andyhb

Lol I was about to be like "whaaaaaa". Cedar Rapids might have a problem here shortly with that cell on the southern end.

Big tornado near Stanhope now.

There literally was a spotter confirming it at the time and a TDS showed up the scan after. Now have this.

Pretty sure that's confirmed...

Tornado ongoing west of Lake City, IA, heading towards town.

Tornado watch out for Iowa, 50/20 probs. Edit: 10% tor now in the 20z D1 update.

Differential heating boundary draped north of I-80 in Iowa looks to be the focal point later. Mesoanalysis progs have large 0-3 km CAPE in that zone and there should be a fair amount of near-surface vort with backing surface winds in its vicinity.

Matt Petkovic is a clown, wouldn't trust anything that guy spews.

That is a nasty looking tornado.

Holy smokes. Debris to at least 15k feet.

Friday could have significant potential just looking at the progged wind fields overlapping a wide warm sector (pending Thursday's convection). Pretty classic WNW flow hodographs showing up in forecast soundings. Shortwaves with 70-80 kt 500 mb maxes this time of year don't tend to go quietly.

ND/MT/S SK target looks pretty ripe this afternoon with mid-upper 60s dewpoints near the triple point, an arcing dryline, strong ESE surface flow and SE flow at 850 mb pushing 50 kts. Upscale growth would be the main concern, but I'd imagine there will be at least a couple tornadoes in that area later. Further south, moisture is overperforming the HRRR (no surprise) and there's certainly an opportunity for initiation in WY/NE later as a subtle shortwave ejects from the Rockies, although 700 mb temps are quite warm. Certainly a lower probability threat than further north, but could yield something pretty spectacular if it works out.

Here we go again.

You live in Addison TX. Have you not been paying attention to the past week in N TX?

Here's my chase account from yesterday on Stormtrack from what will be a top 5 chase personally for a long time to come. https://stormtrack.org/community/threads/2021-04-23-reports-ar-la-ms-ok-tx.31822/post-371406

Day has some similarities to 4/22 (Springer/Madill) last year being right at the base of the trough with cold air aloft promoting a lot of 0-3 km CAPE and strong updraft accelerations. Ingredients that I'd look for more of are low level flow/moisture depth and also the eastward extent of the warm sector. I'm wondering if some warmer temps closer to I-35 could promote a threat closer to the main LLJ axis, which would raise the tornado threat for DFW north to OKC.

That 12z EPS mean for 4/27 is nasty as hell.

Quality posts. Only the best.

What in the crap are these soundings I'm pulling on Sunday off the NAM/NAM 3 km... 3000 J/kg CAPE in the Mid Atlantic in March (not to mention with a shear profile favorable for sig severe)?

The veering of the surface winds in behind the confluence axis in E MS does give me some pause about the early phase of the event. May take some time to respond to pressure falls associated with the deepening low.

Yeah that's a pretty decided shift on the NAM towards a more organized surface low and slower progression, and that has been taking place since last night.

There is definitely an EML here. Capping and the EML are two different things.

The other 12z CAMs (WRF variants) aren’t quite as high end as the HRRR, but they are certainly more active than the 3 km NAM. ARW and NSSL are probably outbreak scenarios taken verbatim.

Well, safe to say this could be a pretty big event. Convective evolution/mode concerns notwithstanding, there seems to be a consensus across all of guidance for hodographs supportive of long-lived supercells with long tracked tornadoes as early as 15-18z in LA/MS. The degree of low-level moisture is on the high side for this time of year, and I wonder if there may be some subsidence in the late morning following the passage of a potential lead shortwave that could help to suppress junk convection. Any discrete storm in the warm sector that manages to root in that boundary layer by early afternoon is likely going to be a problem. Now it's a question of what wrinkles the mesoscale throws in (and whether the NAM comes around more to the potent solutions suggested by the globals, particularly the UK and Euro).