Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 337 PM EDT Sat Apr 06 2019 Valid 00Z Sun Apr 07 2019 - 00Z Tue Apr 09 2019 ...Heavy rainfall possible across parts of the Pacific Northwest this weekend, with snow in the higher elevations of the Intermountain West... ...Several rounds of strong to severe thunderstorms and locally heavy rainfall expected through Sunday in the Southern Plains and Lower Mississippi Valley... ...Showers and thunderstorms expected to spread across the Ohio Valley/Central Great Lakes Sunday and into the northern Mid-Atlantic/New England into Monday... A lingering frontal boundary over the Pacific Northwest will act as a focus for moisture into the region through much of the short range period with heavy rainfall likely across parts of the region especially along the favored terrain. Model guidance shows the potential for several inches of rainfall across western Oregon and northwest California, with flash flooding and flooding a possibility. WPC has a marginal to slight risk for excessive rainfall/flash flooding through Sunday and flood watches are in effect for some locations. Lower elevation rains and mountain snows are also possible farther inland across Washington, Oregon, and the Intermountain West/Northern Rockies. Meanwhile, upper level energy lifting through the Southern Plains this afternoon has sparked convection across parts of eastern Texas and Oklahoma. This activity is expected to continue into this evening, drifting slowly eastward into the Lower Mississippi Valley, with strong to severe thunderstorms possible. Storms may be capable of producing locally heavy rainfall, damaging winds, large hail, and tornadoes. SPC has a slight to enhanced risk for severe weather across much of eastern Texas, Oklahoma, and the lower Mississippi Valley through tonight, while WPC has highlighted parts of this region within a slight risk for excessive rainfall as well. By Sunday, the energy should lift into the Midwest and merge with another system to the north. This will result in rain showers and thunderstorms across the Middle Mississippi Valley into the Ohio Valley, where SPC has a slight risk for severe weather on Sunday. By Monday, rain should shift into the Mid-Atlantic States and the Northeast, with mainly light snow accumulations possible across northern interior New England. Another southern stream upper level trough will advance out of the Southern U.S. on Sunday bringing the potential for a second round of strong to severe thunderstorms and locally heavy rainfall to parts of the Southern Plains and Lower Mississippi Valley on Sunday. SPC and WPC have again highlighted the same region within slight risks for severe weather and flash flooding, respectively. On Sunday evening, a surface low is forecast to develop along the western Gulf Coast and move northeastward into the Lower Mississippi Valley on Monday. This should slowly shift the heavy rainfall and thunderstorms into the Southern Gulf States and the lower Tennessee and Ohio River Valleys on Monday. Santorelli Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php