[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301810
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 30 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...
HURRICANE GUSTAV IS CENTERED NEAR 21.6N 82.5W AT 30/1800 UTC
NEAR THE ISLE OF YOUTH CUBA OR ABOUT 130 NM EAST OF THE WESTERN
TIP OF CUBA AND ABOUT 95 NM SOUTH OF HAVANA CUBA MOVING NW AT 12
KT. THE MINIMUM CENTRAL PRESSURE BASED ON RECENT REPORTS FROM AN
AIR FORCE AND NOAA RECONNAISSANCE AIRCRAFT IS 945 MB. MAXIMUM
SUSTAINED WIND SPEED IS 125 KT WITH HIGHER GUSTS. PLEASE SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/
WTNT22 KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT2/WTNT32 KNHC FOR
MORE DETAILS. GUSTAV CONTINUES TO STRENGTHEN AND NOW IS AN
EXTREMELY DANGEROUS CATEGORY FOUR HURRICANE ON THE
SAFFIR-SIMPSON HURRICANE SCALE. FURTHER STRENGTHENING IS
POSSIBLE IN THE SOUTHERN GULF OF MEXICO ONCE GUSTAV TRACKS
ACROSS WRN CUBA. OUTFLOW REMAINS GOOD IN ALL QUADRANTS WITH
SCATTERED/NUMEROUS STRONG CONVECTION WITHIN 90 NM OF THE CENTER
IN THE NE QUADRANT AND 120 NM OF THE CENTER ELSEWHERE. SCATTERED
MODERATE/STRONG CONVECTION COVERS THE REMAINDER OF THE AREA FROM
18N-26N BETWEEN 78W-85W...INCLUDING OUTER RAINBANDS OF SCATTERED
SHOWERS/ ISOLATED TSTMS ACROSS THE SRN FLORIDA PENINSULA...
FLORIDA KEYS...AND STRAITS OF FLORIDA.

TROPICAL STORM HANNA IS CENTERED NEAR 22.2N 67.0W AT 30/1800 UTC
OR ABOUT 230 NM EAST OF GRAND TURK ISLAND MOVING W AT 7 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED
WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23
KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT3/WTNT33 KNHC FOR MORE
DETAILS. HANNA CONTINUES TO EXPERIENCE SWLY SHEAR RESULTING WITH
MUCH OF THE CONVECTION LOCATED IN THE NE QUADRANT OF THE STORM.
SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 22N-26N BETWEEN
62W-66W WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION
COVERING THE REMAINDER OF THE AREA FROM 19N-27N BETWEEN 61W-67W.

TROPICAL WAVE IS ALONG 25W/26W S OF 19N WITH A 1008 MB SURFACE
LOW ALONG THE WAVE NEAR 14.3N MOVING W 10-15 KT. A BROAD MID
LEVEL CYCLONIC ROTATION IS OBSERVED ON SATELLITE IMAGERY WITH
ASSOCIATED CONVECTION MOSTLY LOCATED NORTH OF THE LOW. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 15N-18N BETWEEN
23W-26W. A SIMILAR SMALLER AREA OF CONVECTION IS LOCATED WITHIN
150 NM E OF THE LOW FROM 13N-16N. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION COVER AN AREA WITHIN 90 NM OF LINE
FROM 10N22W TO 8N39W. CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION
DURING THE NEXT COUPLE OF DAYS.

...TROPICAL WAVES...
TROPICAL WAVE IS FROM 24N45W THROUGH A 1009 MB LOW NEAR 18.5N46W
TO 14N46W MOVING WNW NEAR 10 KT. BROAD INVERTED-V SATELLITE
IMAGERY SIGNATURE IS OBSERVED WELL N OF THE ITCZ. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 19N-24N
BETWEEN 42W-46W.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 16N15W 17N23W...DISRUPTED BY THE
TROPICAL WAVE ALONG 25W/26W TO...11N28W 10N60W. ONLY CONVECTION
ALONG THE ITCZ REMAINS THE LARGE AREA OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION WITHIN 90 NM OF A LINE FROM 10N22W TO
8N39W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE GUSTAV IS THE FOCUS FOR THE SE GULF AND THE FLORIDA
STRAITS AS IT CONTINUES TRACKING NW ACROSS THE NW CARIBBEAN
...SEE SPECIAL FEATURES ABOVE. BROAD UPPER TROUGH DOMINATES MOST
OF THE GULF EXTENDING S FROM NEAR MOBILE ALABAMA TO THE YUCATAN
PENINSULA AND BELIZE. UPPER RIDGE OVER NRN MEXICO EXTENDS ACROSS
THE WRN GULF W OF 90W AND IS PROVIDING UPPER LEVEL DIFFLUENCE TO
GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED TSTMS OVER THE W
GULF W OF A LINE FROM BROWNSVILLE TEXAS TO NEAR 18N93W OVER SRN
MEXICO. THE UPPER RIDGE ASSOCIATED WITH HURRICANE GUSTAV IS
PROVIDING UPPER LEVEL DIFFLUENCE E OF THE UPPER TROUGH
GENERATING SCATTERED SHOWERS/ISOLATED TSTMS S OF 30N E OF 85W TO
OVER THE FLORIDA PENINSULA AND THE STRAITS OF FLORIDA. MODERATE
SUBSIDENCE/DRY AIR IS NOTED WITHIN 90 NM OF THE UPPER TROUGH
AXIS ALONG 89W N OF THE YUCATAN PENINSULA.

