Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 347 AM EDT Wed Oct 21 2020 Valid 12Z Wed Oct 21 2020 - 12Z Fri Oct 23 2020 ...Early season winter storm to blanket portions of the north central U.S. in heavy snow... ...Periods of rain and strong thunderstorms in the Midwest and Great Lakes; torrential downpours in South Florida today... ...Critical Fire Weather Risk continues issued for northern California & the southern High Plains on Thursday; abnormally warm temperatures persist in the South and much of the East... Following on the heels of Tuesday's snow storm in the Upper Midwest, a deepening upper-level trough and a surge of cold Canadian air sets the stage for yet another early season winter storm. Snow showers are forecast to develop from the northern Rockies to portions of the Dakotas later today. As a developing surface low pressure system strengthens in the northern High Plains late Wednesday into Thursday, snowfall coverage will expand throughout the northern Rockies and Plains with the heaviest totals likely to occur in the northern Absaroka Range and the Bighorn Mountains. There is also a chance for significant snowfall to occur Thursday in portions of the Dakotas and northern Minnesota where 8+ inches of snow is possible. Expect treacherous travel conditions and poor visibilities in these affected areas along with much below normal temperatures lasting into Friday. Some daily record cold highs/lows are possible in these areas through Friday. The plunging temperatures are forecast to plunge south into the Great Plains, eventually reaching West Texas by Friday morning. Heavy showers and thunderstorms are soaking parts of the lower Great Lakes and mid-Mississippi early this morning but should diminish during the late morning hours. The impending winter storm system will also contain heavy rainfall. Showers and t-storms are expected to pass over the Midwest and northern Great Lakes today with the heaviest rainfall amounts expected to occur on Thursday. There are Marginal risks for both severe weather and excessive rainfall on Thursday: the former centered in the heart of the Midwest and the latter positioned over the northern Great Lakes. Farther south, a tropical air-mass will foster the development of widespread showers and thunderstorms in South Florida. Some rainfall rates could be excessive and lead to flash flooding in more urbanized areas. As a result, a Slight Risk for excessive rainfall has been issued in far southeast Florida for today. Elsewhere, favorable fire weather conditions look to persist in northern California's Sacramento Valley through Friday due to the persistence of warm/dry conditions over the area. Thursday in particular features a Critical Risk for fire weather in northern California and the southern High Plains of eastern New Mexico and parts of the Texas Panhandle. In addition, balmy temperatures for mid-late October will engulf much of the southern and eastern U.S. with a handful of daily record warm highs and lows possible across these regions through the end of the week. Mullinax Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php