[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU SEP 28 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2345 UTC.

...SPECIAL FEATURE...
TROPICAL STORM ISAAC AT 28/2100 UTC WAS NEAR 28.9N 54.9W...OR
ABOUT 550 NM EAST-SOUTHEAST OF BERMUDA. ISAAC IS MOVING TOWARD
THE NORTH-NORTHWEST AT 7 KT AND A TURN TOWARD THE NORTHWEST IS
EXPECTED LATER TONIGHT OR TOMORROW. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1006 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 40 KT WITH GUSTS TO 50 KT. SOME SLOW INCREASE IS STRENGTH
IS FORECAST DURING THE NEXT 24 HOURS. PLEASE READ THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE
DETAILS.  A CLUSTER OF MODERATE CONVECTION IS MOSTLY N AND NW OF
THE CENTER OF ISAAC FROM 29N-31N BETWEEN 54W-56W.

...TROPICAL WAVES...
AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 25W SOUTH OF
22N MOVING WEST NEAR 10 KT.  A 1011 MB LOW PRESSURE CENTER IS
ALONG THE WAVE AXIS NEAR 15N...NEAR THE SW CAPE VERDE ISLANDS. A
QUIKSCAT PASS AT 28/1930 UTC SUGGESTS THERE IS STILL A BROAD LOW
PRESSURE AREA IN THIS REGION...THOUGH THE CONVECTION IS WELL
NORTH OF THE AREA DUE TO SW SHEAR OVER THE SYSTEM. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 17N-23N BETWEEN
24W-29W. MINIMAL SHOWER/TSTM ACTIVITY IS NOTED WITHIN 200NM OF
THE WAVE AXIS S OF 17N.

A LOW AMPLITUDE ATLANTIC OCEAN TROPICAL WAVE IS ALONG 48W SOUTH
OF 14N MOVING WEST 10-15 KT.  THE SCATTERED MODERATE CONVECTION
THAT WAS SURROUNDING 50W FROM 8N-13N THIS AFTERNOON HAS BEEN
DIMINISHING TO ISOLATED SHOWERS/TSTMS OVER THE LAST FEW HOURS.

A TROPICAL WAVE IS MOVING THROUGH THE LESSER ANTILLES ALONG 62W
S OF 21N MOVING WEST 10-15 KT.  A 1012 MB LOW IS ON THE WAVE
AXIS NEAR 18N. THE ASSOCIATED SHOWER AND THUNDERSTORM ACTIVITY
HAS DIMINISHED THIS AFTERNOON AND SIGNIFICANT DEVELOPMENT OF
THIS SYSTEM IS NOT EXPECTED AS IT MOVES WEST-NORTHWESTWARD.
REGARDLESS OF DEVELOPMENT...SOME SHOWERS WILL LIKELY SPREAD
ACROSS PORTIONS OF THE NORTHERN LEEWARD ISLANDS...THE VIRGIN
ISLANDS...AND PUERTO RICO DURING THE NEXT COUPLE OF DAYS.
ISOLATED MODERATE CONVECTION IS SEEN WITHIN 75NM OF THE WAVE
AXIS.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 84W SOUTH OF 22N
MOVING WEST NEAR 10 KT.  SCATTERED MODERATE CONVECTION IS
AFFECTING NICARAGUA...HONDURAS...AND THE NW CARIBBEAN FROM
11N-21N BETWEEN 81W-86W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 14N23W 12N30W 10N40 10N60W.
BESIDES CONVECTION ASSOCIATED WITH TROPICAL WAVES...A CLUSTER OF
NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS OVER AFRICA AND
THE ADJACENT ATLANTIC WATERS FROM 10N-14N BETWEEN 12W-16W.
ISOLATED MODERATE CONVECTION IS WITHIN 100NM OF THE AXIS BETWEEN
30W-45W.

