Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 414 PM EDT Thu Sep 20 2018 Valid 00Z Fri Sep 21 2018 - 00Z Sun Sep 23 2018 ...Severe weather and a threat for flash flooding across the Upper Midwest today... ...Moderate Risk for flash flooding in place over central Oklahoma on Friday into the overnight hours... ...Substantial temperature contrast on the order of 40-50 degrees F from the Dakotas into the central U.S... ...Wet conditions likely across sections of western Washington up into British Columbia... Showers and thunderstorms will persist across the north-central U.S. as a cold front drops south through the Northern Plains, Upper Midwest and Great Lakes region. Ongoing flooding will persist over much of the Upper Mississippi Valley with the additional rainfall- WPC has a slight risk for excessive rainfall in effect. These storms will have the potential of being severe and capable of producing heavy rain. The Storm Prediction Center has a slight and enhanced risk highlighted over much of Iowa, southern Minnesota and western Wisconsin today. The risk for sever weather and heavy rainfall will shift eastward on Friday, encompassing portions of the Great lakes and Northeast. Strong gusty winds along with much cooler temperatures can be expected Friday and Saturday. Relative to climatology, anomalies will be quite impressive, particularly north of the boundary with departures in the 20 to 25 degree F range. The air mass within the cold sector should modify a bit by the following day as highs stay in the mid to upper 50s across the Northern Plains into the Upper Midwest. A compact upper low dropping down from the Gulf of Alaska will take aim at the Pacific Northwest and will usher in widespread precipitation across western Washington up into British Columbia. The majority of the precipitation will focus against the upslope terrain with the highest amounts expected over the Olympic Mountains. The Southern Plains will be in an active wet pattern into the weekend. Enhanced moisture from the remains of Tropical Depression Nineteen-E will lead to a heavy rainfall event across the south-central U.S as it merges with moisture from the Gulf of Mexico along a frontal boundary. There should be a particular focus across central Oklahoma where a wavy frontal zone is forecast to stall. Several inches of rain are possible on Friday into Saturday morning which led to an upgrade of the flash flood potential to a Moderate Risk which includes the city of Oklahoma City. The footprint of heavier rainfall should surround this region extending into western Arkansas and southward across the Red River into north Texas. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php