[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 070003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON 06 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...

TROPICAL STORM FRANCES IS CENTERED AT 31.1N 84.5W AT 07/0000 UTC
MOVING NORTH NORTHWEST AT 7 KT. MAXIMUM SUSTAINED WIND SPEED IS
35 KT WITH HIGHER GUSTS AND THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 984 MB. SEE LATEST NHC PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC AND THE
FORECAST/ADVISORY UNDER HEADERS MIATCMAT1/WTNT21 KNHC FOR
ADDITIONAL INFORMATION. AFTER MAKING LANDFALL NEAR ST. MARKS
FLORIDA THIS AFTERNOON...FRANCES IS NOW WELL INLAND OVER S
GEORGIA WITH THE CORE OF DEEP CONVECTION QUICKLY DEPARTING THE
NE GLFMEX. OUTER RAINBANDS CONTINUE TO AFFECT N
PORTIONS OF FLORIDA WITH THE STRONGEST ACTIVITY CURRENTLY  ALONG
A TRAILING SURFACE TROUGH FROM JUST W OF JACKSONVILLE TO THE
CENTRAL GLFMEX. LOCALLY HEAVY RAINFALL AND POSSIBLE FLOODING
WILL SPREAD NWD WITH FRANCES AS SHE MOVES ACROSS THE SE UNITED
STATES DURING THE NEXT FEW DAYS.

HURRICANE IVAN IS CENTERED NEAR 11.3N 56.3W AT 07/0000 UTC
MOVING RAPIDLY WEST AT 21 KT. MAXIMUM SUSTAINED WIND SPEED HAS
DECREASED TO 90 KT WITH GUSTS TO 110 KT AND THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 964 MB. SEE LATEST NHC PUBLIC
ADVISORY OR NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT4/WTNT34 KNHC OR MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS.  WHILE AN EARLIER RECONNAISSANCE AIRCRAFT FOUND THAT
IVAN HAS WEAKENED DURING THE DAY...UPPER LEVEL OUTFLOW REMAINS
IMPRESSIVE IN ALL QUADRANTS AND IVAN IS EXPECTED TO
RE-STRENGTHEN AS IT MOVES WNW TOWARD THE LESSER ANTILLES. IN
FACT...A RECENT BURST OF DEEP CONVECTION IS NOTED IN SATELLITE
IMAGERY NEAR THE CENTER AND CLOUD TOP TEMPERATURES OVER THE N
SEMICIRCLE HAVE COOLED SIGNIFICANT. OUTER RAINBANDS ARE NOW
AFFECTING BARBADOS AND HEAVY SHOWERS/GUSTY WINDS CAN BE EXPECTED
THIS EVENING AND TONIGHT AS THE BANDS PASS. RAINBANDS WILL ALSO
BEGIN AFFECTING PORTIONS OF THE WINDWARD ISLANDS LATER
TONIGHT.

...TROPICAL WAVES...
TROPICAL WAVE IN THE E ATLC IS ALONG 33W S OF 18N MOVING W 15
KT. WHILE THE WAVE IS GENERATING A FAIR AMOUNT OF DEEP
CONVECTION...THERE ARE NO SIGNS OF IMMEDIATE DEVELOPMENT.
CONVECTIVE ACTIVITY IS NOT CONCENTRATED ABOUT THE CENTER AND
LATEST SATELLITE IMAGERY CONTINUES TO SHOW A BROAD LOW LEVEL
CIRCULATION.  SCATTERED MODERATE CONVECTION FROM 12N-15N BETWEEN
30W-35W AND FROM 2N-6N BETWEEN 35W-43W.

TROPICAL WAVE OVER CENTRAL AMERICA NEAR NICARAGUA/HONDURAS ALONG
85W/86W S OF 16N MOVING W 15-20 KT. THE LATEST POSITION IS BIT
FURTHER W THAN THE EXTRAPOLATED POSITION BASED ON A RECENT
QUIKSCAT PASS SHOWING A LOW LEVEL CYCLONIC CIRCULATION JUST SW
OF COSTA RICA.  THE WAVE IS GENERATING SCATTERED MODERATE
CONVECTION OVER COSTA RICA...NICARAGUA...AND PANAMA.
HOWEVER...THERE ARE NO SIGNS OF ORGANIZATION.

