[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 261843
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 26 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
HURRICANE KATRINA HAS INTENSIFIED NOW THAT IT IS IN THE EASTERN
GULF OF MEXICO...AND IS A CATEGORY TWO HURRICANE ON THE
SAFFIR-SIMPSON SCALE. THE CENTER OF HURRICANE KATRINA WAS NEAR
25.1N 82.2W...OR ABOUT 45 MILES NORTHWEST OF KEY WEST FLORIDA
AND ABOUT 75 MILES SOUTH-SOUTHWEST OF NAPLES FLORIDA. KATRINA
WAS MOVING WEST 6 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS
971 MB. THE MAXIMUM SUSTAINED WIND SPEEDS WERE 85 KT WITH GUSTS
TO 105 KT. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC
ADVISORY UNDER HEADERS MIATCPAT1/WTNT32 KNHC FOR MORE DETAILS.
IT IS POSSIBLE THAT RAPID INTENSIFICATION OF KATRINA MAY OCCUR
AS IT CONTINUES ITS MOVEMENT IN THE EASTERN GULF WATERS. THE
INNER CORE STRUCTURE OF KATRINA HAS IMPROVED AND A SHARP
PRESSURE DROP HAS BEEN NOTED. THE OFFICIAL FORECAST KEEPS
KATRINA IN THE EASTERN GULF OF MEXICO...MOVING NORTHWESTWARD
AND EVENTUALLY NORTHWARD AND POSSIBLY REACHING LAND AFTER
72 HOURS. NUMEROUS STRONG THUNDERSTORMS EXTEND FROM THE GULF
COAST OF WESTERN CUBA TO SOUTH FLORIDA BETWEEN 80W AND 84W.
SOME OF THIS PRECIPITATION ALSO IS OCCURRING ON THE CARIBBEAN
SEA SIDE OF CENTRAL CUBA TO THE SOUTHEAST OF KATRINA. A LINE
OF SHOWERS HAS DEVELOPED AND RUNS FROM A POINT ABOUT 200 NM
WEST OF KATRINA NORTHWESTWARD TO SOUTHEASTERN LOUISIANA...AND
THEN IN THE LOUISIANA COASTAL WATERS WESTWARD. SOME SCATTERED
MODERATE SHOWERS AND ISOLATED STRONG THUNDERSTORMS IN OUTER
BANDS AWAY FROM KATRINA ARE FOUND IN EASTERN JAMAICA AND ITS
COASTAL WATERS. UPPER LEVEL ANTICYCLONIC WIND FLOW TO THE EAST
OF KATRINA IS MOVING ACROSS THE NORTH CENTRAL AND NORTHWESTERN
CARIBBEAN SEA FROM HISPANIOLA WESTWARD. A MIDDLE TO UPPER LEVEL
TROUGH STRETCHES FROM A SMALL CYCLONIC CIRCULATION CENTER NEAR
31N65W TO JUST NORTH OF PUERTO RICO. UPPER LEVEL ANTICYCLONIC
FLOW REMAINS TO THE NORTH OF KATRINA.

A 1010 MB ATLANTIC OCEAN LOW PRESSURE CENTER WAS NEAR 18N47W
MOVING NORTHWEST ABOUT 10 KT. IT IS POSSIBLE THAT THIS FEATURE
MAY BECOME A TROPICAL CYCLONE DURING THE NEXT 24 HOURS. UPPER
LEVEL WINDS CURRENTLY ARE ONLY MARGINALLY FAVORABLE FOR
DEVELOPMENT. THEY ARE EXPECTED TO BECOME MORE FAVORABLE DURING
THE NEXT DAY OR SO. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS
ARE FOUND FROM 19N TO 21N BETWEEN 45W AND 48W. OVERCAST MULTI-
LAYERED CLOUDS AND OTHER POSSIBLE PRECIPITATION ARE EVEN NORTH
OF THE STRONG SHOWERS/THUNDERSTORMS...REACHING 27N BETWEEN 42W
AND 49W.

...TROPICAL WAVES...
ATLANTIC OCEAN TROPICAL WAVE IS ALONG 37W/38W S OF 17N MOVING W
10 KT. MID LEVEL CYCLONIC TURNING IS OBSERVED ON INFRARED
SATELLITE IMAGERY S OF 15N. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 8N-14N BETWEEN
32W-40W.

