[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 022327
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT 02 OCT 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
2245 UTC.

...SPECIAL FEATURES...
TROPICAL STORM LISA IS CENTERED NEAR 43.1N 34.7W OR ABOUT 535
MILES ...860 KM...NORTHWEST OF THE AZORES AT 02/2100 UTC. LISA
IS MOVING ENE AT 28 KT. MAXIMUM SUSTAINED WIND SPEED IS 55 KT
WITH GUSTS TO 65 KT AND THE ESTIMATED MINIMUM CENTRAL PRESSURE
IS 990 MB. SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO
HEADER MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.  SATELLITE
IMAGERY INDICATES THAT LISA IS RAPIDLY UNDERGOING EXTRATROPICAL
TRANSITION AND WILL LIKELY BE DECLARED EXTRATROPICAL LATER
TONIGHT.

...TROPICAL WAVES...
TROPICAL WAVE OVER THE E ATLC ALONG 39W S OF 18N MOVING W 15-20
KT.  THE WAVE CONTINUES TO GENERATE A FAIR AMOUNT OF CONVECTION
BUT THERE ARE NO SIGNS OF ORGANIZATION.  SCATTERED MODERATE
CONVECTION FROM 5N-10N BETWEEN 38W-41W AND FROM 15N-18N BETWEEN
33W-37W.

MID ATLC TROPICAL WAVE ALONG 48W S OF 17N MOVING W 10-15 KT. A
WELL-DEFINED LOW LEVEL CIRCULATION IS EVIDENT IN SATELLITE
IMAGERY NEAR 11N. HOWEVER...CONVECTION REMAINS LIMITED WITH NO
SIGNS OF FURTHER DEVELOPMENT.  ONLY A SMALL AREA OF SCATTERED
MODERATE CONVECTION ACCOMPANIES THE SYSTEM FROM 10N-13N BETWEEN
45W-50W.

TROPICAL WAVE OVER THE E CARIBBEAN ALONG 64W S OF 20N MOVING W
NEAR 15 KT. THE WAVE IS PRODUCING AN IMPRESSIVE AREA OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 8N-15N
BETWEEN 55W-64W.  HOWEVER...CONVECTION IS BEING SHEARED BY AN
UPPER TROUGH WHICH EXTENDS FROM THE CENTRAL ATLC SWD INTO THE E
CARIBBEAN AND UPPER LEVEL WINDS ARE EXPECTED TO REMAIN
UNFAVORABLE.

TROPICAL WAVE OVER THE W CARIBBEAN ALONG 86W/87W S OF 20N MOVING
W NEAR 15 KT. THE WAVE IS INTERACTING WITH A STRONG UPPER LEVEL
LOW WHICH IS ENHANCING CONVECTIVE ACTIVITY.  CURRENTLY...
SCATTERED TO NUMEROUS STRONG CONVECTION IS LOCATED FROM 12N-17N
BETWEEN 79W-85W.  THIS AREA WILL LIKELY SPREAD ACROSS CENTRAL
AMERICA TONIGHT AND TOMORROW WITH LOCALLY HEAVY RAINS.

...ITCZ...
ITCZ IS CENTERED ALONG 12N10W 6N27W 10N45W 8N50W 10N60W 9N80W.
ASIDE FROM CONVECTION WITH TROPICAL WAVES...SCATTERED MODERATE
CONVECTION FROM 2N-7N BETWEEN 26W-30W.

...DISCUSSION...
GULF OF MEXICO...
LARGE MID-UPPER LEVEL RIDGE DOMINATES THE ENTIRE GLFMEX WITH
MEAN AXIS EXTENDING FROM CENTRAL MEXICO NEAR MEXICO CITY NEWD
OVER CENTRAL FLORIDA.  NEARLY ALL OF THE MID-LATITUDE DYNAMICS
AND MUCH OF THE MID/UPPER LEVEL MOISTURE IS RIDING UP AND OVER
THE RIDGE LEAVING THE ENTIRE GLFMEX UNDER STRONG SUBSIDENCE AND
TRANQUIL WEATHER.  THE ONLY EXCEPTION LIES ALONG THE IMMEDIATE
TEXAS COAST WHERE WIDELY SCATTERED SHOWERS AND THUNDERSTORMS LIE
WITHIN 60 NM OF THE COAST.  THE RIDGE IS EXPECTED TO REMAIN IN
PLACE THROUGH THE NEXT 24-36 HOURS WITH AN UPPER LOW
RETROGRADING OVER CENTRAL AMERICA CLIPPING THE BAY OF CAMPECHE
LATE SUNDAY INTO MONDAY.

