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Post-Tropical Cyclone Helene Forecast Discussion Number 37
2018-09-16 16:43:14| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sun Sep 16 2018 413 WTNT43 KNHC 161443 TCDAT3 Post-Tropical Cyclone Helene Discussion Number 37 NWS National Hurricane Center Miami FL AL082018 1100 AM AST Sun Sep 16 2018 Helene's cloud pattern has transformed into that of an extratropical cyclone, with a large area of cold cloud tops located well to the north and northwest of the center. An ASCAT pass that caught the eastern portion of the circulation revealed maximum winds of 40 to 45 kt, therefore the initial wind speed remains 45 kt for this advisory. The global models suggest that the system will strengthen slightly today due to baroclinic processes, and this is reflected in the official forecast. Weakening is anticipated by late Monday, and the system is forecast to be absorbed by a larger low pressure to the northwest of the United Kingdom by Tuesday morning. The cyclone is moving quickly northeastward or 055/25 kt. Now that the system is embedded within the mid-latitude westerlies, a northeastward motion with some additional increase in forward speed is expected over the next day or so. The global models remain in good agreement on the track of the post-tropical low, and the new official forecast is an update of the previous advisory. This is the last NHC advisory on this system. Interests in Ireland and the United Kingdom should consult products from their local meteorological service for information about potential impacts from the post-tropical cyclone. Local forecasts and warnings for the UK can be found on the website of the UK Met Office at https://www.metoffice.gov.uk/. Local forecasts and warnings for Ireland can be found on the website of Met Eireann at https://www.met.ie/. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 43.8N 25.7W 45 KT 50 MPH...POST-TROPICAL 12H 17/0000Z 45.8N 21.2W 50 KT 60 MPH...POST-TROP/EXTRATROP 24H 17/1200Z 49.0N 14.8W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 18/0000Z 52.8N 6.2W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 18/1200Z...ABSORBED $$ Forecaster Brown
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