[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 280616
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 0315 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL DEPRESSION JEANNE AT 28/0300 UTC WAS
NEAR 33.4N 82.9W...OR 45 MILES SOUTH-SOUTHEAST OF ATHENS GEORGIA.
MAXIMUM SUSTAINED WIND SPEED 20 MPH WITH SOME HIGHER GUSTS.
MINIMUM CENTRAL PRESSURE 999 MB OR 29.50 INCHES...MOVING
NORTH-NORTHEAST 10 MPH. SEE LATEST HPC PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KWNH FOR MORE DETAILS.
TROPICAL DEPRESSION JEANNE CONTINUES TO PRODUCE HEAVY RAIN
THROUGH GEORGIA AND THE SOUTHERN MID ATLANTIC STATES...FLOOD AND
FLASH FLOOD WARNINGS CONTINUE FOR PARTS OF WESTERN NORTH
CAROLINA...UPSTATE SOUTH CAROLINA...AND NORTHERN GEORGIA. FLOOD
AND FLASH FLOOD WATCHES CONTINUE FOR SECTIONS OF GEORGIA...SOUTH
CAROLINA...NORTH CAROLINA...AND...VIRGINIA. NEW WATCHES HAVE
BEEN POSTED FOR NORTHEAST PENNSYLVANIA...AND SOUTHEASTERN NEW
YORK. ISOLATED TORNADOES ARE POSSIBLE THIS EVENING ACROSS
PORTIONS OF THE CAROLINAS.

TROPICAL STORM LISA CENTER AT 28/0300 UTC NEAR 22.3N 46.4W
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.  LISA HAS STRUGGLED MOST OF ITS LIFE AND TODAY
IS NO EXCEPTION.  STRONG WLY SHEAR HAS TAKEN THE CONVECTION TO
THE E AND N OF THE LOW-LEVEL CENTER.  SCATTERED MODERATE
CONVECTION FROM 22N-24.5N BETWEEN 43W-46W.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 27W/28W 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 19N28W.
CYCLONIC FLOW FROM 10N TO 30N BETWEEN 20W AND 36W. ISOLATED TO
WIDELY SCATTERED MODERATE/LOCALLY STRONG SHOWERS AND
THUNDERSTORMS FROM 7N TO 14N BETWEEN 20W AND 30W...
MIXED IN WITH SOME ITCZ PRECIPITATION.

CENTRAL ATLANTIC OCEAN TROPICAL WAVE ALONG 41W/42W SOUTH OF 16N
MOVING WEST 10 TO 15 KT. ISOLATED TO WIDELY SCATTERED MODERATE/
LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 5N TO 10N BETWEEN
38W AND 43W...MIXED IN WITH SOME ITCZ PRECIPITATION.

WESTERN CARIBBEAN SEA TROPICAL WAVE ALONG 81W/82W 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. WARMING CLOUD TOP TEMPERATURES AND
DISSIPATING PRECIPITATION SOUTH OF 15N WEST OF 78W TO THE COAST
OF CENTRAL AMERICA. ISOLATED SHOWERS IN INDIVIDUAL CLUSTERS
JUST WEST OF JAMAICA FROM 18N TO 19N BETWEEN 79W AND 81W.

...ITCZ...
ITCZ 8N13W 5N20W 6N25W 7N30W 7N40W 8N43W 6N56W...AND 5N77W
7N85W BUT IN THE EASTERN PACIFIC OCEAN. SCATTERED TO NUMEROUS
STRONG SHOWERS AND THUNDERSTORMS NORTHEAST OF 4N10W 9N17W.
A FEW OTHER CLUSTERS OF SHOWERS AND THUNDERSTORMS FROM 9N TO
13N BETWEEN 18W AND 20W. ISOLATED TO WIDELY SCATTERED MODERATE/
LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 3N TO 10N BETWEEN
17W AND 43W...SOME OF THIS PRECIPITATION MIXED IN WITH THE
TROPICAL WAVES. IN THE CARIBBEAN SEA...SHOWERS AND
THUNDERSTORMS...WITH DISSIPATING CLOUD TOP TEMPERATURES...
WITHIN 30 TO 40 NM ON EITHER SIDE OF 11N74W 14N76W. WARMING
CLOUD TOP TEMPERATURES AND DISSIPATING PRECIPITATION IN THE
SOUTHWESTERN CORNER OF THE AREA...POSSIBLY MORE RELATED TO THE
81W/82W TROPICAL WAVE. ISOLATED BURST OF SHOWERS/THUNDERSTORMS
IN EASTERN PANAMA WITHIN 15 NM RADIUS 8N78W.

...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...BETWEEN THE
ISTHMUS OF TEHUANTEPEC TO THE BORDER WITH GUATEMALA...AND FROM
JUST WEST OF THE ISTHMUS OF TEHUANTEPEC TO 22N. 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...CONVECTIVE ACTIVITY
IS WEAKENING WEST OF 78W. A TROPICAL WAVE IS ALONG 81W/82W.
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.
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. A SURFACE TROUGH RUNS FROM 27N56W TO 23N55W
TO 20N53W. 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 19N28W 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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