CheeselandSkies

5 minutes ago, Stevo6899 said:

Can you explain this further? Only mixing I'm aware of is winter mixing. Severe novice here.

When you have a relatively shallow low-level moist layer (only up to about 850mb or a little above at best on a couple soundings I just cherry-picked off this morning's 12Z 3KM NAM), vertical mixing (helped along by sunshine) can bring down that drier air, lowering surface dewpoints, thus raising LCLs (cloud bases) and possibly increasing low-level capping. At least, that's how I understand it.

A bit concerned about mixing issues with the full sunshine, SPC notes the same in their outlook especially WRT potential.

Yeah, that's a spicy run. If that stays consistent this morning, chase is a go.

Sent from my Pixel 4a using Tapatalk

1 hour ago, andyhb said:

Recent CAM/short-range guidance seems to be on the upswing for tomorrow's threat. For one, that subtle embedded wave aloft that induces surface cyclogenesis along the surface trough seems to be returning (e.g. the earlier Euro runs) that could increase the low level wind response. The RAP in particular has a fairly potent surface cyclone and pseudo-dryline. Moisture seems sufficient across most models as well.

I'd be wary of the HRRR overmixing and being too far east at this range. The MPAS from NSSL also seems to have an issue with that, although it has improved from the 00z to the 12z run.

Yeah, I thought the same after today's 12Z HRRR run. 18Z seems to be an improvement although not quite ideal.

9 hours ago, RCNYILWX said:

Doing a deeper dive at the office now using ECMWF ERA5 reanalysis maps to look at antecedent conditions prior to some notable cool season events. This one definitely has questionable moisture with Gulf currently scoured out.

2017 not a bad comp w.r.t. Td over the GoM within this range of the event, though it had a better sfc pattern for more rapid moisture advection with the primary CO low a good deal stronger and a much stronger surface high (1035 mb) off the east coast.

Some other notable cool season events, November 17th, March 15, 2016, March 27, 1991 to name a few, had much better source region moisture present.

What Tuesday does have is exceptionally steep mid-level lapse rates as you mentioned with cold -15 to -20 C h5 temps. Seeing how February 8th performed with relatively questionable moisture quality, the cold mid-level temps/steep mid-level LRs could help compensate for the potentially middling moisture quality. We're concerned here that if the sun breaks out at all on Tuesday, Td could mix out substantially especially with northward extent.

Perhaps a narrow zone near the warm frontal zone is best bet where you can pool the moisture with a longer residence time and pump up the 3CAPE to the 50+ threshold. Still thinking southern LOT CWA and points south with this in mind.

 

It's interesting, when they initially put out the Day 4-8 areal highlights on Thursday, SPC seemed pretty confident that moisture return would be less of an issue with this setup than would be expected for the time of year. What changed?

1 hour ago, andyhb said:

12z Euro is probably a localized significant tornado event across central IL from I-70 to I-80.

Yup, keeping an eye on it as posted above.

06Z GFS presents the area roughly near Ottawa-Streator, IL as a possible chase target. FH090 00Z sounding shows a stout low-level inversion but it ought not to be as strong during the preceding couple of hours. There's decent streamwise vorticity in the low levels and a solid westerly component to the 500mb flow.

The higher-end scenarios with this setup don't look to be panning out at this point, but the atmosphere keeps trying to tell me it only takes one (storm) in the sweet spot.

A few flakes flying outside, but it's all melting upon contact on pavement.

00Z GFS. Near Oglesby/La Salle, IL:
 

@andyhb with a nice succinct breakdown of why the models are having such a hard time getting a handle on this setup over in Central/Western.

Zero mention from MKX in the AFD or HWO despite SPC Day 6 risk going right up to the state line and plenty of model runs nudging the warm sector into the southern tier or two of counties at least. Meanwhile the mets at my work have already gone with a "First Alert Day" for Tuesday.

Just a few small, dirty piles/patches left on north-facing/shady embankments/hills or in parking lots where the plows stacked up the two January storms that comprised the bulk of our "winter." Reviewing my railfan pictures/video, that's quite a difference from five years ago today:
 

Ironically, most of that cover likely was the result of the "clipper train" discussed in this thread:
 

Touched 60 in Madison today. Still some snow piles along north-facing hills/embankments. @madwx

8 hours ago, hawkeye_wx said:

I was looking forward to getting some good rain with storms next week, but the models have trended toward pushing everything to the east too quickly.  The Ohio Valley and eastern Lakes get storms, but farther nw we get nothing.

Not great to see but I will add the caveat that models, particularly the GFS, are prone to being excessively progressive at this range. If we do end up with a nice large wavelength trough, it shouldn't move that fast.

12 hours ago, RCNYILWX said:

Late February 2017. It was the 3rd warmest February on record for Chicago. 1998, a super Niño, is second warmest.

