Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
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990 ACUS01 KWNS 120456 SWODY1 SPC AC 120455 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1155 PM CDT Tue Jun 11 2024 Valid 121200Z - 131200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTHERN MINNESOTA... ...SUMMARY... Scattered severe thunderstorms capable of very large hail to 3 inch diameter, damaging wind gusts to 65 mph, and a couple of tornadoes will be possible across parts of the Upper Midwest today. The probable time frame for the most intense storms should be centered on late afternoon to early evening. ...Upper Midwest Vicinity... A 50-60 kt westerly 500 mb jet will overspread MN and portions of northern WI today. As this occurs, an EML plume will advect east into MN and vicinity, with steep midlevel lapse rates to near 8 C/km forecast. Meanwhile a surface trough/cold front will shift east across the eastern Dakotas and MN through the period. Ahead of the surface boundary, southerly low-level flow will aid in low-level theta-e advection, and surface dewpoints will climb into the 60s F. This moist boundary-layer beneath steep midlevel lapse rates will support strong destabilization, and MLCAPE values around 2000-3000 J/kg are expected. Vertically veering wind profiles, also increasing in speed in the mid/upper levels, will support supercells. Forecast soundings show enlarged/looping low-level hodographs becoming elongated/straight above 3 km. This environment will be very favorable for supercells capable of producing very large hail. A couple of tornadoes also will be possible, especially across parts of northern MN where better organized/more intense supercells are expected and SRH increases in the 22-00z time frame. Isolated damaging gusts also will be possible. Confidence has increased sufficiently regarding coverage/spatial extent of a corridor of greater significant hail potential, supporting an upgrade to an Enhanced risk (level 3 of 5) across parts of northern MN. Severe potential will gradually diminish across northern WI and the Upper Peninsula where instability will be less and stronger inhibition is forecast. Further south across eastern SD/southern MN/northern IA, clusters of elevated storms may develop early in the day in response strong warm advection. This activity will initially be elevated, but could still pose a risk for hail. With time into the afternoon as additional heating/moistening occurs, this activity could become more surface-based. If this occurs, damaging gusts in addition to hail will be possible across southern MN/northern IA. ..Leitman/Weinman.. 06/12/2024 $$