andyhb

Too much shear for the updrafts currently. Dewpoints not where they need to be.

Instability worse than forecast, shear better than forecast. Question is which one wins.

Look at the VWP from DMX before deciding that.

Obs > CAMs especially on a day like this.

I mean model soundings up there are yielding moderate buoyancy even with 67/63 type T/Td pairs, which I think is achievable with the dry slot. Cold air aloft helping a lot.

Liking the IA triple point right now given the dry slot pushing in. Should see large hodographs juxtaposed with sufficient low level buoyancy for tornado potential there. The junk further south and lack of warm frontal progression really has me questioning the current moderate risk area.

All of that convection in AR and MO is probably going to have some say in whether better moisture can make it far enough north in time. Mesoscale trends aren’t exactly looking favorable for a bigger event at this time.

Big TBSS on that Jefferson City storm. Looks to be on track to impact some of the STL metro (after they already got hailed on last night).

I mean, you could always try and go work for them then.

12z Euro was a bit of a downtick from earlier. Weaker wind fields/less instability.

Pretty ridiculous fixed layer STP ensemble mean from the 12z HREF.

Synoptics here scream regional severe wx outbreak. One of the more synoptically evident events we’ve seen in recent years. Now it’s down to the mesoscale to decide on ceiling. Not every day you see a trough with a 110+ kt 500 mb max impinging on a warm sector with mid-upper 60s dewpoints regardless of season. Wind fields seem to be gradually shifting towards more of the “these cells could be strongly tornadic” idea, but I’d also like to see what we wake up with tomorrow. I have little doubt the NAM 3 km is at least somewhat off in terms of eastward extent of the warm sector though.

Posting LOT’s discussion for posterity because it is a beast.

This one is a bit different where basically every CAM is in agreement on a string of pearls ahead of that front. We have a very clear focus for initiation this time in the warm sector. I do believe the HRRR parameters may be a bit overblown in terms of instability, but its wind profiles are extremely impressive.

Every other model has temps above 70 over most of the IL warm sector at 21z.

Advertising warmer? Even the GFS has temps in the low-mid 70s at 21z Saturday. Would make a big difference thermo wise, especially with seasonably high levels of moisture. If we can get the LLJ to be at least SSW by go time, that will yield shear profiles more typical with significant tornado events in this region.

Regarding the 3 km NAM, I will eat my hat if it is 65-68˚ in the warm sector at 21z Saturday. Those temps look way too low.

Storms moving at the speed of light would be number one regarding chasing. I do think there’s a pretty strong possibility this stays mostly discrete until the evening though. Would maybe like to see a bit more turning in the lowest 3 km and a bit more instability, but I’m inclined to think that the arcing Pacific front/pseudo-dryline, in addition to the triple point in IA early on, should be a breeding ground for supercells. Tornado potential dependent on how the low level wind fields evolve (and how fast the deep layer cyclone occludes).

Why do you keep tagging me with the weenie emoji?

Definitely a few similarities with the setup that yielded the deadly TN tornadoes on 3/3. Strong westerly flow aloft with similar hodograph structure and I'm going to bet that the NAM/NAM 3 km are too cold at the surface. Any southerly component to the surface wind will yield large 0-1 km SRH when your 850 mb jet is 50 kts out of the WSW.

JISAO PDO is no longer being updated. Also, the +AO has reached an all time record daily value at 6.34, surpassing 2/26/90 at 5.91.

Getting increasingly concerned that the strongest low-mid level FGEN and vertical ascent may set up right over the I-44 corridor in OK and N TX with this. Someone who stays cold enough is going to see 12-18”, which, for here, is crippling. With that said, the 3 km NAM seems stubbornly persistent in its idea of really suffocating the band before anything really gets going.

Euro/EPS have been getting stronger with the cold dumping into the NW during this period as well, more of an Arctic source region than a Pacific one.

That was a very 2008-like 00z Euro run. Probably a couple of severe wx events in the SE and a major winter storm with the first for Chicago/GRR. Big ice storm for DTX/Ontario.

As is tradition, let's give our calls for how active the first tornado season of the decade will be. Looks like we'll be heading towards spring with weak positive ENSO and roughly neutral PDO, in addition to a lack of drought over most of the area east of the Rockies. I have a feeling like we may see another A/AA season given some of these climate states, but obviously sub-seasonal activity will again be key. Will have more analysis later. Number of tornadoes: 1310 First High Risk: 4/18