CARIBBEAN TROPICAL WAVE IS ALONG 85W/86W S OF 20N MOVING W 15-20
KT. WAVE SIGNATURE IN FORM OF CURVATURE IS OBSERVED MAINLY FROM
NICARAGUA TO THE SOUTHERN GULF OF HONDURAS. SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS ARE FROM 12N-17N BETWEEN 83W-86W
MOSTLY OVER NICARAGUA AND HONDURAS.

...THE ITCZ...
ITCZ 15N17W 13N25W 11N37W THEN ALONG 11N39W 15N63W AND ALSO
ALONG 11N50W 10N 61W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE WITHIN 200 NM N OF THE AXIS BETWEEN
24W-33W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN
250 NM N AND 400 NM S OF AXIS BETWEEN 33W AND 41W. SCATTERED
MODERATE AND ISOLATED STRONG CONVECTION ARE WITHIN 60 NM OF THE
AXIS FROM 47W TO 52W.

...DISCUSSION...
THE GULF OF MEXICO...
THE MAIN WEATHER INTEREST CONTINUES TO BE HURRICANE KATRINA
MOVING OVER THE EASTERN GULF OF MEXICO. SEE SPECIAL
FEATURES ABOVE. ELSEWHERE...A NARROW UPPER LEVEL INVERTED TROUGH
IS OVER THE SW GULF OF MEXICO AND W BAY OF CAMPECHE REVEALED BY
IR SATELLITE WINDS. REMAINDER OF THE GULF IS UNDER E AND NE
UPPER FLOW FROM AN UPPER HIGH ANCHORED OVER THE CENTRAL GULF
STATES AND COVERING THE SE UNITED STATES...GULF OF MEXICO...NW
CARIBBEAN...AND PORTIONS OF THE W ATLC OFF THE FLORIDA AND
GEORGIA COAST. THERE ARE NO SURFACE FEATURES IN THE GULF OTHER
THAN HURRICANE KATRINA.

THE CARIBBEAN SEA...
CONVECTION FROM HURRICANE KATRINA EXTENDS ACROSS W CUBA INTO THE
NW CARIBBEAN...WEST OF 80W. UPPER LEVEL HIGH ANCHORED OVER NW
LOUISIANA IS PRODUCING ANTICYCLONIC FLOW EXTENDING INTO THE
CARIBBEAN N OF 11N W OF 72W. N TO NE UPPER LEVEL WINDS DOMINATE
MOST OF THE CARIBBEAN EXCEPT IN THE NE WHERE A RIDGE AXIS FROM
THE LEEWARD/VIRGIN ISLANDS NE TO INTO THE CENTRAL ATLC. THERE
ARE NO SURFACE FEATURES IN THE CARIBBEAN OTHER THAN A TROPICAL
WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60
NM OF LINE FROM E JAMAICA SW TO 15N80W, AND ALSO SCATTERED
MODERATE CONVECTION IS OVER WEST HALF OF HISPANIOLA.

THE ATLANTIC OCEAN...
ASSOCIATED DEEP CONVECTION ASSOCIATED WITH HURRICANE KATRINA IS
W OF THE CENTRAL BAHAMA ISLANDS TO INLAND OVER FLORIDA. BROAD
UPPER RIDGE ANCHORED BY AN UPPER LEVEL HIGH OVER NW LOUISIANA
COVERS THE W ATLC W OF 67W. AN UPPER LEVEL TROUGH THAT CONTINUES
TO DIG SOUTH EXTENDS S TO 23N BETWEEN 60W-70W. MID/UPPER LEVEL
RIDGE FROM THE NE CARIBBEAN EXTENDS ACROSS THE LEEWARD AND
VIRGIN ISLANDS TO NEAR 27N58W. DIFFLUENT FLOW ALOFT OVER THE W
ATLC IS GENERATING CLUSTERS OF SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION ACROSS THE AREA W OF 65W. AN UPPER HIGH IN THE
CENTRAL ATLC IS CENTERED NEAR 31N55W EXTENDING S TO NEAR 23N
FROM 48W-60W. THE E ATLC IS DOMINATED BY A MID/UPPER LEVEL RIDGE
THAT EXTENDS OFF AFRICA ALONG 18N/20N TO AN UPPER HIGH NEAR
17N37W TO 12N50W. VISIBLE SATELLITE IMAGES REVEAL AFRICAN DUST
FROM 13N-23N MOVING ACROSS OR JUST N OF THE CAPE VERDE ISLAND TO
NEAR 40W. AT THE SURFACE...SUBTROPICAL RIDGE IS ANCHORED OVER
THE NE ATLC BY A 1029 MB HIGH JUST W OF THE AZORES.

$$
GB/MT

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