[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 082359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED 08 SEP 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLC 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
2315 UTC.

...SPECIAL FEATURES...

HURRICANE IVAN IS CENTERED NEAR 13.4N 68.4W AT 09/0000 UTC WHICH
IS ABOUT 640 MILES ESE OF KINGSTON JAMAICA. IVAN CONTINUES TO
MOVE W AT 14 KT. MAXIMUM SUSTAINED WIND SPEED HAS INCREASED TO
125 KT WITH GUSTS TO 150 KT AND THE ESTIMATED MINIMUM CENTRAL
PRESSURE HAS FALLEN TO 938 MB. SEE LATEST NHC PUBLIC ADVISORY OR
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34
KNHC OR MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. IVAN CONTINUES
TO DEMONSTRATE AN EXTREMELY IMPRESSIVE SATELLITE SIGNATURE WITH
A CLEARLY DEFINED EYE AND NEARLY SYMMETRIC SURROUNDING DEEP
CONVECTION WITHIN 90 NM RADIUS OF THE CENTER. OUTER RAINBANDS
EXTEND NORTHWARD AS FAR AS THE VIRGIN ISLANDS...PUERTO
RICO...AND HISPANIOLA AS WELL AS SWD OVER N VENEZUELA.  SQUALLY
WEATHER AND GUSTY WINDS CAN BE EXPECTED WITHIN THESE BANDS. IN
THE UPPER LEVELS...IVAN IS SITUATED EAST OF A WELL-DEFINED
UPPER-LEVEL LOW OVER THE W CARIBBEAN. WESTWARD UPPER-LEVEL
OUTFLOW FROM IVAN WAS SOMEWHAT INHIBITED BY THE UPPER LOW
EARLIER TODAY BUT NOW APPEARS UNRESTRICTED IN ALL DIRECTIONS. IN
FACT...A NICE OUTFLOW CHANNEL IS OBSERVED POLEWARD OF IVAN WHICH
IS BEING ASSISTED BY A 50-60 KT UPPER JET ALONG 21N/22N FROM
50W-65W.  THE AFOREMENTIONED UPPER LOW IS EXPECTED TO MOVE
WESTWARD IN TANDEM WITH IVAN OVER THE NEXT FEW DAYS PROVIDING A
DIFFLUENT/FAVORABLE UPPER-LEVEL ENVIRONMENT. BOTTOM LINE...IVAN
SHOULD REMAIN A VERY DANGEROUS HURRICANE AS IT MARCHES
WEST-NORTHWESTWARD OVER THE CENTRAL CARIBBEAN.

...TROPICAL WAVES...
TROPICAL WAVE OVER THE FAR E ATLC ALONG 28W/29W S OF 17N MOVING
W NEAR 15 KT. THE WAVE IS PRODUCING WIDELY SCATTERED CLUSTERS OF
MODERATE/ISOLATED STRONG CONVECTION WITHIN THE ITCZ FROM 6N-11N
BETWEEN 25-35W. NO SIGNS OF ORGANIZATION AT THIS TIME.

TROPICAL WAVE OVER THE CENTRAL ATLC ALONG 45W S OF 18N MOVING W
15 KT. THE WAVE IS ACCOMPANIED BY SCATTERED MODERATE CONVECTION
FROM 12N-17N BETWEEN 41W-49W.  CONVECTION REMAINS DISORGANIZED
WITH NO SIGNS OF DEVELOPMENT.

TROPICAL WAVE OVER CENTRAL AMERICA JUST E OF THE ISTHMUS OF
TEHUANTEPEC ALONG 92W S OF 18N MOVING W 10 KT. THE WAVE IS
POORLY DEFINED IN SATELLITE IMAGERY AND NEARBY CONVECTION
APPEARS MORE DIRECTLY RELATED TO A RETROGRADING UPPER LOW OVER
THE W CARIBBEAN.

