Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 AM EDT Fri Jun 22 2018 Valid 12Z Fri Jun 22 2018 - 12Z Sun Jun 24 2018 ...Severe thunderstorms are likely from the lee of the Central Rockies southeastward through Oklahoma and into the mid-South... ...Flash flooding concerns extend over sections of Oklahoma/Arkansas as well as the Ohio Valley and lower mid-Atlantic... ...Abundant heat in store for the Desert Southwest while fire weather concerns loom over the Four Corners region... A deep upper trough will slowly march toward the central U.S. where it will encounter a rather moist and unstable air mass. Initially thunderstorms should erupt over the higher terrain across the Central Rockies with gradual migration toward the adjacent High Plains. Particular focus is likely in close proximity to a deep surface low expected to travel from southeastern Colorado toward the Texas/Oklahoma panhandles this evening. Initial threats will consist of large hail with perhaps a couple tornadoes before evolving into more of a damaging wind producer as the expected line of storms advances eastward. The Storm Prediction Center currently is advertising an Enhanced Risk for severe thunderstorms from eastern Colorado southeastward to the Oklahoma City metro area. Further convective episodes are also possible for downstream locations spanning a wavy stationary frontal zone. This will include sections of the Lower Mississippi Valley across the mid-South into the Smoky Mountains. In addition to the severe weather potential, there will also be a corresponding threat for flash flooding across areas of central/eastern Oklahoma into Arkansas. Expected 2-day rainfall totals may reach the 2 to 4 inch range through Sunday morning with isolated pockets of higher amounts. Heavy downpours within slow-moving or repeat convection should easily augment flash flood concerns. Elsewhere, in advance of a broad upper low currently moving through eastern Missouri, a stalled frontal boundary should focus periodic episodes of locally intense heavy rainfall. With many sections of the Ohio Valley and Central Appalachians already having received abundant rainfall during the past week, additional precipitation should lead to runoff issues. This remains particularly the case over southern Ohio, much of West Virginia, and into west-central Virginia. In addition to the rainfall threats, below average temperatures should prevail given abundant cloud cover with departures in the 5 to 10 degree range. A building upper ridge across the southwestern U.S. will promote hot conditions into the weekend as highs soar into the 110 to 120 degree range across desert locales. In response, local forecast offices have painted widespread excessive heat warnings which generally expire by Friday evening. The exception will be sections of southern Nevada and across the border into east-central California with a hot day in store for Saturday. The usual hot spot Death Valley, California may approach 125 degrees early this weekend. Farther east, conditions remain adequate for brush fire production across the Four Corners as dry, gusty winds overspread a region characterized by rather significant drought conditions. Elsewhere, a multitude of disturbances sweeping through the Upper Intermountain West into the Northern High Plains will continue to support a period of active precipitation. It appears the highest amounts will likely congregate over much of Wyoming and into the Black Hills with widespread 2-day amounts of 1 to 2 inches in the forecast. Additionally, this should be the cooler sector of the western U.S. with expected highs around 5 to 10 degrees below climatology as readings stay in the low 70s. Rubin-Oster Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php