 

Yup. Also had the outbreak featuring the Marseilles, Washburn & Crossville EF3s and the Perryville, MO-Christopher, IL EF4. This on the heels of one of the more notable icing events in southern Wisconsin in recent memory (for me at least). We actually had enough accretion to noticeably weigh down the trees, and leave a clear glaze on everything even after the sun came out the next day.
 

2016 also had a relatively early season outbreak in the region; March 15th seemed about the earliest possible non-ridiculous time of year (remembering events such as 3/13/90 and 3/12/06) for this area to me so I went out and chased, got a glimpse of the Trivoli-Hanna City EF2.
 

Of course, when the next year rolled around, late February just seemed way too **** early so I sat that one out. Apparently the lesson didn't stick because I also sat out the Winterset day in 2022 because I thought March 5th was too early, although in my defense that setup also looked rather marginal on most of the model runs in the days leading up to it. By the time it began to look genuinely good closer to go time, I had already talked myself out of chasing. Keota day last year was also quite early season for the region, but with it being a moderate/eventually high risk and the models consistently showing that (lack of) deep moisture return would not be an issue, confidence was much higher.

Now of course in 2024 we get something truly stupid, with tornadoes in Wisconsin on February 8th, with dewpoints not even reaching 50, and one of those being one of the longest-tracked and most impactful in the south-central part of the state in nearly ten years (going back to the cluster of late-night strong tornadoes on June 16-17, 2014, when an EF2 missed my apartment building by about two blocks while I was staying in a hotel, having driven to eastern Nebraska to whiff on what turned out to be the Pilger event).

Ironically, the least likely six-week period out of the year to get tornadoes in the Midwest in recent years seems to have become what should be the peak; May through mid-June.

7 hours ago, Mogget said:

Interesting—hadn’t thought about it as other than a funnel cloud.  This AM, I can see that it stirred up some dust and disturbed a brush pile left from last weekend’s pruning.  Or some wind did do, anyway.  There were some good, strong gusts for awhile.

There was another angle showing a pretty clear debris circulation with the one near Albany. Obviously the emphasis is on Evansville etc. today but I think there were likely at least two tornadoes with this storm.

Edit: Juda/Albany supposedly already confirmed EF1 but I have yet to see anything on MKX's event page, a PNS or their Facebook page. May be yet another instance of someone on X stalking the DAT.

1 hour ago, andyhb said:

...or not

That's news to me. I always thought they were rated on the single most destructive thing they did.

Seen a couple videos of the Evansville-Edgerton tornado. Actually looked smaller than I was expecting based on the size/depth of the CC drop. Must have been small but fairly strong, and hit a lot of stuff.

Can see the debris fallout on this scan. Go figure, this 2% day with dewpoints barely (if even) touching 50 will not only go down as the first February in Wisconsin history, but one most destructive/noteworthy in south-central Wisconsin in quite some time. Missed my parents just to the southeast, similar to the Dane Co. one from 3/31/23 which I called them about as I was on my way home from my Keota chase.

2 minutes ago, HillsdaleMIWeather said:

Spc kinda dropping the ball with no watch in effect with this many supercells oippit

I think they did well. This is overachieving my expectations by a lot, otherwise I would have actually gone out lol.

Man.

2 hours ago, CheeselandSkies said:

Not too surprising unfortunately, although SPC has an MD out.

https://www.spc.noaa.gov/products/md/md0113.html

Shame, really because this is a nice setup otherwise.

Famous last words, lol.

1 hour ago, Chicago Storm said:

Regarding today across IA/IL/WI...

Not too surprising, but the four-some of models that were most enthused with today have been too high with dew points across the target area.

The HRRR, RAP, FV3, and RRFS had been consistently advertising a solid area of low-mid 50's dew points developing across the target area. However, in reality dew points are running several degrees behind those projections, only in the mid-upper 40's as of 2PM.

Not too surprising unfortunately, although SPC has an MD out.

https://www.spc.noaa.gov/products/md/md0113.html

Shame, really because this is a nice setup otherwise.

GHD I was fun; although (at least in Milwaukee, where I was living at the time) the wind caused so much drifting that the snow depth elsewhere didn't really seem all that impressive to me. I have no memory at all of GHD II, as I don't think it affected southern Wisconsin all that much in terms of noteworthy totals.

SSWE is still a dirty word to me because I blame it for about 10 straight weeks of freezing my b***s off going to to my car at 2:50 AM for work; and then murdering the season between the April 27-28 Dixie event and the June 16-18 Pilger etc. outbreak in 2014; with BA temps constantly getting pumped into the Midwest all through May from the endless Hudson Bay vortex. I don't understand the nostalgia for that year on this forum. I've since learned it's more nuanced than that, but it still gives me PTSD.