000 AXNT20 KNHC 231753 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT SEP 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... HELENE REGAINED HURRICANE STRENGTH THIS MORNING. EARLIER QUIKSCAT PASS INDICATED THAT HELENE CONTAINED A LARGE AREA OF HURRICANE FORCE WINDS SW OF THE CENTER. A SUBTROPICAL CLASSIFICATION ALSO SUPPORTED THE HURRICANE FORCE OF 80 KT. HELENE IS CENTERED NEAR 37.7N 46.4W OR ABOUT 1055 NM WEST OF THE AZORES AT 23/1500 UTC MOVING EAST-NORTHEAST AT 22 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. MAXIMUM SUSTAINED WIND SPEED IS 80 KT WITH GUSTS TO 100 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/ WTNT23 KNHC FOR MORE DETAILS. SATELLITE IMAGERY SHOWED THAT A SMALL AREA OF DEEP CONVECTION DEVELOPED OVER AND JUST NORTH OF THE CENTER EARLY THIS MORNING. CURRENTLY THIS AREA OF DEEP CONVECTION IS MOVING EWD AND AWAY FROM THE LOW LEVEL CENTER. SCATTERED MODERATE CONVECTION IS FROM 37N-38N BETWEEN 46-48W. DENSE OVERCAST CLOUDS WITH SHOWERS/ THUNDERSTORMS COVERS A LARGER AREA FROM 34N-46N BETWEEN 42W-53W. EVEN THOUGH HELENE HAS STRENGTHENED...IT CONTINUES TO LOSE TROPICAL CHARACTERISTICS AND IS EXPECTED TO TRANSFORM INTO AN EXTRATROPICAL CYCLONE LATER TODAY. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 42W/43W S OF 16N. A 1010 MB LOW IS BEHIND THE WAVE AXIS NEAR 16.5N39.5N. BROAD LOW/MID LEVEL CYCLONIC ROTATION COVERING A LARGE AREA WITH CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION WITHIN 60-80 NM NORTH AND EAST OF THE LOW LEVEL CENTER. SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS IT MOVES TOWARD THE NORTHWEST AT ABOUT 10 MPH. MEANWHILE...THE TROPICAL WAVE WILL CONTINUE TO MOVE WWD AT 10-15 KT. TROPICAL WAVE IS ALONG 58W S OF 20N MOVING W 10 KT. THE WAVE SHOWS AN INVERTED-V CLOUD PATTERN ON SATELLITE PICTURES. SCATTRED SHOWERS AND ISOLATED TSTMS ARE RELATED TO THE WAVE. PART OF THIS SHOWER ACTIVITY IS ALREADY AFFECTING THE WINDWARD ISLANDS. THE WAVE WILL ENTER THE EASTERN CARIBBEAN LATE TODAY AND IS EXPECTED TO MOVE ACROSS THE VIRGIN ISLANDS AND PUERTO RICO LATE SUNDAY THROUGH MONDAY. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N16W 9N30W 13N40W 10N49W 12N56W. OUTSIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-11N BETWEEN 14W-20W. SCATTERED MODERATE CONVECTION WITHIN 150 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 27W-31W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LOW CONTINUES TO SPIN IN THE SE GULF NEAR 23N87W. ABUNDANT UPPER LEVEL MOISTURE IS ON THE EASTERN SIDE OF THE LOW COVERING THE NW CARIBBEAN...WESTERN CUBA AND MOST OF EASTERN GULF. THIS LOW IS GENERATING SCATTERED SHOWERS OVER THIS AREA. AN UPPER ANCHORED OVER NE MEXICO EXTENDS A RIDGE EWD ACROSS THE WESTERN HALF OF THE GULF...WHERE ABUNDANT DRY UPPER AIR IS FOUND. VERY DRY AIR ALSO COVERS NORTHERN MEXICO N OF 25N. ANOTHER UPPER ANTICYCLONE DOMINATES THE STATE OF FLORIDA AND THE W ATLC. MODERATE TO STRONG RETURN SURFACE FLOW COVERS MUCH OF THE GULF...AHEAD OF THE NEW COLD FRONT THAT IS EXPECTED TO MOVE OFF THE TEXAS COAST ON SUNDAY AND EXTEND FROM THE FLORIDA BIG BEND TO NEAR TAMPICO MEXICO ON MONDAY. CARIBBEAN SEA... THE UPPER LOW CENTERED IN THE SE GULF COVERS THE AREA N OF 19N W OF 82W TO OVER THE YUCATAN PENINSULA/CHANNEL AND W CUBA. THIS LOW COMBINED WITH THE BROAD UPPER RIDGE OVER THE W ATLC IS GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 17N FROM 74W-85W AND GIVING THE REMAINDER OF THE CARIBBEAN NE UPPER FLOW WITH MOSTLY DRY AIR. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 10N FROM COLOMBIA TO COSTA RICA. SCATTERED SHOWERS ARE MOVING OVER THE WINDWARD ISLANDS AHEAD OF AN APPROACHING TROPICAL WAVE. ATLANTIC OCEAN... BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED BY AN UPPER HIGH OFF THE NE FLORIDA COAST NEAR 28N78W. A WEAK UPPER LOW MOVING SW IS CENTERED N OF PUERTO RICO NEAR 21N65W AND COULD BRING ISOLATED TO SCATTERED SHOWERS TO HISPANIOLA AND THE SE BAHAMAS ON SUNDAY. NARROW UPPER TROUGH EXTENDS FROM AN UPPER LOW N OF THE REGION NEAR 32N38W SSW INTO THE W TROPICAL ATLC NEAR 16N52W. BROAD UPPER HIGH ANCHORED NW OF THE CAPE VERDE ISLANDS NEAR 18N26W COVERS THE REMAINDER OF THE E ATLC. AT THE SURFACE... W ATLC SURFACE RIDGE EXTENDS FROM A 1023 MB HIGH LOCATED N OF THE REGION ACROSS THE SE U.S AND FAR E GULF OF MEXICO AS WELL AS THE BAHAMAS AND CENTRAL CUBA. THIS SYSTEM IS MOVING MAINLY EAST ALLOWING THE ACTIVE WEATHER THAT IS AFFECTING THE CENTRAL U.S. TO ALSO MOVE EWD TOWARD THE EAST COAST. THE E ATLC RIDGE COVERS THE REGION N OF 24N E OF 40W ANCHORED BY A 1022 MB HIGH NEAR 32N32W. THIS FEATURE IS FORECAST TO MOVE SE DURING THE NEXT 24 HOUR. A BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS ENTERS THE AREA NEAR 32N44W THEN CONTINUES SW ALONG 27N50W 26N54W. THIS BAND IS WRAPPING INTO HELENE. $$ GR