Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 401 PM EDT Tue Aug 21 2018 Valid 00Z Wed Aug 22 2018 - 00Z Fri Aug 24 2018 ...Heavy rain and severe weather expected across the Ohio Valley and Mid-Atlantic today... ...Fire weather and air quality concerns continue for portions of the Western U.S... Thunderstorms along with embedded heavy rainfall is spreading across portions of the Ohio Valley and Mid-Atlantic region today as a slow moving frontal system moves to the east. A large portion of the Ohio Valley, Central Appalachians and the Mid-Atlantic will continue to have favorable conditions for strong to severe thunderstorms through Wednesday morning. Within this same region, slow cell motion will favor high rainfall rates and increase the risk for flash flooding. Although not as high of a risk, the favored area for higher rainfall on Wednesday will be over parts of New England. This system is expected to continue moving east and exit the East Coast by Thursday. Meanwhile, behind this system, a large area of high pressure will set in across the eastern U.S., resulting in much drier weather to finish out the work week. Much of the West will remain in a drier airmass that will be conducive for elevated fire danger. Red flag warnings are in effect for a small area of northeast California and northeast Nevada. The Pacific Northwest and portions of the Intermountain West continues to have widespread, poor air quality due to the smoke from ongoing fires. Air Quality Alerts are in effect for all of the Pacific Northwest, northern Idaho, and western Montana. Furthermore, fires burning in British Columbia, Canada are transporting smoke southward into portions of Minnesota. Scattered to widespread convection will steadily increase over the next few days for the Great Basin and Southern/Central Rockies as monsoonal moisture returns to the region. Individual storms will have the potential to produce heavy rain. The area of convection is expected to shift toward the Southern Plains as the week progresses. Some of these storms could produce flash flooding, especially in favorable terrain and urban areas, as well as across burn scar regions. Flash flooding will also be a concern in the High plains, where above normal rainfall has already occurred over the past week. Campbell/Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php