[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 080002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE 07 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 12.0N 62.6W AT 08/0000 UTC WHICH
IS ABOUT 65 MILES OF TOBAGO. IVAN CONTINUES TO MOVE RAPIDLY
WESTWARD AT 16 KT. MAXIMUM SUSTAINED WIND SPEED IS 105 KT WITH
GUSTS TO 130 KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE IS
950 MB. SEE LATEST NHC PUBLIC ADVISORY OR NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC OR
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. AFTER LOOKING SOMEWHAT
RAGGED YESTERDAY...IVAN NOW DISPLAYS A CLASSIC SATELLITE
SIGNATURE COMPLETE WITH INTENSE CONVECTION NEARLY SYMMETRIC
ABOUT A CLEARLY DEFINED PIN-HOLE EYE. CLOUD TOP TEMPERATURES
HAVE COOLED THROUGHOUT THE DAY AND ARE NOW IN THE -70 TO -80
DEGREE CELSIUS RANGE.  UPPER-LEVEL OUTFLOW IS A BIT RESTRICTED
TO THE WEST COURTESY OF AN UPPER LEVEL LOW S OF HISPANIOLA.
HOWEVER...THIS LOW IS FORECAST TO RETREAT WESTWARD LEAVING IVAN
WITHIN A DIVERGENT/FAVORABLE UPPER LEVEL PATTERN.  A POLEWARD
OUTFLOW JET IS EVIDENT IN SATELLITE IMAGERY AIDED BY A 55 KT JET
ALONG 22N BETWEEN 45W-55W. IN SHORT...THE ENVIRONMENT APPEARS
FAVORABLE FOR IVAN TO REMAIN A MAJOR HURRICANE AS IT MARCHES
WESTWARD ACROSS THE CARIBBEAN. CURRENTLY...NUMEROUS STRONG
CONVECTION WITHIN 100 NM RADIUS OF THE CENTER. OUTER RAINBANDS
STRETCH AS FAR N AS 17N AFFECTING PORTIONS OF THE LEEWARD
ISLANDS WITH SQUALLY WEATHER AND GUSTY WINDS TO TROPICAL STORM
FORCE.

...TROPICAL WAVES...
TROPICAL WAVE IN THE E ATLC IS ALONG 38W S OF 18N MOVING W 15
KT. CONVECTION HAS BECOME SOMEWHAT MORE CONCENTRATED TODAY BUT
THE LOW LEVEL CIRCULATION STILL APPEARS RATHER LARGE AND NOT
INDICATIVE OF A DEVELOPING SYSTEM. NONETHELESS...CONDITIONS
COULD BECOME MORE FAVORABLE FOR DEVELOPMENT OVER THE NEXT FEW
DAYS.

...TROPICAL WAVE OVER GUATEMALA ALONG 89W S OF 17N MOVING W NEAR
10 KT. NEARBY CONVECTION APPEARS MORE DIRECTLY RELATED TO
INSTABILITY ASSOCIATED WITH AN UPPER LEVEL LOW OVER THE
CARIBBEAN. THERE ARE NO SIGNS OF DEVELOPMENT.

...ITCZ...
ITCZ EMERGES OFF AFRICA NEAR DAKAR EXTENDING WESTWARD ALONG
9N25W 10N35W 7N45W 12N55W THEN DISTORTED BY HURRICANE IVAN AND
BECOMING RE-ESTABLISHED OVER N PORTIONS OF S AMERICA ALONG
8N/9N. SCATTERED MODERATE CONVECTION FROM 5N-10N BETWEEN
23W-30W. WIDELY SCATTERED MODERATE CONVECTION FROM 5N-10N
BETWEEN 30W-35W. WIDELY SCATTERED TO LOCALLY SCATTERED MODERATE
CONVECTION S OF 11N BETWEEN 60W-80W.

...DISCUSSION...

GULF OF MEXICO...
NEARLY STATIONARY MID/UPPER LEVEL TROUGH TRAILS FROM TROPICAL
DEPRESSION FRANCES OVER GEORGIA SWD OVER THE CENTRAL GLFMEX
ALONG 26N90W TO THE BAY OF CAMPECHE. FURTHER E...BUILDING
MID-UPPER LEVEL RIDGE EXTENDS FROM CENTRAL FLORIDA SWD TO THE
YUCATAN PENINSULA. THIS PATTERN IS PRODUCING SUBSIDENCE AND DRY
AIR OVER THE CENTRAL GLFMEX SUPPRESSING DEEP CONVECTION.
ELSEWHERE...RESIDUAL MOISTURE FROM FRANCES LINGERS OVER FLORIDA
SPARKING SOME SCATTERED AFTERNOON CONVECTION OVER N PORTIONS OF
THE RAIN-SOAKED STATE.  THE STRONGEST OF THIS ACTIVITY IS
CURRENTLY FOCUSED ALONG A TRAILING SURFACE TROUGH FROM
JACKSONVILLE SW TO 27N86W WITH MORE SPOTTY ACTIVITY FURTHER S.
ANOTHER AREA OF SCATTERED SHOWERS/ THUNDERSTORMS IS NOTED JUST
OFF THE TEXAS/LOUISIANA COAST FROM LAKE CHARLES WESTWARD TO
CORPUS CHRISTI.  SHOWERS/THUNDERSTORMS OVER THE NW CARIBBEAN AND
CUBA WITH A RETROGRADING UPPER LOW HAVE BEEN SLOWLY WORKING NWD
INTO THE FLORIDA STRAITS S OF THE KEYS. THE CENTRAL GLFMEX UPPER
TROUGH IS EXPECTED TO DRIFT WESTWARD AND WEAKEN OVER THE NEXT 2
DAYS WHILE THE RIDGE OVER FLORIDA BUILDS WESTWARD IN ITS WAKE.
MEANWHILE...A RETROGRADING UPPER CURRENTLY OVER THE CENTRAL
CARIBBEAN WILL APPROACH THE YUCATAN PENINSULA BY THU PRODUCING
UNSETTLED WEATHER TO ITS WEST.

