I wouldn’t even be making a post right now if I did say I was going to last night because I don’t know what to tell you lol. God damn models. Usually I’m a pretty big fan of the NAM and despite getting shit on constantly, I think it does a pretty solid job. If we are going to get tornadoes on Friday and Saturday, it will almost certainly be over isolated areas. The devil is in the details with tornadoes and with marginal setups like we are dealing with on Friday and Saturday, you have to have some sort of an idea on the precise details (like moisture quality and distribution, where surface winds are backing, etc.) and those finer scale details both at the surface and with stronger 500mb flow keep jumping around from run to run. Going off the 12Z run this morning it looked like the I70 corridor from western Kansas into Colorado would likely hold the greatest tornado potential late in the day on Friday as LCL heights lowered and deep layer shear picked up slightly. For Saturday the 12Z run showed a pretty solid target near Omaha for supercells just northeast of the surface low. I just got done glancing at the 00Z run and it’s shuffled shit up again. Moisture quality is looking like a serious problem for Friday. The latest NAM run throws in a new curve ball with storms firing along the dryline in the northern Texas panhandle with fairly strong mid level flow over that area associated with a small jet streak/short wave. LCL and LFC heights are really high down there though despite dewpoints near the low 60’s (which really is kind of shit for this time of year). With the questionable moisture we are dealing with on Friday, my gut says the best chance for a tornado will be with storms coming off the higher terrain in central Colorado into eastern Colorado. I’d think late in the day around 7pm or so is when a tail end or discrete storm may be able to get it done. I’m up in the air on whether or not I’m chasing Friday. I am not real pumped about the tornado prospects. I felt a lot better about it this morning, but the downward trend with decent quality moisture wrapping into western Kansas and Colorado is really putting a damper on things. I’ll look at the morning runs and hopefully that will make a decision easier. I plan on being packed and ready to go so really I can put the decision off until Friday morning if I need to.
I think Saturday is more likely a chase day for me simply because there will be stronger deep layer shear with the stronger mid/upper level winds coming in and moisture quality will hopefully be better. Overnight convection complicates the surface pattern a bit, with a big complex of storms forecast to track through Nebraska. Again this morning I thought I was zeroing in on a target near Omaha, but the 00Z run has shifted the stronger mid and upper level jets about half a state south (jet was nosing into NE Kansas Saturday at 00Z with the 12Z NAM, with the 00Z its nosing into SE Kansas and it’s a little weaker). The northeast quadrant of the surface low in Iowa actually looked pretty damn good (at least for this year) with strong directional shear and instability. The 00Z took a dump on that though and without getting into all the details as to why, it basically has a weaker version of the 12Z setup shifted farther SW with a sloppier surface pattern. The drop off in mid level winds is a real bummer. Now, all that being said, I don’t buy what the NAM is selling right now. It’s one run and I think the 12Z solution was more in line with previous runs than this latest run is, so I’ll sit tight on passing judgement until I see the 12Z tomorrow. For now I’m thinking the area for the best tornado potential on Saturday could be anywhere from Salina up to Omaha. I do think there is a slightly better chance for a tornadic storm or two on Saturday than there is on Friday, but really one or two storms could plant a couple tubes either day. It’s nothing special or anything to get excited about, but it’s what we have to work with. After this setup it looks like we may be done until June as a summer pattern takes hold in the plains (death ridge). Historically speaking, this almost always happens around mid to late May and it always seems like it’s about a two week break before you get another little second half of tornado season as the ridge breaks down and a few more troughs manage to dig into the central and northern plains. Even though this year has been anything but normal, I have no reason to doubt that will not be the case this year. The latest runs of the GFS hint at a stronger trough over the west coast as you get towards the end of May, which would be about right on schedule with that typical two week break. I can tell you this much, I can about guarantee you that I’ll see the Dakotas this season because if we do get a strong June trough up there then there is no way I’m passing on it. I am desperate for a strong tornado and there’s not a whole lot I wouldn’t do or places I wouldn’t go to see one.
Alright, enough bullshit for tonight. Sorry for the lack of clarity in the forecast, but so goes the model data so there isn’t much I can do about it. The picture should become more clear over the next 36 hours and I’ll stay on top of it, so check back for updates and a more worthwhile read.