000 AXNT20 KNHC 211813 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU SEP 21 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 1745 UTC. ...SPECIAL FEATURE... THE CENTER OF HURRICANE HELENE AT 21/1500 UTC WAS NEAR 29.6N 56.9W. HELENE IS MOVING NORTH 11 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 70 KT WITH GUSTS TO 85 KT. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC OR THE PUBLIC ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS AND THE COLDEST CLOUD TOP TEMPERATURES NEAR -75C FROM 29N TO 31N BETWEEN 55W AND 58W. OTHER SHOWERS AND THUNDERSTORMS ARE IN A BAND AROUND THE HURRICANE FROM 27N TO 28.5N BETWEEN 54W AND 60W. BROKEN TO OVERCAST MULTILAYERED CLOUDS COVER THE ATLANTIC OCEAN WATERS AROUND HELENE FROM 25N TO 35N BETWEEN 52W AND 65W. OVERCAST HIGH CLOUDS SHOOT OFF TO THE NORTH OF HELENE BEYOND 35N. ...TROPICAL WAVES... AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 34W SOUTH OF 19N MOVING WEST 10 TO 15 KT. A 1012 MB LOW PRESSURE CENTER FORMED ALONG THE WAVE NEAR 12N. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG THUNDERSTORMS IN CLUSTERS FROM 9N TO 20N BETWEEN 28W AND 36W. AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 47W/48W SOUTH OF 20N MOVING WEST 10 TO 15 KT. A 1014 MB LOW PRESSURE CENTER IS NEAR 13N ALONG THE WAVE. ISOLATED MODERATE SHOWERS FROM 12N TO 13N BETWEEN 48W AND 50W...AND FROM 14N TO 16N BETWEEN 48W AND 51W. ISOLATED MODERATE SHOWERS ARE FROM 12N TO 17N BETWEEN 43W AND 47W...IN BETWEEN THE TWO TROPICAL WAVES...AND AT THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH. ...THE ITCZ... 12N16W 11N24W 12N32W 12N36W 13N47W 12N50W 10N62W. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG THUNDERSTORMS... WHICH MAY BE ACCOMPANYING THE NEXT TROPICAL WAVE...FROM 7N TO 15N BETWEEN 20W AND 24W WITH THE NORTHERN PART OF THIS AREA OF PRECIPITATION REACHING THE CAPE VERDE ISLANDS. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG THUNDERSTORMS FROM 5N TO 8N BETWEEN 22W AND 28W. ...DISCUSSION... THE GULF OF MEXICO AND THE WESTERN ATLANTIC OCEAN WITH THE U.S.A. EAST COAST TROUGH... BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE ENTIRE AREA. MIDDLE TO UPPER LEVEL DRY AIR IS EVERYWHERE ALSO...EXCEPT FOR THE SHOWERS AND THUNDERSTORMS MOVING ACROSS COASTAL LOUISIANA AT THIS TIME. THE MIDDLE TO UPPER LEVEL TROUGH WHICH IS SUPPORTING THE SURFACE COLD FRONT PASSES THROUGH 32N66W TO 28N70W...TO THE BAHAMAS NEAR 26N77W. A SURFACE COLD FRONT PASSES THROUGH 32N67W TO THE NORTHERN BAHAMAS NEAR 26N77W... ACROSS THE SOUTHERN TIP OF FLORIDA...INTO THE GULF OF MEXICO NEAR 26N87W. A WARM FRONT HAS BEEN FORMING IN THE RETURN SOUTHERLY FLOW...FROM 26N87W TO 28N94W TO THE MIDDLE-TO- UPPER TEXAS COAST OF TEXAS NEAR 29N96W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE WITHIN 15 TO 20 NM ON EITHER SIDE OF 27N88W 29N90W 29N91W 30N93W. THIS PRECIPITATION IS BEING PUSHED NORTHEASTWARD ACROSS COASTAL LOUISIANA. THE CARIBBEAN SEA... THE DEEP LAYER TROUGH FROM THE LAST FEW DAYS HAS MOVED EASTWARD NOW FROM 25N62W IN THE ATLANTIC OCEAN TO THE VIRGIN ISLANDS JUST EAST OF PUERTO RICO. A MIDDLE TO UPPER LEVEL LOW PRESSURE CENTER IS NEAR 19N83W IN THE NORTHWESTERN CORNER OF THE AREA. A SEPARATE AREA OF UPPER LEVEL ANTICYCLONIC FLOW IS NEAR 15N77W. SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS ARE FROM 13N TO 17N BETWEEN 80W AND 82W. THE STRONGEST PRECIPITATION IN THIS AREA GOES FROM 13N TO 14.5N BETWEEN 80W AND 81.5W. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ALSO HAVE DEVELOPED ALONG THE SOUTHEASTERN COAST OF NICARAGUA. BROAD CYCLONIC FLOW...AS WITH AN INVERTED TROUGH...STRETCHES FROM EASTERN VENEZUELA TO THE COLOMBIA/PANAMA BORDER. THE ATLANTIC OCEAN... BROAD UPPER LEVEL ANTICYCLONIC FLOW AND DRY AIR COVER THE ATLANTIC OCEAN AND THE CARIBBEAN SEA FROM 10N TO 26N BETWEEN 50W AND 70W...RIGHT UP TO THE FLOW AROUND HURRICANE HELENE. AN EASTERN ATLANTIC OCEAN MIDDLE TO UPPER LEVEL TROUGH IS NOW JUST EAST AND NORTHEAST OF THE 47W/48W TROPICAL WAVE...GOING FROM 30N33W TO A LOW PRESSURE CENTER NEAR 25N40W TO 18N43W TO 12N43W. AN INVERTED MIDDLE TO UPPER LEVEL TROUGH IS ALONG 13N44W 9N51W TO NORTHERN GUYANA AND EXTREME NORTHEASTERN VENEZUELA. MIDDLE TO UPPER LEVEL DRY AIR IS SOUTH OF 10N TO THE COAST OF SOUTH AMERICA BETWEEN 36W AND 52W. BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE REST OF THE ATLANTIC OCEAN WATERS NORTH OF 20N EAST OF THE 30N33W 12N43W TROUGH. A COLD FRONT PASSES THROUGH 30N15W 28N29W TO 32N44W. THE EXTRATROPICAL LOW PRESSURE CENTER WHICH USED TO BE T.S. GORDON BRUSHED THE NORTHWESTERN COAST OF SPAIN DURING THE MORNING RUSH HOUR FOR TRAFFIC FOR WESTERN EUROPE. $$ MT