...ITCZ...

ITCZ IS CENTERED ALONG 12N10W 8N20W 10N30W 6N40W BECOMING
ILL-DEFINED NEAR HURRICANE IVAN THEN RESUMING OVER N PORTIONS OF
S AMERICA ALONG 8N/9N.  SCATTERED MODERATE CONVECTION OVER W
AFRICA FROM 9N-13N BETWEEN 10W-16W AND FROM 3N-9N BETWEEN
20W-26W. WIDELY SCATTERED MODERATE CONVECTION OVER N PORTIONS OF
S AMERICA AND THE EXTREME S CARIBBEAN FROM 6N-10N BETWEEN
60W-80W.

...DISCUSSION...

GULF OF MEXICO...
T.S. FRANCES MADE LANDFALL OVER THE FLORIDA PANHANDLE NEAR ST.
MARKS AT 1800 UTC AND CONTINUES TO LIFT NWD OVER S GEORGIA.
STRONG RAINBANDS ACCOMPANIED BY GUSTY WINDS CONTINUE OVER THE
EXTREME NE GLFMEX AND N PORTIONS OF FLORIDA.  THE STRONGEST OF
THIS ACTIVITY WILL SLOWLY DEPART THE GLFMEX OVERNIGHT BUT
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL LINGER ALONG A
TRAILING LOW LEVEL TROUGH CURRENTLY EXTENDING FROM THE FLORIDA
BIG BEND TO THE CENTRAL GLFMEX. IN THE UPPER LEVELS...MIDDLE TO
UPPER LEVEL TROUGH EXTENDS SWD FROM FRANCES TO A WEAK UPPER
LEVEL LOW OVER THE CENTRAL GLFMEX NEAR 24N89W CONTINUING WSW TO
A SECOND UPPER LOW OVER CENTRAL MEXICO NEAR MEXICO CITY.
SUBSIDENCE AND DRY AIR ON THE EQUATORWARD SIDE OF THE TROUGH
COVERS THE S HALF OF THE GLFMEX SAVE THE FLORIDA STRAITS AND S
FLORIDA WHERE SLY FLOW AROUND A HIGH IN THE W ATLC IS ADVECTING
MOISTURE NWD. FURTHER N...STRONG SUBSIDENCE AND DRY AIR OVER THE
S UNITED STATES IS BEING PULLED SWD BY FRANCES NOW N OF A LINE
FROM BROWNSVILLE TEXAS TO SE LOUISIANA.  THE UPPER LOW OVER THE
CENTRAL GLFMEX IS EXPECTED TO RETROGRADE WESTWARD INTO CENTRAL
MEXICO OVER THE NEXT FEW DAYS WHILE THE UPPER TROUGH ASSOCIATED
FRANCES LIFTS NEWD INTO THE E UNITED STATES.  THIS WILL ALLOW
LARGE-SCALE RIDGING OVER THE W ATLC TO BUILD WESTWARD OVER
CENTRAL FLORIDA TO THE BAY OF CAMPECHE BY MID-WEEK.

