[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282330
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION JEANNE HAS DISSIPATED AS A TROPICAL CYCLONE
AND IS EXTRATROPICAL 10 MILES W OF WASHINGTON DC AT 28/2100 UTC.

TROPICAL STORM LISA IS CENTERED ON 28/2100 UTC NEAR 26.4N 46.5W
MOVING N 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB.
MAXIMUM SUSTAINED WIND SPEED IS 45 KT GUSTS 55 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23
KNHC FOR MORE DETAILS.  LISA IS A BIT BETTER-ORGANIZED WITH THE
DEEP CONVECTION CLOSER TO THE LOW-LEVEL CENTER.  AN UPPER TROUGH
IS APPROACHING THE STORM FROM THE WEST AND IS FORECAST TO
CUT-OFF INTO A LOW AND MOVE S OF THE CYCLONE.  IF THE MODELS ARE
CORRECT...THIS WOULD BE A FAVORABLE SYNOPTIC PATTERN FOR GROWTH
AND LISA HAS A OUTSIDE CHANCE TO BECOME 8TH HURRICANE OF THE
SEASON.  SCATTERED MODERATE FROM 26N-30N BETWEEN 41W-47W.

...TROPICAL WAVES...
TROPICAL WAVE IS W OF THE CAPE VERDE ISLANDS ALONG 31W S OF 18N
MOVING W 10-15 KT.  CONDITIONS ARE NOT FAVORABLE FOR TROPICAL
GENESIS WITH A MID/UPPER LOW N OF THE WAVE PROVIDING LOTS OF WLY
SHEAR.  CLUSTER OF MODERATE CONVECTION IS NEAR 13.5N33W.

TROPICAL WAVE ALONG 45W/46W S OF 16N MOVING W 10-15 KT.
CONVECTION HAS BECOME A LITTLE MORE CONCENTRATED THAN YESTERDAY
BUT THERE IS NOT MUCH TURNING IN THE LOW-LEVELS.  IN ADDITION
THE WAVE IS MOVING INTO AN AREA OF DRIER MID/UPPER LEVEL
CONDITION WHICH GENERALLY WOULD NOT FAVOR ANY DEVELOPMENT.
WIDELY SCATTERED MODERATE FROM 7N-12N BETWEEN 40W-44W.

TROPICAL WAVE IS ALONG 87W S OF 23N MOVING W 10-15 KT.  ISOLATED
SHOWERS MARK THE WAVE'S LOCATION IN ANY AREA OF CYCLONIC FLOW
ALOFT.  TSTMS IN THE SW CARIBBEAN DO NOT APPEAR TO BE DIRECTLY
RELATED TO THE WAVE AND MORE ALIGNED WITH THE ITCZ.

...ITCZ...
ITCZ IS CENTERED ALONG 9N14W 7N20W 8N40W 10N61W 11N80W 10N84W.
WIDELY SCATTERED MODERATE S OF 15N W OF 78W AND WITHIN 90 NM OF
5N33W.  SCATTERED MODERATE FROM 6N-12N BETWEEN 25W-28W.  SIMILAR
CONVECTION IS EMERGING OFF W AFRICA BETWEEN 9N-12N.

...DISCUSSION...
GULF OF MEXICO...
DRIER AIR HAS FILTERED INTO THE NW GULF THANKS TO NLY WINDS FROM
JEANNE BEHIND A CENTRAL GULF SURFACE TROUGH.  HOWEVER A NEW PUSH
OF COOLER/DRIER AIR IS STARTING WITH A COLD FRONT MOVING INTO
THE EXTREME NW GULF NOW.  THIS FRONT IS NOT EXPECTED TO MOVE
THROUGH THE ENTIRE GULF WITH A NE-SW ORIENTED UPPER RIDGE FROM
THE BAY OF CAMPECHE TO THE FLORIDA STRAITS.  THERE IS ALSO A
WEAK SHORTWAVE JUST W OF THE FLORIDA PENINSULA THAT HAS ENHANCED
LOCALLY HEAVY RAINS OVER S FLORIDA TODAY.  LITTLE CHANGE IS
LIKELY TO THE UPPER FLOW FOR THE NEXT DAY OR TWO.

CARIBBEAN SEA...
BIG AREA OF UPPER DIVERGENCE ALONG WITH THE ITCZ NEARBY IS
FORCING A LARGE AREA OF WIDELY SCATTERED MODERATE CONVECTION S
OF 15N W OF 78W...SIMILAR TO YESTERDAY.  SMALL UPPER TROUGH
ALONG IN THE NW CARIBBEAN IS WEAKENING AND MOVING INTO CENTRAL
AMERICA.  OTHERWISE LARGE MID/UPPER LOW JUST S OF THE DOMINICAN
REPUBLIC DOMINATES THE WEATHER PATTERN IN THE E CARIBBEAN.
ENHANCED MID/UPPER-LEVEL MOISTURE IS INCREASING THE NUMBER OF
SHOWERS NEAR THE LESSER ANTILLES WITH LOTS OF TINY SHOWERS
VISIBLE ON PUERTO RICO RADAR.  WLY FLOW FROM THE LOW STRETCHES
INTO NW VENEZUELA CAUSING STRONG TSTMS JUST E OF LAKE MARACAIBO.

SUBTROPICAL ATLANTIC OCEAN...
DEEP-LAYERED HIGH IS NEAR 31N68W WITH GENERAL ANTICYCLONIC FLOW
AND DRY CONDITIONS W OF 60W.  AN UPPER LOW S OF DOMINICAN
REPUBLIC IS CAUSING A STRONG ELY JET N OF PUERTO RICO WITH A FEW
SHOWERS WITHIN 90 NM OF 22N63W.   MID/UPPER TROUGH IS DIGGING
JUST W OF 50W N OF 25N... LIFTING LISA FARTHER NORTHWARD.
OTHERWISE RIDGING CONTROLS THE CENTRAL ATLC E OF LISA TO 30W
EXCEPT FOR CYCLONIC FLOW S OF 24N E OF 35W FROM A MID/UPPER
LEVEL LOW NEAR 19N31W.  AT THE SURFACE...WEAK RIDGE IS OVER THE
W ATLC W OF 60W.  LISA DOMINATES THE CENTRAL ATLC WITH A LITTLE
RIDGING IN THE E ATLC FROM A 1023 MB HIGH NEAR 32N31W.

TROPICAL ATLANTIC...
MID/UPPER HIGH NEAR 18N49W AND MID/UPPER LOW NEAR 19N31W ARE THE
MAIN FEATURES IN THE BASIN.  GENERALLY DRY AIR IN THE MID/UPPER
LEVELS IS W OF 40W WITH THE ONLY WEATHER NEAR THE ITCZ AND A
TROPICAL WAVE.  ENHANCING MOISTURE IS E OF THE UPPER LOW INTO W
AFRICA THOUGH UPPER WINDS ARE NOT FAVORABLE FOR TROPICAL
GENESIS.  COMPUTER MODELS SUGGEST INCREASING SHEAR OVER THE
TROPICAL ATLC DURING THE NEXT FEW DAYS... PERHAPS ENDING THE
RECENT OUTBURST OF TROPICAL CYCLONE ACTIVITY.

$$
BLAKE

This weather bulletin was brought to you by:
www.nashvilleweather.net