000 AXNT20 KNHC 150503 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI SEP 15 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 0345 UTC. ...SPECIAL FEATURES... HURRICANE GORDON IS CENTERED NEAR 30.6N 54.3W AT 15/0300 UTC MOVING NORTHEAST AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 960 MB. MAXIMUM SUSTAINED WIND SPEED IS 100 KT WITH GUSTS TO 120 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. DESPITE WARMING CLOUD TOPS GORDON STILL HAS A SMALL VERY DISTINCT EYE WITH UNIFORM CONVECTION SURROUNDING THE EYE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM FROM THE CENTER IN ALL QUADRANTS. SCATTERED MODERATE CONVECTION IS FROM 28N-33N BETWEEN 50W-54W. TROPICAL STORM HELENE IS CENTERED NEAR 14.5N 38.9W AT 15/0300 MOVING WEST-NORTHWEST AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HELENE HAS HAD A HARD TIME MAINTAINING DEEP CONVECTION DURING THE DAY THU AND THIS PATTERN IS EXPECTED TO CONTINUE OVER THE NEXT DAY OR SO. SCATTERED MODERATE TO SCATTERED STRONG CONVECTION COVERS AN AREA FROM 12N-18N BETWEEN 38W-42W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 59W S OF 15N MOVING W 10-15 KT. WEAK WAVE SIGNATURE AS THE WAVE APPROACHES THE LESSER ANTILLES. WAVE IS BENEATH THE W EDGE OF AN UPPER RIDGE AND A LARGE AREA OF VERY DRY AIR...THUS NO ASSOCIATED DEEP CONVECTION. TROPICAL WAVE IS ALONG 69W/70W S OF 19N MOVING W 15 KT. WELL-DEFINED LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE E CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM OF LINE 13N63W-18N69W. TROPICAL WAVE IS ALONG 81W S OF 18N MOVING W 15 KT. WEAK LOW LEVEL INVERTED-V SATELLITE SIGNATURE IS OBSERVED OVER THE W CARIBBEAN. WAVE IS EMBEDDED WITHIN DRY AIR THUS NO ASSOCIATED CONVECTION. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N15W 15N29W 12N40W 7N49W THEN INTO THE CARIBBEAN ALONG 11N65W ACROSS THE N PORTION OF SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION NEAR 9N84W. SCATTERED STRONG CONVECTION IS WITHIN 90/120 NM OF THE AXIS FROM 17W-22W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 150/180 NM S OF THE AXIS FROM 30W-34W. IN THE CARIBBEAN...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 13N TO INLAND OVER COLOMBIA FROM 71W-75W. ...DISCUSSION... GULF OF MEXICO... BROAD DEEP LAYERED TROUGH COVERS THE E US...THE W ATLC AND THE N GULF COAST ANCHORED BY AN UPPER LOW MOVING INTO NEW ENGLAND. ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO THE GULF FROM THE W ATLC ACROSS THE FLORIDA PENINSULA JUST S OF TAMPA WHERE IT BECOMING A SURFACE TROUGH ACROSS THE GULF TO THE CENTRAL TEXAS COAST. WIDELY ISOLATED SHOWERS ARE OVER THE N GULF WITHIN 90/120 NM OF THE FRONT/TROUGH. UPPER RIDGE EXTENDS ACROSS THE REMAINDER OF THE GULF ANCHORED BY AN UPPER HIGH ASSOCIATED WITH A TROPICAL STORM OFF THE W COAST OF MEXICO ENTERING THE GULF NEAR TAMPICO MEXICO TO S FLORIDA JUST N OF THE