[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 221805
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU SEP 22 200521

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

RITA IS AN EXTREMELY DANGEROUS CATEGORY FOUR HURRICANE.
ITS CENTER AT 22/1800 UTC IS NEAR 25.5N 89.2W MOVING WEST
8 KT. A GRADUAL TURN TO THE NORTHWEST IS EXPECTED DURING
THE NEXT 24 TO 36 HOURS. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 915 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 130 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. THIS POSITION ALSO IS ABOUT 380 NM
SOUTHEAST OF GALVESTON TEXAS...AND ABOUT 380 NM SOUTHEAST
OF PORT ARTHUR TEXAS. THE EYE IS WELL-DEFINED ON VISIBLE
AND INFRARED SATELLITE IMAGERY. THE NUMEROUS STRONG SHOWERS
AND THUNDERSTORMS AROUND RITA ARE WITHIN 85 TO 105 NM IN
THE EASTERN SEMICIRCLE AND WITHIN 50 TO 65 NM OF THE CENTER
IN THE WESTERN SEMICIRCLE.

PHILIPPE IS BEGINNING TO LOSE TROPICAL CHARACTERISTICS. THE
CENTER OF TROPICAL STORM PHILIPPE AT 22/1500 UTC IS NEAR 26.2N
57.1W MOVING NORTH 15 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE
IS 1005 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 35 KT WITH
GUSTS TO 45 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24 HOURS.
PHILIPPE APPEARS TO BE LOSING TROPICAL CHARACTERISTICS WITHIN
A LARGER NON-TROPICAL AREA OF LOW PRESSURE. CLOUDS AND
PRECIPITATION SURROUND PHILIPPE IN ONE BIG HALF-CIRCLE...
BORDERED BY THE POINTS 24N66W 32N62W 34N54W 22N54W...WITH SOME
PRECIPITATION EXTENDING EVEN TOWARD THE EASTERN CARIBBEAN
ISLANDS NEAR 16N60W. A MIDDLE TO UPPER LEVEL LOW CENTER IS NEAR
26N63W. A TROUGH HAS BEEN DIGGING INTO THE EASTERN AND
SOUTHEASTERN CARIBBEAN SEA WITH THIS LOW CENTER.  AN UPPER LEVEL
RIDGE IMMEDIATELY EAST OF THIS LOW CENTER. MIDDLE TO UPPER LEVEL
CYCLONIC FLOW AROUND THE LOW CENTER COVERS THE CARIBBEAN SEA AND
ATLANTIC WATERS FROM THE EASTERN CARIBBEAN SEA NEAR 16N TO 30N
BETWEEN 59W AND 70W. THE ANTICYCLONIC FLOW FROM THE UPPER LEVEL
RIDGE COVERS THE ATLANTIC WATERS FROM 16N TO 34N BETWEEN 40W AND
59W.

...TROPICAL WAVES...

ATLANTIC OCEAN TROPICAL WAVE IS ALONG 44W/45W SOUTH OF 17N
MOVING WEST 10 TO 15 KT. A MIDDLE TO UPPER LEVEL TROUGH EXTENDS
SOUTHWESTWARD FROM A LOW CENTER NEAR 25N28W TO 20N39W. A SLIGHT
HINT OF CYCLONIC CURVATURE EXISTS IN THE VISIBLE SATELLITE
IMAGERY NEAR 15N45W. ISOLATED MODERATE SHOWERS FROM 10N TO 15N
BETWEEN 40W AND 50W. THE WAVE HAS MOVED AWAY FROM YESTERDAY'S
MIDDLE TO UPPER LEVEL EASTERN ATLANTIC OCEAN TROUGH.

ATLANTIC OCEAN TROPICAL WAVE IS ALONG 57W/55W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. THIS WAVE IS PASSING RIGHT UNDER THE
UPPER LEVEL RIDGE WHICH IS IMMEDIATELY EAST OF THE 26N63W MIDDLE
TO UPPER LEVEL LOW CENTER. SHOWERS AND THUNDERSTORMS FROM 15N TO
18N BETWEEN 50W AND 60W MAY BE RELATED TO THE PRECIPITATION
AROUND T.S. PHILIPPE THAN THE WAVE.

