Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0330 AM CDT Thu Apr 17 2025 Valid 201200Z - 251200Z ...DISCUSSION... ...Day 4/Sun - ArkLaTex to the Mid-MS Valley... A compact upper shortwave trough is forecast to move from the southern High Plains to the Midwest on Sunday. While some forecast uncertainty continues with regard to exact position of this feature, the overall pattern suggests isolated to scattered severe thunderstorm potential will exist across portions of east TX into the Mid/Lower MS Valley. Strong southwesterly flow aloft will overspread a moist warm sector as a surface low lifts north/northeast from OK into the Lower MO Valley through early evening. A trailing cold front will spread east as this occurs, while a warm front extends eastward from the Mid-MS Valley into the OH Valley. Evolution of prior days convection is resulting in some uncertainty regarding the western/northern extent of severe potential. Nevertheless, a favorable environment supporting at least isolated severe storms should extend from east TX into parts of southern MO/IL ahead of the cold front. ...Days 5-8/Mon-Thu... Forecast ensemble guidance from both the GEFS and EPS suggest low-amplitude west/southwesterly flow will overspread the southern tier of the U.S. next week. Southerly low-level flow on Day 5/Mon across the western Gulf into the southern Plains in the wake of the cold frontal passage on Day 4/Sun will allow for northward transport of modified moisture. This should continue into Day 6/Tue across the Plains. Some localized severe risk could develop across parts of the southern Plains as an upper shortwave trough moves across the north-central U.S. on Day 6/Tue, but poor juxtaposition between higher quality moisture across OK/TX and stronger forcing across the northern Plains/Upper Midwest may limit overall potential. This low-amplitude pattern will continue through Day 8, resulting in low predictability.