Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 PM EDT Mon Apr 02 2018 Valid 00Z Tue Apr 03 2018 - 00Z Thu Apr 05 2018 ...Severe thunderstorms are possible on Tuesday for portions of the southern Plains, lower and middle Mississippi Valley and the Ohio Valley on Tuesday... ...Heavy snow is expected across portions of the northern Plains, upper Midwest, Great Lakes and far northern New England through Wednesday... One of the major weather headlines early this week will be the threat of severe weather on Tuesday across portions of the southern Plains, lower and middle Mississippi Valley and the Ohio Valley as a strong area of low pressure developing in the lee of the Rockies lifts up across the Midwest through Tuesday afternoon and evening. Widespread showers and thunderstorms are expected to develop along and ahead of a trailing cold front as warm and moist southerly flow surges north from the Gulf Coast states while interacting with the arrival of an amplifying upper level trough from the central Plains. Thunderstorms will be capable of producing damaging winds, large hail and a few tornadoes during the late-afternoon and evening hours. Meanwhile, locally heavy rainfall associated with the thunderstorms will also be capable of producing some isolated instances of flash flooding. Temperatures across the Gulf Coast states and the Southeast ahead of this front will be as much as 10 degrees above normal as daytime temperatures reach the upper 70s and low 80s. Areas farther north across the Mid-Atlantic and Northeast will be notably cooler, and generally below normal, as they will be north of an approaching warm front. Some of these areas will be expecting rain to arrive from the upstream storm system later in the day and for Tuesday night. On Wednesday, the Eastern Seaboard will see a temporary warm-up ahead of the approaching upstream cold front, and there should be a rather widespread area of showers and thunderstorms the cold front associated with its arrival. Some locally heavy rains along with some strong to isolated severe thunderstorms cannot be ruled out before the frontal passage. A second major weather story will be yet another winter storm impacting a large portion of the country. This will involve the same storm system producing the severe weather, but the focus will be much farther north where very cold air will be in place extending from portions of the northern Plains, upper Midwest, the Great Lakes and gradually far northern New England. A swath of heavy snowfall is expected across these areas Tuesday and into Wednesday with locally as much as a foot of snow occurring, with the heavier totals most likely focused over portions of central Wisconsin and lower Michigan. Temperatures on Tuesday will be very cold particularly across the northern Plains with daytime readings as much as 30 degrees below normal. This cold air will then surge east across the Mississippi Valley and Ohio Valley by Wednesday in the wake of the aforementioned cold front moving into the East. The Western U.S. will see considerably more tranquil weather by comparison with temperatures near to above normal at least for most of the Great Basin and the Southwest along with dry conditions. One exception to this though will be across the Pacific Northwest and the northern Rockies by Wednesday as moisture streaming east in off the Pacific Ocean allows for plenty of shower activity to arrive along with some higher elevation snowfall. Temperatures here will also be generally below normal given the cloud cover and close proximity to some modified Arctic air just to the north. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php