[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170603
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

TROPICAL STORM JEANNE IS CENTERED NEAR 19.4N 69.9W...OR ABOUT 65
MILES...100 KM... NORTH-NORTHWEST OF SANTO DOMINGO IN THE
DOMINICAN REPUBLIC...AT 17/0600 UTC MOVING WNW AT 6 KT.
MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 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 A SMALL STORM WITH A CLOUD FIELD THAT ONLY EXTENDS OUT ABOUT
100 NM FROM THE CENTER...BUT IS SLOW MOVING AND LIKELY TO
PRODUCE FLOODING AND MUDSLIDES.  A PERSISTENT TRAILING BAND HAS
ALSO BEEN SITTING TO THE E OVER PARTS OF THE VIRGIN ISLANDS AND
PUERTO RICO.  NUMEROUS STRONG CONVECTION IS FROM 18N-20N BETWEEN
67W-70W.  SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS
FROM 16N-20N BETWEEN 62W-67W.

TROPICAL DEPRESSION IVAN IS CENTERED NEAR 34.3N 86.2W...OR ABOUT
25 MILES NORTH-NORTHWEST OF GADSDEN ALABAMA...AT 17/0300 UTC
MOVING NNE 12 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH
GUSTS TO 45 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 986 MB.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. THE LARGE CLOUD SHIELD
ASSOCIATED WITH IVAN HAS EXPANDED NWD ACROSS MUCH OF THE OHIO
VALLEY... MID-ATLANTIC...UNITED STATES.  SCATTERED MODERATE
CONVECTION IS FROM 33N-39N BETWEEN 78W-86W.

TROPICAL STORM KARL IS NEAR 11.4N 33.9W...OR ABOUT  735 MILES
...1185 KM...WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS...AT
17/0300 UTC MOVING W 12 KT. MAXIMUM SUSTAINED WIND SPEED IS 35
KT WITH GUSTS TO 45 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
1005 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. KARL HAS
MAINTAINED A SIZEABLE BAND OF CONVECTION OVER ITS N AND W
QUADRANTS BUT MORE STRONG CONVECTION HAS RECENTLY BEEN
DEVELOPING CLOSER TO THE LOW-LEVEL CENTER. WATER VAPOR IMAGERY
INDICATES THAT THE OUTFLOW IS MOST IMPRESSIVE OVER THE NW
SEMICIRCLE...WHICH PARTLY INDICATES THAT THERE IS A SLIGHT
AMOUNT OF ELY SHEAR OVER THE SYSTEM. SCATTERED MODERATE/STRONG
CONVECTION IS FROM 7N-13N BETWEEN 33W-40W...AND FROM 13N-17N
BETWEEN 27W-36W.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE ALONG 50W/51W S OF 21N 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 14N52W 10N40W. SOME SCATTERED
MODERATE SHOWERS HAVE PERSISTED ALONG THE MAIN WAVE AXIS.

A WEAK TROPICAL WAVE IS MOVING ACROSS GUATEMALA ALONG 90W S OF
19N MOVING W 10 KT.  SCATTERED MODERATE CONVECTION IS OVER
GUATEMALA FROM 15N-18N BETWEEN 90W-92W.

...ITCZ...

ITCZ IS CENTERED ALONG 15N1W 8N10W 10N25W 7N35W 7N60W 6N70W
9N80W.  ISOLATED MODERATE CONVECTION IS FROM 6N-10N BETWEEN
17W-30W.  SCATTERED MODERATE TO STRONG CONVECTION IS OVER N
COLOMBIA AND NW VENEZUELA FROM 5N-11N BETWEEN 71W-77W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE IVAN HAS EXITED THE AREA AND IS NOW DUMPING HEAVY
RAINFALL ACROSS THE SOUTH CENTRAL U.S. SURFACE WINDS ACROSS THE
GULF ARE GENERALLY W/SWLY AROUND THE PERIPHERAL CIRCULATION OF
IVAN...AND SOME OF THE BUOYS ACROSS THE E GULF ARE STILL
REPORTING SUSTAINED WINDS BETWEEN 20 AND 30 KT. THE GOOD NEWS IS
THAT THE WEATHER HAS IMPROVED GREATLY ACROSS THE AREA WITH
MOSTLY FAIR SKIES...WITH THE EXCEPTION OF PATCHY SHOWERS WITHIN
180 NM OF THE MEXICAN COAST. AN UPPER LEVEL ANTICYCLONIC
CIRCULATION IS OVER THE WESTERN GULF OF MEXICO NEAR 24N97W.
ANTICYCLONIC FLOW AND STRONG SUBSIDENCE IS FROM 20N-32N BETWEEN
90W-107W.

WEST ATLANTIC...
BROAD N/NE UPPER LEVEL FLOW EXTENDS WELL E OF HURRICANE IVAN AND
IS PRODUCING A CONSIDERABLE AMOUNT OF STRONG NELY SHEAR NEAR THE
BAHAMAS. IN ADDITION...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 THIS
SUCCESSFULLY...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. THERE IS SOME DRY AIR ACROSS PARTS OF THE CARIBBEAN
BASIN BUT ALL IN ALL THERE IS ENOUGH MOISTURE TO ALLOW SPORADIC
TSTMS ESPECIALLY OVER LAND AREAS OF SOUTH AMERICA...CENTRAL
AMERICA...AND CUBA. AN ANTICYCLONIC CIRCULATION IS LOCATED TO
THE E OF T.S. JEANNE OVER THE NRN LEEWARD ISLANDS NEAR 15N56W
AND THE ASSOCIATED DIVERGENCE HAS ALLOWED VERY HEAVY TSTMS TO
PERSIST OVER THE SAME AREAS FOR THE PAST 2 DAYS.

SUBTROPICS E OF 60W...
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 LOW/TROUGH. TWO DISTINCT
MID/UPPER LOWS ARE MEANDERING OVER THE AREA NEAR 28N33W AND
29N17W (OVER THE CANARY ISLANDS). THE EASTERNMOST LOW DEVELOPED
AS A CUT-OFF FROM A MUCH LARGER TROF WHICH IS MOVING ACROSS
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.

$$
FORMOSA


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