[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 251804 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...COR
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT 25 SEP 2004

CORRECTION FOR THE 2:00 PM EDT/1800 UTC POSITION FOR
HURRICANE JEANNE...

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 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1715 UTC.

...SPECIAL FEATURES...


AT 2 PM EDT...1800Z...THE EYE OF HURRICANE JEANNE WAS ESTIMATED
NEAR LATITUDE 27.0 NORTH...LONGITUDE 78.2 WEST...OR ABOUT
40 MILES/65 KM NORTHEAST OF FREEPORT IN THE BAHAMAS AND
145 MILES/230 KM EAST-SOUTHEAST OF VERO BEACH FLORIDA. IT IS
MOVING WEST 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 955 MB.
JEANNE IS DANGEROUS CATEGORY THREE HURRICANE ON THE
SAFFIR/SIMPSON HURRICANE SCALE WITH MAXIMUM SUSTAINED WIND
SPEEDS OF 100 KT WITH GUSTS 120 KT. SOME ADDITIONAL
STRENGTHENING IS POSSIBLE BEFORE LANDFALL IN FLORIDA. STRONGER
WINDS...ESPECIALLY IN GUSTS...ARE LIKELY TO OCCUR ON HIGH RISE
BUILDINGS. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 70 MILES/
110 KM FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND
OUTWARD UP TO 205 MILES/335 KM....MAINLY TO THE NORTH OF 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. A WELL DEFINED EYE IS
CLEARLY DETECTABLE ON BOTH THE VISIBLE AND INFRARED SATELLITE
IMAGES. THE COLDEST CLOUD TOP TEMPERATURES WITH NUMEROUS STRONG
SHOWERS AND THUNDERSTORMS ARE FOUND FROM 25N TO 28N BETWEEN 76W
AND 78W. OTHER STRONG SHOWERS AND THUNDERSTORMS ELSEWHERE FROM
24N TO 29N BETWEEN 75W AND 80W...GETTING READY TO REACH THE
LITTORAL OF FLORIDA.

CENTER OF TROPICAL STORM LISA AT 25/1500 UTC NEAR 15.9N 45.6W...
OR ABOUT 1435 MILES/2310 KM WEST OF THE CAPE VERDE ISLANDS...
MOVING NORTHWEST 8 KT. MAXIMUM SUSTAINED WIND SPEED 35 KT GUSTS
45 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 1002 MB. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23
KNHC FOR MORE DETAILS. THE LOW LEVEL CENTER REMAINS EXPOSED TO
THE WEST OF THE DEEP CONVECTIVE ACTIVITY. ONE BURST OF STRONG
SHOWERS AND THUNDERSTORMS IS WITHIN 25 TO 40 NM RADIUS OF 16N44W.
ISOLATED TO WIDELY SCATTERED MODERATE/LOCALLY STRONG SHOWERS AND
THUNDERSTORMS ELSEWHERE FROM 12N TO 17N BETWEEN 41W AND 47W.

...TROPICAL WAVES...
TROPICAL WAVE NOW WEST OF THE CAPE VERDE ISLANDS ALONG 28W/29W
SOUTH OF 20N MOVING WEST 10 TO 15 KT. A BROAD LOW TO MIDDLE LEVEL
CYCLONIC CIRCULATION IS EVIDENT IN VISIBLE SATELLITE IMAGERY.
THIS WAVE IS MOVING THROUGH THE BASE OF AN EASTERN ATLANTIC OCEAN
MIDDLE TO UPPER LEVEL TROUGH...WHICH RUNS THROUGH 32N25W TO
24N27W TO 11N29W. SOME MIDDLE TO UPPER LEVEL DRY AIR IS ON THE
WESTERN SIDE OF THIS TROUGH. THE SHOWERS AND THUNDERSTORMS ARE
LESS NUMEROUS NOW THAN YESTERDAY...ISOLATED MODERATE TO LOCALLY
STRONG SHOWERS AND THUNDERSTORMS FROM 15N TO 18N BETWEEN 24W AND
29W...WITH UPPER LEVEL CLOUD ELEMENTS BEING SHEARED BY THE UPPER
LEVEL WIND FLOW WITH THE TROUGH.

...ITCZ...

ITCZ 13N16W 13N28W...13N31W 14N41W...12N45W 10N50W 11N63W...AND
IN THE SOUTHWESTERN CARIBBEAN SEA ALONG 11N70W 9N80W 9N84W.
SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS
FROM 3N TO 7N BETWEEN 21W AND 33W. ISOLATED MODERATE SHOWERS
AND THUNDERSTORMS FROM 3N TO 10N BETWEEN 10W AND 18W IN AFRICA
COASTAL WATERS. MIDDLE TO UPPER LEVEL NORTHEASTERLY FLOW IS
BLOWING MIDDLE AND HIGH LEVEL CLOUDS AWAY FROM T.S. LISA IN
ITS SOUTHWESTERN SEMICIRCLE...BETWEEN 39W AND 53W SOUTH OF 13N.
STRONG SHOWERS AND THUNDERSTORMS IN THE ITCZ FROM 9.5N TO 11N
BETWEEN 77W AND 79W.