...ITCZ...
ITCZ AXIS EMERGES OFF THE COAST OF AFRICA NEAR DAKAR THEN SW
ALONG 7N30W 12N40W 7N52W 13N62W BECOMING DISRUPTED IN THE
VICINITY OF HURRICANE IVAN THEN RE-ESTABLISHED OVER N PORTIONS
OF S AMERICA ALONG 8N/9N. ASIDE FROM CONVECTION OUTLINED WITH
TROPICAL WAVES...WIDELY SCATTERED MODERATE CONVECTION FROM 2N-6N
BETWEEN 27W-36W. SCATTERED MODERATE TO STRONG CONVECTION FROM
7N-9N BETWEEN 40W-43W. ISOLATED MODERATE CONVECTION OVER S
AMERICA AND CENTRAL AMERICA FROM 5N-11N BETWEEN 65W-80W.

...DISCUSSION...

GULF OF MEXICO...
NEARLY STATIONARY MID/UPPER LEVEL TROUGH REMAINS OVER THE
CENTRAL GLFMEX EXTENDING SWD FROM T.D FRANCES NOW OVER THE E
UNITED STATES TO THE BAY OF CAMPECHE. STRONG SUBSIDENCE AND DRY
AIR IS LOCATED OVER THE WESTERN FLANK OF THE TROUGH SUPPRESSING
SHOWERS/THUNDERSTORMS SAVE A SMALL AREA JUST OFF THE SE TEXAS
COAST ALONG A DISSIPATING STATIONARY FRONT FROM THE FLORIDA
PANHANDLE TO S TEXAS. FURTHER E...WELL-DEFINED MID TO UPPER
LEVEL RIDGE EXTENDS FROM CENTRAL FLORIDA SW TO THE YUCATAN
PENINSULA. DIFFLUENT UPPER LEVEL FLOW ALONG THE RIDGE AXIS IS
TRIGGERING SCATTERED SHOWERS/THUNDERSTORMS NEAR A LOW LEVEL
TROUGH EXTENDING FROM THE YUCATAN PENINSULA NEWD TO FLORIDA NEAR
FT. MYERS.  THIS TROUGH IS THE N EXTENSION OF A TROPICAL WAVE
OVER S MEXICO AND IS ACCOMPANIED BY AN ABUNDANCE OF LOW-LEVEL
MOISTURE. THIS LOW-LEVEL TROUGH AND ASSOCIATED MOISTURE IS
FORECAST TO DRIFT SLOWLY NW INTO THE CENTRAL GLFMEX OVER THE
NEXT TWO DAYS. AT THE SAME TIME...THE MID-UPPER RIDGE CURRENTLY
OVER FLORIDA WILL BUILD WESTWARD PROVIDING AN IDEAL ENVIRONMENT
FOR THE FORMATION OF CLOUDINESS AND SHOWERS/THUNDERSTORMS. MAIN
BAND OF ACTIVITY IS EXPECTED TO EXTEND FROM CENTRAL FLORIDA TO
THE COAST OF MEXICO NEAR TAMPICO BY FRI MORNING.

CARIBBEAN SEA...
THE BIGGEST SHOW IN TOWN IS HURRICANE IVAN...SEE SPECIAL
FEATURES ABOVE FOR MORE INFORMATION. ELSEWHERE LARGE UPPER LEVEL
LOW IS SITUATED OVER THE W CARIBBEAN ABOUT 250 NM NNE OF PANAMA
CITY PANAMA.  THE UPPER LOW CONTINUES TO PRODUCING UNSETTLED
WEATHER OVER THE W CARIBBEAN AS IT RETROGRADES SLOWLY WESTWARD.
CURRENTLY...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
MOVING RAPIDLY WESTWARD OVER S MEXICO AND PORTIONS OF CENTRAL
AMERICA FROM W HONDURAS NW OVER THE YUCATAN PENINSULA TO THE
ISTHMUS OF TEHUANTEPEC.  WIDELY SCATTERED MODERATE CONVECTION IS
ALSO NOTED OVER S PORTIONS OF CENTRAL AMERICA INCLUDING COSTA
RICA AND PANAMA. SHOWERS/THUNDERSTORMS ARE ALSO NOTED JUST N OF
THE COLD CORE LOW OVER JAMAICA AND ALONG THE S COAST OF CUBA.
OVER THE E CARIBBEAN...LARGE INDUCED MIDDLE TO UPPER LEVEL RIDGE
LIES E OF HURRICANE IVAN. OUTER RAINBANDS FROM IVAN CONTINUE TO
AFFECT A GOOD PORTION OF THE CARIBBEAN E 72W TO THE LESSER
ANTILLES WHICH ARE FINALLY DRYING OUT.