CARIBBEAN SEA...
A LARGE UPPER LEVEL LOW OVER THE E CARIBBEAN IS THE DOMINANT
WEATHER FEATURE TODAY WITH ASSOCIATED LOWER HEIGHTS
DESTABILIZING THE ATMOSPHERE AND SPARKING ENHANCED AFTERNOON
SHOWERS/THUNDERSTORMS E OF 80W.  THE BULK OF THIS ACTIVITY IS
FOCUSED BETWEEN 75W-80W WITH SCATTERED MODERATE ACTIVITY
EXTENDING FROM THE COAST OF COLOMBIA NWD OVER JAMAICA AND THE
CAYMAN ISLANDS TO E CUBA.  SCATTERED SHOWERS/THUNDERSTORMS ARE
ALSO NOTED OVER PUERTO RICO AND HISPANIOLA.  FURTHER
E...SUBSIDENCE ASSOCIATED WITH THE FAST APPROACHING HURRICANE
IVAN IS PRODUCING FAIRLY TRANQUIL WEATHER OVER THE LESSER
ANTILLES. HOWEVER...THIS WILL QUICKLY GIVE WAY TO THE OUTER
RAINBANDS TONIGHT WHICH ARE ALREADY AFFECTING BARBADOS.  OVER
THE W CARIBBEAN...A WEAK TROUGH IN THE UPPER LEVELS LIES ALONG
ALONG 85W WITH ASSOCIATED SUBSIDENCE IN THE MID-UPPER LEVELS
SUPPRESSING CONVECTIVE ACTIVITY W OF 82W.  THE CURRENT PATTERN
WILL SHIFT QUICKLY WESTWARD DURING THE NEXT FEW DAYS ALLOWING
THE W CARIBBEAN TO BECOME MORE UNSETTLED WHILE IVAN MOVES INTO
THE E CARIBBEAN.

SUBTROPICAL ATLANTIC OCEAN...
LARGE MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE W HALF OF THE
ATLC EXTENDING FROM FLORIDA EWD BETWEEN 20N-30N TO 55W.
MID-UPPER LEVEL MOISTURE ASSOCIATED WITH T.S. FRANCES CONTINUES
TO STREAM EWD N OF 30N TO BERMUDA SUPPORTING WIDELY SCATTERED
SHOWERS/THUNDERSTORMS JUST E OF FLORIDA N OF 28N W OF 75W.  OVER
THE CENTRAL ATLC...A DIGGING MID-LATITUDE TROUGH IS APPROACHING
THE AREA BETWEEN 40W-60W RESULTING IN AN EROSION OF THE E EXTENT
OF THE AFOREMENTIONED ATLC RIDGE. MOST OF DYNAMICS/LIFT AND
ASSOCIATED SHOWERS/THUNDERSTORMS WITH THE MID-LATITUDE TROUGH
REMAIN N OF THE AREA.  FURTHER S...THE MID-OCEANIC TROUGH
UNDERCUTS THE W ATLC RIDGE EXTENDING FROM 30N42W SW ALONG 27N50W
INTO THE CARIBBEAN OVER PUERTO RICO.  THE UPPER TROUGH CONTINUES
TO SHEAR OFF AN IMPRESSIVE AREA OF SHOWERS/THUNDERSTORMS NE OF A
1008 MB LOW NEAR 30N42W.  ADDITIONALLY...SCATTERED
SHOWERS/THUNDERSTORMS ARE NOTED ALONG A REMNANT FRONTAL TROUGH
TRAILING SWD ALONG 25N43W 23N50W WEAKENING TO 22N60W.  OVER THE
E ATLC...MIDDLE TO UPPER LEVEL TROUGH IN BETWEEN THE AZORES AND
CANARY ISLANDS EXTENDS TO 20N35W.  ASSOCIATED SUBSIDENCE
BLANKETS MUCH OF THE E ATLC SUPPRESSIVE WIDESPREAD CONVECTIVE
ACTIVITY.

TROPICAL ATLANTIC...
THE PATTERN OVER THE TROPICAL ATLC IS CHARACTERIZED BY STRONG
MID-LEVEL ELY FLOW WITH A WELL-DEFINED UPPER LEVEL RIDGE E OF
IVAN AND UPPER TROUGH NEAR 40W.  THE TROUGH NEAR 40W IS
PRODUCING STRONG SUBSIDENCE WHICH DIPS WELL INTO THE TROPICAL
ATLC. HOWEVER...DIVERGENT FLOW E OF THE TROUGH IS SUPPORTING
SHOWERS/THUNDERSTORMS WITH A WAVE NEAR 33W.

$$
RHOME





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