Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0238 AM CDT Thu Jul 13 2023 Valid 161200Z - 211200Z ...DISCUSSION... ...Sunday/Day 4 and Monday/Day 5... An upper-level low is forecast to move eastward across southern Ontario from Sunday into Monday. Well to the south of this system, a moist airmass will likely be in place from the Great Plains eastward into the Ohio and Tennessee Valleys. Scattered thunderstorms appear likely to develop within much of this airmass each afternoon. The greatest chance for severe storms could take place in the central Plains to the south of a mid-level speed max. A chance of severe could occur across South Dakota and Nebraska on both Sunday afternoon and Monday afternoon. During this period, mid-level heights are forecast to rise across the central and northern Plains. This introduces uncertainty concerning the magnitude of a severe threat, mainly due to capping which could persist due to the presence of a building upper-level ridge. ....Tuesday/Day 6 to Thursday/Day 8... An upper-level trough is forecast to develop in the northwestern U.S., and move eastward across the northern states from Tuesday to Thursday. A severe threat may accompany this system as it moves from the Dakotas eastward to the Great Lakes. A severe threat will also be possible during the mid week along parts of the middle and northern Atlantic Seaboard, where a moist and unstable airmass is forecast. At this time, model forecasts do not have a strong signal on any specific day late in the Day 4 to 8 period, suggesting that predictability is low concerning a potential severe weather event.