CARIBBEAN SEA...
THE MAIN CONCERN CONTINUES TO BE HURRICANE GUSTAV FOR THE NW
CARIBBEAN...SEE SPECIAL FEATURES ABOVE. SCATTERED SHOWERS REMAIN
OVER THE NRN LEEWARD ISLANDS AND THE VIRGIN ISLANDS ASSOCIATED
WITH OUTER RAINBANDS OF T.S. HANNA. BROAD UPPER HIGH ASSOCIATED
WITH GUSTAV IS DOMINATING THE CARIBBEAN W OF 72W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ASSOCIATED WITH UPPER DIFFLUENCE
ARE OVER THE WRN CARIBBEAN FROM 12N-15N BETWEEN 74W-77W AND AN
AREA OVER THE GULF OF HONDURAS W OF 85W. AN UPPER HIGH IS
CENTERED IN THE NE CARIBBEAN NEAR 16N64W EXTENDING A RIDGE OVER
THE ERN CARIBBEAN TO 72W. MODERATE SUBSIDENCE AND DRY AIR
CONTROL THE ERN CARIBBEAN LIMITING SHOWERS OVER THE AREA
INCLUDING THE WINDWARD ISLANDS...EXCEPTION BEING THE ACTIVITY IN
ASSOCIATION WITH T.S. HANNA OVER THE LEEWARD AND VIRGIN ISLANDS.

ATLANTIC OCEAN...
MAIN FOCUS FOR THE ATLC IS OVER THE SW ATLC IN ASSOCIATION WITH
HURRICANE GUSTAV AND IN THE VICINITY N OF PUERTO RICO WITH T.S.
HANNA...SEE SPECIAL FEATURES ABOVE. THE UPPER HIGH ASSOCIATED
WITH HURRICANE GUSTAV IN THE CARIBBEAN EXTENDS ACROSS CUBA AND
THE BAHAMAS OVER THE FAR W ATLC PROVIDING UPPER LEVEL DIFFLUENCE
TO GENERATE SCATTERED SHOWERS/ISOLATED TSTMS S OF 28N W OF 75W
ACROSS THE NW BAHAMA ISLANDS AND CUBA TO OVER THE FLORIDA
PENINSULA AND THE STRAITS OF FLORIDA. A WEAKENING UPPER LOW
REMAINS N OF HISPANIOLA NEAR 22N69W AND IS PROVIDING T.S. HANNA
WITH ENOUGH UPPER LEVEL SHEAR TO LIMIT ITS CONVECTION ON THE WRN
SIDE OF THE STORM. A SHARP UPPER TROUGH IS IN THE CENTRAL ATLC
EXTENDING THROUGH 32N47W S TO 20N47W. ANOTHER UPPER TROUGH
CONTINUES TO DIG S OVER THE NE ATLC N OF 25N FROM 15W-28W
INDUCING AND AMPLIFYING AN UPPER RIDGE TO THE W WHICH IS
ENHANCING THE SCATTERED SHOWERS ASSOCIATED WITH THE TROPICAL
WAVE IN THE CENTRAL ATLC. THE E/W UPPER RIDGE IS BEGINNING TO
BREAKDOWN OVER THE E ATLC AND IS BECOMING MORE ASSOCIATED WITH
THE TROPICAL WAVE IN THE SPECIAL FEATURES. ALSO AT THE SURFACE
...A SURFACE RIDGE OF HIGH PRESSURE REMAINS OVER MUCH OF THE
ATLC N OF 26N E OF 57W AND N OF 28N E OF 75W ANCHORED BY A
SERIES OF HIGHS N OF THE REGION.

$$
HUFFMAN

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