4/4/10 FCST: MO/IL/IA/KS

[Cody Pryor]

Just wanted to get some thoughts about SPC's Slight Risk for today. Given the Possibilties of tommorrow's setup. I just wonder if today is worth pulling the trigger on. I would just kinda wondered if today would be worth spending chase funds on. Then meandering my way to tomorrow's target area.

Looking at the NAM it does look interesting around the Davenport, IA area, showing a broken line of precip breaking out around the 0z time frame.

So if anyone with a little more forecasting skills could give me some input I would greatly appreciate it.


Cody Pryor

 

[Skip Talbot]

It looks like a slow moving cold front is draped northern Illinois, southwest through Missouri towards SE Kansas. There might be a lack of instability on the northern end of this target area, with SBCAPE values only plotted around 750 J/Kg. Forcing along this front should result in a line of storms to go up in the late afternoon or evening. At the surface, the winds are veered to the southwest. Although deep layer shear is more than strong enough to support supercells, the directional shear is quite weak. Given the forcing on the cold front and lack of directional shear this looks like its going to be mostly a linear event. Storms might be a little more robust to the southwest where instability is better, but the terrain gets really dodgy in central and southwest MO. It might be a worth a shot if you are already in the area setting up for Monday, I'm not sure if I would travel any real distance for this setup on its own though.

 

[Chris Wilburn]

Not too much directional shear for sure. Looks mainly like a linear event like Skip mentioned. The SE KS area should see a line of storms develop this evening and continue into overnight. Small hail and marginal severe winds will be about the extent of things. Directional shear just isn't there for any tornado threat. There is plenty of moisture and instability so there will be some nice storms for sure. It should make for a good evening of some rumbles of thunder and lightning in the area of NE OK and SE KS. Slow moving cold front in northern KS should slowly drift towards the SE KS area during the day. This front will stall overnight and begin to lift northward into KS and along the MO/IA border to provide focus for the setup on Monday.

 

[Chris Heater]

With being in the slight risk at home already...I'm leaning towards giving today a shot. I'm still a bit undecided though, but i'm thinking towards Jacksonville, IL is where I may go. Maybe up towards Peoria. Still unsure though, as it looks like it would be late initiation anyways

 

[Eddie Natenberg]

I saw a couple of features that came up in the latest RUC run I had to question with obs.
1) That nice low amplitude embedded shortwave in the flow:
It actually was sampled pretty nicely by the GDA profiler earlier today, doesn't seem to be a model artifact, so that would serve as a nice trigger.
2)Outflow boundary in Eastern MO associated with ongoing conv. should be a focal point for increased convergence and enhanced SRH. Not showing up in obs or in the models but the radar data convinces me its there .
3) Moisture, Although I am seeing jumps in the moisture in AR, I don't think it will get to N. MO until late in the game, especially into the 60s (this could be hard with diurnal heating). I think the RUC is overestimating moisture. It should get there later tonight.
4) 700 mb temps are warming on the nose of approaching jet, advecting warm air from the SW, another sign that convection may struggle initially.
5) Shear, It looked like directional shear profiles were to be stronger in the previous run, but now look more unidirectional. Again I think this may change late in the game downstream in IN as the wave ejects.

All in all, I would say tornadoes look unlikely today, but I would take any non severe thunderstorm at this point in the year. Later tonight could be a totally different story if storms can stay somewhat discrete (a function of the amount of backing of the winds tonight) especially if storm can initiate downstream of the wave, otherwise I expect a training mess along the frontal zone.

Good luck to anyone going out,
Eddie

 

[Jim Hunt]

While not tremendously unstable, the RUC shows parameters rather good for the middle of the afternoon to evening for the Chicago area. Cape values are highest near 1000 around 2200 to 2300.