[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 230004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

HURRICANE JEANNE IS CENTERED NEAR 26.1N 69.0W OR ABOUT 00
MILES...810 KM...EAST OF GREAT ABACO ISLAND AT 22/2100 UTC.
JEANNE IS MOVING WSW AT 4 KT. MAXIMUM SUSTAINED WIND SPEED IS 85
KT WITH GUSTS TO 105 KT AND THE ESTIMATED MINIMUM CENTRAL
PRESSURE 967 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 SATELLITE
SIGNATURE ASSOCIATED WITH JEANNE CONTINUES TO IMPROVE THIS
EVENING WITH THE EYE BECOMING INCREASINGLY DISTINCT AND THE
UPPER LEVEL OUTFLOW EXPANDING. IN FACT...A MID-LATITUDE TROUGH
PASSING TO THE NORTH OF JEANNE IS CREATING A NICE OUTFLOW JET
ALONG 30N.  NUMEROUS STRONG CONVECTION LIES WITHIN 60 NM RADIUS
OF THE CENTER WITH SCATTERED MODERATE CONVECTION ELSEWHERE
WITHIN 100-150 NM RADIUS.

HURRICANE KARL IS CENTERED NEAR 28.2N 48.3W OR ABOUT 1400
MILES...2255 KM...WEST-SOUTHWEST OF THE AZORES AT 22/2100 UTC.
KARL IS BEGINNING TO ACCELERATE NEWD AND IS NOW MOVING NNE AT 14
KT. MAXIMUM SUSTAINED WIND SPEED IS 90 KT WITH GUSTS TO 110 KT
AND THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/WTNT22
KNHC FOR MORE DETAILS. KARL IS INTERACTING WITH A MID-LATITUDE
TROUGH OVER THE CENTRAL ATLANTIC RESULTING IN AN INCREASINGLY
RAGGED APPEARANCE IN SATELLITE IMAGERY.  CLOUD TEMPERATURES
ASSOCIATED WITH THE CORE CONVECTION HAVE BEEN WARMING OVER THE
LAST FEW HOURS.  CURRENTLY...NUMEROUS STRONG CONVECTION IS
OBSERVED WITHIN 150 NM OVER THE S SEMICIRCLE AND WITHIN 200 NM
OVER THE N SEMICIRCLE. ADDITIONALLY CONVECTION IS OBSERVED
DEVELOPING FURTHER N AS MOISTURE FROM KARL GETS PULLED NWD AHEAD
OF THE UPPER TROUGH AND ATTENDANT COLD JUST TO THE NORTH. THIS
IS RESULTING IN THE OVERALL CLOUD/CONVECTIVE PATTERN TAKING ON
AN INCREASINGLY NORTH/SOUTH ORIENTATION.  KARL IS EXPECTED TO
CONTINUE WEAKENING OVER THE NEXT SEVERAL DAYS AS IT MOVES NWD
INTO STRONGER SHEAR AND COOLER WATER.

TROPICAL STORM LISA CENTER NEAR 13.7N 41.9W OR ABOUT 1205
MILES...1940 KM...WEST OF THE CAPE VERDE ISLANDS AT 22/2100 UTC.
LISA IS MOVING WSW AT 5 KT. MAXIMUM SUSTAINED WIND SPEED 45 KT
WITH GUSTS TO 55 KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE
IS DOWN SLIGHTLY TO 997 MB. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
SATELLITE IMAGERY INDICATES THAT LISA CONTINUES TO BE ADVERSELY
AFFECTED BY ELY SHEAR ON THE SOUTH SIDE OF AN UPPER LEVEL
ANTICYCLONE NEAR 18N44W AND A RAPIDLY APPROACHING TROPICAL
DISTURBANCE TO THE EAST.  THE EARLIER DEEP CONVECTION OVER THE
CENTER HAS ALL BUT DISSIPATED WITH ONLY A SMALL AREA OF
SCATTERED MODERATE ACTIVITY REMAINING FROM 11N-14N BETWEEN
43W-45.5W.  MEANWHILE... CONVECTION ASSOCIATED WITH THE
DISTURBANCE TO THE EAST HAS BEEN IMPROVING.  IT IS POSSIBLE THAT
THE DISTURBANCE TO THE EAST COULD BECOME THE STRONGER OF THE TWO
SYSTEMS RESULTING IN THE FURTHER WEAKENING OF LISA OVER THE NEXT
FEW DAYS.