...DISCUSSION...

THE GULF OF MEXICO...
UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 26.5N 92.5W...A
LITTLE BIT MORE TO THE NORTH AND EAST OF ITS POSITION TWENTY-FOUR
HOURS AGO. BROAD CYCLONIC FLOW FROM A MIDDLE TO UPPER LEVEL
TROUGH COVERS THE GULF WATERS WEST OF 89W. SURFACE TROUGH 24N92W
27N94W 30N95W. ISOLATED MODERATE SHOWERS AND THUNDERSTORMS WITHIN
30 NM RADIUS OF 22N89.5W JUST NORTH OF THE YUCATAN PENINSULA...
IN THE SOUTHWESTERN CORNER SOUTH OF 21N BETWEEN 93W AND 96W...
AND WEAKENING A BIT DURING THE LAST FEW HOURS FROM 24N TO 30N
BETWEEN 91W AND 95W. DEEP LAYER DRY AIR WHICH HAS BEEN
SURROUNDING HURRICANE JEANNE TO THE WEST CONTINUES TO COVER THE
GULF WATERS EAST OF 30N89W 21N85W IN THE YUCATAN CHANNEL. MIDDLE
TO UPPER LEVEL NORTHWESTERLY WIND FLOW IN THE EASTERN ONE-THIRD
WITH A MIDDLE TO UPPER LEVEL TROUGH WHOSE BASE IS IN THE
SOUTHWESTERN CORNER OF THE CARIBBEAN SEA.

THE CARIBBEAN SEA AND SUBTROPICAL ATLANTIC WEST OF 65W...
WATER VAPOR SATELLITE IMAGERY AND CIMSS SATELLITE DERIVED WIND
DATA FROM 25/1200 UTC SHOW THE UPPER LEVEL ANTICYCLONIC
CIRCULATION ON TOP OF HURRICANE JEANNE IN THE ATLANTIC WATERS
WITH ANTICYCLONIC OUTFLOW REACHING 33N77W AND CURVING TOWARD
27N68W. A BROAD MIDDLE TO UPPER LEVEL TROUGH WITH A BASE IN
THE SOUTHWESTERN CORNER OF THE AREA MAINLY WEST OF 70W...AND
VARIABLE WINDS EAST OF 70W. STRONG SHOWERS AND THUNDERSTORMS
IN THE ITCZ FROM 9.5N TO 11N BETWEEN 77W AND 79W. ISOLATED
MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS FROM THE WATERS
SOUTHWEST OF JAMAICA NEAR 17N79W...THROUGH THE WINDWARD
PASSAGE TO THE SOUTHERN BAHAMAS.

THE REST OF THE SUBTROPICAL ATLANTIC AND
THE TROPICAL ATLANTIC...
DEEP LAYER TROUGH THROUGH 36N46W TO 32N54W TO 26N64W. SURFACE
COLD FRONT THAT WAS NORTH OF THE AREA HAS BEEN DISSIPATING
DURING THE LAST SIX HOURS. SURFACE TROUGH THROUGH 32N38W TO
26N50W 27N65W. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS
AND THUNDERSTORMS FROM 25N TO 30N BETWEEN 37W AND 43W. ISOLATED
MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS WITHIN
25 TO 50 NM ON EITHER SIDE OF 29N70W 25N60W...AND WITHIN 60 TO
120 NM ON EITHER SIDE OF 25N60W 28N46W. A TROPICAL WAVE ALONG
28W/29W SOUTH OF 20N IS MOVING THROUGH THE BASE OF AN EASTERN
ATLANTIC OCEAN MIDDLE TO UPPER LEVEL TROUGH...WHICH RUNS THROUGH
32N25W TO 24N27W TO 11N29W. SOME MIDDLE TO UPPER LEVEL DRY AIR
IS ON THE WESTERN SIDE OF THIS TROUGH. THE SHOWERS AND
THUNDERSTORMS ARE LESS NUMEROUS NOW THAN YESTERDAY...ISOLATED
MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS FROM 15N TO
18N BETWEEN 24W AND 29W...WITH UPPER LEVEL CLOUD ELEMENTS BEING
SHEARED BY THE UPPER LEVEL WIND FLOW WITH THE TROUGH.
UPPER LEVEL RIDGE THROUGH 35N21W...OVER THE CAPE VERDE ISLANDS...
TO AN ANTICYCLONIC CENTER IN NORTHERN MAURITANIA. UPPER LEVEL
ANTICYCLONIC FLOW EAST OF THE EASTERN ATLANTIC TROUGH SOUTH
OF 32N.

$$
MT


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