...ITCZ...

ITCZ 16N16W 14N18W...9N21W 5N30W 4N40W 8N52W. A 1009 MB LOW
PRESSURE CENTER IS NEAR 12N19W. SHOWERS AND THUNDERSTORMS ARE
WEST OF THIS LOW CENTER FROM 10N TO 13N BETWEEN 22W AND 25W.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE FOUND FROM 8N TO
11N BETWEEN 46W AND 51W. ISOLATED MODERATE SHOWERS ARE ELSEWHERE
FROM 4N TO 10N BETWEEN AFRICA AND 40W.

...DISCUSSION...

THE GULF OF MEXICO...
RITA IS A DANGEROUS CATEGORY FOUR HURRICANE. IT HAS LOST A BIT
OF ITS PUNCH...GOING FROM A CATEGORY FIVE HURRICANE THIS MORNING
TO A CATEGORY FOUR SYSTEM NOW. IT IS FORECAST TO REACH THE UPPER
TEXAS COAST BY LATE FRIDAY OR EARLY SATURDAY MORNING AS A
CATEGORY FOUR HURRICANE. ITS POSITION ALSO IS ABOUT 380 NM
SOUTHEAST OF GALVESTON TEXAS...AND ABOUT 380 NM SOUTHEAST OF
PORT ARTHUR TEXAS. THE EYE IS WELL-DEFINED ON VISIBLE AND
INFRARED SATELLITE IMAGERY. THE NUMEROUS STRONG SHOWERS AND
THUNDERSTORMS AROUND RITA ARE WITHIN 85 TO 105 NM IN THE EASTERN
SEMICIRCLE AND WITHIN 50 TO 65 NM OF THE CENTER IN THE WESTERN
SEMICIRCLE.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER TROUGH HAS BEEN DIGGING INTO THE EASTERN AND
SOUTHEASTERN CARIBBEAN SEA WITH THE 26N63W LOW CENTER. UPPER
LEVEL ANTICYCLONIC FLOW HAS BEEN SPINNING OFF THE TROUGH'S
CYCLONIC FLOW...EVENTUALLY COMBINING WITH THE UPPER LEVEL
ANTICYCLONIC FLOW DIRECTLY RELATED TO THE ANTICYCLONIC OUTFLOW
OF RITA. THIS ANTICYCLONIC FLOW IS OCCURRING BETWEEN 70W AND
80W. UPPER LEVEL EASTERLY FLOW COVERS THE REST OF THE AREA
WEST OF 80W...EXCEPT FOR SHOWERS AND THUNDERSTORMS FROM 12N TO
16N BETWEEN 78W AND 83W RELATED TO A WEAKENING MIDDLE LEVEL LOW
CENTER FROM YESTERDAY. ITCZ SHOWERS AND THUNDERSTORMS ARE IN THE
EXTREME SOUTHWESTERN CORNER OF THE AREA.

THE ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC OUTFLOW CURVES FROM THE EASTERN GULF OF
MEXICO INTO THE SOUTHWESTERN NORTH ATLANTIC OCEAN...EAST OF
FLORIDA...DIVING SOUTHEASTWARD INTO THE TROUGH WITH THE 26N63W
MIDDLE TO UPPER LEVEL ATLANTIC LOW CENTER. THIS ANTICYCLONIC
FLOW ESTABLISHES THE RIDGE-TO-TROUGH-TO-RIDGE-TO-TROUGH PATTERN
CURRENTLY OBSERVED IN WATER VAPOR IMAGERY. CYCLONIC FLOW
ACCOMPANIES THE TROUGH WITH THE 26N63W LOW CENTER. AN UPPER
LEVEL RIDGE IMMEDIATELY FOLLOWS THIS LOW CENTER...ON TOP OF
TROPICAL STORM PHILIPPE. THE NEXT TROUGH IS JUST NORTH AND EAST
OF THE 44W/45W TROPICAL WAVE. THIS TROUGH RUNS FROM JUST
NORTHEAST OF THE MADEIRAS ISLANDS NEAR 34N15W TO A LOW CENTER
NEAR 27N25W TO 16N37W TO 11N37W.

$$
MT


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