06/12/07 FCST: ND / SD / NE / CO

[John Hudson]

Had a look at the latest GFS for next Tues/Wed, and the trof that is progged to move across the northern plains/southern Manitoba looks like it could create some chaseable cells. Moisture return looks impressive so far, with CAPE sitting at 3000-3500 J/kg over the region.

My main concern thus far for the model output is that it forecasts meagre flow near the surface; not too great for shear.

Does anyone else care to chime in on this one?

John
VE4 JTH

 

[Derek Weston]

Yes, last run of the GFS I looked at showed huge CAPE (5000ish) over North Dakota in particular. Relatively un-capped as well.

Seems to me shear is the major question mark... 500 winds seem especially weak.

 

[Justin Turcotte]

Possible Dakotas chasing Sunday through Tuesday. If the cap breaks on Monday then things could be quite explosive which would have some implication on how Tuesday plays out. Models are in reasonable agreement with the synpotics on Tuesday. The main negative is the cap looks weak enough where storms might pop early and often.

 

[Dave Winslow]

Latest RUC showing a chaseable setup with enough CAPE (3000-3500 J) to compensate for weaker upper flow. Decent turning by 21 Z with SFC winds SE 10-20 kts, 35 KTS SSE at 850 mb and 25-30 kts SSW at 500 mb.
Cap strength doesn't look too strong with 700 MB temps AOB 9 C.

I like the area a little west of Ainsworth and up into South Central South Dakota...but the front will be west of here. I can only target points near Ainsworth because I will need to get back to work for Wednesday morning....
So if upslope flow and a weak cap can produce storms a little west of Ainsworth, that's my target.

 

[Darren Addy]

I tell ya, Nebraska don't get no respect (adjusts too-tight collar). Mods want to add NE to this thread subject line?

I suppose that technically this should go in a NOW thread, but I'm looking at what is to come shortly. The storms currently severe-warned in Colorado are in what appears to be a 1200-1500 CAPE environment (DDC Shortfuse Composite) and seem to be spawning new storms to their east via outflow. Those storm are going to be forming in an even juicier (moisture pooling there), more unstable environment (2100 CAPE) and the mother low should also be sliding east.

Kansas/Nebraska border area (south of McCook) looks like a nice place to be for some early afternoon action. 25 miles west of McCook is currently downwind (backed) of the moisture pooling with a dewpoint of 71 and RH of 87%.

EDIT: (17:57 UT) CAPE NW of McCook now over 2600

 

[Dave Winslow]

cold pool

I am going to withdraw my inkling to chase today in Nebraska. Looking at the way things are evolving, a big MCS with lots of outflow will be the main show coming off of the higher terrain in Western NE. However, if something can get going out ahead of this, there could be some magic but I feel overall it's a little bit marginal. The insane backing of the winds in Nebraska and low LCLs would make this setup one to watch for local chasers, however. Will be virtual chasing this one.

Cheers