|
Show Selection: |
| #111651 (Received by flhurricane at: 4:49 PM 18.Sep.2006) TCDAT3 HURRICANE HELENE DISCUSSION NUMBER 26 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082006 500 PM EDT MON SEP 18 2006 A NOAA RESEARCH AIRCRAFT MADE A PASS THROUGH THE CENTER OF HELENE EARLIER TODAY AND FOUND THAT THE HURRICANE WAS NOT AS STRONG AS PREVIOUSLY ESTIMATED BY SATELLITE. THEY MEASURED A MINIMUM PRESSURE OF 966 MB AND SEVERAL MILLIBARS LOWER TWO HOURS LATER. MAXIMUM WINDS REPORTED FROM THE SFMR INSTRUMENT ONBOARD THE PLANE WERE ONLY 79 KNOTS. HOWEVER...THE SATELLITE PRESENTATION STILL SUPPORTS WINDS STRONGER THAN 100 KNOTS. AT THIS TIME...I AM ASSUMING THAT THE NOAA PLANE DID NOT SAMPLE THE ENTIRE CIRCULATION AND THE INITIAL INTENSITY IS ADJUSTED TO 100 KNOTS. IF THE SATELLITE PRESENTATION DETERIORATES LATER TODAY OR TONIGHT...WINDS COULD BE ADJUSTED DOWNWARD. HELENE COULD STRENGTHEN A LITTLE DURING THE NEXT DAY OR SO SINCE THE SHEAR IS FORECAST TO BE LOW AND THE OCEAN IS WARM. MOST OF THE INTENSITY GUIDANCE SHOWS NO SIGNIFICANT CHANGE IN STRENGTH DURING THE NEXT DAY OR TWO. HELENE IS NOW MOVING TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 8 KNOTS. THE SUBTROPICAL RIDGE NORTH OF HELENE IS FORECAST TO EXPAND WESTWARD DURING THE NEXT DAY OR TWO. THIS PATTERN WOULD TEMPORARILY STEER HELENE TOWARD THE WEST. HOWEVER...BEYOND TWO DAYS A LARGE TROUGH IS FORECAST TO DEVELOP OVER THE WESTERN ATLANTIC...FORCING HELENE TO TURN NORTHWARD AND NORTHEASTWARD WITH INCREASING FORWARD SPEED. I AM MUCH MORE CONFIDENT IN THIS TRACK FORECAST SINCE ALL THE GLOBAL MODELS ARE NOW IN GOOD AGREEMENT...AND THEIR SOLUTION BECAME CLOSER TO THE GFDL...WHICH HAS BEEN STUBBORNLY TURNING HELENE NORTHWARD ALL ALONG. DUE TO THE EASTWARD CHANGE IN THE GLOBAL MODELS IN THE LATEST RUN...THE OFFICIAL FORECAST HAS BEEN SHIFTED A LITTLE BIT EASTWARD AND IS NOW SHOWING RECURVATURE EAST OF 60W LONGITUDE. FORECAST POSITIONS AND MAX WINDS INITIAL 18/2100Z 23.9N 51.1W 100 KT 12HR VT 19/0600Z 24.6N 52.2W 100 KT 24HR VT 19/1800Z 24.7N 54.0W 105 KT 36HR VT 20/0600Z 24.8N 56.5W 105 KT 48HR VT 20/1800Z 26.0N 57.0W 105 KT 72HR VT 21/1800Z 29.5N 58.5W 100 KT 96HR VT 22/1800Z 33.0N 57.5W 90 KT 120HR VT 23/1800Z 40.0N 50.0W 80 KT $$ FORECASTER AVILA |
