[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 310003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
HURRICANE GUSTAV IS CENTERED NEAR 22.7N 83.4W AT 31/0000 UTC OR
OVER WESTERN CUBA NEAR LOS PALACIOS AND 55 NM WEST-SOUTHWEST OF
HAVANA CUBA MOVING NW AT 13 KT. THE MINIMUM CENTRAL PRESSURE
RECENTLY REPORTED BY A NOAA RECONNAISSANCE AIRCRAFT AS GUSTAV
WAS MAKING LANDFALL ACROSS WRN CUBA WAS 941 MB. MAXIMUM
SUSTAINED WIND SPEED IS 130 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 IS BEGINNING TO TRACK ACROSS WRN CUBA AND
REMAINS AN EXTREMELY DANGEROUS CATEGORY FOUR HURRICANE ON THE
SAFFIR-SIMPSON HURRICANE SCALE. FURTHER STRENGTHENING IS
FORECAST ONCE GUSTAV REACHES THE WARMER WATERS OF THE SE GULF OF
MEXICO. OUTFLOW REMAINS GOOD IN ALL QUADRANTS WITH SCATTERED/
NUMEROUS STRONG CONVECTION WITHIN 90 NM OF THE CENTER IN ALL
QUADRANTS. SCATTERED MODERATE/STRONG CONVECTION COVERS THE
REMAINDER OF THE AREA FROM 18N-30N BETWEEN 78W-87W...INCLUDING
OUTER RAINBANDS OF SCATTERED SHOWERS/ISOLATED TSTMS ACROSS THE
FLORIDA PENINSULA AND ERN GULF OF MEXICO.

TROPICAL STORM HANNA IS CENTERED NEAR 22.8N 67.3W AT 31/0000 UTC
OR ABOUT 230 NM EAST-NORTHEAST OF GRAND TURK ISLAND MOVING WNW AT
5 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 WLY
SHEAR RESULTING WITH MUCH OF THE CONVECTION LOCATED IN THE NE
QUADRANT OF THE STORM. SCATTERED/NUMEROUS STRONG CONVECTION IS
FROM 22N-25N BETWEEN 63W-67W WITH SCATTERED MODERATE/ISOLATED
STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM
17N-22N BETWEEN 61W-65W...INCLUDING THE US/UK VIRGIN ISLANDS AND
THE NRN LEEWARD ISLANDS NORTH OF GUADELOUPE.

TROPICAL WAVE IS ALONG 26W/27W S OF 20N WITH A 1008 MB SURFACE
LOW ALONG THE WAVE NEAR 14.5N 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 CONVECTION IS FROM 15N-18N BETWEEN 25W-28W. SCATTERED
SHOWERS COVER THE REMAINDER OF THE AREA FROM 14N-22N BETWEEN
21W-30W. 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 25N46W THROUGH A 1009 MB LOW NEAR 21N46W
TO 15N47W MOVING WNW NEAR 10 KT. INVERTED-V SATELLITE SIGNATURE
IS OBSERVED WELL N OF THE ITCZ. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 19N-24N BETWEEN 42W-46W AND
ARE BEING ENHANCED BY UPPER LEVEL DIFFLUENCE E OF A MID-UPPER
TROUGH OVER THE ATLC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 19N16W 18N24W...DISRUPTED BY THE
TROPICAL WAVE ALONG 26W/27W TO...11N28W 12N44W 10N61W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS ALONG THE W AFRICAN COAST
FROM 8N-11N BETWEEN 11W-15W. SCATTERED SHOWERS AND POSSIBLE
ISOLATED TSTMS ARE WITHIN 120 NM OF A LINE FROM 9N23W TO 9N39W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE GUSTAV IS THE FOCUS FOR THE SE GULF...STRAITS OF
FLORIDA AND FLORIDA PENINSULA AS IT CONTINUES TRACKING NW ACROSS
WRN CUBA...SEE SPECIAL FEATURES ABOVE. BROAD UPPER TROUGH
DOMINATES MOST OF THE GULF EXTENDING S FROM NEAR NEW ORLEANS
LOUISIANA TO THE YUCATAN PENINSULA AND BELIZE. UPPER RIDGE OVER
NE MEXICO EXTENDS ACROSS THE WRN GULF W OF 94W AND IS PROVIDING
UPPER LEVEL DIFFLUENCE TO GENERATE CLUSTERS OF SCATTERED SHOWERS
AND ISOLATED TSTMS OVER THE FAR WRN GULF W OF A LINE FROM
BROWNSVILLE TEXAS TO OVER THE ISTHMUS OF TEHUANTEPEC IN SRN
MEXICO. THE UPPER RIDGE ASSOCIATED WITH HURRICANE GUSTAV IS
PROVIDING VERY FAVORABLE UPPER LEVEL DIFFLUENCE E OF THE UPPER
TROUGH GENERATING SCATTERED SHOWERS AND TSTMS S OF 31N E OF 87W
TO OVER THE FLORIDA PENINSULA. MODERATE SUBSIDENCE/DRY AIR IS
NOTED WITHIN 120 NM OF THE UPPER TROUGH AXIS ALONG 92W N OF THE
YUCATAN PENINSULA TO OVER LOUISIANA AND FAR ERN TEXAS.

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 31N W OF 76W
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 21N69W AND IS PROVIDING T.S. HANNA
WITH JUST ENOUGH UPPER LEVEL SHEAR TO LIMIT CONVECTION ON THE
WRN SIDE OF THE STORM. SCATTERED STRONG CONVECTION HAS FLARED UP
OVER THE PAST 3-6 HOURS SW OF THE CENTER FROM 21N-23N BETWEEN
67W-70W. A SHARP UPPER TROUGH IS IN THE CENTRAL ATLC EXTENDING
THROUGH 32N48W S TO 19N48W. ANOTHER UPPER TROUGH CONTINUES TO
SLIDE EWD OVER THE NE ATLC N OF 24N FROM 14W-28W INDUCING AN
AMPLIFYING UPPER RIDGE TO THE W WHICH IS ENHANCING THE SCATTERED
SHOWERS ASSOCIATED WITH THE TROPICAL WAVE IN THE CENTRAL ATLC.
AN UPPER RIDGE IS CENTERED N OF THE CAPE VERDE ISLANDS AND IS
AIDING IN GENERATING THE CONVECTIVE ACTIVITY 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 55W AND N OF 30N E OF 75W ANCHORED BY A SERIES OF
HIGHS N OF THE REGION.

$$
HUFFMAN




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