[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 190553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN 19 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 IS CENTERED NEAR 22.6N 72.3W...OR WITHIN
35 MILES NE OF THE EASTERN END OF MAYAGUANA ISLAND IN THE
SOUTHEASTERN BAHAMAS AT 19/0300 UTC MOVING N AT 5 KT. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1002 MB. SEE LATEST NHC PUBLIC
ADVISORY OR NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC OR MIATCMAT1/ WTNT21 KNHC FOR MORE
DETAILS. THE CONVECTION IS POORLY ORGANIZED AND IS LIMITED TO E
OF THE LOW LEVEL CIRCULATION. A MID/UPPER LOW IS CENTERED SE OF
JEANNE NEAR 21N75W ADVECTING MODERATE SUBSIDENCE AND DRY AIR S
OF JEANNE. SCATTERED STRONG CONVECTION IS WITHIN A 45 NM RADIUS
OF 22N71W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 45/60 NM OF LINE FROM 24N70W TO OVER HAITI NEAR 19N73W.
SINCE JEANNE IS MOVING SO SLOWLY...VERY HEAVY RAINFALL WILL
CONTINUE OVER THE TURKS AND CAICOS ISLANDS AND HAITI.

HURRICANE KARL IS CENTERED NEAR 16.2N 41.3W...OR ABOUT 1000 NM W
OF THE CAPE VERDE ISLANDS OR ABOUT 1200 NM E OF THE LESSER
ANTILLES AT 19/0300 UTC MOVING WNW AT 10 KT. MAXIMUM SUSTAINED
WIND SPEED IS 100 KT WITH GUSTS TO 120 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 960 MB. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
THE EYE PREVIOUSLY OBSERVED IS NO LONGER DISCERNIBLE. HURRICANE
KARL HAS SEVERAL SPIRAL BANDS IN ALMOST EVERY QUADRANT AND GOOD
OUTFLOW IN ALL DIRECTIONS. IN PARTICULAR...A OUTFLOW JET APPEARS
TO EXTEND TO THE NE OF KARL DUE TO AN UPPER LOW LOCATED ABOUT
725 NM NE OF KARL. SCATTERED STRONG CONVECTION IS FROM 15N-17N
BETWEEN 40W-42W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
COVERS THE REMAINDER OF THE AREA FROM 13-20N BETWEEN 37W-44W.

A STRONG TROPICAL WAVE IS LOCATED JUST W OF THE CAPE VERDE
ISLANDS ALONG 28W/29W S OF 19N MOVING W 10-15 KT WITH A 1010 MB
LOW ALONG THE WAVE NEAR 13N. A MID LEVEL LOW IS OBSERVED ON
INFRARED SATELLITE IMAGERY. THE CONVECTION ASSOCIATED WITH THIS
LOW/WAVE IS NOT AS WELL ORGANIZED AS EARLIER WITH SCATTERED
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM
10N-16N BETWEEN 27W-32W. THIS SYSTEM HAS THE POTENTIAL OF
TROPICAL CYCLONE DEVELOPMENT OVER THE NEXT FEW DAYS AS IT MOVES
WESTWARD.

...TROPICAL WAVES...

TROPICAL WAVE APPROACHING BARBADOS IS ALONG 58W/59W S OF 23N
MOVING W 5-10 KT. VERY LITTLE INDICATION OF THE WAVE IS PRESENT
ON INFRARED SATELLITE IMAGERY. THIS WAVE IS BENEATH UPPER LEVEL
RIDGING E OF T.S. JEANNE. THE PRESENCE OF STRONG SUBSIDENCE AT
THE UPPER LEVELS AND DRY AIR AT THE SURFACE IS SEVERELY LIMITING
ANY SHOWERS OVER THE LESSER ANTILLES.

...ITCZ...

ITCZ AXIS EXTENDS ALONG 15N10W 12N20W 14N26W 8N30W 14N38W 9M42W
7N57W. THE ITCZ CONTINUES TO BE DISTORTED BY THE TROPICAL WAVES
AND HURRICANE KARL. OVERCAST CLOUDS COVER THE TROPICS S OF 10N E
OF 40W. SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 6N-11N
BETWEEN 21W-25W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
FROM 1N-6N BETWEEN 12W-27W.

...DISCUSSION...

