Update: Large Hail, 75 MPH Winds Target Rockies-to-Dakotas Stretch — SevereWX

Large Hail, 75 MPH Winds Target Rockies-to-Dakotas Stretch

Afternoon thunderstorms are igniting across a vast swath from northeast Nevada through the northern Rockies into the northern Plains, packing large hail up to 2 inches and damaging wind gusts to 75 mph. The Storm Prediction Center's three new Mesoscale Discussions signal high odds (60% each) for severe thunderstorm watches as these storms mature.

Western Ignition Points: Storms are bubbling up over northeast Nevada, northern Utah, southeast Idaho, and into southwest Wyoming thanks to daytime heating in the upper 80s, moist low levels, and orographic lift over mountains. Moderate instability (500-1000 J/kg CAPE) and 30-40 kt mid-level winds will steer early discrete cells eastward, starting with hail threats before clustering boosts wind potential.

Montana Core and Eastward Push: Central Montana, plus adjacent Idaho and northwest Wyoming, sees similar setup—growing cumulus from dynamic lift ahead of an upper wave eroding caps over warming air. Expect initial supercells or semis with 1-1.75 inch hail, transitioning to windier clusters spreading into central Montana by evening.

Dakotas Peak Threat: Southeast North Dakota, western South Dakota, and the Nebraska Panhandle face the most intense hazards. Black Hills convection, aided by a surface low, will evolve amid 1500-2000 J/kg CAPE and strengthening shear aloft. Supercells here could drop baseball-sized hail and 75 mph blasts as storms widen.

A Mesoscale Discussion (MCD) from SPC means meteorologists spot short-term, localized severe risks too new for formal outlooks—think watches coming soon if trends hold. This clustered threat stems from shared ingredients: terrain-triggered storms riding shear into unstable air.

Stay Prepared: Monitor radar and NOAA Weather Radio. Anchor outdoor items, seek sturdy shelter if storms near, and have a severe weather plan. Check local NWS offices for updates as watches likely emerge soon.

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