000 AXNT20 KNHC 201044 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED SEP 20 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 GORDON IS CENTERED NEAR 37.8N 24.2W OR ABOUT 43 NM EAST OF THE ISLAND OF SAO MIGUEL IN THE EASTERN AZORES AT 20/0900 UTC MOVING EAST AT 30 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. GORDON PASSED THE AZORES OVERNIGHT AND IS EXPECTED TO MERGE WITH A FRONTAL BOUNDARY LATER THIS MORNING LOSING ITS TROPICAL CHARACTERISTICS THEN BECOMING A STRONG EXTRATROPICAL STORM AS IT APPROACHES SPAIN/PORTUGAL. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA FROM 36N-39N BETWEEN 20W-24W. HURRICANE HELENE IS CENTERED NEAR 25.3N 55.4W OR ABOUT 650 MILES SOUTHEAST OF BERMUDA AT 20/0900 UTC MOVING NORTHWEST AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 958 MB. MAXIMUM SUSTAINED WIND SPEED IS 95 KT WITH GUSTS TO 115 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE REMAINS A CATEGORY TWO HURRICANE WITH A NEAR PINPOINT EYE. SCATTERED STRONG CONVECTION IS WITHIN 30 NM OF THE CENTER IN ALL QUADRANTS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA FROM 23N-29N BETWEEN 51W-57W. ...TROPICAL WAVES... TROPICAL WAVE IS OVER THE W CAPE VERDE ISLANDS ALONG 26W S OF 17N MOVING W 15-20 KT. BROAD MID LEVEL CURVATURE IS OBSERVED ON VISIBLE SATELLITE IMAGERY. SCATTERED MODERATE/STRONG CONVECTION IS W OF THE WAVE AXIS FROM 11N-16N BETWEEN 26W-30W. TROPICAL WAVE IS ALONG 42W/43W S OF 18N MOVING W 15 KT. WELL-DEFINED INVERTED-V SIGNATURE. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 12N-16N BETWEEN 40W-46W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N11W 7N18W 8N32W 13N41W 9N61W ACROSS N PORTION OF SOUTH AMERICA AND PANAMA ALONG 10N71W INTO THE E PACIFIC REGION NEAR 9N79W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF THE AXIS FROM 28W-36W AND WITHIN 75 NM OF 5N FROM 28W-34W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 180 NM OF THE AXIS E OF 28W. ...DISCUSSION... GULF OF MEXICO... DEEP LAYER TROUGH IS MOVING OVER THE E US AND THE N GULF N OF 25N EXTENDING AN ASSOCIATED COLD FRONT INTO THE GULF OVER NE FLORIDA NEAR 30N82W ACROSS THE N/CENTRAL GULF ALONG 25N94W THEN S TO THE MEXICAN COAST NEAR TAMPICO CONTINUING AS A STATIONARY FRONT UP THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM OF THE COLD FRONT E OF 87W AND FROM 24N-27N W OF 95W TO INLAND OVER TEXAS/MEXICO. AN UPPER HIGH OVER CENTRAL MEXICO EXTENDS AN UPPER RIDGE NE AHEAD OF THE UPPER TROUGH ACROSS THE GULF ALONG 22N89W INTO THE W ATLC OVER S FLORIDA BELOW LAKE OKEECHOBEE. DIFFLUENCE OVER THE BAY OF CAMPECHE IS GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION S OF 21N W OF 91W TO INLAND OVER MEXICO. CARIBBEAN SEA... NARROW UPPER TROUGH IN THE W ATLC EXTENDS ACROSS CENTRAL CUBA SW TO THE GULF OF HONDURAS OVER THE NW CARIBBEAN N OF 14N W OF 77W. UPPER HIGH OVER THE REMAINDER OF THE CARIBBEAN IS ANCHORED JUST S OF HISPANIOLA NEAR 15N73W EXTENDING A RIDGE SW TO OVER CENTRAL AMERICA NEAR THE NICARAGUA/COSTA RICA BORDER AND NE INTO THE CENTRAL ATLC TO NEAR 21N61W. THIS IS ADVECTING TROPICAL MOISTURE OVER THE S CARIBBEAN AND GENERATING ISOLATED SHOWERS/ THUNDERSTORMS S OF 16N W OF 73W. THE REMAINDER OF THE CARIBBEAN REMAINS RATHER DRY THIS MORNING. ATLANTIC OCEAN... BROAD UPPER TROUGH OVER THE E US AND THE GULF OF MEXICO IS MOVING INTO THE NW ATLC WITH THE ASSOCIATED COLD FRONT ALONG THE COAST OF THE CAROLINAS INTO THE GULF OF MEXICO NEAR 30N82W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 120 NM SE OF THE FRONT. UPPER RIDGE ANCHORED IN THE GULF OF MEXICO EXTENDS ACROSS S FLORIDA INTO THE W ATLC NNE TO BEYOND 32N75W. NARROW UPPER TROUGH EXTENDS FROM AN UPPER LOW WELL N OF THE REGION THROUGH 32N67W ACROSS CENTRAL CUBA NEAR 21N77W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF 21N FROM 70W-76W INCLUDING THE TURKS AND CAICOS. WEAK SURFACE TROUGH EXTENDS THROUGH 32N66W TO NEAR 25N70W WITH A WEAKENING 1018 MB HIGH OVER S FLORIDA. UPPER HIGH ANCHORED IN THE CARIBBEAN EXTENDS A RIDGE NE ACROSS THE VIRGIN ISLANDS TO 21N61W JUST W OF HURRICANE HELENE. THIS IS GIVING THE E CARIBBEAN AND THE W TROPICAL ATLC VERY DRY AIR. THE UPPER RIDGE ASSOCIATED WITH HURRICANE HELENE IS FAIRLY SYMMETRICAL ALLOWING THE CONVECTION ASSOCIATED WITH HELENE TO SYMMETRICAL AND THE OUTFLOW GOOD IN ALL QUADRANTS. ELONGATED CUT-OFF UPPER LOW E OF HELENE IS CENTERED NEAR 22N36W AND EXTENDS A TROUGH AXIS NE/SW FROM 30N29W-15N44W. THIS AREA HAS DRY AIR WITH SMALL AREA OF SCATTERED MODERATE CONVECTION LOCATED NEAR THE UPPER LOW WITHIN 60 NM OF LINE 25N34W-21N37W. AN UPPER TROUGH IS DIPPING S ACROSS THE CANARY ISLANDS TO WELL INLAND OVER NW AFRICA DISTORTING UPPER HIGH ANCHORED OFF THE COAST OF AFRICA NEAR 18N18W AND COVERS THE REMAINDER OF THE E ATLC. AT THE SURFACE...A 1021 MB HIGH IS LOCATED NEAR 29N35W WITH A RIDGE EXTENDING E TO THE CANARY ISLANDS. $$ WALLACE