000 WTPZ44 KNHC 280840 TCDEP4 Tropical Storm Hilary Discussion Number 28 NWS National Hurricane Center Miami FL EP092017 200 AM PDT Fri Jul 28 2017 The structure of Hilary has changed little over the past several hours, as a small area of convection persists near the center mainly in the southeastern quadrant. Recent satellite intensity estimates range from 45-70 kt, and based on these, the initial intensity remains a possibly generous 60 kt. Hilary should cross the 26C isotherm in 12-18 h, and given the current level of convective organization, significant re- intensification seems unlikely during that time. After that, the cyclone is forecast to move over steadily decreasing sea surface temperatures and into a drier air mass, and this combination should result in steady weakening. The cyclone is now forecast to weaken to a depression in about 72 h over 24C sea surface temperatures and degenerate to a remnant low shortly thereafter. The new intensity forecast shows a faster weakening than the previous forecast after 12 h, and it is in best overall agreement with the SHIPS and LGEM models. It is possible that interaction with Tropical Storm Irwin could lead to a faster decay than currently forecast. The initial motion is 300/7, a little to the right of that in the previous advisory. A mid-level ridge to the north of Hilary is expected to steer the cyclone generally west-northwestward for 48 h or so. Around 72 h, a westward turn appears likely as the cyclone interacts with, and eventually absorbs Irwin. After this event, Hilary or its remnants should resume a west-northwestward motion as the weakening system is steered by the low-level flow. The new forecast track is nudged north of the previous track, but it lies south of the consensus models, which have shifted northward since the last advisory. FORECAST POSITIONS AND MAX WINDS INIT 28/0900Z 18.7N 117.9W 60 KT 70 MPH 12H 28/1800Z 19.3N 119.0W 60 KT 70 MPH 24H 29/0600Z 20.3N 120.6W 55 KT 65 MPH 36H 29/1800Z 21.1N 122.6W 45 KT 50 MPH 48H 30/0600Z 21.9N 124.9W 40 KT 45 MPH 72H 31/0600Z 22.5N 129.0W 30 KT 35 MPH 96H 01/0600Z 23.5N 132.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 02/0600Z 25.0N 135.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Beven