...DISCUSSION...
THE GULF OF MEXICO...
A SLOW MOVING COLD FRONT EXTENDS FROM JUST BEYOND THE SE TIP OF
FLORIDA TO THE SOUTH CENTRAL GULF OF MEXICO ALONG 25N80W 23N87W.
SATELLITE AND AVAILABLE RADAR DATA SHOW VERY LITTLE CONVECTION
ASSOCIATED WITH THE FRONT ASIDE FROM A FEW ISOLATED CELLS
BETWEEN CENTRAL CUBA AND THE FLORIDA KEYS...MOSTLY AFFECTING THE
FLORIDA STRAITS. HIGH CLOUDS ARE STREAMING TO THE NE ACROSS THE
EASTERN GULF AND SOUTH CENTRAL FLORIDA ASSOCIATED WITH AN UPPER
SW JET.  IN FACT...CYCLONIC UPPER W/SW FLOW IS SEEN OVER MOST OF
THE GULF THIS EVENING SOUTH OF A DEEP MID TO UPPER LEVEL TROUGH
MOVING OVER THE EASTERN THIRD OF THE UNITED STATES. UPPER
DIFFLUENCE BETWEEN THIS TROUGH AND RIDGING EXTENDING E THROUGH
CENTRAL MEXICO HAS BEEN GENERATING A FEW ISOLATED SHOWERS IN THE
WRN BAY OF CAMPECHE AND NE MEXICO THE LAST FEW HOURS. A 1017MB
SURFACE HIGH IS LINGERING IN THE NW GULF NEAR 25N93W...WHILE A
WEAK COLD FRONT IS BEGINNING TO MOVE INTO THE EXTREME NW
GULF/COASTAL TEXAS. THIS FRONT WILL CONTINUE TO PUSH SLOWLY E/SE
OVER THE NEXT 24HRS WITH A FEW ISOLATED SHOWERS/TSTMS POSSIBLE
NEAR THE BOUNDARY...THOUGH CURRENTLY NOT MUCH SEEN IN THE MIDST
OF DRY AIR AND MOST OF THE UPPER SUPPORT WELL NE OF THE AREA.

THE CARIBBEAN SEA...
MOST OF THE WEATHER IN THE CARIBBEAN TONIGHT IS ASSOCIATED WITH
THE TROPICAL WAVES AS DESCRIBED ABOVE. THERE IS A BROAD UPPER
HIGH CENTERED JUST NORTH OF PANAMA NEAR 11N79W THAT IS AFFECTING
MUCH OF THE WESTERN CARIBBEAN SEA. THERE IS A MID TO UPPER LOW
SEEN ON WV IMAGERY JUST SOUTH OF THE DOMINICAN REPUBLIC NEAR
17N71W...THAT HAS ISOLATED SHOWERS SPINNING CYCLONICALLY WITHIN
200NM OF ANY SIDE OF THE CENTER. 10 TO 20 KT TRADES PERSIST THIS
EVENING WITH SW PORTION OF THE ATLC HIGH INTERACTING WITH LOWER
PRESSURE NEAR THE COLOMBIAN COAST.

THE ATLANTIC OCEAN...
A SLOW MOVING COLD FRONT IS OVER THE W ATLC ALONG 30N76W
25N80W. ASSOCIATED CLOUDINESS WITH ISOLATED SHOWERS/TSTMS MOSTLY
AHEAD OF THE FRONT ARE FROM 25N-30N BETWEEN 68W-80W...ALSO BEING
SUPPORTED BY UPPER DIFFLUENCE BETWEEN AN UPPER RIDGE EXTENDING
NE THROUGH THE SE BAHAMAS AND THE DEEP TROUGHING OVER THE
EASTERN THIRD OF THE COUNTRY. THERE IS AN UPPER LOW VERY CLOSE
TO TROPICAL STORM ISAAC NEAR 29N55W PRODUCING SOUTHERLY SHEAR
OVER THE STORM. THERE IS A MID TO UPPER LEVEL ANTICYCLONE NE OF
THE LEEWARD ISLANDS NEAR 24N51W. A WELL DEFINED UPPER LOW IS
NEAR 24N31W IN THE ERN ATLC. SCATTERED MODERATE CONVECTION IS
JUST W OF THIS UPPER LOW IN THE ERN ATLC FROM 17N-28N BETWEEN
21W-30W. THIS IS ASSOCIATED WITH UPPER DIFFLUENCE BETWEEN THE
UPPER LOW TO THE W AND AN UPPER HIGH OVER WRN AFRICA...AND SOME
ENHANCEMENT BY THE TROPICAL WAVE/LOW MOVING W/SW OF THE CAPE
VERDE ISLANDS. ELSEWHERE AT THE SURFACE...A 1024MB HIGH IS
AFFECTING PORTIONS OF THE REGION OUTSIDE OF THE TROPICAL
WAVES...ISAAC...AND THE COLD FRONT...FROM ITS CENTER IN THE
CENTRAL ATLANTIC NEAR 36N45W.  A VERY SMALL LOW LEVEL VORTICITY
MAXIMUM IS SEEN AS A SWIRL OF LOW CLOUDS WITH NO CONVECTION NEAR
23N67W...NORTH OF THE MONA PASSAGE. A SHIP REPORTED A 10 KT E
WIND ABOUT 100 NM WSW OF THIS SWIRL...SO NO LOW HAS CURRENTLY
BEEN ADDED FOR THIS FEATURE.


$$
WILLIS


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