NEWLY FORMED T.D. IVAN IS CENTERED OVER THE N GULF OF MEXICO
NEAR 26.9N 89.3W AT 22/2300 UTC.  THE DEPRESSION IS MOVING
TOWARD THE WNW AT 12 KT.  MAXIMUM SUSTAINED WIND SPEED IS 30 KT
WITH GUSTS TO 40 KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE
IS 1008 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.  THE DEPRESSION
HAS GOTTEN BETTER ORGANIZED THIS EVENING AND T.S. WARNINGS HAVE
BEEN ISSUED FOR A PORTION OF THE GULF COAST FROM THE MOUTH OF
THE MISSISSIPPI WESTWARD TO SARGENT TEXAS.  THE DEPRESSION IS
LOCATED 400-500 NM NE OF AN UPPER LOW OVER THE BAY OF CAMPECHE
WHICH IS PRODUCING UPPER LEVEL SLY FLOW OVER THE IVAN. AS A
RESULT...MOST OF THE CONVECTION IS DISPLACED ON THE N SIDE OF
THE LOW LEVEL CIRCULATION.  CURRENTLY...SCATTERED TO LOCALLY
NUMEROUS MODERATE CONVECTION COVERS THE AREA FROM 27N-30N
BETWEEN 86W-92W. THIS ACTIVITY IS BEGINNING TO SPREAD NWD OVER
SE LOUISIANA.

TROPICAL DISTURBANCE...1010 MB LOW...LOCATED APPROXIMATELY
700-800 NM WEST OF THE SOUTHERNMOST CAPE VERDE ISLAND NEAR 12.5N
37.0 AT 2100 UTC MOVING WNW 5-10 KT. SATELLITE IMAGERY INDICATES
THE SYSTEM REMAINS WELL ORGANIZED WITH NUMEROUS STRONG
CONVECTION NOW FROM 12N-15.5N BETWEEN 37W-41W. CONDITIONS APPEAR
FAVORABLE FOR DEVELOPMENT DESPITE ITS CLOSE PROXIMITY TO T.S.
LISA.  A TROPICAL CYCLONE MAY FORM WITHIN THE NEXT DAY OR SO.

...TROPICAL WAVES...
NONE.

...ITCZ...

ITCZ EXTENDS ALONG 10N10W 14N35W...DISRUPTED BY T.S LISA AND A
TROPICAL DISTURBANCE TO THE EAST BETWEEN 35W-50W...14N50W 8N60W
6N70W 8N80W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE THE
TROPICAL SYSTEMS DISCUSSED IN THE SPECIAL FEATURE SECTION...AREA
OF WIDELY SCATTERED MODERATE CONVECTION OFF THE COAST OF AFRICA
FROM 3N-15N BETWEEN 10W-23W.

...DISCUSSION...

GULF OF MEXICO...
ASIDE FROM ACTIVITY ASSOCIATED WITH THE NEWLY DEVELOPED T.D.
IVAN...WELL DEFINED MIDDLE TO UPPER LEVEL LOW IS LOCATED OVER
THE W GLFMEX NEAR 23N95W WITH A DEVELOPING MID-UPPER LEVEL RIDGE
TO THE EAST ALONG 85W.  THE RIDGE IS EXPECTED TO CONTINUE
BUILDING NWD INTO THE SE UNITED STATES DURING THE NEXT SEVERAL
DAYS WHILE THE W GLFMEX UPPER LOW REMAINS ESSENTIALLY
STATIONARY.  THIS EVOLUTION SHOULD PRODUCE SOME IMPROVEMENT IN
THE MID-UPPER LEVEL ENVIRONMENT OVER T.D. IVAN.  AT THE
SURFACE...T.D. IVAN TRAILS A REMNANT FRONTAL BOUNDARY ESE OVER
EXTREME S FLORIDA.  THE BOUNDARY IS PRODUCING SCATTERED TO
NUMEROUS SHOWERS/THUNDERSTORMS WITHIN 60 NM EITHER SIDE WITH
STRONGEST ACTIVITY PRIMARILY TO THE NORTH.  THE BOUNDARY HAS
BEEN SLOWLY SAGGING SWD THROUGHOUT THE DAY WITH MUCH DRIER AIR
MOVING IN FROM THE SW ATLC.  SURFACE DEWPOINT TEMPERATURES N OF
THE BOUNDARY ARE PRIMARILY IN THE MID-UPPER 60'S WHILE IN THE
LOWER TO MID 70'S S OF THE BOUNDARY.

