Saturday Severe Weather

Well as mentioned in previous posts, this weekend holds the potential for a decent severe weather episode across the plain states. SPC has issued their day 3 outlook for Saturday, it was actually issued early this morning. Nonetheless, they have put in a 30% probability for much of western Iowa as well as portions of surrounding states, including SD/MN/NE/KS/MO. This potential will likely increase as the event nears and models have time to come to a complete solution. The threats with this system are likely to be large hail and especially damaging wind given a strong cold front/dryline that will be surging to the east during the night on Saturday. But, there will be potential for isolated tornadoes with storms that fire away from the front or ones that move away from the front during the afternoon/evening hours. Storms will be likely to move ahead of the front, given that storm motions are forecasted to be 35-45 kts! This will be due to such strong mid and upper level winds, this also is what is responsible for the good shear values as well. Although directionally not strong, speed wise they should be quite good, with some models hinting at values well above 50 kts worth of deep layer shear.

So, a strong system with a potent cold front/dryline combination should allow for plenty of lift. With a strong low pressure system forecasted, this should help with directional shear values in localized locations. Decent heating will be in place, but moisture is currently a minor concern with the amount of return not known. Indications do show that at least low to mid 60 degree dewpoints should be obtainable, thus only a minor concern for this at the moment. Model consistancy has been fairly good as of late, at least with the GFS and other ensemble models. The outlier at the moment is of course the NAM/WRF which has been very fast with the cold front, but in tonights run it has considerably slowed the forward progress of it. Although it is still fast, likely by tomorrow morning and by the 00z on Saturday (Friday Night’s run) it will likely be back in line with decent agreement with other models. It seems to be the trend of the NAM/WRF in situations like this. For now still just watching, not sure on the chase possibilities right now, especially with exact threats still unknown. I’ll already be in place in northwest Iowa, so likely will simply play whatever comes my way unless we are looking at a big outbreak, which to me seems unlikely at the moment. That is all I have for now, hopefully I will get another update in either late tomorrow night or early Saturday on what the final plan will be.