Rookie Forecast for 5/28/11

[Jared Orr]

I'm not quite to the level of "Target Area" forecasting yet, so I would love critique if anyone wants to chime in.

Nam is showing a warm front draped across central Mo, SW towards the KS/OK border, which may serve as a focus for scattered surface-based convective activity tomorrow afternoon. Largely zonal flow with a slight trough-like tilt is in place over the high plains, which will provide in upwards of 60km bulk shear (sfc-500mb). Earl's skew-t page is showing nice curved hodographs for Pleasant Hill, Mo, with fantastic instability south of there along the warm front. There will likely be a corridor of overlap between these areas in E KS and W MO, and 70+ dews in this area will contribute to low LCL's.

The problem will be obtaining the necessary forcing to overcome the punishing cap due to 700mb temperatures around 12 degrees over the front. It may come down to finding mesoscale forcing triggers (topography etc). I see a little glimmer of hope due to slight precip showing up on the NAM composite reflectivity and the GFS 3 hour precip. But these aren't incredibly reliable. Basically, this is one of those setups that you look into if you live close to the aforementioned areas, and you stay away from it otherwise...


Please let me know if I'm on or off base!

~Jared

 

[Michael Riedl]

Can I have a link to that sounding you refer to?

 

[Matt Hunt]

Jared, I just posted a forecast thread for tomorrow as well. Depending on what model you're looking at, I don't think the cap will be an issue. I think the only issue is going to be whether or not AM convection stabalizes the environment (or creates a cap, I suppose). I'm about 3 hours from St. Louis and plan on making the trip, assuming things still look good in the morning. There will also be a weak impulse moving across central MO during the evening attendant to the mid-level low up north. This, along with any outflow boundaries from the early convection should serve as triggers... hopefully. I feel like it's either going to be a bust, or an amazing chase! Storm motions are going to be slow, 10-15 kts.

Also, don't put any stock into the simulated reflectivity. It is difficult for those models to predict this at the mesoscale level. Take a look at the HRRR day of, but again don't trust it 100%. I've seen it be dead on, and I've also seen it show nothing when storms indeed fired, or show storms when nothing happened.

If storms fire, the parameters are definitely there. Large clockwise curving hodographs both east and west of St. Louis area, plenty of moisture, and good instability assuming early convection doesn't interfere.

 

[Adam Simone]

I'm liking the cu field in se KS, sw MO...I'm going to predict initiation around 23Z. I don't think the SPC is giving that area enough credit for tornadic potential. But I don't have a doctorate, so.

If I were chasing this one, I would drive to Pittsburg, KS.

I'm also a rookie at this but Ill give my 2 cents. The HRRR model does show storms forming after 9:00pm in NE OK, SE KS but I'm not convinced yet. 850mb temps look to be above 16c and 700mb temps above 12c. Thats a pretty strong cap to overcome. Also the speed shear between 850mb and 500mb are pretty weak in that area. Low level directional shear looks to be good though along the warm front. Other parameters in that 4 state region look good for severe storms I'm just not sure they will form. The models show good helicity numbers >100 at 1km and >250 at 3km, low LCL, plenty of cape but I just don't know if it will be enough. I thought about going out today but I saw all the clouds on the satellite and decided not too. Good decision so far. I'll keep an eye on the radar for tonight though.

 

[Jeff Duda]

I'm not quite to the level of "Target Area" forecasting yet, so I would love critique if anyone wants to chime in.

Nam is showing a warm front draped across central Mo, SW towards the KS/OK border, which may serve as a focus for scattered surface-based convective activity tomorrow afternoon. Largely zonal flow with a slight trough-like tilt is in place over the high plains, which will provide in upwards of 60km bulk shear (sfc-500mb). Earl's skew-t page is showing nice curved hodographs for Pleasant Hill, Mo, with fantastic instability south of there along the warm front. There will likely be a corridor of overlap between these areas in E KS and W MO, and 70+ dews in this area will contribute to low LCL's.

The problem will be obtaining the necessary forcing to overcome the punishing cap due to 700mb temperatures around 12 degrees over the front. It may come down to finding mesoscale forcing triggers (topography etc). I see a little glimmer of hope due to slight precip showing up on the NAM composite reflectivity and the GFS 3 hour precip. But these aren't incredibly reliable. Basically, this is one of those setups that you look into if you live close to the aforementioned areas, and you stay away from it otherwise...


Please let me know if I'm on or off base!

~Jared

Jared, that is a very well analyzed forecast. I would have no problem seeing that written in the Target Area forums. Good work and keep it up.

 

[Jared Orr]

I know it's been a while, but thanks for the kind words, Jeff.