| Track: http://www.nhc.noaa.gov/refresh/graphics_at2+shtml/?cone#contents Floater: http://www.ssd.noaa.gov/PS/TROP/floaters/17L/17L_floater.html Wider Atlantic views: http://www.ssd.noaa.gov/PS/TROP/trop-atl.html Models: http://hurricanecity.com/models/models.cgi?basin=al&year=2017&storm=17&display=google_map&latestrun=1 Euro: https://www.tropicaltidbits.com/analysis/models/?model=ecmwf®ion=atl&pkg=z500_mslp GFS: https://www.tropicaltidbits.com/analysis/models/?model=gfs®ion=atl&pkg=z500_mslp Hurricane Ophelia Discussion Number 16 NWS National Hurricane Center Miami FL AL172017 1100 PM AST Thu Oct 12 2017 Remarkably, the hurricane has continued to strengthen this evening. Satellite images indicate that cloud tops in the eyewall have cooled in the past several hours, with a warm eye remaining. Dvorak estimates from TAFB, SAB and CIMSS range between 90 to 95 kt, so the initial intensity is raised to 90 kt. It seems that the marginal SSTs that Ophelia has been moving over have been offset by the cold upper-level temperatures and low shear environment. SSTs only slightly cool in the next 24 hours with similar shear conditions, so a minor decrease in strength is in the forecast. After that time, while the hurricane should move over colder waters, it will likely be accelerating to the northeast and experiencing favorable mid-latitude jet dynamics, which will help to maintain the cyclone's intensity. All of the guidance show extratropical transition by 3 days with the cyclone keeping hurricane-force winds, as indicated in the new forecast. Little change was made to the previous prediction, except to account for the higher initial wind speed. Ophelia is finally moving, estimated at 6 kt to the east-northeast. This general motion with an increase in forward speed is expected for the next couple of days as the hurricane gets picked up by a large mid-latitude trough. Confidence in the track forecast remains fairly high for the first 72 h, although the spread increases after that time. The GFS-based guidance generally then show a more northward track to the west of Ireland then over the far North Atlantic, while the UKMET/ECMWF show a track over Ireland and Great Britain then eastward and dissipating over northern Europe. The forecast is close to the consensus at long range, but some large changes could be required for later forecasts. While the NHC track keeps the center of Ophelia south and east of the Azores, tropical-storm-force winds are possible throughout the Azores by Saturday night due to an approaching front. In addition, the wind field of Ophelia will likely expand as the cyclone begins extratropical transition, and any deviation to the left of the forecast track could bring stronger winds to the islands. Interests in the Azores should refer to products issued by the Azores Weather Forecast and Watch Center. KEY MESSAGES: 1. Ophelia is expected to transition to a hurricane-force post- tropical cyclone by Monday when it moves near Ireland and the United Kingdom. While post-tropical Ophelia will likely bring some direct impacts from wind and heavy rain to portions of these areas, as well as dangerous marine conditions, given the forecast uncertainty at these time ranges it is too soon to determine the exact magnitude, timing and location of the impacts. Residents in Ireland and the United Kingdom should monitor the progress of Ophelia for the next several days. For more information on local impacts, residents of Ireland should refer to products issued by Met Eireann and residents in the United Kingdom should refer to products issued by the Met Office. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 30.7N 34.7W 90 KT 105 MPH 12H 13/1200Z 31.2N 33.5W 90 KT 105 MPH 24H 14/0000Z 32.2N 31.1W 85 KT 100 MPH 36H 14/1200Z 33.7N 27.5W 80 KT 90 MPH 48H 15/0000Z 36.0N 23.0W 80 KT 90 MPH 72H 16/0000Z 45.0N 14.5W 75 KT 85 MPH...POST-TROP/EXTRATROP 96H 17/0000Z 56.0N 7.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 18/0000Z 64.0N 0.5W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Blake Hurricane Ophelia Advisory Number 16 NWS National Hurricane Center Miami FL AL172017 1100 PM AST Thu Oct 12 2017 ...SMALL BUT POWERFUL OPHELIA WITH 105-MPH WINDS OVER THE EASTERN ATLANTIC... SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...30.7N 34.7W ABOUT 670 MI...1075 KM SW OF THE AZORES MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H PRESENT MOVEMENT...ENE OR 60 DEGREES AT 7 MPH...11 KM/H MINIMUM CENTRAL PRESSURE...970 MB...28.65 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. Interests in the Azores should refer to products issued by the Azores Weather Forecast and Watch Center. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 1100 PM AST (0300 UTC), the eye of Hurricane Ophelia was located near latitude 30.7 North, longitude 34.7 West. Ophelia is moving toward the east-northeast near 7 mph (11 km/h), and this general motion is expected to continue for the next couple of days with a large increase in forward speed. Maximum sustained winds have increased to near 105 mph (165 km/h) with higher gusts. Some slow weakening is forecast to begin Friday night but Ophelia should remain a hurricane for the next couple of days. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 90 miles (150 km). The estimated minimum central pressure is 970 mb (28.65 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Ophelia is expected to produce total rain accumulations of 2 to 4 inches over the southeastern Azores Saturday and Saturday night. During the same time, a cold front and moisture associated with Ophelia is expected to produce total rain accumulations of 1 to 3 inches over the other islands of the Azores. This rainfall could produce flooding, especially over the southeastern Azores. NEXT ADVISORY ------------- Next complete advisory at 500 AM AST. $$ Forecaster Blake Met Eireann - Irish Meteorological Service: https://www.met.ie/ Met Office - United Kingdom's Meteorological Service: https://www.metoffice.gov.uk/ Portuguese Institute for Sea and Atmosphere (Azores is an autonomous region of Portugal): http://www.ipma.pt/en/ |