Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
830 ACUS48 KWNS 100858 SWOD48 SPC AC 100856 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CDT Mon Jun 10 2024 Valid 131200Z - 181200Z ...DISCUSSION... ...Thursday/Day 4 to Saturday/Day 6... On Thursday, an upper-level trough is forecast to move into the Great Lakes region, as a cold front advances southward across the Central Plains and mid to upper Mississippi Valley. Moderate instability is forecast south of the front by afternoon, where the models suggest that scattered thunderstorm development will take place. In addition, a mid-level jet is forecast to move eastward across the north-central U.S. on Thursday. Moderate deep-layer shear is forecast along the southern edge of this broad mid-level jet, which should support a severe threat during the late afternoon and early evening. On Friday, an upper-level ridge is forecast to move across the north-central U.S. Some models suggest that an axis of maximized low-level moisture will setup beneath the ridge over the central states. If this scenario pans out, then severe storms would be possible Friday afternoon and evening across parts of the central Plains. The presence of the ridge and the lack of large-scale ascent casts doubt on any particular scenario. On Saturday, a shortwave trough is forecast to move into the southern High Plains, as the upper-level ridge moves into the upper Mississippi Valley. In the wake of the ridge, a pocket of moderate instability could be in place across the Dakotas and Minnesota, as is suggested by the ECMWF. This area would be favored for severe storm development. However, uncertainty is still substantial at this range, especially due to significant spread among the model solutions. ...Sunday/Day 7 and Monday/Day 8... On Sunday and Monday, model forecasts suggest that a moist and unstable airmass will be in place across much of the north-central U.S., as multiple short troughs move northeastward through the region. Scattered severe storms will be possible each day ahead of these features in areas that destabilize the most, with the greatest potential likely from Nebraska northward into the Dakotas. However, model spread continues to be large late in the Day 4 to 8 period. Once the model solutions become in better agreement, a 15 percent contour may need to be added in parts of the north-central states for either Sunday or Monday. ..Broyles.. 06/10/2024