Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 313 AM EDT Tue Jun 04 2024 Valid 12Z Tue Jun 04 2024 - 12Z Thu Jun 06 2024 ...There is a Moderate Risk of Excessive Rainfall leading to Flash Flooding over parts of southeastern Oklahoma and the ArkLaTex today... ...Severe Thunderstorms possible across parts of the Mississippi Valley today... ...Growing Excessive Heat potential over portions of California's central valley region as well as the Desert Southwest; southern Texas heat risk persists... An amplified upper trough will swing through the Great Plains and Mississippi Valley, bringing with it a pair of cold fronts and thunderstorm activity over the next couple of days. Potent mid-level energy on the southern periphery of the trough anchored over southern-central Canada will move slowly across the Deep South today and promote a pair of MCSs to propagate across the ArkLaTex region this morning and then again tonight. The repeating thunderstorms (potentially severe) over the same area prompted the issuance of a Moderate Risk (at least 40%) of Excessive Rainfall leading to Flash Flooding over portions of southeastern Oklahoma through the ArkLaTex for the 24 hour period ending Wednesday morning. Frontally driven diurnal convection will also occur across the Upper/Middle Mississippi Valley this afternoon and evening. The Storm Prediction Center issued Slight Risks (level 2/5) of Severe Thunderstorms over parts of the Upper/Middle Mississippi Valley and another one across the ArkLaTex into western Mississippi. Large hail and severe wind gusts will be the main threat for any severe storms that develop over the Upper/Middle Mississippi Valley, while damaging wind gusts will be the sole threat across the ArkLaTex/Lower Mississippi Valley. A deepening upper ridge in the West and cutoff low west of Baja will support a heat wave across much of the Western U.S. over the next several days. Temperatures will be below average for the Pacific Northwest today but will be overtaken by warmer conditions beginning on Wednesday. Areas of particular concern include the low elevation regions of California's central valley and the Desert Southwest where high temperatures will easily climb over 100 degrees beginning today. High temperature anomalies of 20-30 degrees above average are likely. Widespread temperature records are expected to be tied or broken across much of the aforementioned areas. Excessive Heat Warnings and Watches extend from the central valley down through southern California's deserts, southern Nevada and southern/western Arizona. HeatRisk will peak over California's central valley on Wednesday before expanding into the Desert Southwest later this week. Little overnight relief will make for dangerous conditions for those without effective cooling and/or adequate hydration. HeatRisk over southern Texas peaks today but persists for the next few days. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php