[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180601
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT 18 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
0345 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION JEANNE WAS UPGRADED AGAIN TO TROPICAL STORM
AT 18/0300 UTC. T.S. JEANNE IS CENTERED NEAR 20.4N 72.4W...ALONG
N COAST OF HAITI COAST...AT 18/0300 UTC DRIFTING WNW. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1000 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 LOW LEVEL CENTER IS NOW EXPOSED JUST OFFSHORE OF THE N COAST
OF HAITI. CONVECTION HAS REGENERATED MOSTLY WELL EAST OF THE
LOW. SCATTERED STRONG CONVECTION IS WITHIN 45/60 NM OF LINE FROM
15N71W TO W PUERTO RICO NEAR 18N67W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION COVERS THE REMAINDER OF PUERTO RICO FROM
17N-21N BETWEEN 64W-67W AND WITHIN 125 NM ALONG THE N COAST OF
HISPANIOLA FROM 69W72W. SIMILAR CONVECTION IS OVER THE S
PENINSULA OF HAITI WITHIN A 30 NM RADIUS OF 18N73W. THE LOW
LEVEL CENTER IS AT THE SW END OF AN UPPER LEVEL TROUGH THAT
EXTENDS FROM THE CENTRAL ATLANTIC TO CUBA. AN AREA OF MODERATE
SUBSIDENCE/DRY AIR EXTENDS FROM THE CENTRAL/WESTERN ATLC ACROSS
THE BAHAMAS AND THE LOW LEVEL CENTER TO THE N COAST OF HAITI.
THIS DRY WILL LIMIT CONVECTION DIRECTLY OVER THE LOW LEVEL
CENTER SO INTENSIFICATION MAY BE LIMITED FOR THE NEXT FEW HOURS.

TROPICAL STORM KARL IS CENTERED NEAR 14.2N 37.4W...OR ABOUT 800
NM W OF THE CAPE VERDE ISLANDS...AT 18/0300 UTC MOVING NW AT 12
KT. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
FOR MORE DETAILS. INFRARED SATELLITE IMAGERY CONTINUES TO
INDICATE THAT KARL HAS DEVELOPED A STRONG CORE OF CONVECTION
OVER ITS LOW-LEVEL CENTER WITH A SIGNIFICANT BAND WRAPPING
AROUND THE W SEMICIRCLE. THE UPPER LEVEL OUTFLOW REMAINS
IMPRESSIVE TO THE N OF THE SYSTEM BUT HAS NOT IMPROVED TO THE
S. KARL IS LAGGING TO THE E OF A LARGE AREA OF DRY SAHARAN
AIR...BUT WITH ITS FORECAST TRACK TURNING IT TO THE N OVER THE
ATLC IT WILL PROBABLY BE ABLE TO ESCAPE THE BRUNT OF THE
UNFAVORABLE ENVIRONMENT. SCATTERED MODERATE/STRONG CONVECTION IS
WITHIN 90/120 NM OF LINE FROM 15N35W-12N39W. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVER THE
REMAINDER OF THE AREA FROM 10N-19N BETWEEN 30W-43W.

...TROPICAL WAVES...

TROPICAL WAVE JUST E OF THE CAPE VERDE ISLANDS IS ALONG 22W S OF
20N MOVING W 5-10 KT. A LOWER TO MID LEVEL LOW CENTER...BUT NOT
ON THE SURFACE...IS OBSERVED ON INFRARED AND WATER VAPOR
SATELLITE IMAGERY NEAR 13N. NARROW BAND OF SCATTERED STRONG
CONVECTION IS ALONG 14.5N MOVING W TO OVER THE SOUTHERN MOST
CAPE VERDE ISLANDS.

TROPICAL WAVE E OF THE LESSER ANTILLES IS ALONG 57W/58W S OF 22N
MOVING W 15 KT. WELL DEFINED SIGNATURE CURVATURE OF AN INVERTED
V IS OBSERVED IN THE INFRARED SATELLITE IMAGERY. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION HAS DEVELOPED ALONG THE
CENTER OF THE WAVE FROM 13N-17N BETWEEN 55W-58W. AT THE UPPER
LEVELS...THE WAVE IS EMBEDDED WITH MODERATE/STRONG SUBSIDENCE
AND IS ALONG THE LEADING EDGE OF THE SAHARAN DUST THAT STRETCHES
ACROSS THE ATLC. THEREFORE...FURTHER DEVELOPMENT IS NOT
EXPECTED.

TROPICAL WAVE LOCATED OVER S MEXICO AND THE BAY OF CAMPECHE IS
ALONG 95W/96W S OF 22N MOVING W 15 KT. WAVE POSITION IS BASED
PURELY ON EXTRAPOLATION. AT THE UPPER LEVELS...THIS WAVE IS
UNDER A STRONG MID/UPPER LEVEL HIGH LOCATED JUST N OF THE WAVE
WITH NE FLOW ACROSS THE WAVE...THUS MASKING ANY SIGNATURE ON
INFRARED SATELLITE IMAGERY. UPPER AIR SOUNDINGS ARE LIMITED IN
THE AREA OF S MEXICO. NO ASSOCIATED DEEP CONVECTION.

...ITCZ...

