[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171041
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

TROPICAL STORM JEANNE IS CENTERED NEAR 19.5N 70.1W...OR ABOUT 70
MILES...115 KM... NORTH OF SANTO DOMINGO IN THE DOMINICAN
REPUBLIC...AT 17/0900 UTC MOVING WNW AT 6 KT. MAXIMUM SUSTAINED
WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 992 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 CENTER OF
JEANNE IS OVER THE NE COAST OF HISPANIOLA.  JEANNE IS MOVING
SLOWLY AND IS LIKELY TO PRODUCE FLOODING AND MUDSLIDES.  A
PERSISTENT BAND IS OVER PUERTO RICO. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 16N-21N BETWEEN 65W-72W.

TROPICAL DEPRESSION IVAN IS CENTERED NEAR 34.9N 84.9W...NEAR
CHATTANOOGA TENNESSEE...AT 17/0900 UTC MOVING NE 10 KT. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 45 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 994 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS. THE LARGE CLOUD SHIELD ASSOCIATED WITH IVAN IS
NOW OVER THE OHIO VALLEY.  SCATTERED MODERATE CONVECTION IS FROM
36N-41N BETWEEN 77W-86W.

TROPICAL STORM KARL IS NEAR 11.5N 35.3W...OR ABOUT  820 MILES
...1320 KM...WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS...AT
17/0900 UTC MOVING W 12 KT. MAXIMUM SUSTAINED WIND SPEED IS 55
KT WITH GUSTS TO 65 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
994 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. KARL HAS
CONSOLIDATED CONVECTION NEAR THE CENTER AND HAS AN IMPRESSIVE
FEEDER BAND TO THE NORTH...WHICH PARTLY INDICATES THAT THERE IS
A SLIGHT AMOUNT OF SOUTHERLY SHEAR OVER THE SYSTEM. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 8N-12N BETWEEN 33W-40W...AND
FROM 14N-18N BETWEEN 28W-38W.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE ALONG 52W S OF 20N MOVING W 15
KT. THE WAVE CONTINUES TO MOVE W IN TANDEM WITH THE LEADING EDGE
OF AN EXTENSIVE SAHARAN AIR LAYER (SAL)...WHICH EXTENDS ALONG A
NW/SE LINE FROM 22N54W TO 14N54W 10N40W. SOME SCATTERED MODERATE
SHOWERS HAVE PERSISTED ALONG THE MAIN WAVE AXIS.

A WEAK TROPICAL WAVE IS MOVING ACROSS GUATEMALA ALONG 89W/90W S
OF 19N MOVING W 10 KT.  NO SIGNIFICANT CONVECTION IS NOTED.

...ITCZ...

ITCZ IS CENTERED ALONG 15N1W 10N10W 10N40W 8N55W 13N70W 9N80W.
SCATTERED MODERATE TO STRONG CONVECTION IS OFF THE COAST OF W
AFRICA FROM 13N-16N BETWEEN 19W-23W.  SCATTERED MODERATE
CONVECTION IS FROM 6N-8N BETWEEN 27W-29W.  SCATTERED MODERATE TO
STRONG CONVECTION IS OVER N COLOMBIA FROM 4N-11N BETWEEN
75W-80W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE IVAN HAS EXITED THE AREA AND IS NOW DUMPING HEAVY
RAINFALL ACROSS THE OHIO VALLEY. SURFACE WINDS ACROSS THE GULF
ARE GENERALLY W/SWLY AROUND THE PERIPHERAL CIRCULATION OF IVAN.
WEATHER HAS IMPROVED GREATLY ACROSS THE AREA WITH MOSTLY FAIR
SKIES...WITH THE EXCEPTION OF SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS THE BAY OF CAMPECHE FROM 17N-20N BETWEEN
92W-97W.  AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS OVER THE
WESTERN GULF OF MEXICO NEAR 23N97W.  ANTICYCLONIC FLOW AND
STRONG SUBSIDENCE IS FROM 20N-32N BETWEEN 88W-107W.

WEST ATLANTIC...
BROAD N/NE UPPER LEVEL FLOW EXTENDS WELL E OF HURRICANE IVAN TO
70W.  A REMNANT UPPER TROUGH IS W OF T.S. JEANNE ALONG 29N68W
20N75W. JEANNE ITSELF IS TRYING TO ESCAPE THE RUGGED TERRAIN OF
HISPANIOLA AND IF IT DOES ...IT WILL THEN HAVE TO CONTEND
WITH THE HOSTILE UPPER LEVEL ENVIRONMENT AHEAD OF IT.

CARIBBEAN...
THE BROAD NELY UPPER FLOW OVER THE W ATLC EXTENDS ALL THE WAY
DOWN INTO THE W CARIBBEAN...OR JUST TO THE W OF AN INVERTED
UPPER TROUGH WHICH EXTENDS FROM E PANAMA TO 20N72W OVER
HISPANIOLA.  DRY AIR IS OVER MOST OF THE CARIBBEAN EXCEPT NEAR
JEANNE AND NEAR COLOMBIA AND PANAMA DUE TO AN ACTIVE ITCZ.  AN
ANTICYCLONIC CIRCULATION IS LOCATED TO THE E OF T.S. JEANNE OVER
THE NRN LEEWARD ISLANDS NEAR 15N56W.

SUBTROPICS E OF 60W...
A 1016 MB LOW IS OVER THE CENTRAL ATLANTIC NEAR 30N52W.  A
TROUGH EXTENDS SW TO 28N55W 27N60W.  SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 22N-33N BETWEEN 45W-55W.  IN
THE UPPER LEVELS...A TIGHTLY-WOUND CYCLONIC CIRCULATION IS
LOCATED IN THE CENTRAL ATLANTIC NEAR 27N57W.  UPPER LEVEL
MOISTURE FROM JEANNE IS BEING DRAWN NEWD ON THE E SIDE OF THE
CYCLONIC CIRCULATION. TWO OTHER SMALL MID/UPPER CYCLONIC
CIRCULATIONS  ARE MEANDERING OVER THE AREA NEAR 28N33W AND
29N17W (OVER THE CANARY ISLANDS). THE EASTERN MOST SYSTEM
DEVELOPED AS A CUT-OFF FROM A MUCH LARGER SYSTEM OVER
EUROPE...AND IS BRINGING MUCH DRIER AIR IN THE UPPER LEVELS N OF
20N E OF 28W.

TROPICAL ATLANTIC...
AN UPPER LEVEL RIDGE EXTENDS FROM W AFRICA TO 40W ALONG 17N1W
14N40W.  ANTICYCLONIC FLOW IS WITHIN 600 NM OF THE RIDGE AXIS.
T.S. KARL IS UNDER THIS RIDGE.

$$
FORMOSA



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