Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Tue Sep 25 2018 Valid 12Z Tue Sep 25 2018 - 12Z Thu Sep 27 2018 ...Heavy to excessive rainfall possible from the Tennessee Valley to the Northeast... ...Strong to severe thunderstorms expected with a strong cold front pushing from the Midwest to the Northeast Tuesday and Wednesday... The upper-level pattern across the U.S. continues to favor a wet pattern across much of the eastern half of the country the next couple of days. Moisture overriding a remnant surface boundary draped across the mid-south continues the threat for heavy to excessive rainfall across portions of the Tennessee and Ohio Valleys on Tuesday but the focus should begin shifting into New England as this boundary lifts northward as a warm front. As a result, WPC has much of the region from the Tennessee Valley to the Northeast within a marginal to slight risk for excessive rainfall/flash flooding on Tuesday. The temperature pattern across the East is also changing, as this warm front erodes away a wedge of surface high pressure and summery heat and humidity returns by Wednesday. A number of record warm overnight temperatures are forecast from the Gulf Coast to the Ohio Valley and Mid-Atlantic. A strong cold front will sweep quickly eastward from the Mississippi Valley to the Southern Plains on Tuesday, reaching the Ohio Valley and Northeast by Wednesday. Thunderstorms developing along the boundary could be strong to severe across the Midwest on Tuesday, and the Northeast/Mid-Atlantic states on Wednesday where The Storm Prediction Center has slight risks in effect. A threat for heavy rainfall is also possible along the front from the lower Mississippi Valley to the southern Appalachians on Wednesday and WPC has highlighted this region in marginal to slight risk for excessive rainfall/flash flooding. On the backside of the front, much cooler air filters in from Canada with well below normal temperatures (on the order of 10 to 20 degrees below average) reaching the Southern Plains by Wednesday. Elsewhere, surface high pressure across the Western U.S. will result in warm and dry conditions and a continued elevated to critical fire weather threat for portions of northern California where red flag warnings are in effect. Additionally, a broad area of low pressure is expected to skirt the Outer Banks on Tuesday which may bring some locally heavy rainfall to the area. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php