Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Thu May 31 2018 Valid 12Z Thu May 31 2018 - 12Z Sat Jun 02 2018 ...Severe weather and possible flash flooding to impact areas of the lower Ohio/upper Tennessee valleys today... ...Wet conditions to continue over the mid-Atlantic favoring additional bouts of flash flooding the next couple of days... ...Severe thunderstorms are likely to impact the northern Rockies eventually into the north-central states by Friday... ...Overnight warmth to lead to more daily records east of the Rockies... While what remains of Alberto pushes across the Great Lakes early this morning, the focus will shift toward a convective complex currently rushing through Oklahoma. The parent upper trough should gradually move into the Missouri River valley which will provide a very moist and unstable air atmosphere to work with. As such, expect a number of thunderstorms to erupt during the diurnal heating cycle with many becoming severe anywhere from southern Missouri/Illinois eastward into the lower Ohio/upper Tennessee valleys. Based on the Storm Prediction Center outlook, damaging winds and large hail should be the primary threats although a couple of tornadoes cannot be ruled out. Of course flash flooding may also occur with some of the slower moving convective storms. An incredibly moist pattern remains in place over the eastern U.S., mostly responsible to the presence of Alberto and its tropical moisture feed. Daily thunderstorms should brew in the presence of sufficient daytime heating, aided by any impulses to the west which may spark a more organized rainfall event. Most recently, the mid-Atlantic region has been prone to flash flooding events in this pattern with Ellicott City, MD, Charlottesville, VA, and upstate North Carolina all being impacted the past week. Any additional heavy rainfall on top of the saturated soils could lead to further concerns the next couple of days. With a more potent, slow-moving upper trough crossing the central Appalachians on Friday afternoon, such hydrologic concerns should pick up with many of the mentioned regions outlined in the latest Excessive Rainfall Outlook. A rather robust upper trough sweeping through the Pacific Northwest will be a driver for active convection anywhere from upper Intermountain West eastward through the northern Rockies and into the central/northern Great Plains. In terms of precipitation, the heaviest amounts are likely over such regions of the Great Plains where much better moisture will be in place. However, further back in Montana, conditions have been abnormally wet for a while thus raising flash flood concerns in many locations. Additionally, a multi-day severe weather risk is outlined from central Montana eastward into the Dakotas down to Nebraska through early Saturday. The current Day 2 convective outlook places an enhanced risk for severe weather over a good chunk of these Great Plains states. The cool spots in the country will be along the West Coast given the large-scale trough with coastal locations remaining under the influence of onshore flow. With gradual eastward push of the upper trough, areas of the Intermountain West should see a notable lowering of temperatures as well. However, in terms of record breaking numbers, it will be the anomalous overnight warmth generally east of the Rockies. Warm, muggy overnight conditions fostered by the high dew point temperatures will lead to widespread lows in the 70s from the Southern Plains into the mid-South and lower mid-Atlantic. A couple dozen locations east of the Rockies may see overnight records with anomalies generally in the 10 to 15 degree range each day. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php