CARIBBEAN SEA...
THE BIGGEST FEATURE OVER THE CARIBBEAN IS HURRICANE IVAN WHICH
MOVED ACROSS GRENADA THIS AFTERNOON AND IS NOW AFFECTING THE SE
CARIBBEAN WITH ITS INTENSE CONVECTION AND STRONG WINDS. SEE
SPECIAL FEATURES ABOVE FOR MORE ON IVAN.  ELSEWHERE...LARGE
MIDDLE TO UPPER LEVEL LOW S OF HISPANIOLA NEAR 15N75W CONTINUES
TO CREATE UNSETTLED WEATHER OVER A GOOD PORTION OF THE W AND SW
CARIBBEAN.  CLOUDINESS AND SCATTERED SHOWERS/THUNDERSTORMS
EXTENDS FROM W CUBA SWD OVER NICARAGUA/HONDURAS THEN SEWD OVER
THE REMAINDER OF THE CENTRAL AMERICA AND THE SW CARIBBEAN S OF
13N.  ENHANCED INSTABILITY NEAR THE COLD CORE LOW ALSO GENERATED
AFTERNOON CONVECTION OVER HISPANIOLA AND PUERTO RICO BUT THIS
ACTIVITY HAS BEEN ON THE DOWNWARD TREND.  THE UPPER LOW WILL
RETROGRADE SLOWLY WESTWARD DURING THE NEXT 2 DAYS ALLOWING
UNSETTLED WEATHER CURRENTLY OVER THE W CARIBBEAN TO MIGRATE
TOWARDS THE YUCATAN PENINSULA.

SUBTROPICAL ATLANTIC OCEAN...
THERE HAS BEEN LITTLE CHANGE TO THE LARGE SCALE PATTERN OVER THE
SUBTROPICAL ATLC WITH AN E/W ORIENTED MID/UPPER LEVEL
RIDGE...FROM FLORIDA EWD TO 25N60W...BLOCKING UPSTREAM
DISTURBANCES. DIVERGENT UPPER LEVEL FLOW ALONG THE RIDGE AXIS
COUPLED WITH MOISTURE STREAMING EWD FROM FRANCES IS GENERATING A
FAIR AMOUNT OF HIGH CLOUDINESS AND ISOLATED SHOWERS/
THUNDERSTORMS.  OVER THE CENTRAL ATLC...MID-LATITUDE TROUGH IS
AMPLIFYING SLOWLY SWD BETWEEN 40-60W WITH ATTENDANT COLD FRONT
JUST N OF THE AREA ALONG 31N/32N. WIDELY SCATTERED
SHOWERS/THUNDERSTORMS LIE AHEAD/SOUTH OF THE FRONT FROM 26N-32N
BETWEEN 45W-55W.  WIDELY SCATTERED SHOWERS/THUNDERSTORMS ALSO
ACCOMPANY A FRONTAL TROUGH TRAILS SWD FROM A 1009 MB LOW NEAR
32N40W ALONG 25N40W 21N50W. THE COLD FRONT AND SURFACE TROUGH
ARE EFFECTIVELY SPLITTING THE SURFACE SUBTROPICAL RIDGE OVER THE
CENTRAL ATLC.  OVER THE FAR E ATLC...AN UPPER LEVEL TROUGH
ROUGHLY HALFWAY IN BETWEEN THE AZORES AND CANARY ISLANDS EXTENDS
SWD ALONG 30N20W TO 15N30W. THERE IS NO SIGNIFICANT WEATHER WITH
THIS FEATURE.

TROPICAL ATLANTIC...
AN E TO W ORIENTED MID/UPPER LEVEL RIDGE EXTENDS FROM W AFRICA
ALONG 22N TO 40W WHERE IT BECOMES DISRUPTED BY THE S EXTENT OF A
MID/UPPER LEVEL TROUGH OVER THE CENTRAL SUBTROPICAL ATLC N OF
20N WEST OF 40W.  ASIDE FROM HURRICANE IVAN...A TROPICAL WAVE
ALONG 38W IS PRODUCING WIDELY SCATTERED SHOWERS/THUNDERSTORMS
AND ITCZ CONVECTION IS MOST ACTIVE BETWEEN 25W-35W.

$$
RHOME


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