ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm Flossie Discussion Number 15 NWS National Hurricane Center Miami FL EP072019 500 PM HST Wed Jul 31 2019 Flossie is struggling this evening, with almost all of its deep convection in the southeastern quadrant of the circulation. While some thunderstorms have recently formed closer to the low-level center, the bursts have not been able to maintain themselves due to northwesterly shear. Satellite intensity estimates are a consensus 55 kt, so that will be the initial wind speed. The intensity forecast, as usual, is challenging this evening. Shear is predicted to remain moderate/strong overnight, so some weakening is shown then. Afterward, while the upper-level wind pattern looks like it will become more conducive for strengthening through Saturday, the mid-level flow could keep the storm in a higher shear environment than would be expected from only a simple 850-200 mb shear calculation. Intensity models are also lower than the last cycle; however, a few of the models make Flossie a hurricane again. This isn't a particularly confident scenario, so it is usually wise to be conservative when changing the forecast. Thus, the wind speed forecast is only about 5 kt lower than the previous one through 72 hours. The new NHC forecast is still higher than the model consensus, especially at long range, and further downward reductions are possible overnight if trends continue. The storm continues to move westward at 14 kt, steered by a deep-layer ridge that stretches across much of the eastern Pacific. This ridge should steer Flossie westward to west-northwestward during the next several days. Model guidance shows less of a reduction in forward speed during the next 5 days than the last cycle, perhaps due to the now-weaker cyclone being more steered by the lower-level flow. Thus the new forecast is faster than the previous one, but lies basically along the previous NHC track. There is considerable uncertainty in the 5-day position and intensity, with average errors near 200 miles and 20 mph, respectively, so it's best not to focus on specifics at that range. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 14.3N 128.8W 55 KT 65 MPH 12H 01/1200Z 14.7N 131.0W 50 KT 60 MPH 24H 02/0000Z 15.4N 133.9W 55 KT 65 MPH 36H 02/1200Z 16.0N 136.8W 55 KT 65 MPH 48H 03/0000Z 16.6N 139.7W 60 KT 70 MPH 72H 04/0000Z 17.7N 145.1W 65 KT 75 MPH 96H 05/0000Z 18.5N 150.1W 60 KT 70 MPH 120H 06/0000Z 20.0N 154.5W 45 KT 50 MPH $$ Forecaster Blake NNNN