000 WTPZ41 KNHC 052038 TCDEP1 Hurricane Sergio Discussion Number 26 NWS National Hurricane Center Miami FL EP212018 200 PM PDT Fri Oct 05 2018 This afternoon's satellite presentation shows that Sergio has become a little better organized. Eyewall cloud temperatures have once again cooled, and the ragged, cloud-filled eye has warmed during the past 6 hours. Accordingly, the subjective and objective T-numbers support increasing the initial intensity to 105 kt for this advisory. As mentioned in this morning's discussion, unforeseen short term inner-core structure changes could cause some intensity fluctuations. Since the environment is forecast to remain favorable during the next 24 hours or so, little change in strength is forecast, and again, the cyclone could become a little stronger than reflected in the forecast. Beyond this period, gradual weakening is expected through day 5 as Sergio moves toward decreasing sea-surface temperatures and into a more stable surrounding environment. The Decay-SHIPS and LGEM intensity guidance, as well as the large-scale models, show increasing southwesterly shear disrupting Sergio's outflow pattern after 72 hours. The intensity forecast is similar to the previous package, and is just above the NOAA-HCCA and IVCN consensus models and below the statistical intensity aids. Sergio's motion is estimated to be west-southwestward, or 250/6 kt within the mid-level steering flow produced by a building high pressure system located north-northeast of the Hawaiian Islands. By early next week, a decrease in forward speed and a turn toward the northwest to north-northwest is forecast as the aforementioned mid-level high retrogrades in response to an amplifying trough over the southwestern United States and Baja California peninsula. Beyond day 3, increasing southwesterly mid-tropospheric flow should induce a northeastward accelerated motion through day 5. The NHC forecast is again adjusted south of the last advisory through 48 hours, and is close to the various multi-model consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 15.7N 122.3W 105 KT 120 MPH 12H 06/0600Z 15.3N 123.1W 105 KT 120 MPH 24H 06/1800Z 14.9N 124.3W 100 KT 115 MPH 36H 07/0600Z 14.8N 125.4W 100 KT 115 MPH 48H 07/1800Z 15.1N 126.3W 90 KT 105 MPH 72H 08/1800Z 16.7N 126.5W 80 KT 90 MPH 96H 09/1800Z 18.9N 123.9W 70 KT 80 MPH 120H 10/1800Z 22.0N 119.3W 65 KT 75 MPH $$ Forecaster Roberts