05/20/07 FCST: MT / SD / ND

[Bill Schintler]

Target:
Mott, ND (60 miles WSW of Bismarck).

Timing:
Storm initiation 7 PM CDT.

Storm mode:
Multicell-storms which should remain below severe limits.

Discussion:
00Z analysis indicated deepening trough over the NWRN CONUS with several of pieces of energy embedded within it. A lead S/WV was translating through ERN MT with an area of convection associated with it, while a second feature was over ID. Return flow was established from TX through SD as a 20kt LLJ was transporting 8C H85 dewpoints towards the SD/ND border. A strong baroclinic zone extended along an OGA, FSD, to LSE line in NEB and MN with a shallow cool layer to its north. Up-wind soundings (SLC, RIW, and LKN) showed nearly dry-adiabatic lapse rates in the SFC-500mb layer, and differential advection of mid-level lapse rates of 8-8.5C/km on top of moisture from the south should result in modest MLCAPE’s of 1500J/kg by late afternoon tomorrow.

Sunday, the area should remain capped to SFC-based convection until late in the day as one or more outflow boundaries from a morning MCS over ND focuses the northward moving synoptic boundary and a compact vort max provides the necessary lift to overcome warm mid-levels. Moderate instability along with weak deep layer shear AOB 25 kts should result in primarily multicell storms. Overnight, the convection should grow into a large MCS and travel E through ND while producing heavy rain as a 40kt LLJ noses into the region.

[FONT=&quot]- bill[/FONT]

 

[David Wolfson]

Currently in Sturgis, SD. This is a tough forecast with little violent storm potential. My objective is scenery with a spinning supercell. Best convergence and winds will be needed for this marginal situation. It looks like there will be a front running somewhere near the ND/SD border to a low south of Miles City induced by increasing upper winds and the lee of the mountains to the southwest. There's a modest height-of-land running northwest toward Ekalaka, and some nice scenery so they say. If Bill's read looks better in the early afternoon, there's the option to scream east on I94.

Soooo. Target: Ekalaka, MT, at 23:00Z. Leave around noon planning a circuit Sturgis, SD - Broadus, MT - Miles City - Baker - Ekalaka - Bowman, ND - Sturgis.

 

[Andrew Pritchard]

Considering gas prices and tomorrow's target, I don't think a drive well into Montana or Wyoming is going to be worth it. I think there will be storms and potential supercells out there, but not really any better than here in western SD. Storms out there will likely also form into a linear/bow echo complex as they head into the eastern parts of MT and WY and onwards into North Dakota and NW South Dakota later in the evening/overnite.

Instead of messing with that, one might consider heading near Rapid City and waiting for something north of the black hills. Might get something going on the upslope in that area. Models show moderate instability, and do show some forcing and eventually precip breaking out in this vicinity. Shear isn't great by any means, but you may be able to squeeze out a shorter lived supercell over some photogenic terrain. Considering tomorrow's target being nearby, I think this might be a nice alternative than plowing into no mans land and emptying out your wallet.

 

[David Wolfson]

Agreed, Andrew, based on morning's data. Target is basically here (Sturgis), with scenery beckoning a little north of here. Am anticipating tomorrow's target as Chadron/Valentine TBD later.

 

[Robert Edmonds]

I really don't want to go back to MT since I was there yesterday, so I'm going to try the area up here in NW WY, looking forward to tomorrow more. Looking at the data I'm tempted to go sight seeing instead of looking for the elusive rain cloud. I've never seen devils tower or Mount Rushmore. Oh, I'm over in Buffalo, WY right now...

 

[Michael Thompson]

Currently sitting in Broadus, Montana playing the waiting game, cirrus or anvil flow has increased towards the southwest in the last hour. Hoping to get something by 6pm and ride it for while, but they are moving on the radar.