ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM HURRICANE OLAF DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL EP192015 200 AM PDT MON OCT 19 2015 The overall satellite presentation of the hurricane has not changed since the previous advisory. The ragged eye that was seen in the last few visible satellite pictures has not become apparent in overnight infrared images, but recent microwave data have indicated the presence of a small well-defined eye. Objective and subjective Dvorak satellite intensity estimates still support an initial wind speed of 85 kt. Olaf is expected to remain over warm water and in a low vertical wind shear environment during the next several days. These factors favor intensification and Olaf is expected to become a major hurricane during the next 12 to 24 hours. After that time, some additional strengthening is forecast, but fluctuations in intensity are likely due to eyewall cycles. The new NHC forecast is unchanged from the previous advisory and is near the upper-end of the intensity guidance, closest to the SHIPS/LGEM models. Some gradual weakening is shown at days 4 and 5 when Olaf moves over slightly cooler waters and into an area of drier mid-level air. Recent satellite and microwave fixes show that Olaf is moving westward or 280/10 kt. The track forecast reasoning remains unchanged, as Olaf is expected to move around the southwestern and western portions of a deep-layer subtropical ridge during the next several days. The hurricane is forecast to turn west- northwestward later today before it moves into the Central Pacific basin tonight. A northwestward motion is expected in 2 to 3 days, and a turn toward the north should occur late in the period when Olaf nears a break in the ridge along 145W. The new NHC track is similar to the previous advisory through 72 hours, but has been adjusted westward at days 4 and 5 to be closer to the latest multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 10.0N 136.4W 85 KT 100 MPH 12H 19/1800Z 10.3N 137.8W 95 KT 110 MPH 24H 20/0600Z 10.8N 139.6W 105 KT 120 MPH 36H 20/1800Z 11.4N 141.1W 110 KT 125 MPH 48H 21/0600Z 12.3N 142.5W 110 KT 125 MPH 72H 22/0600Z 14.3N 144.8W 110 KT 125 MPH 96H 23/0600Z 16.5N 146.0W 100 KT 115 MPH 120H 24/0600Z 19.0N 146.0W 85 KT 100 MPH $$ Forecaster Brown NNNN