[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281058
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE 28 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...
THE CENTER OF TROPICAL DEPRESSION JEANNE AT 28/0900 UTC WAS
NEAR 34.7N 81.8W... OR ABOUT 28 MILES EAST-SOUTHEAST OF
GREENVILLE SOUTH CAROLINA...MOVING NORTH-NORTHEAST NEAR 20 MPH.
MAXIMUM SUSTAINED WIND SPEED 20 MPH WITH SOME HIGHER GUSTS.
MINIMUM CENTRAL PRESSURE 999 MB OR 29.50 INCHES. SEE LATEST HPC
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KWNH
FOR MORE DETAILS. TROPICAL DEPRESSION JEANNE CONTINUES TO
PRODUCE SIGNIFICANT RAINFALL AMOUNTS THROUGH THE APPALACHIANS
AND MID ATLANTIC REGION. FLOOD AND FLASH FLOOD WARNINGS ARE IN
EFFECT FOR PARTS OF CENTRAL NORTH CAROLINA...AND SOUTHWESTERN
VIRGINIA. FLOOD AND FLASH FLOOD WATCHES CONTINUE FOR SECTIONS
OF GEORGIA...SOUTH CAROLINA...NORTH CAROLINA...VIRGINIA...
MARYLAND...DELMARVA PENINSULA...WEST VIRGINIA...PENNSYLVANIA...
AND SOUTHEASTERN NEW YORK.

TROPICAL STORM LISA CENTER AT 28/0900 UTC NEAR 23.1N 46.5W
MOVING NORTH 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 1005 MB.
MAXIMUM SUSTAINED WIND SPEED 35 KT GUSTS 45 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM
24N TO 27N BETWEEN 44W AND 48W. LISA IS MOVING SLOWLY THROUGH A
WEAKNESS IN THE SUBTROPICAL RIDGE...AND THIS IS EXPECTED TO
CONTINUE FOR THE NEXT 24 HOURS. AFTER THAT.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 28W/29W JUST WEST OF THE CAPE VERDE ISLANDS
SOUTH OF 18N MOVING WEST 15 KT. IT IS MOVING INTO AN AREA OF A
MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 20N29W.
CYCLONIC FLOW FROM 10N TO 30N BETWEEN 20W AND 36W. ISOLATED
MODERATE SHOWERS AND THUNDERSTORMS FROM 13N TO 15N BETWEEN 25W
AND 28W. ITCZ PRECIPITATION FROM 8N TO 10N BETWEEN 25W AND 28W.

CENTRAL ATLANTIC OCEAN TROPICAL WAVE ALONG 42W/44W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. WIDELY SCATTERED MODERATE/LOCALLY
STRONG SHOWERS AND THUNDERSTORMS FROM 6N TO 10N BETWEEN 35W AND
40W.

WESTERN CARIBBEAN SEA TROPICAL WAVE ALONG 83W/84W SOUTH OF 21N
MOVING WEST 10 TO 15 KT. THIS WAVE WAS INTRODUCED TO THE
28/0000 UTC SURFACE MAP ANALYSIS AFTER STUDYING SATELLITE IMAGERY
FOR THE LAST FEW DAYS. CLUSTERS OF SHOWERS AND THUNDERSTORMS
FROM 12N TO 13N BETWEEN 81W AND 82W. A FEW CLUSTERS ARE IN THE
EASTERN PACIFIC OCEAN JUST SOUTH OF COSTA RICA AND PANAMA...
AND NORTH OF 7N BETWEEN ALL ALONG THE PANAMA COAST.

...ITCZ...
ITCZ 10N15W 7N26W 7N31W 8N42W 8N44W 5N56W...AND FROM 11N73W TO
11N85W. SCATTERED STRONG SHOWERS AND THUNDERSTORMS WITHIN
15 NM ON EITHER SIDE OF 6N12W 7N16W 9N20W. ISOLATED MODERATE
TO LOCALLY STRONG SHOWERS FROM 3N TO 10N BETWEEN 25W AND 45W.

