000 AXNT20 KNHC 161039 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT SEP 16 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 31.3N 53.7W AT 16/0900 UTC AND IS NEAR STATIONARY. 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 FOR MORE DETAILS. GORDON HAS REMAINS NEAR STATIONARY AND THE EYE HAS BECOME RAGGED WITH WARMER CLOUD TOP TEMPERATURES. GORDON IS EXPECTED TO CONTINUE WEAKENING OVER THE NEXT DAY OR SO. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF THE CENTER IN THE N QUADRANT. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM FROM THE CENTER IN THE REMAINING QUADRANTS. TROPICAL STORM HELENE IS CENTERED NEAR 17.9N 44.7W AT 16/0900 MOVING WEST-NORTHWEST AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 992 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. CONVECTION ASSOCIATED WITH HELENE SEEMS TO PULSATE IN DIFFERENT QUADRANTS AS THE SYSTEM CONTINUES TO INTENSIFY AND COULD BE COME A HURRICANE LATER TODAY. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 30/45 NM RADIUS OF 19N45W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE AREA WITHIN 140 NM OF LINE 21N41W-16N47W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 21W/22W S OF 20N WITH A 1011 MB LOW ALONG THE WAVE NEAR 15N MOVING W NEAR 10 KT. WELL-DEFINED LOW/MID LEVEL CYCLONIC CIRCULATION WITH SCATTERED MODERATE/STRONG CONVECTION FROM 15N-19N BETWEEN 19W-24W INCLUDING SOME THE CAPE VERDE ISLANDS. TROPICAL WAVE IS ALONG 77W S OF 17N MOVING W 15 KT. BROAD WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE CENTRAL CARIBBEAN AS THE WAVE PASSES BENEATH AN UPPER RIDGE WHICH IS ENHANCING SCATTERED MODERATE/STRONG CONVECTION WITHIN 9N-13N BETWEEN 76W-80W. TROPICAL WAVE IS ALONG 85W S OF 16N MOVING W 10-15 KT. WELL-DEFINED LOW/MID LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED IN THE E PACIFIC REGION AS THE N PORTION IS INLAND OVER CENTRAL AMERICA. WAVE IS BENEATH THE WESTERN EDGE OF AN UPPER RIDGE WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 13N-16N BETWEEN 82W-84W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N10W 6N16W 14N37W 9N56W ACROSS THE N PORTION OF SOUTH AMERICA AND THE S CARIBBEAN ALONG 11N72W INTO THE E PACIFIC REGION NEAR 9N82W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 13N-18N BETWEEN 37W-43W. ...DISCUSSION... GULF OF MEXICO... BROAD DEEP LAYERED TROUGH COVERS THE E US AND THE W ATLC ANCHORED BY AN UPPER LOW ALONG THE NE COAST COVERING THE NE GULF N OF 25N E OF 90W WITH ASSOCIATED FRONTAL BOUNDARY IN THE W ATLC. BROAD UPPER RIDGE EXTENDS ACROSS THE W GULF ANCHORED BY AN UPPER HIGH ASSOCIATED WITH A HURRICANE OFF THE W COAST OF MEXICO COVERING THE GULF W OF 90W. AN UPPER TROUGH IN THE W CARIBBEAN IS PRODUCING ISOLATED SHOWERS ACROSS THE STRAITS OF FLORIDA S OF 24N E OF 84W. OTHERWISE THE GULF GULF REMAINS RATHER CLEAR THIS MORNING. CARIBBEAN SEA... NARROW UPPER TROUGH EXTENDS FROM AN UPPER LOW JUST N OF E CUBA ALONG 20N77W SW TO THE GULF OF HONDURAS AND CENTRAL AMERICA. ISOLATED SHOWERS ARE FROM 20N-22N W OF 81W TO THE YUCATAN PENINSULA. AN UPPER HIGH IS LOCATED OFF THE COAST OF COLOMBIA NEAR 13N75W WITH A RIDGE EXTENDING W TO NEAR 16N84W ENHANCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM OF LINE FROM HAITI ACROSS JAMAICA TO NE HONDURAS. AN UPPER RIDGE ANCHORED IN THE CENTRAL ATLC IS ADVECTING DRY AIR OVER THE E CARIBBEAN E OF 70W. ATLANTIC OCEAN... BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE NE GULF EXTENDS INTO THE W ATLC N OF 25N W OF 75W AND IS ANCHORED BY AN UPPER LOW ALONG THE NE US COAST WITH THE ASSOCIATED FRONTAL BOUNDARY EXTENDING INTO THE W ATLC FROM A 1010 MB LOW N OF THE REGION THROUGH 32N72W TO THE UPPER FLORIDA KEYS.SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 22N-28N BETWEEN 77W-80W AND WITHIN 60 NM E OF THE FRONT FROM 27N-30N. NARROW UPPER TROUGH EXTENDS FROM 28N66W TO AN UPPER LOW BETWEEN THE BAHAMAS AND E CUBA NEAR 22N75W CONTINUING INTO THE W CARIBBEAN. SURFACE TROUGH EXTENDS FROM 31N66W TO THE CENTRAL BAHAMAS NEAR 25N76W GENERATING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 90 NM OF THE SURFACE TROUGH. BROAD UPPER RIDGE COVERS THE W/CENTRAL ATLC ANCHORED NEAR 22N58W COVERING THE AREA S OF 26N FROM 50W-71W. TROPICAL MOISTURE IS BEING DRAWN N OF HAITI TO GENERATE AN AREA OF SCATTERED SHOWERS S OF 23N TO OVER HAITI FROM 72W-74W. GORDON REMAINS N OF THIS UPPER RIDGE. AN UPPER TROUGH IS TO THE E OF GORDON N OF 24N FROM 28W-43W BUT IS A RATHER BENIGN FEATURE AND NOT PRODUCING ANY SHOWER ACTIVITY. AN UPPER HIGH ASSOCIATED WITH TROPICAL STORM HELENE COVERS THE SE TROPICAL ATLC WITH AN UPPER LOW TO THE E CENTERED N OF THE CAPE VERDE ISLANDS NEAR 20N24W COVERING THE AREA FROM 15N-24N BETWEEN 19W-28W. THE SUBTROPICAL RIDGE IS ONCE AGAIN SPREADING W OVER THE ATLC IN SPITE OF THE PRESENCE OF HURRICANE GORDON. AN AREA OF AFRICAN DUST COVERS THE W TROPICAL ATLC AND E CARIBBEAN S OF 23N FROM 50W-72W. $$ WALLACE