000 AXNT20 KNHC 241058 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN SEP 24 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... HURRICANE HELENE IS CENTERED NEAR 39.9N 39.9W OR ABOUT 612 NM WEST-NORTHWEST OF THE AZORES AT 24/0900 UTC MOVING EAST- NORTHEAST AT 20 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 973 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE RETAINS TROPICAL CHARACTERISTICS BUT STILL IS IS EXPECTED TO BECOME EXTRATROPICAL OVER THE NEXT 12 TO 24 HOURS. SCATTERED MODERATE CONVECTION IS WITHIN 300 NM OF THE CENTER IN THE NW QUADRANT. DENSE OVERCAST CLOUDS WITH SHOWERS/THUNDERSTORMS IS N OF 37N FROM 37W-45W. ...TROPICAL WAVES... A 1009 MB LOW IS CENTERED NEAR 19N43W NEAR STATIONARY. LOW LEVEL CENTER IS SW OF THE ASSOCIATED DEEP CONVECTION. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75/90 NM OF LINE 18N40W-23N43W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 75 NM OF 38W FROM 17N-23N. TROPICAL WAVE IS ALONG 45W/46W S OF 17N MOVING W 10 KT. WEAK WAVE EMBEDDED WITHIN DRY AIR AND HAS NO ASSOCIATED SHOWERS/CONVECTION. TROPICAL WAVE IS OVER THE LESSER ANTILLES ALONG 62W S OF 20N MOVING W 10 KT. BROADENING INVERTED-V SIGNATURE CURVATURE FROM 56W-65W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 13N-19N BETWEEN 56W-63W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N13W 7N21W 7N31W 10N40W BECOMING DISTORTED BY THE TROPICAL LOW/WAVE THEN ALONG 11N48W 13N63W 10N68W ACROSS N PORTION OF SOUTH AMERICA AND S OF PANAMA INTO THE E PACIFIC REGION. APART FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL LOW/WAVE...SCATTERED MODERATE/STRONG CONVECTION IS FROM 8N-11N BETWEEN 21W-26W. CLUSTERS OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION ARE FROM 4N-8N BETWEEN 20W-29W AND WITHIN 120 NM ALONG THE COAST OF AFRICA S OF 8N W OF 8W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER TROUGH EXTENDS FROM AN UPPER LOW MOVING ACROSS THE GREAT LAKES TO TEXAS WITH THE ASSOCIATED STRONG COLD FRONT STILL INLAND OVER THE TEXAS COAST. A SQUALL LINE EXTENDS INTO THE GULF ACROSS CENTRAL LOUISIANA TO INLAND OVER S TEXAS NEAR CORPUS CHRISTI. AN UPPER HIGH IS CENTERED OVER NE MEXICO NEAR 23N99W WITH A BROAD RIDGE COVERING THE W GULF W OF 91W. ANOTHER UPPER HIGH IS ANCHORED IN THE W ATLC EXTENDING A RIDGE OVER THE E GULF E OF 85W. THE UPPER LOW IS SQUEEZED BETWEEN THESE RIDGES AND CENTERED IN THE SE GULF N OF THE YUCATAN PENINSULA NEAR 23N88W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 80W-87W. CARIBBEAN SEA... THE UPPER LOW CENTERED IN THE SE GULF COVERS A SMALL PORTION OF NW CARIBBEAN N OF 20N W OF 85W. BROAD UPPER RIDGE OVER THE W ATLC DIPS S OVER CUBA INTO THE CARIBBEAN N OF 17N FROM 74W-85W. THIS COMBINATION IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 16N W OF 73W. REMAINDER OF THE CARIBBEAN IS UNDER NE UPPER FLOW WITH MOSTLY DRY AIR. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND AND WITHIN 30/60 NM ALONG THE COAST OF PANAMA DUE TO THE CLOSE PROXIMITY OF THE ITCZ AXIS. THE REMAINDER OF THE CARIBBEAN REMAINS CLEAR THIS MORNING. ATLANTIC OCEAN... BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED BY AN UPPER HIGH NEAR 29N75W AND COVERS THE AREA W OF 62W INTO THE N CARIBBEAN. WEAK UPPER TROUGH EXTENDS FROM 25N45W SW TO JUST E OF THE LEEWARD ISLANDS NEAR 18N59W AND IS ENHANCING THE SHOWER ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE OVER THE LESSER ANTILLES. UPPER LEVEL TROUGH IS PUSHING SE OVER THE CANARY ISLANDS AND WESTERN SAHARA IN AFRICA. BROAD UPPER HIGH ANCHORED NW OF THE CAPE VERDE ISLANDS NEAR 18N28W COVERS THE REMAINDER OF THE E ATLC. AT THE SURFACE...A COLD FRONT HAS PUSHED S INTO THE AREA IN THE CENTRAL ATLC IN THE WAKE OF HURRICANE HELENE THROUGH 32N42W SW TO 28N51W THUS SPLITTING THE SUBTROPICAL RIDGE THAT CROSSES THE ATLC. W ATLC SURFACE RIDGE EXTENDS FROM A 1022 MB HIGH WELL N OF THE REGION THROUGH 32N70W ACROSS NE FLORIDA TO NEAR 29N85W. THE E ATLC RIDGE COVERS THE REGION N OF 20N FROM 20W-37W ANCHORED BY A 1018 MB HIGH NEAR 32N29W. $$ WALLACE