000 AXNT20 KNHC 222348 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI SEP 22 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC 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... HELENE IS CENTERED NEAR 35.4N 53.0W OR ABOUT 710 MILES...1140 KM...EAST-NORTHEAST OF BERMUDA AT 22/2100 UTC MOVING NORTHEAST AT 18 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE HAS WEAKENED SLIGHTLY OVER THE LAST SEVERAL HOURS DUE TO INCREASING VERTICAL SHEAR...DECREASING SSTS...AND DRY MIDDLE TO UPPER-LEVEL AIR WRAPPING AROUND THE SOUTHERN SIDE OF THE CYCLONE. HELENE IS ALSO ENTERING THE EARLY STAGES OF EXTRATROPICAL TRANSITION. SCATTERED MODERATE CONVECTION COVERS THE AREA FROM 35N-43N BETWEEN 50W-56W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 39W/40W S OF 19N WITH A 1010 MB LOW ALONG THE WAVE NEAR 13N MOVING W 15 KT. THIS SYSTEM HAS NOT BECOME ANY BETTER ORGANIZED THAN YESTERDAY...BUT STILL HAS POTENTIAL FOR SLOW DEVELOPMENT OVER THE NEXT COUPLE OF DAYS. SCATTERED MODERATE CONVECTION IS FROM 12N-15N BETWEEN 36W-38W...AND FROM 10N-13N BETWEEN 40W-43W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 15N-20N BETWEEN 35W-40W. TROPICAL WAVE IS ALONG 54W S OF 17N WITH A 1012 MB LOW ALONG THE WAVE NEAR 13N MOVING W NEAR 10 KT. SOME CYCLONIC ROTATION IS EVIDENT ON SATELLITE IMAGERY. SCATTERED SHOWERS REMAIN FROM 10N-18N BETWEEN 53W-56W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 8N25W 13N40W 10N45W 12N53W 9N60W. APART FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...WIDELY SCATTERED MODERATE CONVECTION IS FOUND FROM 5N-8N BETWEEN 18W-26W...AND FROM 4N-10N BETWEEN 28W-34W. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO HAS SLY RETURN FLOW DUE TO SURFACE RIDGING. ISOLATED MODERATE CONVECTION IS OVER S FLORIDA FROM 24N-26N BETWEEN 80W-82W. SIMILAR CONVECTION IS OVER W CUBA FROM 22N-23N BETWEEN 83W-85W. FAIR WEATHER DOMINATES THE REMAINDER OF THE GULF. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS CENTERED OVER THE SE GULF OF MEXICO NEAR 23N87W WITH STRONG SUBSIDENCE EXCEPT NEAR THE CONVECTION MENTIONED ABOVE. EXPECT SIMILAR CONDITIONS OVER THE NEXT 24 HOURS. CARIBBEAN SEA... MODERATE TRADEWINDS ARE NOTED OVER THE CARIBBEAN SEA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS MOSTLY INLAND OVER NICARAGUA AND HONDURAS FROM 12N-16N BETWEEN 84W-87W. SIMILAR CONVECTION IS INLAND OVER EL SALVADOR AND GUATEMALA FROM 13N-18N BETWEEN 88W-93W. SCATTERED MODERATE CONVECTION IS OVER INLAND HISPANIOLA...AND W CUBA...BETWEEN 71W-80W. PATCHES OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS MOSTLY INLAND OVER NW VENEZUELA AND N COLOMBIA FROM 8N-11N BETWEEN 70W-76W. IN THE UPPER LEVELS... NELY TO ELY UPPER LEVEL FLOW COVERS THE ENTIRE CARIBBEAN SEA WITH STRONG SUBSIDENCE EXCEPT NEAR THE CONVECTION MENTIONED ABOVE. EXPECT MORE CONVECTION OVER THE W CARIBBEAN AND CENTRAL AMERICA OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... A DISSIPATING COLD FRONT IS OVER THE W ATLANTIC ALONG 31N60W 29N70W 30N77W. NO CONVECTION IS ALONG THE FRONT. A SURFACE TROUGH IS S OF HURRICANE HELENE ALONG 30N56W 25N60W. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE TROUGH. A 1023 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 35N36W. IN THE UPPER LEVELS... RIDGING IS OVER THE W ATLANTIC N OF 23N BETWEEN 65W-80W. AN UPPER LEVEL LOW IS CENTERED NEAR 23N58W. ANOTHER UPPER LEVEL LOW IS CENTERED NEAR 25N41W. A LARGE HIGH IS CENTERED OVER THE CAPE VERDE ISLANDS NEAR 18N25W. $$ FORMOSA