[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 290614
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED 29 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 REMNANT LOW CENTER OF JEANNE...NOW AN EXTRATROPICAL
CYCLONE...WAS NEAR 39.6N 74.9W...OR ABOUT 20 MILES NORTHWEST OF
ATLANTIC CITY NEW JERSEY...AT 29/0300 UTC. MAXIMUM SUSTAINED
WIND SPEED 35 MPH WITH SOME HIGHER GUSTS...MOVING NORTHEAST
23 MPH. MINIMUM CENTRAL PRESSURE 999 MB OR 29.50 INCHES.

TROPICAL STORM LISA CENTER NEAR 27.0N 46.5W AT 29/0300 UTC...
MOVING NORTH 11 KT. MAXIMUM SUSTAINED WIND SPEED 55 KT GUSTS
65 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 994 MB. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23
KNHC FOR MORE DETAILS. CLOUD TOP TEMPERATURES RANGING FROM
-65 CELSIUS TO -71 CELSIUS AND STRONG SHOWERS AND THUNDERSTORMS
FROM 27.5N TO 30N BETWEEN 41.5W AND 46W. THE SHOWER/THUNDERSTORM
ACTIVITY IS CLOSER TO THE LOW-LEVEL CENTER...A BIT BETTER
ORGANIZED. THE WIND SPEED AROUND THE CENTER HAS INCREASED A BIT
ALSO. AN UPPER LEVEL TROUGH IS APPROACHING THE STORM FROM THE
WEST AND IS FORECAST TO CUT-OFF INTO A LOW AND MOVE SOUTH OF THE
CYCLONE. THIS WOULD BE A FAVORABLE SYNOPTIC PATTERN FOR GROWTH
AND LISA HAS A OUTSIDE CHANCE TO BECOME THE 8TH HURRICANE OF THE
SEASON...IF THE MODELS ARE CORRECT.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 33W/34W SOUTH OF 16N MOVING WEST 10 TO
15 KT. CONDITIONS ARE NOT FAVORABLE FOR TROPICAL GENESIS WITH
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR
19N32W...APPEARING TO BE MOVING IN PHASE WITH THIS WAVE DURING
AT LEAST THE LAST 24 HOURS. THE CYCLONIC FLOW FROM 11N TO 29N
BETWEEN 23W AND 40W WILL PROVIDE LOTS OF WESTERLY SHEAR. WIDELY
SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS
FROM 12N TO 15N BETWEEN 31W AND 33W.

TROPICAL WAVE ALONG 44W/45W SOUTH OF 16N MOVING WEST 10 TO
15 KT. WARMING CLOUD TOP TEMPERATURES AND DISSIPATING SHOWERS
AND THUNDERSTORMS FROM 8N TO 11N BETWEEN 43W AND 45W. BROKEN
TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE SHOWERS AND
THUNDERSTORMS...INCLUDING IN THE ITCZ...FROM 2N TO 12N
BETWEEN 40W AND 50W.

TROPICAL WAVE 88W/89W SOUTH OF 23N MOVING WEST 10 TO 15 KT.
SHOWERS AND THUNDERSTORMS FROM 11N TO 14N BETWEEN 87W AND 89W
OVER PARTS OF THE COASTAL WATERS OF NICARAGUA INTO INTERIOR
EASTERN EL SALVADOR MAY BE RELATED TO THIS WAVE. THE SHOWER
AND THUNDERSTORM ACTIVITY FROM 13N TO 17N BETWEEN 79W AND 85W
APPEARS TO BE MORE RELATED TO UPPER LEVEL DIFFLUENT FLOW
AS THE FLOW HEADS TO EASTWARD BECAUSE OF THE MIDDLE TO UPPER
LEVEL TROUGH OVER HISPANIOLA.

