Jeff Frame

Morning Class Weather Discussion: March 10, 2026 In this video, I discuss the severe weather potential across Illinois on March 10, 2026.

My weather discussion from class this morning mediaspace.illinois.edu/media/t/1_7o...

More veered winds in the sun with greater vertical mixing is causing this

I've that several times too. MPAS is worse, unfortunately

Subtle shifts in the HRRR from the 12Z to the 17Z run: The lake-breeze infused front is farther south over NE IL, and temperatures are a few degrees cooler across E IL/IN due to persistent low cloud cover

Tornado potential is basically zero north of the front

Most models are underforecasting the extent of low clouds across the warm sector (we had this problem yesterday), so I'm less confident in the mid-afternoon round of storms that most guidance from last night depicted

Tornado-driven Moderate Risk issued. The tornado risk should peak around and in the few hours after sunset, as low-level hodographs enlarge significantly (compare 21Z and 00Z) and LCLs lower

It still has a fundamental flaw in its core solver that results in storms are much too big. Relative to verifications, convective footprint is massive — among other issues.

RRFS output showing 21335446 supercells developing over northern Illinois in 60 minutes

There's a reason why I don't take the RRFS seriously, and you shouldn't either.

While some overnight storms could be severe, this risk is more muddled, but these storms should not be as intense as those forecast over northern Illinois and Indiana this afternoon.

It still looks like the bulk of the severe storms remain north of Champaign-Urbana this afternoon, but they may be just close enough that we're included in a tornado watch at some point.

Under the old system, hatching was abbreviated SIG, for significant severe, while it's CIG under the new system, for conditional intensity guidance. It's a coincidence that they're pronounced the same.

CIG2 tornado risk across northern Illinois

( #NWSLincolnIL): Isolated to scattered thunderstorms will develop by late this afternoon or early evening near a warm front draped between the I-74 and I-80 corridor.

Storms will become more widespread across central #Illinois late this evening and overnight. #ILwx #wx #wxsky

I have a department seminar until 4:30, so I won't be chasing either!

Evening model guidance indicates that the bulk of tomorrow's severe weather threat is north of Champaign-Urbana, along and just south of I-80 in northern Illinois. Severe weather potential has increased for that area, including tornadoes and large hail.

The 00Z HRRR reminds me a lot of some of the CAM runs from yesterday

( #NWSIWX): This 4th, and anticipated FINAL UPDATE to the March 6 #tornado event includes full information on the Three Rivers #MIwx tornado

Additionally, the narrative was updated for the Union City, MI tornado and more definitively states the EF3 rating mesonet.agron.iastate.edu/wx/afos/p.ph...

I think they're showing the same thing, only MPAS is much warmer due to no low clouds. MPAS completely blew the cloud forecast today though

Hodographs are also quite favorable for large hail, and the strongest storms may produce hailstones greater than two inches in diameter.

If the low-level jet is the initiation mechanism, this may lead to more clustered storms once they form over northern Illinois. While tornado potential is evident from soundings, it may also rely on storm interactions, which are impossible to predict in advance.

The general trend toward later convective initiation across Illinois tomorrow, around or just after sunset, continues with the morning model suite.

IEMBot Image

The Storm Prediction Center issues Day 2 Convective Outlook (Max Risk: Enhanced) at Mar 9, 6:00z Link

( #NWSLincolnIL): Severe thunderstorms are expected across central #Illinois starting late Tuesday afternoon/evening, continuing overnight.

ALL severe hazards will be possible: damaging #wind, large #hail, and a few #tornadoes. Heavy rain & localized flooding may also develop. #ILwx

Models are trending later and farther west with convective initiation over Illinois on Tuesday, consistent with the synoptic pattern, and likely also owing to midlevel subsidence behind a midday shortwave trough (shown in the image).

IEMBot Image

The Storm Prediction Center issues Day 3 Convective Outlook (Max Risk: Enhanced) at Mar 8, 19:33z Link

We probably won't know the answers to all these questions until after storms form Tuesday afternoon, but this is the difference between a heavy rain and hail risk and a risk for potentially significant tornadoes.

How does the boundary move during the afternoon?
How do the cold waters of Lake Michigan influence these boundary characteristics?
How many storms form along the boundary and how does their outflow influence boundary characteristics?

Questions include:
How sharp is the boundary (more diffuse favors a greater tornado threat)?
What is the position of the boundary (tornadoes favored along and just south of it)?
Do storms track along and south of the boundary, or do they become elevated atop the cold air N of it?

The character of the boundary forecast across northern Illinois on Tuesday illustrates how small scale details can be crucial to severe weather forecasting. Here are two different high resolution model forecasts valid Tuesday afternoon