[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 270605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON 27 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...

TROPICAL STORM JEANNE CENTER AT 27/0600 UTC NEAR 30.1N 83.3W
OR ABOUT 50 MILES SOUTH OF VALDOSTA GEORGIA. IT IS MOVING NORTH
12 KT. MAXIMUM SUSTAINED WIND SPEED HAS DECREASED TO 45 KT WITH
GUSTS TO 60 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 978 MB.
TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175 MILES FROM
THE CENTER. SEE LATEST NHC PUBLIC ADVISORY OR NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC OR
MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM THE FLORIDA/
GEORGIA BORDER FROM 30N TO 33N BETWEEN 81W AND 84W. LOW TO
BROKEN CLOUDS WAY AT THE PERIPHERY OF JEANNE COVER THE GULF
WATERS FROM 24N TO 30N BETWEEN 78W IN THE PACIFIC OCEAN AND 91W.

TROPICAL STORM LISA CENTER AT 27/0900 UTC NEAR 19.7N 46.1W...
OR ABOUT 1045 MILES/1680 KM...EAST-NORTHEAST OF CAPE VERDE
ISLANDS. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
115 MILES ...185 KM FROM THE CENTER. MAXIMUM SUSTAINED WIND
SPEED 45 KT GUSTS 55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1000 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER
MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. TROPICAL STORM FORCE
WINDS EXTEND OUTWARD UP TO 115 MILES ...185 KM FROM THE CENTER.
WIDELY SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND
THUNDERSTORMS PERSIST FROM 14N TO 25N BETWEEN 46W AND 50W.

...TROPICAL WAVES...

TROPICAL WAVE ALONG 36W/37W SOUTH OF 20N MOVING MOVING WEST
10-15 KT. A WEAK 1010 MB LOW PRESSURE CENTER IS NEAR 15N ALONG
THE WAVE. IT IS MOVING TOWARD T.S. LISA.

...ITCZ...

ITCZ 10N14W 6N20W 10N34W 10N43W 9N60W. ISOLATED MODERATE TO
LOCALLY STRONG SHOWERS AND THUNDERSTORMS HAVE BEEN OCCURRING
SOUTH OF 10N EAST OF 40W. STRONG SHOWERS AND THUNDERSTORMS IN
TWO INDIVIDUAL CLUSTERS...ONE WITHIN 40 NM RADIUS OF 12N74W.
THE OTHER ONE IS WITHIN 40 NM RADIUS OF 13N76W.

...DISCUSSION...

GULF OF MEXICO...19.7 NORTH...LONGITUDE  46.1 WEST OR ABOUT 1045
MILES...1680 KM...EAST-NORTHEAST OF THE LESSER ANTILLES.
SLOWLY-WEAKENING TROPICAL STORM JEANNE IS MOVING N OVER THE
FLORIDA PENINSULA WITH HEAVY SPIRAL BANDS SWEEPING ACROSS THE
FAR NE PARTS OF THE GULF OF MEXICO WATERS...NE OF A LINE FROM
APALACHICOLA TO TAMPA BAY. FARTHER W...JEANNE'S CIRCULATION IS
DRAWING DRIER CONTINENTAL AIR SWD OVER THE CNTRL GULF...WITH
AMSU AND SSM/I IMAGERY BOTH SHOWING PWAT VALUES LOWERING BELOW
1.25" AND AGREEING WITH RADIOSONDE DATA FROM STATIONS ALONG THE
GULF COAST. THIS IS PARTIALLY DUE TO MODERATE SUBSIDENCE UP TO
500 NM TO THE SW OF JEANNE ALONG A MID/UPPER LEVEL TROF
EXTENDING FROM SW LOUISIANA TO NEAR THE YUCATAN PENINSULA.
ELSEWHERE...A REMNANT SFC TROF IS BEING PUSHED SWD OVER THE BAY
OF CAMPECHE WHILE TRIGGERING ISOLATED SHOWERS GENERALLY WITHIN
150 NM OF THE MEXICAN COAST.

CARIBBEAN...
SHOWERS/TSTMS ARE FOCUSING ALONG A BOUNDARY FROM CNTRL CUBA TO
THE GULF OF HONDURAS AS STRONGER EASTERLY FLOW BECOMES
RE-ESTABLISHED OVER THE E/CNTRL CARIBBEAN IN THE WAKE OF
JEANNE...AND CONVERGES WITH LIGHTER WLY FLOW OVER THE NW
CARIBBEAN. WIDELY SCATTERED SHOWERS/TSTMS ARE N OF 17N BETWEEN
76W-84W AND EXTEND ACROSS CNTRL CUBA AND THE CAYMAN ISLANDS. A
BROAD MID/UPPER LOW IS CENTERED OFF THE W TIP OF JAMAICA...WHICH
IS ENHANCING THIS SHOWER ACTIVITY. UPPER LEVEL DIVERGENCE TO THE
S OF THIS FEATURE IS ALSO ENHANCING ITCZ CONVECTION OVER N
COLOMBIA AND PULLING IT NWD OVER THE SW CARIBBEAN WATERS.

SUBTROPICAL ATLANTIC...
STRONG UPPER LEVEL RIDGING IS BUILDING NWD FROM THE BAHAMAS TO
THE SE UNITED STATES COAST IN THE WAKE OF JEANNE...AND SOME OF
THE STORM'S OUTFLOW IS BEING PULLED SEWD ON THE E SIDE OF THE
RIDGE. A BROAD UPPER TROF REMAINS OVER THE W/CNTRL ATLANTIC WITH
THE AXIS ALONG 32N47W 24N66W AND MUCH DRIER AIR SWEEPING IN
BEHIND IT. A REMNANT TROF...PUSHED S BY THE UPPER LEVEL
FEATURE...IS STILL DRAPED ALONG 32N36W 23N60W 30N70W. SCATTERED
SHOWERS/TSTMS EXTEND WITHIN 70 NM OF THE TROF E OF 50W AND
WITHIN 90 NM OF THE TROF W OF 60W. A BUILDING RIDGE IS LOCATED E
OF THE UPPER TROF EXTENDING FROM T.S. LISA NEWD BEYOND 32N31W
WITH A 70+ KT JET RIDING UP THE W SIDE OF THE AXIS INTO THE N
ATLC. FARTHER E...A PAIR OF MID/UPPER LOWS ARE SPIRALING ACROSS
AND NEAR THE AREA...NEAR 22N26W AND 35N16W...CONNECTED BY A
SHEAR AXIS WHICH STRETCHES E/W ACROSS THE CANARY ISLANDS.

TROPICAL ATLANTIC...
AN EXPANSIVE MID/UPPER LEVEL HIGH REMAINS ENTRENCHED E OF THE
LESSER ANTILLES NEAR 14N53W WITH DRY AIR ACROSS THE ENTIRE AREA
W OF 48W. BROAD CYCLONIC FLOW EXTENDS INTO THE AREA FROM THE N
BETWEEN AFRICA AND 35W...AND A SHEAR AXIS STRETCHES SW OF THIS
FEATURE ALONG 10N32W EQ45W. ITCZ CONVECTION IS MUCH MORE
SPORADIC AND LESS INTENSE COMPARED TO THE PAST SEVERAL
DAYS...PRIMARILY BECAUSE THERE IS VERY LITTLE DIVERGENCE IN THE
UPPER LEVELS OF THE ATMOSPHERE.

$$
MT





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