000 WTPZ41 KNHC 171440 TCDEP1 Hurricane Fernanda Discussion Number 23 NWS National Hurricane Center Miami FL EP062017 800 AM PDT Mon Jul 17 2017 Fernanda's eye has - once again - become clear in the shortwave infrared imagery with a slightly asymmetric ring of very cold cloud tops surrounding the 15 nm eye. A blend of the subjective Dvorak fixes from SAB/TAFB along with the objective Advanced Dvorak Technique gives 110 kt intensity, maintaining Fernanda as a Category 3 hurricane. In the short term, the SSTs beneath Fernanda will gradually cool, reaching 26C in about 36 hours. By days 4 and 5, the vertical shear should go up substantially due to Fernanda moving closer to a tropical upper-tropospheric trough. Thus the official intensity forecast shows steady weakening with the system becoming a remnant low around day 5. This forecast is closest to a blend of the LGEM and D-SHIPS statistical intensity schemes, as well as the HCCA corrected consensus technique. (The HWRF and COAMPS dynamical models appear to hold on to too strong a system at days 3 and beyond, based upon the environment that Fernanda is expected to encounter.) The hurricane is tracking toward the west-northwest at about 9 kt. Fernanda is expected to turn slightly toward the northwest during the next couple of days as it moves around the southwestern periphery of a deep-layer subtropical ridge. By days 3 to 5, the system should turn back toward the west as it gets advected along in the low-level flow as a weakening tropical cyclone. The NHC forecast is nearly unchanged from the previous advisory and is based upon the TVCN multi-model consensus technique. The initial wind radii were maintained based on the earlier 0542Z and 0626Z ASCAT scatterometer overpasses. The forecast wind radii are based upon the RVCN multi-model consensus technique. FORECAST POSITIONS AND MAX WINDS INIT 17/1500Z 13.7N 130.9W 110 KT 125 MPH 12H 18/0000Z 14.4N 132.0W 100 KT 115 MPH 24H 18/1200Z 15.3N 133.3W 90 KT 105 MPH 36H 19/0000Z 16.1N 134.4W 80 KT 90 MPH 48H 19/1200Z 16.8N 135.6W 70 KT 80 MPH 72H 20/1200Z 17.5N 138.9W 50 KT 60 MPH 96H 21/1200Z 17.9N 142.3W 35 KT 40 MPH 120H 22/1200Z 18.3N 146.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Landsea