THE CARIBBEAN SEA...
LARGE MID/UPPER LEVEL HIGH OVER THE NW CARIBBEAN ROUGHLY HALFWAY
IN BETWEEN JAMAICA AND BELIZE NEAR 18N82W CONTINUES TO DOMINATE
ALL BUT THE EXTREME E CARIBBEAN WHERE A WEAK UPPER TROUGH
EXTENDS FROM THE VIRGIN ISLANDS TO W VENEZUELA.  CONVECTION
CONTINUES TO BE PRIMARILY FOCUSED OVER LAND INCLUDING ALL OF
CENTRAL AMERICA...THE YUCATAN PENINSULA...AND THE S COAST OF
CUBA. ADDITIONALLY...A WEAK LOW LEVEL TROUGH TRAILS SWD FROM
HURRICANE JEANNE IN THE ATLC THROUGH THE MONA PASSAGE. THE
TROUGH IS SPARKING WIDELY SCATTERED SHOWERS/THUNDERSTORMS OVER E
HISPANIOLA AND PUERTO RICO. ELSEWHERE...DRY AIR IN THE MID/UPPER
LEVELS ESPECIALLY OVER THE E CARIBBEAN WHERE THERE IS A
NOTICEABLE LACK OF CLOUDINESS.

SUBTROPICAL ATLANTIC...
LARGE MID-LATITUDE TROUGH NORTH OF THE AREA IS BEGINNING TO LIFT
NEWD. ACCORDINGLY...ATTENDANT SURFACE FRONT IS NOW STATIONARY
ALONG 32N49W 28N60W 29N70W THEN DISSIPATING STATIONARY OVER THE
CENTRAL BAHAMAS INTO THE FLORIDA STRAITS.  HURRICANE KARL HAS
BEEN PULLING THE W EXTENT OF THIS BOUNDARY SWD OVER FLORIDA
RESULTING IN MUCH DRIER AIR OVER THE SW ATLC FILTERING OVER
FLORIDA.  THIS DRIER AIR SHOULD REDUCE THE TYPICAL CONVECTIVE
ACTIVITY OVER THE SUNSHINE STATE TOMORROW.  ELSEWHERE OVER THE W
ATLC...BROAD/FLAT MID-LEVEL TROUGH HAS BEEN CARVED OUT BY THE
COMBINED EFFECT OF HURRICANE KARL AND HURRICANE JEANNE. MODERATE
SUBSIDENCE AND DRY AIR SURROUNDING THE TWO SYSTEMS IS PRODUCING
FAIRLY TRANQUIL CONDITIONS OUTSIDE THE IMMEDIATE VICINITY OF THE
CYCLONES.  OVER THE CENTRAL ATLANTIC...LARGE AND HIGH AMPLITUDE
MIDDLE TO UPPER LEVEL RIDGE CONTINUES TO BUILD NWD E OF
HURRICANE KARL.  THE RIDGE IS ANCHORED BY AN LARGE ANTICYCLONE
NEAR 18N44W WHICH IS PRODUCING ELY SHEAR OVER T.S. LISA.  NEARLY
MID/UPPER LEVEL TROUGH REMAINS OVER THE E ATLANTIC JUST W OF THE
CANARY ISLANDS ALONG 25W N OF 20N.  SURFACE SUBTROPICAL RIDGE
REMAINS LARGELY DISRUPTED OVER THE W ATLC BUT WELL ESTABLISHED
OVER THE E ATLC FROM THE AZORES SW TO 21N43W.  1028 MB HIGH
PRESSURE OVER THE E UNITED STATES IS PRODUCING STRONG NE FLOW
OVER THE W ATLC NORTH AND WEST OF HURRICANE JEANNE.

TROPICAL ATLANTIC...
MID/UPPER LEVEL RIDGE EXTENDS E/W ALONG 20N BUT IS
DISRUPTED/SPLIT NEAR 25W BY THE S EXTENT OF A MID-LATITUDE
TROUGH TO THE NORTH.

$$
RHOME






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