Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 422 AM EDT Tue Apr 07 2015 Valid 12Z Tue Apr 07 2015 - 12Z Thu Apr 09 2015 ...Heavy rainfall and severe weather is likely across the Southern/Central Plains into the Middle Mississippi Valley on Wednesday... ...Warm, dry, and breezy conditions will support an enhanced wildfire risk across the Four Corners and Southern High Plains... ...Well above normal temperatures to prevail from the Southern Plains to the Ohio Valley and Lower Great Lakes... It will be quite an active weather pattern during the week with wintry precipitation, flash flooding, severe weather, and an enhanced wildfire risk all in the forecast through Thursday morning. The culprit is a strong upper trough currently working its way through Northern California. Enhanced moisture surging into California will spread precipitation to the region which is a welcome sight given the prolonged drought conditions. The WPC winter weather desk is forecasting 6 to 12 inches of snow across the Central Sierra Nevada range with even heavier amounts farther inland across the Ruby Mountains of northeastern Nevada. As is common with an upper trough ejecting out of the southwestern U.S., a persistent dry line will be in place across the Southern/Central Plains. Observations west of the dry line show very low relative humidity values accompanied by warm, gusty winds. This dangerous combination has led to a slew of red flag warnings being issued by the local forecast offices across the Four Corners region and Southern High Plains. In addition to the enhanced wildfire danger, a threat for severe weather and flash flooding exists by mid-week. The combination of a strong upper trough ejecting toward the High Plains with enhanced Gulf moisture and large amounts of instability will set the stages for severe thunderstorm activity across the Southern/Central Plains. Currently the Storm Prediction Center has outlined an area from Central Oklahoma up through much of Missouri and western Illinois in a slight risk for severe weather from Wednesday morning through the following morning. Meanwhile, the threat will eventually transition into a heavy rainfall event with possible flash flooding. The excessive rainfall forecast from WPC suggests this is most likely from Northern Missouri eastward to the Ohio Valley. Of course the latter location just experienced flash flooding within the past week so the saturated grounds will make any additional heavy rainfall a potential issue this week. A west-to-east frontal zone currently stretching from lower New England back through the Ohio Valley and into the Middle Mississippi Valley has been a focus for a strong temperature gradient and overrunning precipitation. This has allowed some light snow to fall over interior New England while south of the boundary showers and thunderstorms continue to fire in the unstable air. This sharp temperature gradient will support rather pronounced anomalies with readings 15 to 20 degrees above normal in the warm sector while the back-door cold front ushers in much colder air to the north. This boundary will take temperatures across the Mid-Atlantic from the low/mid 70s down into the upper 40s/low 50s by Wednesday and Thursday. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php