Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 259 AM EST Tue Feb 20 2018 Valid 12Z Tue Feb 20 2018 - 12Z Thu Feb 22 2018 ...Heavy snow likely over the Northern Plains and Upper Mississippi Valley... ...Heavy rain and flooding possible for portions of the Southern Plains to the Western Ohio Valley and into the Lower Great Lakes... ...Rain/freezing rain possible from of the Middle/Upper Mississippi Valley into the Upper Great Lakes... ...Temperatures will be 15 to 35 degrees below average over the Northern Rockies into parts of the Northern/Central Plains... Over the next couple of days a quasi-stationary front over the central U.S. will bring widespread rain and thunderstorms from the Southern Plains to the Great Lakes/Ohio Valley and east; with heavy snow across the Northern Plains and Upper Mississippi Valley. A narrow transition zone will setup across the Middle and Upper Mississippi Valley toward the Great Lakes where freezing rain will be possible. Winter Weather Advisories are in effect from Nebraska to the Dakotas and east to northern Michigan. Northwest Nebraska to central South Dakota have Winter Storm Warnings in effect. Flash Flood Watches, Flood Warnings and Advisories are in effect from northeast Texas to the southern Missouri and for the Lower Great Lakes region. Several inches of rain is expected along the stalled front over a lengthy time frame- likely continuing into the weekend. Run off from the abundant rain will cause local creeks and streams to rise which may lead to rivers to swell or overflow their banks. Urban flooding may also occur due to the excessive rainfall. Upper-level energy just off the Pacific Northwest Coast will move southward to off the Central/Southern California Coast by Wednesday. Additional upper-level energy will move over the Pacific Northwest on Tuesday evening into Wednesday spreading. snow to parts of the Pacific Northwest Coast on Tuesday afternoon that will change over to rain along the Northwest and Northern California Coast by Tuesday evening. The snow will continue just inland over parts of the Northwest into Northern California through Wednesday. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php