...DISCUSSION...
THE GULF OF MEXICO...
TROUGHING FROM JEANNE DOMINATES THE EASTERN GULF WHILE RIDGING
IS MOVING IN FROM MEXICO IN THE WESTERN GULF. NORTHERLY SURFACE
WINDS THROUGHOUT THE SOUTHEASTERN UNITED STATES WEST OF JEANNE
ARE KEEPING DEWPOINTS COMPARATIVELY LOW FOR SEPTEMBER. RIDGE
GOES FROM THE SOUTHWESTERN CORNER OF THE GULF TO SOUTHEASTERN
TEXAS WITH ISOLATED TO WIDELY SCATTERED MODERATE/LOCALLY STRONG
SHOWERS AND THUNDERSTORMS OVER INTERIOR MEXICO FROM 15N TO 23N
BETWEEN 93W AND 102W. BROAD HIGH PRESSURE IS EXPECTED TO BUILD
AS JEANNE DEPARTS IN THE MIDDLE TO UPPER LEVELS THROUGH THE
SOUTHERN GULF WITH FAST SOUTHWESTERLY FLOW FORECAST OVER THE
GULF COAST STATES.

THE CARIBBEAN SEA...
UPPER TROUGH FROM CENTRAL CUBA TO 10N80W. TROPICAL WAVE ALONG
83W/84W. TROUGH IS MOVING SLOWLY WEST AND LIKELY WILL INCREASE
SHOWER CHANCES OVER CENTRAL AMERICA AND THE WESTERN CARIBBEAN
WATERS FOR THE NEXT TWENTY FOUR HOURS. DEEPER TROUGH EXTENDS
FROM NORTH OF PUERTO RICO NEAR 22N62W WEST-SOUTHWEST ACROSS
HISPANIOLA. ISOLATED MODERATE SHOWERS AND THUNDERSTORMS NORTH OF
17N BETWEEN 60W AND 74W.  GENERALLY DRY CONDITIONS NW OF TROUGH
AXIS THIS UPPER LEVEL TROUGH IS EXPECTED TO CUT OFF FROM THE
MID-OCEANIC TROUGH AND MOVE WESTWARD... REPLACING THE WESTERN
CARIBBEAN TROUGH BY THE END OF THE WEEK.

SUBTROPICAL ATLANTIC OCEAN...
BAND OF MOISTURE IS ON WATER VAPOR PICTURES WEST OF 30N70W
25N74W 20N74W UNDER A SMALL RIDGE. MID-OCEANIC TROUGH DOMINATES
THE WESTERN AND CENTRAL ATLANTIC OCEAN...STRETCHING FROM 30N50W
TO 20N64W. THE WEATHER IS FAIRLY QUIET WEST OF THE TROUGH...
EXCEPT FOR ISOLATED TRADE-WIND SHOWERS AND A FEW TSTMS WITHIN
60 NM RADIUS OF 26N55W...NEAR A MIDDLE TO UPPER LEVEL CYCLONIC
CIRCULATION CENTER. T.S. LISA IS CAUGHT IN SOUTHWEST SHEARING
FLOW AHEAD OF THE UPPER TROUGH WITH SOME RIDGING BUILDING ON THE
NORTH AND EAST SIDE OF THE SYSTEM.  LARGE UPPER LEVEL CYCLONIC
CIRCULATION CENTER IN THE ATLANTIC OCEAN IS NEAR 20N28W WITH
GENERALLY DRY CONDITIONS NORTH OF 20N EAST OF 30W.

TROPICAL ATLANTIC...
MIDDLE TO UPPER LEVEL ANTICYCLONE IS OVER THE WESTERN TROPICAL
ATLANTIC NEAR 15N50W WITH RATHER DRY CONDITIONS ALOFT.  IT
APPEARS THAT THE CAPE VERDE SEASON HAS SHUT DOWN FOR NOW WITH A
LARGE UPPER LOW NEAR 20N29W STRETCHING A TROUGH SOUTH TO
10N30W.  THIS FEATURE IS CAUSING STRONG SHEAR IN THE EASTERN
ATLANTIC WITH LITTLE CHANCE OF TROPICAL DEVELOPMENT.  ITCZ
PRECIPITATION IS ACTIVE EAST OF 42W WITH MIDDLE TO UPPER LEVEL
MOISTURE LIMITED IN THE DEEP TROPICS WEST OF 45W.  WITH KARL AND
LISA MOVING ALONG SIMILAR PATHS...THE TRADE WINDS HAVE BEEN
QUITE WEAK ESPECIALLY AROUND THE LESSER ANTILLES WITH MUCH
WARMER-THAN-AVERAGE WATER TEMPERATURES.

$$
MT


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