[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211816
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 21 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
1745 UTC.

...SPECIAL FEATURES...

RITA IS AN EXTREMELY DANGEROUS CATEGORY FOUR HURRICANE. ITS
CENTER AT 21/1800 UTC IS NEAR 24.3N 85.9W MOVING WEST 11 KT.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 944 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 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. THIS POSITION ALSO IS
ABOUT 225 NM WEST OF KEY WEST FLORIDA...AND ABOUT 650 NM
EAST-SOUTHEAST OF CORPUS CHRISTI TEXAS. THE EYE IS WELL-DEFINED
ON VISIBLE AND INFRARED SATELLITE IMAGERY. CLOUD COVER AROUND
RITA COVERS THE GULF WATERS FROM THE NORTHERN YUCATAN PENINSULA
TO 28N BETWEEN 80W AND 92W. THE NUMEROUS STRONG SHOWERS AND
THUNDERSTORMS AROUND RITA ARE WITHIN 80 TO 90 NM IN THE EASTERN
SEMICIRCLE AND WITHIN 70 TO 80 NM OF THE CENTER IN THE WESTERN
SEMICIRCLE.

THE CENTER OF TROPICAL STORM PHILIPPE AT 21/1500 UTC IS NEAR
20.2N 57.2W MOVING NORTH 5 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1000 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE
45 KT WITH GUSTS TO 55 KT. SEE THE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE FOUND FROM 19N TO
21N BETWEEN 54W AND 57W. WIDELY SCATTERED MODERATE TO ISOLATED
STRONG SHOWERS AND THUNDERSTORMS ARE ELSEWHERE FROM THE EASTERN
CARIBBEAN SEA WITHIN 30 TO 45 NM ON EITHER SIDE OF 13N63W 15N59W
18N56W...AND ELSEWHERE FROM 16N TO 20N BETWEEN 50W AND 55W.
BROKEN TO OVERCAST MULTILAYERED CLOUDS AND SCATTERED MODERATE
SHOWERS TO ISOLATED STRONG THUNDERSTORMS HAVE BEEN SPREAD WELL
NORTHWARD AND NORTHEASTWARD...AWAY FROM PHILIPPE...AND AROUND
A 31N52W 27N54W 22N55W SURFACE TROUGH...FROM 20N TO 34N BETWEEN
40W AND 65W. A MIDDLE TO UPPER LEVEL LOW CENTER IS NEAR
24N62W...WITH 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 36W/37W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. A MIDDLE TO UPPER LEVEL TROUGH EXTENDS
SOUTHWESTWARD FROM A LOW CENTER NEAR 25N28W TO 20N39W. THE WAVE
IS PASSING JUST SOUTH AND SOUTHEAST OF THE BASE OF THIS
TROUGH...AS HIGH CLOUDS ON THE EASTERN SIDE OF THIS TROUGH ARE
CURVING EASTWARD AND NORTHEASTWARD. ISOLATED MODERATE SHOWERS...
WITH SOME WARMING CLOUD TOP TEMPERATURES...FROM 13N TO 16N
BETWEEN 32W AND 36W.

ATLANTIC OCEAN TROPICAL WAVE IS ALONG 47W/48W. A 1013 MB LOW
PRESSURE CENTER IS NEAR 18N46W MOVING WEST 10 KT. THIS WAVE IS
PASSING THROUGH AN AREA WHICH IS UNDER THE INFLUENCE OF UPPER
LEVEL NORTHWESTERLY WIND FLOW...ON THE EASTERN SIDE OF THE
19N55W 27N49W 34N43W ATLANTIC RIDGE IMMEDIATELY EAST OF T.S.
PHILIPPE. ISOLATED MODERATE SHOWERS FROM 10N TO 20N BETWEEN
40W AND 45W.

...ITCZ...

ITCZ 10N13W 6N20W 5N40W 9N60W. WIDELY SCATTERED TO SCATTERED
MODERATE SHOWERS AND ISOLATED STRONG THUNDERSTORMS FROM 5N TO
10N BETWEEN 37W AND 52W. ISOLATED MODERATE SHOWERS AND LOCALLY
STRONG THUNDERSTORMS FROM 4N TO 10N BETWEEN THE COAST OF AFRICA
AND 25W. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE OVER
INLAND COASTAL LOCATIONS FROM 8N13W TO 13N16W.

...DISCUSSION...

THE GULF OF MEXICO...
RITA IS A DANGEROUS CATEGORY FOUR HURRICANE. IT HAS BEEN
PULLING AWAY FROM THE STRAITS OF FLORIDA INTO THE SOUTHEASTERN
GULF WATERS MORE AND MORE FOR THE LAST 24 HOURS. THE EYE IS
WELL-DEFINED ON VISIBLE AND INFRARED SATELLITE IMAGERY.
CLOUD COVER AROUND RITA COVERS THE GULF WATERS FROM THE
NORTHERN YUCATAN PENINSULA TO 28N BETWEEN 80W AND 92W.
THE NUMEROUS STRONG SHOWERS AND THUNDERSTORMS AROUND RITA
ARE WITHIN 80 TO 90 NM IN THE EASTERN SEMICIRCLE AND WITHIN
70 TO 80 NM OF THE CENTER IN THE WESTERN SEMICIRCLE. THE UPPER
LEVEL ANTICYCLONE ON TOP OF RITA AND THE WARM SEA GULF OF
MEXICO SURFACE TEMPERATURES WILL HELP RITA TO REMAIN AS
A MAJOR HURRICANE. MIDDLE TO UPPER LEVEL CYCLONIC FLOW
IN THE SOUTHWESTERN CORNER OF THE GULF IS CENTERED
22N95W...SURROUNDED BY MIDDLE TO UPPER LEVEL DRY AIR.

THE CARIBBEAN SEA...
MIDDLE TO UPPER LEVEL CYCLONIC FLOW IS IN THE AREA NORTH OF 16N
BETWEEN 60W AND 70W...THANKS TO A MIDDLE TO UPPER LEVEL TROUGH
FROM AN ATLANTIC 24N62W LOW CENTER. REMNANT SHOWERS AND
THUNDERSTORMS...SOME HAVE BEEN WEAKENING DURING THE LAST FOUR
TO FIVE HOURS...FROM 14N TO 17N BETWEEN 60W AND 70W. WEAK MIDDLE
LEVEL CYCLONIC FLOW HAS A CENTER NEAR 16N81W...IN THE
NORTHWESTERN CORNER OF THE AREA...WITH SCATTERED MODERATE TO
STRONG SHOWERS AND THUNDERSTORMS JUST EAST OF THIS 16N81W LOW
CENTER...FROM 13N TO 16N BETWEEN 76W AND 81W. NUMEROUS STRONG
ITCZ SHOWERS AND THUNDERSTORMS ARE OCCURRING FROM COLOMBIA NEAR
9N TO 11N BETWEEN 74W AND 79W.

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 24N62W
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 24N62W 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 36W/37W TROPICAL WAVE.

$$
MT


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