Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 408 PM EDT Tue Apr 20 2021 Valid 00Z Wed Apr 21 2021 - 00Z Fri Apr 23 2021 ...Snow is expected to spread quickly from the Central U.S. to the Midwest today, and then across northern New England on Wednesday into Thursday... ...Subfreezing record cold temperatures expected across much of the south-central U.S. Wednesday morning, shifting to parts of the eastern U.S. Thursday morning... ...Critical fire weather threat over Arizona through Friday... Late season snow event continues to spread eastward across the Ozarks into the Ohio Valley as a developing area of low pressure is forecast to race along the Alleghenies into the Northeast later today into tomorrow morning. As the low pressure system progresses northeastward, rain and mixed precipitation will continue to envelop the Midwest, before a swath of wet snow falls along the Canadian border from New York into Northern New England beginning Wednesday morning through Friday. 6 to locally 8 inches is possible along the border through Friday. As such, "Moderate" impacts are expected in these locations from snow-load, per the Weather Prediction Center Winter Storm Severity Index, and Winter Weather Advisories are in effect for the region. Further south in the Mid-Atlantic, some rain and a few rumbles of thunder are possible as the storm moves through. In the wake of the developing storm system, a bout of unseasonably cold air is forecast to spill into the Central U.S. today and tomorrow, leading to widespread freeze and frost concerns tonight across the central/southern Plains and the Midwest. Freeze Watches and Warnings extend continuously from north-central Michigan into central Texas. Numerous daily record low temperatures are forecast to be tied or broken on Wednesday morning as temperatures dip to below freezing, around 20-25 degrees below average for late April. Residents in these areas are encouraged to take preventative measures to mitigate the impacts of sub-freezing temperatures on vulnerable vegetation if possible. By Friday, the frigid airmass will moderate as it drifts east, although low temperatures will remain around 10 degrees below normal in the Central U.S., with lows hovering in the mid-30's to 40's. Meanwhile, active weather across Florida has been edging very slowly southward into southern Florida ahead of a slow-moving front. A low pressure wave forming on the front could bring additional heavy showers and thunderstorms today across central Florida. Improving conditions should begin Wednesday morning as the wave moves off into the Atlantic and rain chances decrease across southern Florida. While excessive rain may be problematic in Florida, dry, windy conditions will set the stage for a fire weather threat in Arizona over the next three days as low pressure deepens in the region. Accordingly, the Storm Prediction Center has issued an Elevated Risk of fire weather today, and a Critical Risk tomorrow, with the potential for additional impactful fire weather also highlighted on Friday. Asherman/Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php