| Warnings issued. Meanwhile, with Gordon tropical storm watches issued for part of the Azores. ---------- 5 Day Track: http://www.nhc.noaa.gov/refresh/graphics_at2+shtml/212429.shtml?5-daynl?large#contents ---------- TROPICAL STORM HELENE SPECIAL ADVISORY NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012 430 PM CDT FRI AUG 17 2012 ...AIRCRAFT FINDS TROPICAL STORM HELENE...TROPICAL STORM WARNING ISSUED FOR THE COAST OF MEXICO... SUMMARY OF 430 PM CDT...2130 UTC...INFORMATION ---------------------------------------------- LOCATION...20.6N 96.1W ABOUT 90 MI...140 KM ESE OF TUXPAN MEXICO ABOUT 160 MI...260 KM SE OF TAMPICO MEXICO MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 7 MPH...11 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY... THE GOVERNMENT OF MEXICO HAS ISSUED A TROPICAL STORM WARNING FOR THE COAST OF MEXICO FROM BARRA DE NAUTLA TO LA CRUZ. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A TROPICAL STORM WARNING IS IN EFFECT FOR... * THE COAST OF MEXICO FROM BARRA DE NAUTLA TO LA CRUZ A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN THE NEXT 24 HOURS. FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 430 PM CDT...2130 UTC...THE CENTER OF TROPICAL STORM HELENE WAS LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR LATITUDE 20.6 NORTH...LONGITUDE 96.1 WEST. HELENE IS MOVING TOWARD THE NORTHWEST NEAR 7 MPH...11 KM/H...AND THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT DAY OR TWO. ON THE FORECAST TRACK...THE CENTER OF HELENE WILL MAKE LANDFALL IN THE WARNING AREA ON SATURDAY. DATA FROM THE AIRCRAFT INDICATE THAT MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/H...WITH HIGHER GUSTS. SOME STRENGTHENING IS POSSIBLE BEFORE THE HELENE MOVES INLAND...WITH WEAKENING EXPECTED AFTER LANDFALL. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 35 MILES...55 KM FROM THE CENTER. THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY THE AIRCRAFT WAS 1004 MB...29.65 INCHES. HAZARDS AFFECTING LAND ---------------------- WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO FIRST REACH THE COAST WITHIN THE WARNING AREA LATER TONIGHT. RAINFALL...HELENE IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 5 TO 10 INCHES..WITH ISOLATED MAXIMUM AMOUNTS OF 15 INCHES ACROSS NORTHEASTERN PORTIONS OF MEXICO FROM NORTHERN VERACRUZ...ACROSS SOUTHERN TAMAULIPAS AND EASTERN SAN LUIS STATES. THESE RAINS MAY PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES ACROSS HIGHER ELEVATIONS. STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1 TO 2 FEET ABOVE NORMAL TIDE LEVELS ALONG THE IMMEDIATE COAST NEAR AND TO THE NORTH OF WHERE THE CENTER MAKES LANDFALL. NEXT ADVISORY ------------- NEXT INTERMEDIATE ADVISORY...700 PM CDT. NEXT COMPLETE ADVISORY...1000 PM CDT. $$ FORECASTER BRENNAN ---------- TROPICAL STORM HELENE SPECIAL DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012 430 PM CDT FRI AUG 17 2012 THE AIR FORCE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE REMNANTS OF TROPICAL DEPRESSION SEVEN FOUND A WELL-DEFINED CIRCULATION AND PEAK FLIGHT LEVEL WINDS OF ABOUT 50 KT AND BIAS-CORRECTED SFMR WINDS OF 38 KT. BASED ON THESE DATA...THE SYSTEM IS NOW UPGRADED TO TROPICAL STORM HELENE WITH AN INTENSITY OF 40 KT...ALTHOUGH THESE WINDS COULD BE ENHANCED SOMEWHAT BY TOPOGRAPHY AND DECAYING CONVECTION NEAR THE CENTER. THE SATELLITE PRESENTATION OF THE CYCLONE IS SOMEWHAT LACKLUSTER...WITH MOST OF THE DEEP CONVECTION DISPLACED WEST OF THE CENTER LOCATION. THAT BEING SAID...THERE IS SOME POTENTIAL FOR SLIGHT INTENSIFICATION BEFORE THE CYCLONE MOVES INLAND WITHIN 24 HOURS. AFTER LANDFALL...STEADY DECAY IS EXPECTED TO REMNANT LOW STATUS BY 48 HOURS WITH DISSIPATION EXPECTED BY 72 HOURS. THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 310/06. HELENE IS EXPECTED TO MOVE NORTHWESTWARD AND INLAND OVER THE GULF COAST OF MEXICO IN THE NEXT DAY OR SO AS THE MID-LEVEL RIDGE OVER NORTHERN MEXICO AND THE SOUTHWESTERN U.S. RETREATS NORTHWARD. THE NHC FORECAST IS A LITTLE TO THE LEFT OF THE TVCA CONSENSUS AND TO THE RIGHT OF THE ECMWF THROUGH DISSIPATION. THE MAIN THREAT FROM HELENE WILL BE HEAVY RAINFALL...WHICH WILL CONTINUE EVEN AS THE CYCLONE MOVES INLAND AND WEAKENS. FORECAST POSITIONS AND MAX WINDS INIT 17/2130Z 20.6N 96.1W 40 KT 45 MPH 12H 18/0600Z 21.1N 96.9W 45 KT 50 MPH 24H 18/1800Z 22.1N 98.1W 35 KT 40 MPH...INLAND 36H 19/0600Z 22.9N 99.0W 30 KT 35 MPH...INLAND 48H 19/1800Z 23.5N 99.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 20/1800Z...DISSIPATED $$ FORECASTER BRENNAN |