CARIBBEAN SEA...
STRONG MID-UPPER LEVEL LOW OVER HONDURAS COUPLED WITH A TROPICAL
WAVE ALONG 86W/87W ARE THE MAIN WEATHER MAKERS.  THE TROPICAL
WAVE IS POSITIONED WITHIN AN AREA OF DIFFLUENCE EAST OF THE
UPPER LOW PRODUCING AN IMPRESSIVE AREA OF SCATTERED TO NUMEROUS
STRONG CONVECTION OVER THE W CARIBBEAN AND PORTIONS OF CENTRAL
AMERICA FROM 12N-17N BETWEEN 79W-85W. BOTH THE UPPER LOW AND
TROPICAL WAVE ARE MOVING WESTWARD AND THE ASSOCIATED
THUNDERSTORMS SHOULD SPREAD ACROSS CENTRAL AMERICA TONIGHT AND
TOMORROW.  THE COLD CORE UPPER LOW IS ALSO PRODUCING SCATTERED
SHOWERS AND THUNDERSTORMS OVER MUCH OF THE YUCATAN
PENINSULA...BELIZE...AND N GUATEMALA.  FURTHER E...LARGE MID TO
UPPER LEVEL TROUGH OVER THE CENTRAL ATLC EXTENDS SWD OVER PUERTO
RICO AND THE E CARIBBEAN INTO S AMERICA NEAR W VENEZUELA.
CONFLUENT FLOW AND MODERATE SUBSIDENCE ON THE BACK/WEST SIDE OF
THE TROUGH AXIS IS PRODUCING DRY/TRANQUIL WEATHER BETWEEN
65W-75W.  THE UPPER FLOW BECOMES DIFFLUENT E OF THE TROUGH AXIS
WHICH IS SUPPORTING ANOTHER IMPRESSIVE AREA OF
SHOWERS/THUNDERSTORMS NEAR A TROPICAL WAVE EMERGING INTO THE E
CARIBBEAN.  ASSOCIATED CONVECTION IS CURRENTLY AFFECTING MUCH OF
WINDWARD ISLANDS SPREADING SW INTO E PORTIONS OF VENEZUELA.  THE
UPPER LOW CURRENTLY OVER HONDURAS IS EXPECTED TO RETREAT RAPIDLY
WESTWARD ALLOWING A MID/UPPER LEVEL RIDGE TO BUILD FROM COLOMBIA
TO THE YUCATAN CHANNEL BY LATE SUNDAY.  MEANWHILE THE UPPER
TROUGH OVER THE E CARIBBEAN IS EXPECTED TO REMAIN NEARLY
STATIONARY SHEARING THE TROPICAL WAVE NOW MOVING INTO THE AREA
AND KEEPING THE BULK OF THE CLOUDINESS AND SHOWERS/THUNDERSTORMS
CONFINED E OF 65W.

SUBTROPICAL ATLANTIC...
LARGE MID-UPPER LEVEL RIDGE PREVAILS OVER THE W ATLC EXTENDING
FROM CENTRAL FLORIDA NEWD BEYOND 31N60W.  THE RIDGE IS PARTIALLY
DISRUPTED BY A WEAK UPPER TROUGH EXTENDING FROM BERMUDA SWD TO
THE N BAHAMAS.  HOWEVER...THIS FEATURE IS NOT PRODUCING ANY
SIGNIFICANT WEATHER.  OVER THE CENTRAL ATLC...A LARGE MIDDLE TO
UPPER LEVEL LOW NEAR 26N56W CONTINUES TO PRODUCE CLOUDINESS AND
WIDELY SCATTERED SHOWERS/THUNDERSTORMS FROM 20N-30N BETWEEN
50W-60W. OVER THE E ATLC...A WELL DEFINED MID-UPPER LEVEL
ANTICYCLONE IS SITUATED JUST N OF THE AREA NEAR 32N40W WITH
RIDGE EXTENDING WSW TO 50N30W. ELSEWHERE...A MID-UPPER LEVEL LOW
IS LOCATED 300-400 NM W OF THE CANARY ISLANDS NEAR 28N23W WITH
ASSOCIATED TROUGH TRAILING SWD ALONG 23N30W. MODERATE SUBSIDENCE
COVERS THE AREA W OF TROUGH AXIS TO 45W.  AT THE SURFACE...
SUBTROPICAL RIDGE IS PRIMARILY CONFINED N OF THE AREA WITH
GENERALLY LIGHT TO MODERATE TRADES. THE PRES GRADIENT IS
ESPECIALLY WEAK BETWEEN 50W-70W WHERE A WEAK TROUGH LIES ALONG
22N61W TO 30N54W.

TROPICAL ATLANTIC...
WELL DEFINED MID-UPPER LEVEL RIDGE EMERGES FROM W AFRICA NEAR
13N EXTENDING WSW TO 8N35W.  THE RIDGE BECOMES DISRUPTED W OF
35W BY AN UPPER LEVEL TROUGH ALONG 20N37W 2N55W.  A SECOND
TROUGH EXTENDS SWD FROM THE CENTRAL SUBTROPICAL ATLC OVER THE E
CARIBBEAN.  THIS PATTERN IS PRODUCING GENERALLY UNFAVORABLE
CONDITIONS FOR TROPICAL CYCLONE DEVELOPMENT.

$$
RHOME





This weather bulletin was brought to you by:
www.nashvilleweather.net