Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Wed Oct 03 2018 Valid 00Z Thu Oct 04 2018 - 00Z Sat Oct 06 2018 ...Heavy rainfall and severe weather possible across the Upper Great Lakes tonight... ...Below normal temperatures across the northern Plains, with above normal temps across the southern tier... A rapidly deepening surface low will cross the Upper Great Lakes into Ontario this evening as it drags a cold front southward across the Middle Mississippi Valley and the Ohio Valley the next few days. The potential for heavy rainfall and severe weather will accompany the surface low passage across the Upper Great Lakes through this evening and into tonight. WPC is highlighting a slight risk for flash flooding across this region tonight, while the Storm Prediction Center has a slight to enhanced risk across this same area for severe weather, including the threat for damaging winds, large hail, and tornadoes. Showers and thunderstorms along the trailing cold front will also be possible as the front progresses across the Ohio Valley tomorrow and into the Northeast/Mid-Atlantic on Friday. Behind this front, a cold high pressure system moves in to the northern Plains, which will allow for afternoon highs as much as 20 degrees below normal for this time of the year. Across the Southern tier, and into the Mid-Atlantic, upper level ridging buidling across the area will keep temperatures warm and humid. Out west, a deep upper level low entering the Southwest will allow for scattered showers and thunderstorms across California and the Desert Southwest tonight, lifting into the Great Basin and Rockies by tomorrow. Locally heavy rainfall is possible, especially along the favored terrain in the Southwest this evening, and WPC has highlighted parts of the region with a slight risk through tomorrow morning. Cold air to the north of this may also allow for moderate to locally heavy snowfall in the higher terrain of the northern Rockies. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php