Extended Forecast Discussion...UPDATED NWS Weather Prediction Center College Park MD 258 AM EDT Thu Mar 21 2024 Valid 12Z Sun Mar 24 2024 - 12Z Thu Mar 28 2024 ***Late season winter storm for the Dakotas and into Minnesota and Wisconsin Sunday and into Monday*** ...General Overview... A strong low pressure system will be developing across the Central Plains and then crossing the Upper Midwest going into the beginning of next week, in response to an amplifying upper level trough over the Rockies. This will result in heavy snow northwest of the low, and numerous showers and thunderstorms ahead of the cold front across the south-central states. A second surface low is likely to develop over the Southeast U.S. by next Thursday and result in renewed prospects for additional rain for this region. Meanwhile, a low pressure system from the Pacific is progged to move inland across the northwestern U.S. and result in additional rain and mountain snow for mid-week. ...Guidance/Predictability Assessment... The 00Z model guidance now has a good overall depiction on the expected evolution of the Central U.S. low pressure system, and there has been a trend for the low to lift out farther north into southern Canada compared to earlier model runs. The UKMET still strays some from the model consensus with the low off the East Coast on Sunday, so it was not favored as a result since it had little in the way of ensemble support. Model agreement has improved for the storm system reaching the Pacific Northwest late in the forecast period. The WPC fronts/pressures forecast was primarily derived from a CMC/GFS/ECMWF blend through Monday, followed by gradually increasing percentages of the ensemble means through Thursday while using some previous WPC continuity through Wednesday. ...Weather/Hazards Highlights... On Sunday, a Marginal Risk area for excessive rainfall is planned for portions of the Central Plains with a corridor of heavier rain likely developing from northern Kansas to eastern Nebraska as a strong surface low is forecast to develop in the lee of the Rockies. The low then tracks towards the Upper Midwest by Monday morning and becomes the driver for a big late season winter storm. There continues to be an upward trend for significant snowfall accumulations (8"+) across northern South Dakota, southern North Dakota, central Minnesota, and northwestern Wisconsin, as this region will be on the colder side of the low with a deformation zone developing, and producing bands of heavier wet snow with gusty winds. There may also be a swath of potentially impactful mixed precipitation, including some freezing rain, most likely to the southeast of the heavy snow swath from eastern Nebraska to northwest Iowa and into southern Minnesota. Timing/track uncertainty may change the eventual location of the impactful winter weather, but the risk for disruptions to daily life and hazardous travel is likely. Multiple rounds of showers and thunderstorms, some of which could be strong to severe, can be expected in the warm sector of the system, beginning from the Southern Plains Sunday, and then spreading eastward to the Deep South on Monday where a Marginal Risk area is planned for Day 5. There are still question marks about how much instability will exist ahead of the front as the system progresses eastward, even though the kinematic environment will be more favorable for potential severe weather. Nonetheless, a quasi-linear convective system (QLCS) is evident on the latest GFS and ECMWF runs. The stormy weather then reaches the Florida Panhandle and portions of Alabama and Georgia on Tuesday with a secondary low likely developing over the northern Gulf. In terms of temperatures, it will feel more like January across the western High Plains from western Kansas to Montana and the Dakotas in the wake of the strong cold front. Highs will only be in the 20s and 30s for these areas on Monday, but a moderating trend will commence going into the middle of the week, even though Montana and North Dakota will still remain chilly by late March standards. Warmer weather likely makes a return to much of the south-central U.S. by next Wednesday and Thursday. Hamrick Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw