5/22/2010 FCST: NE, SD

[jshields]

i'm no longer going out as this appears to be out of my range of chasing. the latest day 1 outlook has moved the slight risk even further north and west. right now moneywise, i just can't commit to a 6 or 7 hour drive with questionable storm chances. but if i were out i would be further west than aberdeen for sure. i would almost head down south and west to the pierre area. there you can cross the river to head east or west and also go north. some notes with the 12Z RUC, i like how the 12Z RUC has cape values over 6000 j/kg over most of nebraska and even a small area of 7,000 j/kg!! i know it grossly overstimates cape, but its a shame something can't move through that juice and set something off. it has the center of the low way up near the canada border in nw n. dakota by tonight. the surface winds are pretty much due south over the whole area with no real backing until north dakota and the 12Z ruc also shows nothing on radar as of 0Z(7pm) tonight anywhere in sd or nebraska. i'm sure something will fire somewhere, but it might not be until after dark. the latest nam shows storms at 03Z tonight over central s. dakota.

 

[George Grant]

The capping inversion is still my biggest concern at this time. The RUC and NAM have the cap eroding in the Mission/Valentine area by late afternoon. But, the cooler H7 temps aren't rolling in until 00Z or later, if they even move into the eastern half of SD or not. And, H5 height falls are slight and trailing the favorable area.

The SRH/EHI indices are somewhat juxtaposed to the north and east of the aforementioned area. But, moisture will not be a problem as 70+ Tds have finally reached the north central Plains after having experienced 40s Tds through mid May! And, CAPE will be standing tall at 3500 - 4000j/kg.

Also, the low level jet, while cranking along at 40-50kts, is tending to a south/almost southwesterly line. It doesn't start backing until hitting the ND line.

But, even being in Nebraska, this will be a drive, but vacation is here. I'll have to set sights on the Plankinton to Huron area for now.

Geo

 

[Mark Blue]

I think the atmospheric variables have been covered pretty well in previous posts, so no need to reiterate that. We're going to try and play the triple point today. Right now it appears the surface low is in SW SD and is progged to move NNE throughout the day. I initially thought Murdo was a good target, but I keep thinking further north since the best upper air support is up that way and the surface low will migrate that direction as well. It seems the best forcing and helicity is further north than the best instability and moisture (EHI), but hoping throughout the day the ingredients become juxtaposed. I'm watching the Mesoanalysis page on SPC very closely to try and track with the movement of the low pressure center throughout the day.

 

[Derek Weston]

Significant severe parameters setting up across central SD right now. . . quite the loaded gun.

Surface based CAPE near 6000 j/kg, pockets of 300+ 0-1KM SRH... sig Tornado index of 8, supercell of 28.

If we see initiation during daylight... potential for a significant tornado across NC to NE South Dakota. (as it ought to be a rather isolated cell in an extremely unstable environment)

 

[Mikey Gribble]

Man I haven't been paying any attention to todays setup until now, and damn it looks good over central South Dakota. I would be sitting north of Pierre, South Dakota. Maybe northeast of there. I haven't gone over suface data yet. I have only started to look at data, but extreme instability, decent directional shear and sufficiently low LCL heights should all make for a favorable environment for strong tornadoes. Any persistent discrete storm firing in the Pierre vicinity will almost certainly be tornadic.
God I wish I was chasing today. This is probably one of the top five opportunities I've seen for tornadoes this year assuming the cap doesn't hold. Again I just started looking at this so I don't know what kind of CINH we are dealing with.
Anyway, target north of Pierre a ways to start off. Good luck if you're out there.

 

[Nick Nolte]

Yes, today started looking a lot better, especially as the day went on. I am N of Pierre right now. Yesterday CINH was forecast to be 150-200. When I looked at SPC Meso Analysis around lunch it was all eroded, or in the process thereof. There's some nice Cu starting to go up here. With CAPE through the roof, they should start taking off once they overcome what little cap is left in this area.

 

[David Reimer]

Very Impressive Loaded Gun profile in place over South Dakota this afternoon. Had I not been so concerned about the lack of sleep or the cap last night I would have made the 13-14 hour drive up there for today. Although there still is concern over the cap, I'm going to base this discussion on the thought process there will be convection this evening. Looking at instability, with SBCAPE over 5000 J/Kg providing 1 KM EHI values of 9. Craven/Brooks Sig. Severe Index is at 130K over C. SD as of 21Z. Since only a few storms are likely they should be able to easily dominate the local atmosphere. I would be surprised if the dominant storms were not cyclic in nature and did not produce several tornadoes. Easily one of the more impressive setups for the plains severe weather setup. Fortunately a majority of that part of SD is just rural farmland. We could easily have one of the top storms of the year this evening, like June 17th of last year. That is all assuming a storm does indeed fire, which SPC seems fairly confident on occurring since they added the Sig. TOR at 20Z.

 

[Mikey Gribble]

CU is definitely sharpening up along the perimeter of the moisture wrap around. I don't have a good map available at the moment, but the area around and northeast of the town of Gettysburg looks absolutely prime for a tornadic supercell. Based on the most recent satellite images if you are sitting there you are money. It does look like the cap will break and that area is right about where any storm firing near the curl in the moisture wrap around should begin to mature and become tornadic. If you are out there I'm jealous.

 

[jshields]

i really hope i don't regret not driving the 7 hours to get in on the potential action. like its been said the atmosphere looks ready to explode with some of the most impressive parameters we've seen yet this year. i see a few little cells just nw of gettysburg, sd. surprised a tornado watch hasn't been issued yet given the md came out almost 3 hrs ago talking about issuing one.

 

[Andrew Stoller]

Initiation has occurred near Mabridge, SD. If that thing takes a right turn, it's going to go right though the area of best dynamics!

:edit: lots of live streaming on the storm. It's just billowing up like a mushroom cloud. You can visually see it.