...ITCZ...
ITCZ 10N14W 7N24W 7N31W 9N43W 9N46W 10N61W...AND 10N76W 11N81W
10N86W IN THE SOUTHWESTERN CARIBBEAN SEA AND INTO THE EASTERN
PACIFIC OCEAN JUST WEST OF COSTA RICA. STRONG SHOWERS AND
THUNDERSTORMS IN CLUSTERS DURING THE LAST FEW HOURS FROM 8N TO
10N BETWEEN 16W AND 18W...FROM 6N TO 7N BETWEEN 27W AND 29W...
FROM 6N TO 8N BETWEEN 31W AND 33W...AND FROM 2N TO 4N BETWEEN
33W AND 35W. STRONG SHOWERS AND THUNDERSTORMS IN NORTHWESTERN
VENEZUELA AND NORTHERN COLOMBIA FROM 7.5N TO 9N BETWEEN 72W
AND 73W...AND WITHIN A 30 NM RADIUS OF 9N74W AND 11N75.5W.
WARMING CLOUD TOP TEMPERATURES AND DECREASING SHOWERS AND
THUNDERSTORMS FROM PANAMA/COLOMBIA TO 12N BETWEEN 78W AND
CENTRAL AMERICA.

...DISCUSSION...

THE GULF OF MEXICO...
DRIER AIR HAS FILTERED INTO THE NW GULF THANKS TO NLY WINDS FROM
JEANNE BEHIND A CENTRAL GULF SURFACE TROUGH. 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
SOUTHWESTERN GULF OF MEXICO TO THE FLORIDA STRAITS. THE UPPER
LEVEL TROUGH SOUTH OF THE REMNANT OF JEANNE IS MOVING OFF THE
UNITED STATES MIDDLE ATLANTIC COAST...NORTHEASTWARD...DRAGGING
UPPER LEVEL WESTERLY WINDS WITH IT ACROSS FLORIDA. MIDDLE TO
UPPER LEVEL DRY AIR WITHIN 120 NM ON EITHER SIDE OF LINE THROUGH
32N78W TO 27N84W TO 22N89W.

THE CARIBBEAN SEA...
BIG AREA OF UPPER LEVEL DIFFLUENT FLOW ALONG WITH THE ITCZ...
IS FORCING A LARGE AREA OF CLOUDS AND SHOWERS AND
THUNDERSTORMS...SOME DISSIPATING DURING THE LAST FEW HOURS...
SOUTH OF 17N83W 13N69W. SMALL UPPER TROUGH ALONG IN THE
NORTHWESTERN CARIBBEAN IS WEAKENING AND MOVING INTO CENTRAL
AMERICA. LARGE MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
JUST SOUTH OF THE DOMINICAN REPUBLIC DOMINATES THE WEATHER
PATTERN IN THE EASTERN CARIBBEAN. ENHANCED MIDDLE TO UPPER LEVEL
MOISTURE HELPS TO ENHANCE THE SHOWER/THUNDERSTORM CAPABILITIES.

THE SUBTROPICAL ATLANTIC OCEAN...
DEEP-LAYERED ANTICYCLONIC CIRCULATION CENTER NEAR 31N68W WITH
GENERAL ANTICYCLONIC FLOW AND DRY CONDITIONS WEST OF 60W.
AN UPPER CYCLONIC CIRCULATION CENTER SOUTH OF THE DOMINICAN
REPUBLIC IS CAUSING A STRONG EASTERLY JET NORTH OF PUERTO RICO.
MIDDLE TO UPPER LEVEL TROUGH IS DIGGING JUST WEST OF 50W NORTH
OF 25N...LIFTING T.S. LISA MORE NORTHWARD. RIDGING CONTROLS THE
CENTRAL ATLC EAST OF LISA TO 30W EXCEPT FOR CYCLONIC FLOW SOUTH
OF 24N EAST OF 35W FROM A MID/UPPER LEVEL CYCLONIC CIRCULATION
CENTER NEAR 19N32W. WEAK SURFACE RIDGE IN THE WESTERN ATLANTIC
OCEAN WEST OF WEST OF 60W. LISA DOMINATES THE CENTRAL ATLANTIC
OCEAN. BROAD RIDGE THROUGH 32N31W TO 20N32W.

THE TROPICAL ATLANTIC OCEAN...
MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION CENTER NEAR
18N49W AND MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER
NEAR 19N32W ARE THE MAIN FEATURES IN THE BASIN. GENERALLY DRY
AIR IN THE MIDDLE TO UPPER LEVELS WEST OF 40W WITH THE ONLY
WEATHER NEAR THE ITCZ AND A TROPICAL WAVE.  ENHANCING MOISTURE
IS EAST OF THE UPPER LOW INTO WEST 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.

$$
MT

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