Models show Monday severe risk

A weather model run shared Sunday points to a Monday evening window for severe thunderstorms in the Plains, with hail, damaging wind and tornado potential. (x.com) The post cited the North American Mesoscale 3-kilometer model, a high-resolution forecast that simulates precipitation and storm structure in hourly steps. The National Weather Service said Sunday that the Lower 48 faced an increasing severe-thunderstorm threat next week in the Plains. (tropicaltidbits.com, weather.gov) Forecast models are guidance, not a warning. The Storm Prediction Center issues the official severe-weather outlooks, while local National Weather Service offices issue watches and warnings as storms get closer. (spc.noaa.gov, weather.gov) The hazards in the post match the three main severe-thunderstorm categories forecasters track: wind gusts of at least 58 miles per hour, hail at least 1 inch in diameter, and tornadoes. Those thresholds are the basis for Storm Prediction Center outlooks and severe thunderstorm warnings. (spc.noaa.gov, weather.gov) The same setup can produce very different weather over a broad area. Colder air on the north side of a spring storm can support rain and snow, while warmer, more humid air farther south can fuel thunderstorms along and ahead of a front. (weather.gov, weather.gov) High-resolution models such as the NAM 3-kilometer can show where storms may form, but exact timing and town-by-town impacts often shift from one run to the next. The National Weather Service tells people to rely on updated forecasts, outlooks and warnings rather than a single model image. (tropicaltidbits.com, weather.gov) The Storm Prediction Center’s outlook pages and the National Weather Service alerts page are the main public checkpoints as Monday gets closer. If the model signal holds, the forecast will narrow from a broad risk area to watches and then warnings for specific counties. (spc.noaa.gov, weather.gov)