2012-06-06 FCST: CO

[Adam Adkins]

It is looking more and more to be the first real day of severe weather in the northeastern plains of CO on Wednesday. A frontal surge should drop through around noon and bring in 50s dpts with eventual highs in the upper 70s to mid 80s. CAPE looks nice over the entire northeastern plains with 1500 to 2500 j/kg anticipated with almost no inhibition. Shear is certainly adequate with influence from western trough for supercells with a few tornadoes. Both the GFS and NAM develop a bulls eye of precip over the northern border, but models also show an area of convergence around and just south of the Denver metro, which would enhance storm and tornado chances there tomorrow afternoon. We'll see!

 

[Terrence Cook]

Agree with Adam, this set-up looking better as the N Plains set-up goes down hill. If the dews can verify then CAPE will be exceptional. Turning is supportive of slow moving sup's with a decent hail threat and perhaps something extra... Like Sterling for a starting ground and see what unfolds from there.

 

[Ben Toms]

Ahhh the reason why I started chasing in the first place and continue to do so - High Plains supercells. Adam covered the ingredients well, but I think 2500 J/kg of CAPE would be a little on the optimistic side given upper 50 dews. That aside, the 00z NAM continues to hold strong on a Cheyenne Ridge/Fort Collins storm blowing up mid-afternoon (precip. signals break at around 21z) which is a typical time for Front Range storms, if not one or two hours earlier. Given that there is a disturbance at play here, the timing and placement of said disturbance will be crucial on location and timing of most explosive development. There should be storms all along the instability axis, but with local pooling of moisture aiding in an instability bubble on the south end of the Cheyenne, I believe this will be the primary focus for initial development. A DCVZ (Denver Convergence Zone) looks to set up, which would suggest a boundary developing slightly east of that forecast area. Convective feedback is corrupting the forecast skew-t's, but assuming continuous E/SE inflow, hodographs should be hooked all evening long.

I'll be out patrolling the High Plains tomorrow near Fort Collins and the Cheyenne looking for a gorgeous, structured potentially HP High Plains supercell with low end to moderate (for the High Plains) tornadic potential. Weld county is notorious for funky tornadic events, so that is not out of the question! Hopefully Colorado can redeem itself from its horrendous 2011 season.

*Edited because of accidentally calling the Cheyenne the "Laramie" Doh!*

 

[mkavulich]

The last three runs of the NAM (12z-00z) have been hinting at the reversal of the front in NE Colorado, stalling and then turning north as a warm front starting around 18z tomorrow. Storm motions should roughly parallel the front (and be near-zero anyway), so this extra low-level convergence/vorticity could really make things interesting, even into southwestern WY and far-eastern NE. The best CAPE will be solidly in NE Colorado though, and the surface winds will be nicely backed, so I think I-76 looks like the place to set up and follow the front north until initiation. LCLs will be a bit high for tornadoes in this area, but supercells seem like a sure bet, and ya never know what will happen once the storms get spinning

I'm not too excited about the Denver/south area, hodographs and CAPE are poorer in this region. However, the 00z NAM does develop convection here as well, so the potential for nice storms is there.

 

[Adam Adkins]

It looks to me that storms will likely be following eachother northeast with less actual eastward progression of convection. I can see it possible that the same areas could see multiple cells, again right up that I-76 corridor. Shear doesn't look all that great to me until closer to 00z but thats right around peak heating assuming no cloud cover. I'll be leaving Castle Rock around noon or 1 to head north and east with hopefully some initiation occurring soon following. 00z models are very consistent with previous runs so all should be on track for an eastern CO severe event tomorrow afternoon. And it is about time; what a ghastly season this has been so far.