[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211057
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE 21 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 0600 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1015 UTC.

...SPECIAL FEATURES...

HURRICANE JEANNE CENTER AT 21/0900 UTC NEAR 27.6N 70.0W OR ABOUT
445 MILES... 715 KM...EAST-NORTHEAST OF GREAT ABACO ISLAND IN
THE BAHAMAS...MOVING EAST-NORTHEAST 5 KT. STEERING CURRENT ARE
WEAKENING...AND JEANNE IS EXPECTED TO MOVE SLOWLY EASTWARD OR
SOUTHEASTWARD DURING THE NEXT 24 HOURS. MAXIMUM SUSTAINED WIND
SPEED 80 KT GUSTS 100 KT. UPPER LEVEL WINDS ARE BECOMING LESS
FAVORABLE FOR STRENGTHENING...AND LITTLE CHANGE IN STRENGTH IS
FORECAST DURING THE NEXT 24 HOURS. ESTIMATED MINIMUM CENTRAL
PRESSURE 972 MB. SEE LATEST NHC PUBLIC ADVISORY OR NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC OR
MIATCMAT1/ WTNT21 KNHC FOR MORE DETAILS. HURRICANE FORCE WINDS
EXTEND OUTWARD UP TO  50 MILES/85 KM FROM THE CENTER...AND
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 120 MILES/195 KM.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 26N TO 28N
BETWEEN 69W AND 71W. SCATTERED STRONG SHOWERS AND THUNDERSTORMS
FROM 27N TO 31N BETWEEN 66W AND 69W.

HURRICANE KARL CENTER AT 21/0900 UTC NEAR 20.1N 47.5W OR ABOUT
1025 MILES/1650 KM...EAST OF THE NORTHERN LEEWARD ISLANDS...
MOVING NORTH-NORTHWEST 10 KT. MAXIMUM SUSTAINED WIND SPEED
120 KT GUSTS 145 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 940 MB.
HURRICANE FORCE WINDS EXTEND OUTWARD UP TO  70 MILES/110 KM...
FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD
UP TO 200 MILES/325 KM. SEE LATEST NHC FORECAST/ ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 19N TO 22N
BETWEEN 44W AND 48W. OTHER STRONG SHOWERS AND THUNDERSTORMS
FROM 21N TO 24N BETWEEN 46W AND 49W.

TROPICAL STORM LISA CENTER AT 21/0900 UTC NEAR 13.8N 37.9W OR
ABOUT 1005 MILES/1615 KM WEST OF THE CAPE VERDE ISLANDS...
MOVING WEST 10 KT. MAXIMUM SUSTAINED WIND SPEED 50 KT GUSTS
60 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 998 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. LISA REMAINS A VERY COMPACT SYSTEM WITH
ASSOCIATED NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 13N
TO 15N BETWEEN 38W AND 40W.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 29W/30W SOUTH OF 17N MOVING WEST 10 TO 15
KT. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 10N TO 12N
BETWEEN 29.5W AND 31.5W. OTHER WIDELY SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 5N TO 13N BETWEEN
30W AND 36W. A MIDDLE TO UPPER LEVEL TROUGH STRETCHES FROM A
CYCLONIC CIRCULATION CENTER NEAR 31N15W JUST NORTH OF THE CANARY
ISLANDS TO AN ILL-DEFINED CYCLONIC CENTER NEAR 22N24W TO 15N25W
RIGHT ON TOP OF THE CAPE VERDE ISLANDS.

...ITCZ...

ITCZ FROM AFRICA NEAR 10N14W TO 5N28W 6N40W...DISRUPTED BY
TROPICAL STORM LISA...14N47W 10N57W 10N66W...AND FROM 11N70W TO
11N85W IN THE SOUTHWESTERN CARIBBEAN SEA. ISOLATED MODERATE TO
LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 4N TO 10N BETWEEN
AFRICA AND 26W. A FEW CLUSTERS OF ISOLATED MODERATE TO LOCALLY
STRONG SHOWERS AND THUNDERSTORMS ARE SOUTH OF 13N BETWEEN 76W
AND THE EASTERN COAST OF CENTRAL AMERICA.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER LEVEL TROUGH WHICH MOVED OFF THE E COAST OF THE UNITED
STATES YESTERDAY HAS AMPLIFIED SW INTO THE GLFMEX WITH AXIS
EXTENDING FROM NORTHERN FLORIDA TO THE SOUTHWESTERN GULF OF
MEXICO. SURFACE STATIONARY FRONT FROM 30N61W TO 30N70W TO 28N76W
ACROSS FLORIDA INTO THE EAST-CENTRAL GULF OF MEXICO NEAR 26N84W.
ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND THUNDERSTORMS
ARE SPREAD THROUGHOUT ALL PARTS OF THE GULF WATERS. THE CLUSTERS
ARE PRETTY MUCH WIDESPREAD. THE 1009 MB LOW PRESSURE CENTER
ASSOCIATED WITH THE REMNANTS OF T.D. IVAN HAVE MOVED INLAND OVER
THE SOUTHWESTERN CORNER OF FLORIDA.

