Stormy Weekend 5/16-5/17

Day 3 Severe Weather Outlook Iowa

The potential for severe weather is back in our forecast, with Saturday looking to be the best day for widespread severe weather. The potential for numerous strong to severe storms will exist Saturday over a large part of the plains into a portion of the middle and upper Mississippi Valley regions. Large hail, damaging wind and a few tornadoes will be possible.

mgWeb_WRF_20150514-180000_ANC_ECONUS_F00430000_PsatVisible_R4kmHowever, there is a lot of uncertainty that revolves around the severe potential on Saturday. One of the biggest impacts will be the ongoing/lingering convection Saturday morning. Depending on when this convection clears out, will have an impact on instability, just like we saw on Mother’s Day.  The longer the clouds stick around, the shorter the amount of time the atmosphere has to become unstable.

mgWeb_WRF_20150514-180000_ANC_ECONUS_F00510000_PwinterThickness_R4kmUsing one of the high resolution models, called the RPM, it is showing that enough clearing will take place that storms will be allowed to develop along the Iowa/Nebraska border after 4pm. If this is the case, these storms will be severe.

nam4kmCGP_prec_radar_051However, looking at another high resolution model, called the 4km NAM at the same exact time, you will notice that nothing is forming near the state. This model is actually not forming anything until after dark, and it is doing so across eastern Nebraska. Because of these differences, Saturday will be a conditional day, so we will have to watch this set up to see how things evolve.

day4probDepending on the timing of when this system pulls through, Sunday may also provide another severe weather chance. Currently the Storm Prediction Center has this risk across eastern Iowa, however, some of the models, like the 4km NAM, try to slow this system down, where it would bring a severe weather potential to central and eastern Iowa on Sunday. Everything will depend on timing, so continue to check back here for all of the very latest updates.


Zach Sharpe

My name is Zach Sharpe. I am the president and forecaster for the Iowa Storm Chasing Network. You can find me on Twitter @Stormchaserzach and on Facebook at:

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