345 WTPZ42 KNHC 070232 TCDEP2 Hurricane Olivia Discussion Number 26 NWS National Hurricane Center Miami FL EP172018 800 PM PDT Thu Sep 06 2018 Olivia's satellite presentation is an outstanding example of an annular hurricane with the shape of a truck tire. In fact, the Annular Hurricane Index on the SHIPS model output is 100. The hurricane has a distinct clear eye surrounded by a ring of very deep convection. The Dvorak numbers, both objective and subjective, are T6.0, and on this basis, the winds are increased to 115 kt in this advisory. The current annular pattern indicates that hurricane should weaken more slowly that indicated by guidance in the short term. Nevertheless, since the ocean is a little bit cooler along the forecast track, very gradual weakening is forecast through the next 5 days. The confidence in the intensity forecast is not very high. On the contrary, the confidence in the track forecast is high. Olivia is fully embedded within the easterly flow south of a subtropical high, and the hurricane is moving toward the west-northwest or 290 degrees at 12 kt. The subtropical high will persist, and most likely expand farther westward, and this flow pattern will force Olivia to move on the general westward track or even south of due west by the end of the forecast period. Guidance for the next 5 days is in extremely good agreement, and the NHC forecast in on top of the skinny guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 19.1N 129.7W 115 KT 130 MPH 12H 07/1200Z 19.7N 131.6W 115 KT 130 MPH 24H 08/0000Z 20.5N 134.2W 100 KT 115 MPH 36H 08/1200Z 21.2N 136.8W 90 KT 105 MPH 48H 09/0000Z 21.5N 139.5W 85 KT 100 MPH 72H 10/0000Z 21.8N 144.5W 75 KT 85 MPH 96H 11/0000Z 22.0N 148.5W 70 KT 80 MPH 120H 12/0000Z 21.5N 152.5W 65 KT 75 MPH $$ Forecaster Avila