CARIBBEAN SEA...
STRONG MIDDLE TO UPPER LEVEL RIDGE NOW COVERS ALL BUT THE
EXTREME NW CARIBBEAN WHERE A TROUGH OVER THE E GLFMEX CLIPS THE
AREA. THE MEAN RIDGE AXIS EXTENDS FROM HISPANIOLA SW OVER
CENTRAL AMERICA NEAR HONDURAS. ANTICYCLONIC FLOW AROUND THE
RIDGE HAS PUSHED VERY DRY MIDDLE TO UPPER LEVEL AIR FROM THE
TROPICAL ATLC WESTWARD INTO THE EASTERN CARIBBEAN SEA...NOW EAST
OF 75W. A WEAK LOWER TO MIDDLE LEVEL TROUGH TRAILING SWD FROM
HURRICANE IVAN OVER THE ATLC CONTINUES TO SPARK CONVECTION OVER
E CUBA AND W HISPANIOLA.  THE UPPER RIDGE IS EXPECTED TO REMAIN
ESSENTIALLY STATIONARY OVER THE NEXT 2 DAYS.

SUBTROPICAL ATLANTIC...
STRONG MID/UPPER LEVEL TROUGH JUST N OF THE AREA EXTENDS SWD
OVER THE W ATLC FROM THE CANADIAN MARITIMES TO JUST OFF THE
MID-ATLANTIC COAST. SURFACE STATIONARY FRONT THROUGH 30N61W TO
30N70W TO 28N76W ACROSS FLORIDA INTO THE EAST-CENTRAL GULF OF
MEXICO NEAR 26N84W. AREA OF STRONG MIDDLE TO UPPER LEVEL
SUBSIDENCE REMAINS JUST N OF THE AREA. SHIFTING EWD...UPPER
LEVEL RIDGE JUST E OF JEANNE EXTENDS NEWD BEYOND 32N55W.  THE
RIDGE IS CURRENTLY PROVIDING A FAVORABLE ENVIRONMENT FOR JEANNE
TO INTENSIFY. ADDITIONALLY...ANTICYCLONIC FLOW IS ALLOWING
MOISTURE FROM JEANNE TO SURGE NEWD OVER BERMUDA. OVER THE
CENTRAL ATLC...MID/UPPER LEVEL TROUGH ENTERS AREA ALONG 32N50W
EXTENDING SWD ALONG 51W TO 20N.  A HIGH AMPLITUDE MID/UPPER
LEVEL RIDGE EXTENDS FROM JUST E OF KARL NWD ALONG 40W COVERING
THE AREA WITH ANTICYCLONIC FLOW FROM 35W TO 50W. A MID/UPPER
LEVEL TROUGH COVERS THE REMAINDER OF THE AREA E OF 35W WITH
ASSOCIATED MID-LEVEL SUBSIDENCE AND DRY AIR BLANKETING THE E
ATLC.  AT THE SURFACE...SUBTROPICAL RIDGE ENTERS AREA IN BETWEEN
HURRICANE KARL AND HURRICANE JEANNE ALONG 30N50W SW TO
HISPANIOLA.

TROPICAL ATLANTIC...
MID/UPPER LEVEL RIDGING WHICH TYPICALLY EXTENDS E/W ACROSS THE
AREA REMAINS DISRUPTED BY HURRICANE KARL AND TROPICAL STORM
LISA. A WEAK RIDGE EXTENDS E/W ALONG 13N/14N FROM CAPE VERDE TO
40W. THE RIDGE IS PRODUCING DEEP LAYERED ELY FLOW TO THE SOUTH.

$$
MT


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