[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301050
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE AUG 30 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 34.7N 88.4W AT 30/0900
UTC ABOUT 35 MILES...30 NM...NE OF TUPELO MISSISSIPPI MOVING
NNE AT 16 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 981 MB.
MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SEE
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. KATRINA
CONTINUES TO MOVE N JUST E OF THE MISSISSIPPI VALLEY INTO
TENNESSEE WITH THE HEAVIEST SHOWERS AND THUNDERSTORMS MOVING OUT
OF TENNESSEE OVER KENTUCKY AND THE LOWER GREAT LAKE STATES.
FEEDER BANDS WITH SCATTERED SHOWERS/THUNDERSTORMS EXTEND FROM
THE N GULF COAST N OF 28N TO OVER THE FLORIDA PANHANDLE...
ALABAMA AND GEORGIA. THIS SYSTEM IS BEGINNING TO LOSE ITS
TROPICAL CHARACTERISTICS AND WILL PROBABLY BE DOWNGRADED LATER
IN THE DAY.

A BROAD 1008 MB ATLC TROPICAL SURFACE LOW IS CENTERED NEAR
10N35W MOVING W 10-15 KT. THIS LOW HAS NOT BECOME BETTER
ORGANIZED THAN YESTERDAY BUT STILL HAS THE POTENTIAL FOR FURTHER
DEVELOPMENT WITHIN THE NEXT DAY OR TWO. SCATTERED CLUSTERS OF
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN 220
NM OF LINE 6N42W-16N29W.

...TROPICAL WAVES...

A 1010 MB LOW...FORMERLY T.D. THIRTEEN...IS E OF THE LEEWARD
ISLANDS NEAR 19N55W MOVING NW NEAR 10 KT. SCATTERED MODERATE
CONVECTION IS NE OF THE LOW WITHIN A 75 NM RADIUS OF
21.5N54.5W.

WEAK CARIBBEAN TROPICAL WAVE IS CENTERED ALONG 70W/71W S OF 18N
MOVING W 10-15 KT. POSITION IS BASED ON EXTRAPOLATION BECAUSE
LITTLE SIGNATURE CURVATURE OBSERVED. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS INLAND OVER LAKE MARACAIBO.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 13N15W 15N32W THEN ALONG 9N38W
5N54W. SCATTERED/NUMEROUS STRONG CONVECTION IS MOVING OFF AFRICA
N OF THE ITCZ FROM 13N-17N E OF 19W TO THE COAST OF AFRICA.
SCATTERED MODERATE/STRONG CONVECTION IS S OF THE AXIS FROM
7N-13N E OF 17W TO JUST INLAND OVER AFRICA. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF LINE 8N21W-9N27W.

...DISCUSSION...

GULF OF MEXICO...
KATRINA IS NOW WELL INLAND OVER THE SE UNITED STATES. IN ITS
WAKE...OUTFLOW FROM THE STORM CONTINUES TO FUNNEL ACROSS THE W
ATLC INTO THE GULF COURTESY OF BROAD UPPER HIGH SITUATED E OF
KATRINA. UPPER LEVEL MOISTURE AND HIGH CLOUDS COVER THE E GULF E
OF 89W. A LARGE MID/UPPER LEVEL TROUGH EXTENDS FROM THE CENTRAL
UNITED STATES S ALONG THE TEXAS AND N MEXICO COAST COVERING THE
NW GULF. THIS IS GIVING THE W GULF DRYING AIR AND CLEARING
SKIES. THE UPPER LEVEL HIGH WILL REMAIN OVER THE AREA FORCING
THE TROUGH OVER THE CENTRAL UNITED STATES NE OVER NEW ENGLAND.

CARIBBEAN SEA...
THE BROAD UPPER HIGH FROM THE GULF IS COVERING THE NW CARIBBEAN
N OF 15N W OF 70W WITH STRONG UPPER LEVEL WINDS MOSTLY FROM THE
NE. THIS IS FORCING UPPER LEVEL MOISTURE ACROSS THE NW
CARIBBEAN. AN INVERTED MID/UPPER LEVEL TROUGH EXTENDS FROM THE
ABC ISLANDS NNE TO OVER THE VIRGIN ISLANDS GENERATING SCATTERED
SHOWERS/THUNDERSTORMS N OF 17N FROM THE MONA PASSAGE TO CENTRAL
CUBA THEN SPREADING WSW IN THE THE UPPER LEVEL FLOW. THIS IS
ALSO GIVING THE NE CARIBBEAN STRONG SUBSIDENCE AND DRY UPPER
AIR. THE SW CARIBBEAN IS ALSO UNDER STRONG EASTERLY UPPER FLOW
POSSIBLY GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S
OF 13N. THE INVERTED TROUGH WILL BECOME AMPLIFIED AS IT SHIFTS
WESTWARD.

ATLANTIC OCEAN...
THE BROAD UPPER HIGH FROM THE GULF EXTENDS INTO THE W ATLC WITH
N TO NE WINDS W OF 66W. THIS IS BRING OUTFLOW FROM KATRINA OUT
OVER THE AREA WITH A SMALL AREA OF SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS NE OF THE BAHAMAS FROM 25N-28N BETWEEN 70W-76W.
MID/UPPER LOW IS JUST TO THE E OF THIS FLOW NEAR 30N63W WITH A
SECOND LARGER UPPER LOW CENTERED NEAR 29N54W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS TO THE W OF THE UPPER LOW
FROM 25N-29N BETWEEN 57W-62W. BROAD MID/UPPER LEVEL HIGH IS
SITUATED JUST TO THE E OF THE 1010 MB LOW IN TROPICAL LOW/WAVE
SECTION ABOVE. THE RIDGE AXIS EXTENDS FROM THE WINDWARD ISLANDS
NEAR 12N62W TO 33N46W. SCATTERED MODERATE/STRONG CONVECTION IS
WITHIN 90/120 NM OF LINE 25N50W-30N48W WITH CLUSTERS OF SIMILAR
CONVECTION WITHIN 75/90 NM OF LINE 23N53W-31N51W. THIS IS
LEAVING THE S/CENTRAL ATLC WITH MODERATE/STRONG SUBSIDENCE AND
DRY AIR WITHIN 300/400 NM OF LINE FROM 20N44W SW TO OVER SOUTH
AMERICA NEAR 6N55W. OVER THE NE ATLC...A MID/UPPER LOW CONTINUES
TO MOVE NE OUT OF THE REGION AND NOW COVERS THE AREA N OF 30N E
OF 30W. THE REMAINDER OF THE E ATLC IS UNDER UPPER LEVEL RIDGING
EXTENDING FROM INLAND OVER AFRICA W ALONG 15N/16N E OF 41W. THE
1008 MB LOW IN THE SPECIAL FEATURES SECTION IS AT THE LEADING
EDGE OF THE RIDGE AXIS PUSHING INTO THE DRIER AIR TO THE WEST.

$$
WALLACE




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