ITCZ AXIS EXTENDS ALONG 11N10W 14N20W 9N24W 15N32W 11N40W 9N54W
6N60W. THIS AXIS IS DISTORTED BY TWO TROPICAL WAVES AND T.S.
KARL. SCATTERED STRONG CONVECTION IS WITHIN 30 NM OF 14N E OF
19W TO INLAND OVER SENEGAL. SCATTERED MODERATE/STRONG CONVECTION
IS N OF 4N TO INLAND OVER LIBERIA AND SIERRA LEONE FROM 9W-12W.
LARGE CLUSTERS OF SIMILAR CONVECTION ARE FROM 7N-12N BETWEEN
24W-32W. LARGE CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 2N-8N BETWEEN 13W-28W.

...DISCUSSION...

GULF OF MEXICO...
GULF IS DOMINATED BY A LARGE MID/UPPER LEVEL HIGH ALONG THE
COAST OF MEXICO CENTERED NEAR 25N96W WITH THE ANTICYCLONIC FLOW
COVERING ALL BUT THE NE GULF. BROAD DIFFLUENCE TO THE IMMEDIATE
S HAS TRIGGERED A FEW SHOWERS/THUNDERSTORMS OVER THE FAR SW
GULF. THE MID/UPPER LEVEL TROUGH OVER THE E UNITED STATES
CONTINUES MOVE NE OVER NEW ENGLAND WITH THE REMNANTS OF IVAN.
MODERATE/STRONG SUBSIDENCE COVERS THE NE GULF INCLUDING THE N
PORTION FLORIDA AND THE SE STATES. ISOLATED SHOWERS ARE OVER
FLORIDA S OF LAKE OKEECHOBEE.

CARIBBEAN...
OVER THE NW CARIBBEAN IS MID/UPPER LEVEL NE FLOW THAT IS A
RESULT OF THE HIGH OVER THE GULF OF MEXICO. THE REMAINDER OF THE
CARIBBEAN IS DOMINATED BY A MID/UPPER LEVEL HIGH CENTERED S OF
HAITI NEAR 13N72W. THIS IS INFLUENCING T.S. JEANNE WHICH IS
CENTERED ALONG THE N COAST OF HAITI. THE RESULTING ANTICYCLONIC
FLOW IS RESPONSIBLE FOR THE DISPLACEMENT OF THE CONVECTION WELL
E OF THE LOW LEVEL CENTER OF JEANNE. MODERATE SUBSIDENCE/DRY
AIR EXTENDS ACROSS CUBA INTO THE CARIBBEAN N OF 15N FROM 79W-84W
AND IS ASSOCIATED WITH AN INDUCED TROF BETWEEN THE ANTICYCLONIC
FLOWS. A SURFACE TROF EXTENDS FROM HAITI AND T.S. JEANNE SW TO
16N7W.

SUBTROPICAL ATLANTIC....
N OF THE REGION...UPPER LEVEL RIDGING CONTINUES TO BUILD TO THE
E OF T.D. IVAN BUT NARROWS NEAR 32N. RIDGE AXIS EXTENDS FROM S
FLORIDA NEAR 26N80W NE TO BEYOND 32N73W. NARROW SWATH OF UPPER
LEVEL MOISTURE EXTENDS TO THE W OF THE RIDGE AXIS ACROSS THE W
ATLC AND THE STRAITS OF FLORIDA WITH ISOLATED SHOWERS. MID/UPPER
LEVEL TROF EXTENDS S INTO THE CENTRAL ATLC N OF 26N FROM
50W-65W. THIS TROF ALSO COVERS THE REMAINDER OF THE W ATLC BUT
IS DISTORTED BY T.S. JEANNE WITH A WEAKER AXIS EXTEND FROM
26N65W SW TO E CUBA NEAR 21N75W. THIS IS FUNNELING STRONG
SUBSIDENCE/DRY AIR OVER THE W ATLC ACROSS CUBA AND EXPOSING THE
LOW LEVEL CENTER OF JEANNE. AN EMBEDDED UPPER LEVEL LOW IS
CENTERED NEAR 28N53W AND IS MOVING N. AT THE SURFACE IS A WEAK
1016 MB LOW JUST N OF THE AREA NEAR 34N53W WITH A SURFACE TROF
EXTENDING SW TO 28N56W. RIDGE AXIS EXTENDS FROM 22N50W NE TO
BEYOND 32N44W WITH BROAD DIFFLUENCE TO THE W OF THE AXIS
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN A 90 NM
RADIUS OF 29N48W. SHOWERS/THUNDERSTORMS ARE N OF 30N FROM
46W-55W. THE E ATLC IS DOMINATE BY AN UPPER LEVEL TROF N OF 25N
E OF 38W WITH A WEAK EMBEDDED UPPER LOW NEAR 27N32W AND A STRONG
MID/UPPER LOW OVER THE CANARY ISLANDS NEAR 29N18W. STRONG
SUBSIDENCE/DRY AIR COVERS THE SAME AREA.

TROPICAL ATLANTIC...
MID/UPPER RIDGE AXIS EXTENDS ACROSS THE TROPICAL ATLC WITH A
UPPER LEVEL HIGH NEAR 13N20W W TO A STRONGER UPPER LEVEL HIGH
ASSOCIATED WITH T.S. KARL TO OVER THE LESSER ANTILLES NEAR
15N62W. AN INDUCED TROF IS BETWEEN KARL AND THE CARIBBEAN
ISLANDS ALONG 45W/47W.

$$
WALLACE


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