06/25/2005 FCST: CO Front Range

[Tom Dulong]

For those who are tired of chasing the cap that can't be broken, Saturday may be your day along the CO Front Range. Could be a classic day-2 severe storm event...the biggest threat would be large hail but would not rule out an isolated tornado or two. Weak frontal passage Friday will set the stage for Saturday as southeast return flow should advect in lots of moisture (surface dews near 60 if you believe the new NAM). This should also get the DCVZ going for better low level vorticity/helicity. The cap is forecast to weaken ...700 mb Temp from +15 down to +12...outflow from mountain convection should be more than enough to get things going. Models also bring in a 60 knot upper jet and place the Front Range under the favorable right-rear entrance region.

Here's what the Boulder WFO AFD says...

IT MAY BE THAT SATURDAY IS THE REAL DAY 2 AND HAVE THE BEST CHANCE OF SEVERE THUNDERSTORMS...

 

[Jonathan Merage]

Well, Tom--per tonight's ETA, looks like we're in for a real high-plains treat this weekend!! ETA showing good consistency in the past few runs (especially those P.M. updates, for some weird reason) with pulling that surge of moisture (now solid 60s Tds!) right into NE CO. Can't remember the last time I saw such a strong influx of moisture, instability (CAPE upwards of 3,000 J/kg over the entire NE corner by 18Z Sat?!) AND upper support forecast to rapidly[i/] increase to ~50kts (FINALLY)--all on the same afternoon!! :lol: .
Shear doesn't look to be an issue (not like it ever is around these parts, LOL) with signficant uplsope just hauling beneath a west-southwesterly 500Mb flow (hopefully veering more NW!) At this point, my only minor concern would be the lack of cap. On a day like this, a slightly stronger lid might make for some real 6'o'clock magic. Of course, that's all assuming this whole forecast verifies. Definitely keeping my weekend clear!
Verne, here's hoping for your next May 10, '04!! :wink:

 

[Verne Carlson]

Wow, this time of year I kind of let the SPC do my forecasting and hadn't really looked at saturday for e. CO. I see all the parameters you guys are talking about. One fly in the ointment though is in the latest ETA runs the upper level winds don't arrive until 6Z sunday. I hope this one pans out, I would love another May 10, 2004 setup!

 

[Jonathan Merage]

Hey all,

Well--today looks like a case of near total forecast verification failure (or more likely we just read too-much into it, LOL!:roll. Extensive cloud cover over the entire southern front range & very weak upper flow across the whole area (shortwave energy still lingering over UT) has pretty much killled off any real chances of tornadic supercells. Today's 'marginal' type setup will probably yield some rock-hard towers & perhaps even a couple spin-ups (along with the usual large hail), but not much else.
At best, this'll probably turn into a Day-3 event as the DCVZ intensifies overnight & draws deeper moisure into the northeast corner. SPC says the shortwave should cross NE CO tomorrow afternoon-- so there u have it!
Still watching for tomorrow (assuming tonights convection doesn't spoil the setup too badly overnight! That would be dissappointing...