[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 251152
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 25 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
1015 UTC.

...SPECIAL FEATURES...
TROPICAL STORM KATRINA IS CENTERED NEAR 26.2N 79.0W...OR ABOUT
30 MILES...45 KM...SSW OF FREEPORT GRAND BAHAMA ISLAND AND ABOUT
70 MILES...115 KM...E OF FORT LAUDERDALE FLORIDA AT 25/1200 UTC
MOVING W AT 7 KT. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH
GUSTS TO 55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER HEADERS
MIATCPAT1/WTNT32 KNHC FOR MORE DETAILS. KATRINA CONTINUES TO
MOVE TOWARD S FLORIDA WITH SCATTERED MODERATE/STRONG CONVECTION
WITHIN 60 NM OF THE CENTER IN THE N SEMICIRCLE. FEEDER BANDS
WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
EXTEND OUT TO WITHIN 200 NM OF THE CENTER IN THE SE SEMICIRCLE.
RADAR INDICATES S FLORIDA HAS SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ROTATING INLAND FROM DAYTONA BEACH TO S OF LAKE
OKEECHOBEE BUT THE AREA FROM PALM BEACH COUNTY S WITH ONLY
SCATTERED SHOWERS. ON THE FORECASTED TRACK...KATRINA WILL MAKE
LANDFALL WITHIN THE NEXT 24 HOURS.

A 1009 MB LOW IS CENTERED BETWEEN THE CAPE VERDE ISLANDS AND THE
LESSER ANTILLES NEAR 17.5N43.5W...ALONG A TROPICAL WAVE S OF 25N
ALONG 43W/44W MOVING W NEAR 10 KT. THE LOW LEVEL CENTER REMAINS
COMPLETELY EXPOSED DUE TO SOUTHWESTERLY SHEAR AS A RESULT OF A
MID LEVEL INVERTED TROUGH EXTENDING FROM 15N44W TO 21N42W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS E OF THE LOW
FROM 17N-21N BETWEEN 37W-42W. THIS SYSTEM STILL HAS THE
POSSIBILITY OF BECOMING A TROPICAL CYCLONE.

...TROPICAL WAVES...
E ATLC TROPICAL WAVE IS ALONG 30W S OF 17N MOVING W 10 KT. LOW
AMPLITUDE WAVE WITH WEAK SIGNATURE CURVATURE OBSERVED S OF 15N.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN THE ITCZ
FROM 4N-11N BETWEEN 23W-37W.

SEE SPECIAL FEATURES FOR LOW/TROPICAL WAVE ALONG 43W/44W.

CARIBBEAN TROPICAL WAVE IS ALONG 75W/76W S OF 20N MOVING W 15-20
KT. WAVE SIGNATURE CURVATURE IS MASKED BY HIGH CLOUDS THAT COVER
MOST OF THE CENTRAL CARIBBEAN. CONVECTION HAS INCREASED OVER THE
PAST 6 HOURS. SCATTERED/NUMEROUS STRONG CONVECTION IS FROM
9N-13N BETWEEN 73W-80W INCLUDING PORTIONS OF COLOMBIA AND TO THE
COAST OF E PANAMA.

SW GULF OF MEXICO TROPICAL WAVE IS ALONG 97W S OF 21N MOVING W
10-15 KT. WAVE IS BENEATH THE E SIDE OF AN UPPER CYCLONIC FLOW
WHICH IS DRAWING SCATTERED STRONG CONVECTION FROM OVER SE MEXICO
INTO THE BAY OF CAMPECHE S OF 21N FROM 91W-95W.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N16W 8N32W 11N39W THEN ALONG
15N47W 13N55W 14N63W. SCATTERED MODERATE/STRONG CONVECTION IS
WITHIN 75 NM S OF THE AXIS FROM 17W-19W. A WEDGE OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS BEING DRAWN INTO THE
LOW/TROPICAL WAVE ALONG 43W/44W WITHIN 120/150 NM OF LINE FROM
8N49W TO 15N41W AND FROM 7N-11N E OF 22W TO THE COAST OF AFRICA.

