7/20/2004 FCST: ND, SD, MN, NE

[Amos Magliocco]

Three consecutive ETA runs depict a potent 700 mb shortwave intersecting an area of extreme instability from northeast NE through eastern South Dakota, eastern North Dakota and west central Minnesota. What catches my eye about this setup is a stout LLJ through the evolution of the system and a strong dry punch at the surface.

Too early for targets, but somewhere east of that surface trough might be interesting. Midlevel winds are modest, (and there's some upper level ridging) but my high plains and northern plains friends are helping me overcome my south plains bias regarding H5 and early summer winds aloft in general up there. 8)

Should be interesting to see this early summer system evolve.

 

[Robert Dewey]

Amos since you live in IN, did you also check out the 72H-84H 12Z ETA? I believe this run may be suffering from conv. feedback, but these are the parameters for the IWX through DTX areas:

CAPE: 3500J/KG
0-3KM HELICITY: 400M2/S2
TDs: 70-75F

Anyway, if this trend continues, I will start a thread for 7/21 for the Great Lakes region...

 

[Jim Bishop]

Looks interesting

I saw the 1200 UTC run of the ETA today. The 0-6 km shear looks lincredible, as well as the 0-3 km shear, which looks to be supportive of tornadoes. CAPE looks incredbile, and the moisture availability does as well. There's going to be a strong cap, but initiation shouldn't be a problem along the warm front where the 850 mb winds are backed with cooler temps.

My only real concern is the lack of strong upper level winds (300-200 mb). With this type of scenario, it seems supercells will form and produce low-level mesocyclones "briefly", or for say 10 or 20 minutes, and then become undercut by outflow. Not to mention the massive HP monsters they will very likely be! Of course, it's still a couple days out....

Jim
http://stormgasm.com

 

[Mike Hollingshead]

I hope tonights 0z doesn't follow the path of what the 18z spit out.

 

[Glen Romine]

Didn't look at the 18Z, but the 00Z is certainly trending in an unfavorable direction. Much weaker wave, subsequent hemorrhaging to lower level shear, and a stronger cap to add insult to injury.

Glen

 

[Glen Romine]

06Z run unimpressive, but the 12Z ETA run looks interesting again. Gotta love that run-to-run consistency.... This is kind of an interesting forecast, as you can clearly make out the upper disturbance in current water vapor imagery, but the handling of this wave as it shears out over the top of the ridge axis has been very consistent by the ETA with regards to timing, just disagreement over the intensity of subsequent waves. Overall setup isn't that bad, aside from weak storm-relative flow aloft. Still worth watching I guess.

Glen

 

[Amos Magliocco]

I have backed off chasing plans because of other committments, but I still like Tuesday's setup and agree with Jim Bishop and other that there will probably be a monster isolated storm alone under the cap and tornadic.

 

[Gabe Garfield]

18z run is interesting, to say the least...Back to extreme instability (on the order of 4000 j/kg) and juxtaposed with strong 0-3 km shear (>300 m2/s2) over a broad area from SW Iowa to WC Minnesota. I think that any outflow boundaries from tonight's convection will greatly influence tomorrow's probabilities. If convective debris can clear out in time, watch out. Right now, I like SW MN because it appears that an OFB will set up in this region.

Gabe

 

[Glen Romine]

06Z run unimpressive, but the 12Z ETA run looks interesting again. Gotta love that run-to-run consistency....

12Z run looking like the outlier again - deep layer shear really falling apart without the strongly backed winds at the surface. Unless there is a huge MCS marching into nw IA in the morning.....


Glen

 

[Amos Magliocco]

I'm impressed with how consistent the ETA has been with the timing and strength of the shortwave. I think a feature this strong with moderate to extreme sfc instability means the surface features might be better than advertised, though the setup has a storng cap and upper level ridging to contend with. I expect one or two supercells in eastern South Dakota with a modest tornado chance if a surface trough sharpens and pushes east as a boundary on which the storms can propogate. Guess I'd pick Watertown if I could go.

 

[JHadorn]

This is one of the few times I hope the pattern stays well to my north. I've got two important (as in job critical) practicums I need to take Tuesday and possibly Wednesday.

It can all go to Hell on Thursday and Friday for all I care. I'll need something to do.

 

[mikegeukes]

Original target city, I mention last night in chat: Worthington MN.
Have not look at the latest 6Z or the RUC,

Mike

 

[Jordan Manderfield]

Re: FCST

Who's headed to MN/SD today? :wink:

ummmmmmm I'm already here lol........But we'll probably go west towards worthington then once storms develop follow them back to mankato or plan B just wait here in Mankato...but thats only if my dad is off late :roll:

 

[Edward Ballou]

Pipestone, MN

I'm going to have to say Pipestone, MN. Things look pretty good from this:

http://www.wxcaster.com/modelskewt.php3?mo...&STATIONID=KPQN

But, I could be wrong. Anyone got an ETA for all of this? Spotter activation is possible after 400 pm for me in Brookings. I'm going to try to time it right so I can get out of softball as soon as things start heating up.

Anyways, that's my two cents.

 

[Glen Romine]

Re: Pipestone, MN

I'm going to have to say Pipestone, MN. Things look pretty good from this:

http://www.wxcaster.com/modelskewt.php3?mo...&STATIONID=KPQN

But, I could be wrong. Anyone got an ETA for all of this? Spotter activation is possible after 400 pm for me in Brookings. I'm going to try to time it right so I can get out of softball as soon as things start heating up.

Anyways, that's my two cents.

Ed, can I call you Ed? Anyway, the forecast sounding you provided a link to is valid Wednesday night, not tonight - so it wouldn't be applicable to this thread. Further, it is actually not a very favorable sounding. Note how shallow the moisture is in the boundary layer, mix this moisture out and you have very little CAPE. Also, the dry boundary layer air would favor very high based convection, if any, and the 0-3 SREH of 75 is also pretty low. Maybe you provided an accidental link?

The 12hr forecast sounding from this morning's run for the same location does look better, but has high relative humidity through the depth of the sounding - which could mean extensive cloudiness, and this also limits the mid-level lapse rates, though the low-level lapse rates (just above the surface inversion) are decent, with 0-3 km CAPE of ~ 350 J/Kg. 0-6 km shear of ~35 knots is not so great - but is probably ok for the degree of instability (MLCAPE 3700), and 0-3 helicity of just over 200 is ok, but you'll probably need a boundary as well to get a tornado. Surface winds of 5 knts will rarely get it done.

Following that extended blurb, I'd never recommend using a forecast sounding to pick a target. While they are cool to look at - I don't think they verify very well - and can be very misleading. Will Pipestone be a good target for later today? IMO, it's a bit too far north, but it's too early to pinpoint. Right now I'd lean more towards Vermillion for initiation, but subject to change. Seem you are already in the general vicinity - so I'd worry about a target when things are clearer - say early afternoon.

Glen