SUBTROPICAL ATLANTIC...
A LARGE SCALE RIDGE-TROUGH-RIDGE PATTERN DOMINATES MOST OF THE
SUBTROPICAL ATLC WITH A STRONG MID-UPPER LEVEL RIDGE OVER THE W
ATLC FROM FLORIDA NEWD ALONG THE UNITED STATES E
COAST...MID-OCEANIC TROUGH EXTENDING FROM 35N45W SWD TO THE S
BAHAMAS...AND RIDGE OVER THE E ATLC E OF 40W.  ASIDE FROM
CONVECTION OVER FLORIDA...THE BULK OF THE ACTIVITY IS FOCUSED
OVER THE CENTRAL ATLC WHERE UPPER DYNAMICS ASSOCIATED WITH THE
MID-OCEANIC TROUGH IS TRIGGERING SHOWERS/THUNDERSTORMS WITHIN
200 NM AHEAD OF A REMNANT FRONTAL TROUGH ALONG 32N46W 28N55W
32N60W.  MORE ISOLATED ACTIVITY IS NOTED ALONG A SECOND
LOW-LEVEL TROUGH EXTENDING FROM 32N34W SWD TO 22N50W.   OVER THE
E ATLC...CONFLUENT FLOW AND SUBSIDENCE ASSOCIATED WITH THE UPPER
RIDGE IS LIMITING SIGNIFICANT CLOUDINESS/CONVECTION.  AT THE
SURFACE...THE MID-OCEANIC TROUGH AND ASSOCIATED FRONTAL BOUNDARY
CONTINUES TO CREATE A WEAKNESS WITHIN THE SUBTROPICAL RIDGE OVER
THE CENTRAL ATLC.  A RIDGE LIES OVER THE W ATLC FROM BERMUDA TO
THE FLORIDA STRAITS AND E ATLC FROM THE AZORES SWD ALONG 30N25W
TO 25N35W. THE GENERAL UPPER LEVEL PATTERN CURRENTLY IN PLACE
WILL REMAIN OVER THE SUBTROPICAL ATLC DURING NEXT COUPLE OF DAYS
WITH THE TRAILING END OF THE MID-OCEANIC TROUGH GRADUALLY
RETROGRADING WEST AS AN UPPER LOW FORMS NEAR 25N55W AND BECOMES
CUT OFF.

TROPICAL ATLANTIC...
UPPER LEVEL TROUGH IS DIGGING SWD OVER THE CAPE VERDE ISLANDS
WITH ASSOCIATED SUBSIDENCE AND DRY AIR COVERING MUCH OF THE AREA
E OF 35W. MID-UPPER LEVEL RIDGE BETWEEN 35W-50W IS PRODUCING
DEEP EASTERLY FLOW...A GENERALLY FAVORABLE ENVIRONMENT FOR
ITCZ/TROPICAL WAVE CONVECTION. FURTHER W...A WEAK MID-UPPER
LEVEL TROUGH ALONG 52W IS PRODUCING STRONG SUBSIDENCE TO ITS
WEST SUPPRESSING ITCZ ACTIVITY AS IT MOVES SLOWLY WEST.

$$
RHOME


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