GULF OF MEXICO...
ONE OF THE FIRST COLD FRONTS OF THIS LATE SUMMER/EARLY FALL HAS
PUSHED ITS WAY INTO THE GULF OF MEXICO...EXTENDING FROM THE W
ATLC ACROSS CNTRL FLORIDA NEAR LAKE OKEECHOBEE TO 26N84W THEN
DISSIPATES TO S OF LOUISIANA. THE FRONT WAS PROBABLY HELPED
ALONG BY THE CIRCULATION ASSOCIATED WITH EX-HURRICANE IVAN. IT
HAS BROUGHT IN MUCH DRIER AIR BEHIND THE FRONT. A DEEP LAYERED
TROF ALSO SITUATED ALONG THE EASTERN SEABOARD AND TRAILING INTO
THE E GULF HAS BROUGHT STRONG SUBSIDENCE OVER THE AREA AT THE
MID/UPPER LEVELS. FARTHER W...AN UPPER LEVEL HIGH IS CENTERED
250 NM WSW OF BROWNSVILLE TEXAS AND IT APPEARS THAT THE
ASSOCIATED UPPER LEVEL DIVERGENCE IS TRIGGERING ISOLATED
THUNDERSTORMS ALONG THE COAST OF MEXICO FROM 20N-24N.

CARIBBEAN...
THE NORMAL EASTERLY TRADES ARE PRETTY MUCH NON-EXISTENT ACROSS
THE CARIBBEAN FOR THE SECOND STRAIGHT DAY DUE TO THE WEAKENED
GRADIENT CAUSED BY T.S. JEANNE. THIS HAS PRODUCED HIGHER THAN
NORMAL TEMPERATURES OVER THE LESSER ANTILLES ALONG THE COAST OF
SOUTH AMERICA. A MID/UPPER LEVEL HIGH IS OVER PUERTO RICO NEAR
18N66W WITH RIDGE AXIS EXTENDING TO THE N TO 25N68W AND THE
EXPANDING ANTICYCLONIC OUTFLOW OF T.S. JEANNE. SURFACE TROF
EXTENDS FROM S OF JEANNE ACROSS HAITI ALONG THE E COAST OF
JAMAICA TO 14N81W IN THE SW CARIBBEAN. ONLY ISOLATED SHOWERS
REMAIN FROM THE STORMS OF EARLIER TODAY. AT THE PRESENT
SCATTERED THUNDERSTORMS ARE OBSERVED ALONG THE S COAST OF
HISPANIOLA/CUBA E OF 80W AND ALONG THE COAST OF COLOMBIA AND
COSTA RICA.

SUBTROPICAL ATLANTIC...
STRONG RIDGING CONTINUES OVER THE W ATLC WITH AN UPPER LEVEL
HIGH LOCATED NEAR 32N69W. SEE SPECIAL FEATURES ABOVE. MID/UPPER
LEVEL TROF EXTENDS INTO THE CNTRL ATLC FROM A MID/UPPER LEVEL
LOW CENTERED NEAR 32N56W SW TO 25N63W. MOISTURE FROM T.S. JEANNE
IS FEEDING INTO THIS TROF ON THE E SIDE PRODUCING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM OF LINE FROM
23N68W23N55W TO BEYOND 32N51W. AN UPPER RIDGE LIES TO THE E OF
THIS LOW ALONG 20N53W TO BEYOND 32N43W AND TWO MID/UPPER LOWS
CONTINUE TO SWIRL OVER THE E ATLC NEAR 26N31W AND 30N17W. THE
EASTERNMOST LOW IS BRINGING DRIER AIR OVER THE CANARY ISLANDS
BUT A FEW SHOWERS MAY BE EMBEDDED WITHIN THE MID/UPPER LEVEL
CLOUDINESS OVER W SAHARA...MOROCCO...AND THE ADJACENT WATERS.

TROPICAL ATLANTIC...
AN UPPER LEVEL RIDGE AND UPPER LEVEL MOISTURE IS SITUATED OVER
THE LEEWARD ISLANDS EXTENDING NEWD INTO THE SUBTROPICAL WATERS
BUT DRIER AIR IS MOVING IN FROM THE E BETWEEN 45W-55W ALONG AN
INVERTED TROF ALONG 11N55W-21N47W. A SECOND UPPER RIDGE EXTENDS
TO THE E OF HURRICANE KARL ALONG 15N WITH STRONG WLY FLOW
PROBABLY AN OUTFLOW JET JUST TO THE N BETWEEN 20N-25N.

$$
WALLACE


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