6/5/07 FCST: CO / WY / MT / NE / KS / OK / TX

[Jeff Snyder]

Possible southwestern Kansas play tomorrow, perhaps as a primer for Wednesday. Northwest flow will stick around one more day, as a warm front develops and moves northward across southwestern Kansas. At the same time, the NAM continues to indicate a vort max / shortwave trough moving into western Kansas during the mid-late afternoon, providing well-timed mid-level support for convection. Tds will be marginal, and LCLs will be high, but forecast 1500 j/kg SBCAPE and potentially-significant low-level shear invof and north of the warm front may support supercells and a minor tornado threat tomorrow afternoon and evening. With southeasterly or even ESEly surface winds along and ahead of the warm front under NWrly or NNWrly 250mb flow, potential for more than 180 degrees of directional shear is interesting.

00z/04 GFS run (12z isn't in yet) indicates similar conditions as NAM, except it shows considerably lower Tds across western KS, with subsequent negative impacts on instability. Well, at least it may provide some minor eye candy for anyone making the trek northward from the panhandles to get in position for Wednesday.

FWIW, the NAM forecast soudning valid 00z for Great Bend KS looks decent --> http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_overlays.cgi?fcsthr=036&STATIONID=KGBD

 

[Gerrit Gulden]

Hey Jeff, Might want to Add "MT,ID,WY" in this fcst. Possible 2000 j/kg, 50+ dewpoints, 40-45mph sufficient shear which could favor supercells and possible isolated tornados from Southeastern Idaho into Montana and Wyoming.

-gerrit

 

[Joseph Spencer]

Add Colorado to that as well. SPC calling for the ever famous and mysterious Denver Cyclone to aid in shear profiles. Perhaps an interaction between boundaries for development.

 

[Mark Farnik]

Tomorrow is starting to look extremely interesting for eastern Colorado. Per the latest model soundings, temps in the high 70's with dewpoints in the low to mid 50's give 2000-3000 j/kg of CAPE over eastern Colorado by late tomorrow afternoon. The surface flow is forecast to veer to a south/southeasterly direction by tomorrow afternoon, which when combined with the west/southwesterly flow aloft, will provide a strongly backed shear profile over the area. It has all the ingredients to be a classic High Plains Day 2 post-frontal severe weather outbreak. The Denver WFO, which rarely gets too excited about severe weather situations, has some pretty strong wording in this afternoon's AFD in regards to tomorrow's severe potential:

THE INCREASING WINDS WILL LEAD TO A SIGNIFICANT
THREAT OF SEVERE STORMS TUESDAY EVENING AS THE WIND PROFILE BECOMES VERY FAVORABLE FOR SUPERCELLS. LOW LEVEL JET INCREASES IN THE EVENING WITH NAM SOUNDING AT AKRON SHOWING SOUTH WINDS AT 35 KT AT 800 MB...GIVING 0-3 KM HELICITY OF 360 M2/S2. SO...SIGNIFICANT TORNADO POTENTIAL IF THE SITUATION SETS UP AS THE NAM SHOWS.

If a Denver Cyclone does indeed develop tomorrow as forecast, this would only further enhance the tornadic potential over eastern Colorado. It also appears there will be an area of convergence over the northeastern corner of the state between easterly winds coming out of Nebraska, southeasterly winds coming out of Kansas, and westerly winds coming off of the lee side of the Continental Divide, which would serve as a focusing mechanism for intense convection and potential tornadic activity.
It'd be awesome to bag a few 'naders in my own backyard before heading to Nebraska for Wednesday's outbreak...
If it pans out anything like the NAM solution shows, there could be a considerable mini-tornado outbreak over the Colorado plains tomorrow evening, and with 3000 j/kg of CAPE, LCL's around 1000 meters AGL and almost 400 ms/2 of helicity, there is the distinct possibility of an isolated strong tornado occurring somewhere in eastern Colorado tomorrow.
This situation bears very close watching indeed...

 

[Michael O'Keeffe]

Leaving here shortly for NE Colorado. I think with tds around 55F and cape around 1800j/kg along with helicity around 400 we can see a few tornadoes today along the I-76 corridor. The Denver Cyclone will play a role too. Conditions seem favorable for at least a few supercells and with ese storm motions the storms will be able to enhance the shear to aid tornadic development. We will end the day in North Platte tonight before we head out to SD tomorrow. Good luck to anyone who heads out today and stay safe!

Target: Brush,CO

 

[Rocky Rascovich]

First chase with my son!!!

Today is a real gamble, moisture is barely there, in my target area from Sidney, NE. to Imperial, maybe on down to Goodland over to Burlington by 0Z, my further north target seems a little better for cape and helicity values.

Best thing going for today, a nice striated classic to possibly HP mothership, and maybe a brief tornado if your in the right spot. Also.....

I'm taking my son Leif out for his first chase with his old fart but young at heart dad!!! After our NE./Co. intercept today, its off to SD tomorrow.

We're out the door in a few moments.
Cell: 405-226-2996

 

[Paul Sherman]

About to leave Denver area and target the Wray area and along the I76 Corridoor and then position for the Moderate Risk tomorrow.

Paul S

 

[Bill Schintler]

Chase target for today, June 5

Chase target:
Akron, CO (20 miles south of Sterling).

Comments:
Storms will initially fire over the front range of the Rockies west of Boulder and Fort Collins during the early afternoon hours, and then move east towards the deeper moisture through in the target area through 4 PM CDT. Supercell storms may locally produce a wide spectrum of severe weather including a few tornadoes. Storms should later congeal into an MCS and move to the SE towards Colby, KS during the evening hours.

Synopsis:
Major portion of CNTRL CONUS characterized by NWRLY UVL flow while Hudson Bay low is pushing E in response to 140kt H3 streak entering PAC NW. In far SRN TX, a forward propagating MCS has pushing into the Gulf of Mexico. Over the high-Plains, abundant LLV moisture was in place as evidenced by area soundings and ST field over WRN NEB into SERN CO where weak upslope flow was developing. Meanwhile, WV imagery indicated increasing large scale assent over NV into WRN CO in response to EWRD movement of PAC NW trough. Flow at low and mid-levels continues to be weak and ERLY over ERN CO, KS and NEB as SFC high-pressure over the Dakotas quickly shifts to the E.

Discussion:
SFC low pressure will become established over SRN WY by late afternoon while an orographically-influenced WF extends ESE from this feature over SERN CO with increasingly backed upsloping flow to its NE. Storms should initiate over the mountains as a compact vort max slides through NRN CO and SERN WY. Moderate low- and mid-level lapse rates coupled with modest BL moisture with dewpoints in the mid-50’s F will result in MLCAPEs to 1500J/kg in a region where the SFC elevation is 3000-4000ft. Deep layer shear will increase to 50kts as stronger WRLY H5 flow overspreads the area, while hodograph curvatures in the SFC-3km layer will increase to 300m2/s2 as a developing 30kt SRLY LLJ rides over backing 20kt SFC flow.

- bill

 

[Mark Farnik]

Currently mooching off the Wi-Fi at the Comfort Inn in Fort Morgan; plan on heading to Brush momentarily for lunch with my grandparents, and then will relocate to the parking lot of the Microtel Inn on the north side of Brush and mooch off their Wi-Fi until a dominant cell develops. I'm driving a dark blue F-150 extended cab with a topper and Colorado plates, so if you see me, stop and chat me up! Good luck to all and here's hoping for some good ol' fashioned High Plains magic!

 

[Grant Gutierrez]

Stopped in Hudson, CO now. In a Ford Taurus with Texas plates, probably gonna head toward Brush/Ft Morgan area.