...DISCUSSION...
GULF OF MEXICO...
WEAK MID/UPPER LEVEL LOW IS INLAND OVER MEXICO W OF 100W PULLING
UPPER MOISTURE AND CONVECTION FROM S MEXICO AND THE TROPICAL
WAVE INTO THE BAY OF CAMPECHE. REMAINDER OF THE GULF REMAINS
DOMINATED BY A STRONG UPPER HIGH LOCATED OVER CENTRAL LOUISIANA
NEAR 31N93W WITH PREDOMINANTLY EASTERLY UPPER FLOW ACROSS THE
GULF. AT THE SURFACE...A WEAK RIDGE COVERS THE GULF. SCATTERED
SHOWERS/THUNDERSTORMS ARE OVER THE STRAITS OF FLORIDA W OF 82W
BEING GENERATED BY T.S. KATRINA. THE NE GULF IS DOTTED BY
DEVELOPING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 22N W
OF 85W TO THE N AND W COASTLINES. MOISTURE AND THUNDERSTORM
ACTIVITY WILL BE SPREADING ACROSS FLORIDA TODAY INTO THE GULF AS
T.S. KATRINA CONTINUES TO MOVE TOWARD FLORIDA.

CARIBBEAN...
WEAK UPPER LEVEL INVERTED TROUGH REMAINS OVER THE S CARIBBEAN
ENHANCING THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG
75W/76W. OTHERWISE THE UPPER FLOW IS GENERALLY EASTERLY ACROSS
THE REMAINDER OF THE BASIN. SCATTERED SHOWERS/ THUNDERSTORMS ARE
S OF 12N W OF 80W TO INLAND OVER PANAMA...COSTA RICA...AND
NICARAGUA. A MID/UPPER RIDGE EXTENDS FROM NEAR T.S. KATRINA SW
OVER HISPANIOLA TO PUERTO RICO WITH DIFFLUENCE GENERATING A
LARGE AREA STRONG CONVECTION N OF HISPANIOLA AND PUERTO RICO.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS N OF 16N ACROSS
HISPANIOLA FROM THE MONA PASSAGE TO 73W.

ATLANTIC...
A MID/UPPER RIDGE EXTENDS FROM NEAR T.S. KATRINA SW OVER
HISPANIOLA TO PUERTO RICO WITH DIFFLUENCE GENERATING AN AREA OF
SCATTERED/NUMEROUS STRONG CONVECTION WITHIN 60 NM OF LINE
19.5N67.5W-22N70W. THIS CONVECTION IS EMBEDDED WITHIN A LARGER
AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING
THE AREA S OF 27.5N BETWEEN 65W-73W INCLUDING THE TURKS AND
CAICOS. A MID/UPPER E/W TROUGH EXTENDS FROM AN UPPER LOW NEAR
25N46W ALONG 23N54W TO A SECOND LOW NEAR 26N67W. THE TROPICS ARE
DOMINATE BY THE RIDGE FROM THE N CARIBBEAN ISLANDS AND THE RIDGE
EXTENDING OFF AFRICA ALONG 16N W ACROSS THE CAPE VERDE ISLANDS
TO 40W...THUS GENERATING THE INVERTED TROUGH EFFECTING THE
TROPICAL WAVE ALONG 43W/44W. N FLOW IN THE FAR W TROPICAL ATLC
INTERSECTING THE MODERATE EASTERLY FLOW IS GENERATING SCATTERED
SHOWERS/THUNDERSTORMS E OF THE LESSER ANTILLES FROM 14N-18N
BETWEEN 57W-61W. STRONG SUBSIDENCE AND VERY DRY UPPER AIR REMAIN
OVER THE REMAINDER OF THE W TROPICAL ATLC FROM 14N-21N BETWEEN
THE TROPICAL WAVE NEAR 43W/44W TO 57W. AT THE SURFACE...THE
SUBTROPICAL RIDGE REMAINS ACROSS THE ATLC N OF 20N E OF 65W.

$$
WALLACE







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