06/04/09 FCST: CO/NE/WY

[Jacob Ferden]

This day could be somewhat of a sleeper ahead of the more classic setup on Friday and Saturday, IMO. Good shear profiles and a pool of CAPE around 2,000-2,500 j/kg near North Platte on the GFS. Moisture is a concern, with dewpoints progged to be AOB 60 F. I don't expect anything too crazy, but I would take a nice LP supercell or two over the high plains to whet my appetite.

 

[Bill Schintler]

Chase Target for Thursday, June 4

Chase target:
Woodrow, CO (21 miles south of Fort Morgan).

Timing and storm mode:
Storms will initiate in southeastern WY and further south over the Front Range by early afternoon, and spread east of the Denver Area by 4 PM MDT. High-based supercells will be likely, with large hail and damaging winds the main threats. Storm motion will be towards the southeast at 20 mph.

Synopsis:
Little change will take place in the broad NRN stream trough along CONUS/CAN border over the next 24 hours. Further S, a piece of energy will eject from the mid-level low off the CA coast, and then ride over the Four Corners ridge and then dive SE across CO and NEB. The SFC map indicates few features, with weak return flow and modest moisture return W of a LLVL ridge.

Discussion:
Moisture remains meager over the High Plains, however dewpoints should increase to 50 F and perhaps locally to 55F in an upsloping regime in NERN CO., where MLCAPE’s should approach 800J/kg with steep lapse rates overspreading the region.

Storms will initiate first in the Cheyenne, WY area by noon; followed by convection over the Front Range W of Denver to Fort Collins. By mid afternoon, storms will spread E to about Last Chance, CO (60 miles E of Denver) with orographic enhancement as SERLY SFC flow rounds the Palmer divide – Denver cyclone. Further S, another area of storms should fire over the Sangre de Cristo Mountains, and later over the Johnson Mesa in NERN NM; where weaker overall shear will limit severe potential. Strong capping via the EML and mid-level ridging should inhibit further development E of the Front Range.

In NERN CO, deep-layer shear will increase to 40-50kts as a mid-level shortwave overspreads the area. In addition, a helicity bulls-eye will exist just north of the Palmer divide were SFC flow backs.

- Bill

10:05 PM CDT, 06/03/09

 

[Scott Hammel]

We will be heading out for this for sure. Too close to home not to! Like Bill mentioned before, we finally have some shear to play with. 50kts will be more than sufficient to get cells rotating. Dew points in the mid 50's and adequate moisture returns looks to me like a great setup. We are targeting a triangle area of Ft. Morgan to Sterling to Yuma.

 

[Mark Blue]

Unlike the last few days (and posts) I won't have the luxury of sitting in the field watching conditions develop and adjusting my position on the fly. I will be at work watching conditions develop as time allows and hoping that I can get off around 2 pm to catch a couple of nice supercells along I-76 or perhaps I-70. If things go the way they normally do in Colorado with these kind of setups, storms will initiate around 12 - 1 pm MST on the Cheyenne Ridge or the foothills west of Ft Collins in Larimer county and then move ESE into Weld county. From there they will continue to move SE into Morgan and Washington counties and will generally catch the eastern end of Adams and Arapahoe counties. Dewpoints will be close to 50 degrees and we will finally have some bulk shear to deal with, hopefully 40 knots. A surface trough and orographic features will provide the necessary lift and plenty of winds turning with height. The surface winds will be light and out of the SE. Hopefully they will pick up as currently that is the one fly in the ointment. I am looking to see a nice supercell or two and if all goes well perhaps a landspout or brief tornado.

 

[Matthew Crowther]

SPC removed the 5% tornado risk- good call, the new NAM is more realistic with dewpoints in the low 50s maybe. Still expect a few supercells, maybe we can get some good "mothership" type structure and some lightning photo ops. The Palmer Divide and Cheyenne ridge both need to be watched- will decide on a more specific target later.

 

[Andrew Stoller]

I'm sitting on my roof as I type, looking north towards the Palmer Divide. Very high based convection is firing all around, as the visible satellite imagery shows. If this activity can move east along the divide towards Limon and organize into something more surface based, I'd say there's a chance for a photogenic supercell.

looks like points to the north near Denver/Ft. Collins/Greeley area were socked in with more cloud cover through the morning, limiting isolation and heating.

If it looks like something's going to go, I'll be out the door.

 

[Patrick Martin]

Andrew is correct pertaining to surface heating. Areas north of I-70 were socked in with fog and low clouds this morning, which did not fully burn off until after 9am MDT. Looking at surface obs, areas south of the Palmer Divide are 5-8 degrees warmer than areas north. There is plentiful sunshine and dews are near 50 along the front range north of I-70 with things warming quickly, although with the delay in surface heating north of I-70 today, initiation is likely occur first to the south of the Palmer Divide, and then later this afternoon further north.

 

[Kelley Austin]

We are now sitting in Fort Morgan, Co. in Frankey's coffie shop watching GRL3. Looks like some initation is taking place NW ATTM. We will sit here and wait for a while to see what happens with the storms heading our way and decide witch way to go from here.

 

[Larry J. Kosch]

SWW Issued for CO & NM

SPC has issued a SWW for Eastern CO, Northeastern NM and the panhandles of TX, OK. Nexrad radar is showing a few active cells SE of Denver CO. Threat is mostly for strong winds and moderate hail. SPC has classified the chances of tornadoes as "LOW".

 

[Larry J. Kosch]

SWW for OR and UT??

SPC has pulled a new one on us...a SWW for OR and UT!! Apparently that upper level low in the Pacific is churning up storms on the West Coast!

How often does that happen??