIRAL BANDS. THE BULK OF
THE MOISTURE ASSOCIATED WITH RITA WILL MOVE INLAND DURING THE
NEXT 48 HRS ALTHOUGH A FEW LEFTOVER SHOWERS WILL STILL BE
POSSIBLE ESPECIALLY OVER THE N GULF WATERS THROUGH THE EARLY
PART OF NEXT WEEK. SEE SPECIAL FEATURES FOR FURTHER DISCUSSION
ON RITA.

CARIBBEAN...
AN UPPER LEVEL HIGH IS CENTERED OVER THE SE GULF OF MEXICO NEAR
25N84W WITH A RIDGE AXIS EXTENDING SE ACROSS W CUBA TO JAMAICA
AND 17N70W. A LARGE AREA OF CIRRUS HAS SPREAD ACROSS THE W HALF
OF THE CARIBBEAN CARRIED BY A STRONG 50 KT EASTERLY JET RACING
TOWARDS THE NICARAGUA COAST. AN UPPER TROUGH AXIS STRETCHES
THROUGH THE MONA PASSAGE SW TO THE ABC ISLANDS AND DRIER AIR IS
BEING BROUGHT IN FROM THE E TOWARDS THIS TROUGH AXIS WHICH IS
KEEPING RELATIVELY NICE WEATHER OVER THE LESSER ANTILLES FOR THE
MOMENT. ISOLATED SHOWERS/TSTMS SPECKLE THE AREA FROM 16N-20N
BETWEEN 67W-83W EXTENDING FROM PUERTO RICO TO JAMAICA TO THE
ISLE OF YOUTH AND SCATTERED MODERATE CONVECTION ALSO STRETCHES
FROM NW VENEZUELA THROUGH COLOMBIA TO CENTRAL AMERICA. SCATTERED
TSTMS ARE ALSO APPROACHING BARBADOS AHEAD OF TROPICAL WAVE ALONG
55W.

ATLANTIC...
A LARGE UPPER LEVEL LOW IS LOCATED OVER THE W ATLC NEAR 28N72W
WITH DRY AIR SURGING SWD N OF 23N BETWEEN 70W-80W. UPPER LEVEL
CIRRUS IS WRAPPING AROUND THE S SIDE OF THE LOW'S CIRCULATION
STRETCHING FROM FLORIDA TO THE SRN BAHAMAS THEN NEWD TO 30N67W.
FARTHER E...A LARGE UPPER HIGH IS CENTERED NEAR 23N56W AND
COVERS VIRTUALLY THE ENTIRE CENTRAL ATLANTIC. THE REMNANTS OF
PHILIPPE ARE EMBEDDED WITHIN THE STRONG SLY FLOW BETWEEN THESE
TWO FEATURES AND IS BEING INFLUENCED BY DETRIMENTAL VERTICAL
SHEAR. A SECOND UPPER LOW IS CENTERED OVER THE E/CENTRAL ATLC
NEAR 16N37W AND IS SUPPORTING DIFFLUENT FLOW TO ITS W AS IT
SPLITS BETWEEN THE LOW AND HIGH. THIS ENVIRONMENT IS SUPPORTING
A STRONG CLUSTER OF CONVECTION NEAR THE TROPICAL WAVE ALONG
55W...SOME OF WHICH WILL LIKELY SPREAD ACROSS PARTS OF THE
WINDWARD/SRN LEEWARD ISLANDS. THE UPPER LOW IS PRODUCING STRONG
SLY SHEAR OVER THE TROPICAL WAVE ALONG 34W AND IS LIKELY
IMPEDING DEVELOPMENT AT THIS TIME. AN UPPER RIDGE POKES WWD FROM
AFRICA ALONG 20N AND IS SPREADING HIGH LEVEL CIRRUS FROM 10N-30N
E OF 35W.

$$
BERG



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