Spring Storms, Solar Flares, and a Late-Season Freeze

Welcome back to the Weekly Dispatch. March is going out like a lion this year, and honestly it has been one of the more active final weeks of the month in recent memory. Let us break down what happened.

Severe Storms Rattle the Ohio Valley

A powerful low-pressure system tracked northeast out of the southern Plains on Wednesday, dragging a warm front through the Ohio Valley and setting the stage for widespread severe weather. Surface dewpoints climbed into the upper 50s across southern Ohio and Indiana by the afternoon, and the Storm Prediction Center had already issued a moderate risk for the region -- their first moderate-level outlook of 2026.

By 4 PM EDT, supercells were firing along the warm front from Louisville through Columbus. Cincinnati took the brunt of it, with a confirmed EF-1 tornado touching down in Warren County around 5:30 PM. Wind gusts hit 74 mph at the Dayton International Airport. Hail up to 2 inches in diameter was reported in at least eight counties across southern Indiana.

The convective line pushed into western Pennsylvania by evening, weakening as it outran the instability axis. All told, roughly 180,000 customers lost power across Ohio, Indiana, and Kentucky. The SPC logged 47 severe wind reports and 12 tornado warnings by the end of the event.

What Made This Event Stand Out

The timing was notable. While late March severe weather is not unheard of in the Ohio Valley, this level of organization -- discrete supercells with rotating updrafts -- usually waits until mid-April. A 140-knot jet streak at 250 mb provided exceptional upper-level divergence, and 0-6 km shear values were running 50 to 60 knots across the warm sector. That is textbook supercell country.

Solar Activity Picks Up

Meanwhile, 93 million miles away, the Sun reminded us that Solar Cycle 25 is not done yet. Active Region 3942 unleashed an M7.3-class flare early Thursday morning at 0214 UTC, producing a Type II radio sweep and a fast-moving coronal mass ejection. NOAA's Space Weather Prediction Center estimated the CME would arrive at Earth by Saturday afternoon.

The Kp index spiked to 6 overnight Saturday into Sunday, pushing auroral visibility as far south as the northern tier of the US. Observers in northern Minnesota, Wisconsin, and Maine reported vivid green and purple displays. The Bz component of the interplanetary magnetic field turned sharply southward around 0400 UTC Sunday, which is exactly the trigger you need for enhanced geomagnetic storming.

For anyone running HF radio, conditions were rough on the dayside for about 18 hours post-flare. The 10.7 cm solar flux index was sitting at 178 heading into the weekend, well above the cycle average.

Late-Season Freeze Catches Farmers Off Guard

As if the severe weather and space weather were not enough, an unusually cold airmass dropped out of central Canada behind the departing storm system. Bismarck, North Dakota bottomed out at 9 degrees Fahrenheit Friday morning -- a full 28 degrees below normal for late March. Fargo hit 11 degrees. Pierre, South Dakota recorded 14 degrees with a wind chill of minus 5.

The National Weather Service issued freeze warnings and hard freeze warnings from Montana through Minnesota and into northern Iowa. This is a real problem for winter wheat that had already broken dormancy across the Dakotas after a mild stretch earlier in the month. Agricultural extension offices in North Dakota estimated that roughly 1.2 million acres of winter wheat were in the vulnerable green-up phase when the cold hit.

Temperatures moderated by Sunday, but the damage assessment is ongoing. This is a good reminder that March in the northern Plains is a coin flip and early planting decisions carry real risk.

Bottom Line

Late March 2026 delivered a bit of everything. The Ohio Valley severe event was a wake-up call that storm season is here -- keep your severe weather plans current. The M7.3 flare and subsequent Kp 6 storming were a treat for aurora watchers and a headache for HF operators. And the northern Plains freeze is a painful reminder that spring does not arrive on a calendar date.

Stay weather aware out there. We will be back next week with more.