[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171817
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI 17 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 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1745 UTC.

...SPECIAL FEATURES...

 TROPICAL STORM JEANNE CENTER NEAR 20.1N 71.6W...JUST NORTH OF
THE COAST OF HISPANIOLA NEAR THE DOMINICAN REPUBLIC/HAITI BORDER
AND ABOUT 95 MILES/150 KM...SOUTH-SOUTHWEST OF GRAND TURK
ISLAND...AT 17/1800 UTC...MOVING WEST-NORTHWEST 7 KT. MAXIMUM
SUSTAINED WIND SPEED 55 KT GUSTS 65 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE 1002 MB. TROPICAL STORM FORCE WINDS EXTEND
OUTWARD UP TO 200 MILES/325 KM 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. KARL'S STRUCTURE AND ITS ENVIRONMENT FAVOR SIGNIFICANT
STRENGTHENING. KARL HAS AN EXCELLENT ANTICYCLONIC OUTFLOW
PATTERN...WATERS WILL BE WARM AND THE SHEAR LOW.  NUMEROUS
STRONG SHOWERS AND THUNDERSTORMS WITHIN 30 TO 60 NM ON EITHER
SIDE OF 16N71W 17N69W 19N67W. WIDELY SCATTERED TO SCATTERED
MODERATE/ISOLATED STRONG SHOWERS AND THUNDERSTORMS ELSEWHERE
FROM 16N TO 23N BETWEEN 63W AND 72W. WEAK VERTICAL SHEAR IS
FORECAST FOR THE NEXT 48 HOURS...FOLLOWED BY INCREASING
SOUTHWESTERLY SHEAR. JEANNE HAS THE CHANCE TO DEVELOP TO
HURRICANE STAGE DURING THE NEXT 48 HOURS. UPPER LEVEL
ANTICYCLONIC OUTFLOW REACHES 26N63W TO THE NORTH...TO 23N53W TO
THE WEST...AND TO 14N73W TO THE SOUTHWEST.

TROPICAL STORM KARL CENTER NEAR 12.3N 35.5W AT 17/1500 UTC
MOVING WEST-NORTHWEST 9 KT. MAXIMUM SUSTAINED WIND SPEED 55 KT
GUSTS 65 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 994 MB. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. KARL'S STRUCTURE AND
ITS ENVIRONMENT FAVOR SIGNIFICANT STRENGTHENING. KARL HAS AN
EXCELLENT ANTICYCLONIC OUTFLOW PATTERN...WATERS WILL BE WARM
AND THE SHEAR LOW. SCATTERED STRONG SHOWERS AND THUNDERSTORMS
IN ONE BAND...WITHIN 120 TO 180 NM OF CENTER FROM WEST THROUGH
NORTH. WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED STRONG
SHOWERS AND THUNDERSTORMS IN ANOTHER BAND WITHIN 300 TO 500 NM
TO THE NORTH AND NORTHEAST OF THE CENTER...AND OVERCAST
MULTILAYERED CLOUDS AND OTHER AREAS OF SHOWERS AND THUNDERSTORMS
ARE FOUND ELSEWHERE FROM 7N TO 20N BETWEEN 28W AND 44W.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE ALONG 53W/54W SOUTH OF 20N MOVING
WEST 15 KT. WHAT APPEAR TO BE TWO CYCLONIC CLOUD SWIRLS IN THE
VISIBLE IMAGERY FROM 12N TO 14N BETWEEN 53W AND 57W MARK THIS
WAVE. ISOLATED SHOWERS FROM 12N TO 15N BETWEEN 53W AND 57W.

A WEAK TROPICAL WAVE ALONG 90W/91W SOUTH OF 17N MOVES THROUGH
SOUTHERN GUATEMALA AT THIS TIME...MOVING WEST 10 KT. NO DEEP
CONVECTIVE ACTIVITY.

...ITCZ...

ITCZ 11N14W 12N32W 11N38W 11N52W 13N66W 12N75W 9N86W.
ISOLATED MODERATE SHOWERS AND THUNDERSTORMS OVER THE WATERS FROM
3N TO 4N BETWEEN THE PRIME MERIDIAN AND 10W. WIDELY SCATTERED
MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 3N TO
16N BETWEEN 19W AND 30W. STRONG SHOWERS AND THUNDERSTORMS FROM
11N TO 12N BETWEEN 76W AND 78W...IN AN AREA OF UPPER LEVEL
SOUTHERLY WIND MOVING OVER THE TOP OF THIS PRECIPITATION AREA.

...DISCUSSION...

THE GULF OF MEXICO...THE CARIBBEAN SEA...AND THE
WESTERN ATLANTIC OCEAN...
MIDDLE TO UPPER LEVEL TROUGH IN THE AREA FROM THE NORTHEASTERN
GULF COAST TO THE NORTH CENTRAL GULF WATERS. UPPER LEVEL
NORTHEASTERLY WIND FLOW FROM THE ENORMOUS UPPER LEVEL ANTICYCLONE
EMANATING GOES FROM THE WESTERN ATLANTIC OCEAN...ACROSS THE
BAHAMAS INTO THE NORTHWESTERN AND PARTS OF THE WEST CENTRAL
CARIBBEAN SEA. UPPER LEVEL SOUTHERLY WIND FLOW CUTS ACROSS SOME
OF THIS UPPER LEVEL NORTHEASTERLY FLOW AND EVENTUALLY REACHES
THE NORTH CENTRAL CARIBBEAN WATERS NEAR 18N BETWEEN 73W AND 81W.
UPPER LEVEL ANTICYCLONIC FLOW COVERS THE REST OF THE GULF WATERS
SOUTH AND SOUTHWEST OF THE MIDDLE TO UPPER LEVEL TROUGH. MIDDLE
TO UPPER LEVEL DRY AIR EVERYWHERE IN THE GULF WATERS...EXCEPT FOR
SOUTH OF 24N98W 24N90W...WHERE SCATTERED MODERATE TO ISOLATED
STRONG SHOWERS AND THUNDERSTORMS ARE OCCURRING IN THE
SOUTHWESTERN CORNER OF THE AREA. WEAK SURFACE PRESSURE GRADIENT
IN THE GULF OF MEXICO.

THE REST OF THE SUBTROPICAL ATLANTIC OCEAN...
BROAD SURFACE ANTICYCLONIC FLOW NORTH OF 24N BETWEEN AFRICA AND
40W. BROAD SURFACE TROUGH IN THE ISOBARIC FIELD FROM AN 1017 MB
LOW PRESSURE CENTER NEAR 32N52W TO 27N55W. MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER NEAR 28N55W. CYCLONIC FLOW FROM 24N
TO 32N BETWEEN 50W AND 60W. WIDELY SCATTERED MODERATE TO ISOLATED
STRONG SHOWERS AND THUNDERSTORMS WITHIN 30 NM ON EITHER SIDE OF
22N52W 25N50W 28N50W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND
OTHER SHOWERS/THUNDERSTORMS NORTH OF 22N BETWEEN 32N36W 22N48W
AND 56W.

TROPICAL ATLANTIC...
MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTERS ARE NEAR
27N34W AND OVER THE WESTERN CANARY ISLANDS NEAR 29N18W.
A TROUGH GOES FROM THE CANARY ISLANDS CYCLONIC CENTER TO THE
CAPE VERDE ISLANDS. EVERYTHING THERE IS EMBEDDED IN MIDDLE TO
UPPER LEVEL DRY AIR EAST OF 30W...FROM THE CAPE VERDE ISLANDS
TO 38N.

$$
MT

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