je.st
news
Tropical Storm Norbert Forecast Discussion Number 5
2020-10-06 22:34:27| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Tue Oct 06 2020 065 WTPZ44 KNHC 062034 TCDEP4 Tropical Storm Norbert Discussion Number 5 NWS National Hurricane Center Miami FL EP192020 300 PM MDT Tue Oct 06 2020 A compact central dense overcast with cloud tops occasionally cooling to -80 degrees C has persisted over the center of Norbert throughout the day. A recent ASCAT overpass showed peak winds of 41 kt near the center of storm. However, due to the small size of the cyclone, the highest winds are likely not being sampled. Therefore, the initial intensity is being raised to 45 kt, and this is in good agreement with the latest Dvorak CI values from TAFB and SAB. Norbert is expected to remain in an environment of low vertical wind shear while over very warm waters for the next couple of days. Despite the positive environmental factors in the near term, model guidance is in poor agreement on the future intensity of Norbert. The spread in the forecast intensity has widened even further today, with most of the global and hi-resolution dynamical models weakening the system over the next few days, while the SHIPS and LGEM guidance favor slow strengthening. Since the SHIPS guidance has been the most accurate for Norbert's intensity thus far, the latest NHC forecast is close to, but just below the SHIPS guidance values through 48 h. After 48 h, the shear is expected to become moderate, and there are indications that subsidence will increase over the cyclone. These negative environmental factors should inhibit further intensification, and could cause the cyclone to weaken. The steering currents around Norbert are collapsing, as the mid-level ridge over southern Mexico dissipates in response to Hurricane Delta over the northwestern Caribbean Sea. Model tracks diverge by a few hundred miles in varying directions while the steering flow is weak. The consensus guidance is in between these solutions and shows very little movement for the next 72 h. By late this week, a weak mid-level ridge should build north of the cyclone, which would result in a slow west-northwestward to westward motion. The latest NHC track forecast remains close to the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 14.4N 106.6W 45 KT 50 MPH 12H 07/0600Z 14.5N 106.7W 50 KT 60 MPH 24H 07/1800Z 14.5N 106.7W 50 KT 60 MPH 36H 08/0600Z 14.5N 106.7W 55 KT 65 MPH 48H 08/1800Z 14.5N 106.7W 55 KT 65 MPH 60H 09/0600Z 14.5N 107.2W 50 KT 60 MPH 72H 09/1800Z 14.8N 108.0W 50 KT 60 MPH 96H 10/1800Z 15.5N 110.1W 50 KT 60 MPH 120H 11/1800Z 16.0N 112.0W 50 KT 60 MPH $$ Forecaster Latto
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics