[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291804
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 29 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...
TROPICAL STORM GUSTAV IS CENTERED NEAR 18.8N 79.3W AT 29/1800
UTC OR ABOUT 110 NM EAST-SOUTHEAST OF GRAND CAYMAN AND ABOUT 370
NM EAST-SOUTHEAST OF THE WESTERN TIP OF CUBA MOVING WNW AT 7 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 984 MB. MAXIMUM SUSTAINED
WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. 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. OUTFLOW FROM GUSTAV REMAINS GOOD IN ALL QUADRANTS AS
THE STORM MOVES UNDER AN UPPER RIDGE LOCATED OVER THE NW
CARIBBEAN. SCATTERED STRONG CONVECTION IS WITHIN 170 NM OF THE
CENTER IN THE ERN SEMICIRCLE AND WITHIN 130 NM OF THE CENTER IN
THE WRN SEMICIRCLE.

TROPICAL STORM HANNA IS CENTERED NEAR 21.3N 62.7W AT 29/1500 UTC
OR ABOUT 185 NM NORTH OF THE NORTHERN LEEWARD ISLANDS MOVING WNW
AT 10 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 IS EXPERIENCING
WESTERLY SHEAR THUS OUTFLOW FROM HANNA IS MAINLY LIMITED TO THE
E AND S. SCATTERED STRONG CONVECTION COVERS THE AREA FROM
19N-24N BETWEEN 59W-64W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS E OF THE NRN LEEWARD ISLANDS FROM 16N-19N BETWEEN
59W-63W.

TROPICAL WAVE IS ALONG 21W S OF 18N WITH A 1009 MB LOW CENTER
ALONG THE WAVE NEAR 14N MOVING W NEAR 10 KT. A BROAD CYCLONIC
ROTATION IS OBSERVED ON SATELLITE IMAGERY AND AN EARLIER
QUIKSCAT PASS THIS MORNING CONFIRMED THE POSITION OF THE WAVE
AND LOW CENTER. CLUSTERS OF SCATTERED MODERATE CONVECTION COVERS
THE AREA FROM 7N-18N BETWEEN 18W-27W. CONDITIONS APPEAR
FAVORABLE FOR POSSIBLE DEVELOPMENT OF THIS SYSTEM DURING THE
NEXT COUPLE OF DAYS AS IT TRACKS WESTWARD.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 42W FROM 12N TO 21N WITH A 1010 MB LOW
ALONG THE WAVE AXIS NEAR 18N MOVING WNW NEAR 10-15 KT. HIGH
AMPLITUDE WAVE WITH A BROAD INVERTED-V SATELLITE IMAGERY
SIGNATURE OBSERVED. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 18N-22N BETWEEN 38W-41W.

TROPICAL WAVE IS ALONG 58W S OF 13N MOVING W NEAR 15 KT. THIS
ILL-DEFINED WAVE LACKS ANY SHOWERS/DEEP CONVECTION.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 10N14W 11N19W 11N22W 9N40W 9N57W.
THE ITCZ HAS BEEN DISRUPTED BY THE TROPICAL WAVES WITH CLUSTERS
OF SCATTERED MODERATE CONVECTION FROM 7N-14N BETWEEN 18W-29W AND
FROM 7N-10N BETWEEN 33W-39W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH DOMINATES MOST OF THE GULF EXTENDING FROM AN
UPPER LOW CENTERED NEAR 28N86W EXTENDING SOUTH TO OVER THE NRN
YUCATAN PENINSULA. UPPER RIDGE OVER MEXICO EXTENDS ACROSS THE
WRN GULF W OF 92W AND IS PROVIDING UPPER LEVEL DIFFLUENCE TO
GENERATE A FEW SCATTERED SHOWERS/ISOLATED TSTMS IN THE WRN BAY
OF CAMPECHE. SIMILARLY ISOLATED SHOWERS/TSTMS ARE FROM 22N-27N
W OF 92W. AN AREA OF UPPER DIFFLUENCE E OF THE TROUGH IS LOCATED
ACROSS THE SE GULF AND STRAITS OF FLORIDA GENERATING SCATTERED
SHOWERS/TSTMS FROM 23N-25N BETWEEN 81W-85W. A VERY WEAK SURFACE
RIDGE ENCOMPASSES THE N GULF. MODERATE SUBSIDENCE/DRY AIR IS
NOTED N OF 25N E OF 92W TO OVER NRN FLORIDA SUPPRESSING ANY
SHOWER ACTIVITY AND KEEPING THE REMAINDER OF THE GULF RATHER
TRANQUIL.

CARIBBEAN SEA...
THE MAIN CONCERN CONTINUES TO BE T.S. GUSTAV FOR THE NW AND NORTH
CENTRAL CARIBBEAN ALONG WITH SCATTERED SHOWERS ASSOCIATED WITH
T.S. HANNA ACROSS THE LESSER ANTILLES...SEE SPECIAL FEATURES
ABOVE. THE BROAD UPPER HIGH ASSOCIATED WITH GUSTAV IS DOMINATING
MOST OF THE WRN CARIBBEAN. SCATTERED SHOWERS/ISOLATED TSTMS ARE
OVER THE GULF OF HONDURAS FROM 15N-17N BETWEEN 85W-89W. AN UPPER
HIGH LOCATED NE OF THE NRN LEEWARD ISLANDS IN THE W ATLC EXTENDS
RIDGING ACROSS THE NE AND CENTRAL CARIBBEAN. MODERATE SUBSIDENCE
AND DRY AIR IS NOTED E OF 72W WITH THE EXCEPTION OF THE
SCATTERED SHOWERS ACROSS THE LESSER ANTILLES.

ATLANTIC OCEAN...
MAIN FOCUS FOR THE ATLC IS IN THE VICINITY OF THE LEEWARD
ISLANDS AS T.S. HANNA APPROACHES...SEE SPECIAL FEATURES ABOVE.
AN UPPER HIGH IS CENTERED NEAR 29N63W WITH AN UPPER LOW TO THE
S...N OF THE MONA PASSAGE NEAR 22N68W WITH BOTH ENCOMPASSING THE
W ATLC. THE UPPER LOW IS GENERATING SCATTERED SHOWERS/ISOLATED
TSTMS WITHIN 120 NM OF LINE FROM 23N68W TO 28N64W. REMNANTS OF A
DISSIPATED SURFACE TROUGH ARE ACROSS THE BAHAMAS GENERATING AN
AREA OF SCATTERED SHOWERS/TSTMS WITHIN 60 NM OF A LINE FROM
26N74W ACROSS ANDROS ISLAND TO 24N79W. A SHARP UPPER TROUGH IS
IN THE CENTRAL ATLC EXTENDING ALONG 46W TO NEAR 22N INDUCING AN
UPPER RIDGE TO THE W FROM NEAR T.S. HANNA NNE TO BEYOND 32N55W.
AN E/W UPPER RIDGE COVERS THE E ATLC ALONG 22N TO 40W. AT THE
SURFACE ...A BROAD SURFACE RIDGE REMAINS OVER THE ATLC N OF 25N
E OF 50W ANCHORED BY A 1026 MB HIGH CENTERED NORTH OF THE REGION
NEAR 35N35W.

$$
HUFFMAN


This weather bulletin was brought to you by:
www.nashvilleweather.net