FLORIDA KEYS THEN INTO THE W ATLC. THIS IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N-23N W OF 94W TO INLAND OVER MEXICO. CARIBBEAN SEA... W CARIBBEAN IS DOMINATED BY NE UPPER FLOW FROM THE UPPER RIDGE THAT EXTENDS ACROSS THE GULF OF MEXICO INTO THE W ATLC. THIS IS PROVIDING DRY AIR ACROSS THE AREA INCLUDING THE TROPICAL WAVE ALONG 81W. NARROWING UPPER TROUGH EXTENDS FROM HAITI SW TO COSTA RICA/NICARAGUA BORDER. REMAINDER OF THE CARIBBEAN IS DOMINATED BY SW TO S UPPER FLOW FROM AN UPPER RIDGE ANCHORED IN THE TROPICAL/CENTRAL ATLC. THIS RIDGE IS DRAWING ABUNDANT TROPICAL MOISTURE ACROSS THE S CARIBBEAN AND ESPECIALLY ENHANCING CONVECTION ASSOCIATED WITH THE ITCZ AXIS OVER COLOMBIA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE THE N CARIBBEAN FROM THE N LEEWARD ISLANDS TO OVER CUBA. ATLANTIC OCEAN... BROAD DEEP LAYERED TROUGH THAT COVERS THE E US AND THE N GULF EXTENDS INTO THE W ATLC IS ANCHORED BY AN UPPER LOW MOVING INTO NEW ENGLAND. THE ASSOCIATED FRONTAL BOUNDARY EXTENDS INTO THE W ATLC FROM A 1010 MB LOW ALONG THE NORTH/SOUTH CAROLINA COAST THROUGH 32N77W INTO THE GULF NEAR DAYTONA BEACH FLORIDA GIVING THE AREA SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF THE FRONT AND NW OF A LINE FROM SE FLORIDA NEAR MIAMI TO BEYOND 32N73W. UPPER RIDGE AXIS EXTENDS FROM THE GULF OF MEXICO INTO THE W ATLC ACROSS THE FLORIDA KEYS NE TO NEAR 32N68W. NARROW UPPER TROUGH EXTENDS ACROSS THE W ATLC JUST TO THE E OF THE UPPER RIDGE THROUGH 32N63W TO 26N68W CONNECTING TO THE UPPER TROUGH IN THE CARIBBEAN THAT EXTENDS ACROSS HAITI. THIS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM THE CENTRAL BAHAMAS NEAR 23N75W TO ALONG 27N70W TO BEYOND 32N68W. BROAD UPPER RIDGE COVERS THE W/CENTRAL AND TROPICAL ATLC ANCHORED NEAR 21N57W COVERING THE AREA S OF 27N FROM 47W-67W. TROPICAL MOISTURE IS BEING DRAWN NE OF THE CARIBBEAN AND WITH SUFFICIENT DIFFLUENCE TO GENERATE AN AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 16N-23N BETWEEN 61W-68W. GORDON IS N OF THIS UPPER RIDGE. NARROWING UPPER TROUGH EXTENDS INTO THE E/CENTRAL ATLC NEAR 32N38W S TO 23N43W. HOWEVER...DUE TO THE DRY AIR IN PLACE NO SHOWER ACTIVITY IS EVIDENT. AN UPPER RIDGE COVERS THE REMAINDER OF THE E ATLC E OF 37W ANCHORED NEAR 30N26W EXTENDING E TO OVER THE CANARY ISLANDS. AN UPPER HIGH ASSOCIATED WITH TROPICAL STORM HELENE COVERS THE SE TROPICAL ATLC WITH A SMALL UPPER LOW JUST TO THE E CENTERED NE OF THE CAPE VERDE ISLANDS NEAR 20N24W. THE SUBTROPICAL RIDGE IS BEGINNING TO SPREAD W OVER THE ATLC IN SPITE OF THE PRESENCE OF HURRICANE GORDON WITH A 1026 MB HIGH OVER THE S MOST ISLANDS OF THE AZORES. THE LAST VISIBLE SATELLITE IMAGES OF THU SHOWS A LARGE AREA OF AFRICA DUST FROM THE ITCZ TO 26N BETWEEN 40W-60W WITH HELENE JUST TO THE E AND YET ANOTHER AREA OF AFRICAN DUST MOVING OFF AFRICA FROM 13N-22N E OF THE CAPE VERDE ISLANDS. $$ WALLACE