Jump to content
  • Member Statistics

    Total Members
    Most Online
    Newest Member

2021 Short/Medium Range Severe Thread


Recommended Posts

Solid surprise tornado outbreak across OH the past several hours, now working into PA too.

Environment is lower end, but definitely supportive based on meso and short term analysis. It’s one of those enviro’s that will not work out 8/10 times, but the few times it does, production is efficient.


Link to comment
Share on other sites

  • 1 month later...

diggin it up


Highly anomalous neg tilt s/w ejecting wednesday afternoon looks poised to provide a damaging wind/tornado threat in IA/MN. Storm motions look to be some of the fastest I've ever seen beneath a 100 knot LLJ, so we're basically in uncharted territory with that. Currently, models show warm sector airmass characterized by upper 50s dews by 00z, but are very aggressive on mixing. Given strength of advection and potential cloud cover, I'm wondering if dews end up closer to 60-61 in reality. That is probably the difference maker between what is a few weak tornadoes and a localized outbreak. Secondly, forcing/ascent is exceptionally strong, so despite good shear vectors off the pacific front, would expect a QLCS in northern portions of the boundary with perhaps a few discrete/semidiscrete supercell structures to exist on the southern flank. An extremely dynamic system is in store and is certainly one that bears watching. I dont know of any good analogs to the parameter space.

As far as the ceiling of this event, concerns I have include aforementioned mixing, whether or not the MLCAPE available is enough to sustain an updraft in that hodograph, and potentially the tendency for mixed/linear modes from forcing.

Secondly, and courtesy of the 100kt 700mb jet, non thunderstorm wind gusts of 60-80mph appear possible across much of Iowa, especially if the models do end up being correct on the degree of mixing.



  • Like 3
Link to comment
Share on other sites

6 hours ago, MNstorms said:

Not buying the severe threat on Wednesday yet. GFS and NAM have been terrible at reading the snow depth. I'll doubt the 8-12'' of snow will melt by Wednesday afternoon. Minnesota hasn't had severe weather in December and the latest tornado is November 16.

I have to wonder if the sharp snowpack gradient will help sharpen the warm front in some way. Broyles not impressed by Wednesday due to lack of instability, and he's historically been SPC's most bullish forecaster. That said it seems like SPC loses their nerve in recent years when it comes to hitting cool season events hard, which is unfortunate because in the same timeframe those seem to have been the ones producing high-impact outcomes more often than the high-hype, long lead time spring setups.

Link to comment
Share on other sites

Very puzzling to not even have a marginal risk on the day 3 outlook, and could definitely argue for a slight.

I wonder if part of this is because of the geographic area we are talking about.  A December severe threat is pretty rare there.  If the exact same parameters were forecast in the Ohio/Tennessee Valley, would there have been a risk area introduced?  

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...