ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm Guillermo Discussion Number 8 NWS National Hurricane Center Miami FL EP072021 1100 PM HST Sun Jul 18 2021 Guillermo is not a well-organized tropical cyclone. The low-level center is displaced about 90 n mi to the northwest of the main area of deep convection due to northwesterly shear. Taking the mean of Dvorak final T and current intensity numbers from TAFB and SAB gives 40 kt, and scatterometer data from a few hours ago suggest that this may be a generous estimate for the advisory intensity. Using center fixes from geostationary and microwave imagery along with the scatterometer winds gives a westward initial motion, or about 270/13 kt. A well-defined mid-level ridge of high pressure to the north of the cyclone should maintain a generally westward motion throughout the forecast period. The official forecast track is nudged slightly south of the previous one, mainly on account of the short-term motion. This track forecast is very close to the latest dynamical model consensus, TVCE, which is usually a very good performer. Assuming that some deep convection redevelops nearer to the center over the next day or two, Guillermo may be able to maintain some of its intensity for a while. Also, the relatively large circulation should take some time to spin down as shown by the global models. However, gradually cooling SSTs, dry mid-level air and continued shear are expected to cause the cyclone to weaken to a depression in a couple of days and to degenerate into a remnant low by the end of the forecast period, if not sooner. The official intensity forecast is similar to the numerical consensus, IVCN. FORECAST POSITIONS AND MAX WINDS INIT 19/0900Z 18.8N 116.8W 40 KT 45 MPH 12H 19/1800Z 18.9N 118.9W 40 KT 45 MPH 24H 20/0600Z 18.9N 121.7W 40 KT 45 MPH 36H 20/1800Z 18.7N 124.6W 35 KT 40 MPH 48H 21/0600Z 18.5N 127.5W 35 KT 40 MPH 60H 21/1800Z 18.3N 130.3W 30 KT 35 MPH 72H 22/0600Z 18.2N 132.8W 25 KT 30 MPH 96H 23/0600Z 18.2N 137.8W 25 KT 30 MPH 120H 24/0600Z 18.0N 144.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Pasch NNNN
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