ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm John Discussion Number 16 NWS National Hurricane Center Miami FL EP122018 800 AM PDT Thu Aug 09 2018 John's structure hasn't changed much over the past few hours. A combination of cool SSTs and stable air appear to be causing convection to erode in the southern portion of the cyclone's circulation. A blend of objective and subjective Dvorak classifications was used to determine the initial intensity of 60 kt. The tropical storm will be moving over progressively cooler SSTs for the next couple of days, and further weakening is inevitable. The intensity models are in good agreement on the forecast weakening rate, and John is still forecast to become a remnant low within the next 48 h. The initial motion continues near 305/14 kt. There is no change to the reasoning behind the track forecast, and the new NHC forecast is merely an update of the previous advisory. All of the guidance remains in good agreement that the cyclone should will gradually turn west-northwestward as it moves around a mid-level ridge centered over the southwestern U.S. for the next few days. By the end of the forecast period, the remnant low is likely to slow down to a drift within an area of weak low-level steering flow. Large swells associated with John are already affecting portions of the coast of the Baja California peninsula and are forecast to spread northward and reach portions of the southern California coast by tonight. These swells are likely to cause life- threatening surf and rip current conditions. Please consult products from your local weather office. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 24.5N 117.3W 60 KT 70 MPH 12H 10/0000Z 25.5N 119.1W 50 KT 60 MPH 24H 10/1200Z 26.6N 121.1W 40 KT 45 MPH 36H 11/0000Z 27.4N 122.8W 35 KT 40 MPH 48H 11/1200Z 27.9N 124.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 12/1200Z 28.6N 125.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 13/1200Z 29.5N 125.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 14/1200Z...DISSIPATED $$ Forecaster Zelinsky NNNN
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Page last modified: Monday, 31-Dec-2018 12:10:43 UTC