5/13/20 Forecast Post

I didn’t forecast much. There were some major differences between the NAM and GFS with this mornings runs, with the NAM retarding moisture return into the central plains ahead of the dryline relative to the GFS. The GFS brought moisture all the way up into north central Kansas, where the NAM kept the north edge of the moist tongue in Oklahoma. The NAM took a dump with the 18Z run so I ignored that. Just got done looking at the 00Z run and the NAM is trending the right way with the surface pattern. It’s putting a dryline bulge into NW Oklahoma and SW Kansas. The GFS still has moisture much farther north than the NAM, but they’re moving towards each other. I dug into the cause of the differences at the surface between the two models a little bit, but I really don’t want to ramble about those details which are largely irrelevant at this point. I think the NAM is closer to right, but I also think it will continue to trend north and bring the triple point up farther into Kansas. Right now my guess is a starting target of Minneola, KS to Woodward, Oklahoma area. That could change a lot, but that’s my guess as of now. Deep layer shear is not going to be very strong, but it should be strong enough in the northern portions of the warm sector (NW Oklahoma and Kansas) for supercells with around 40kts sfc-6km. The bottom half of hodographs look good with solid low level shear, but there’s not much length to the top half with weaker mid level winds and weak upper level winds. Given the strong instability we’ll get supercells, but there may not be a whole lot of updraft/downdraft separation.

The NAM is rather stingy with precipitation coming off the dryline, but I don’t trust that at all. It’s seems like the NAM has under forecast precipitation almost every time this year and it has the dryline uncapped by the triple point during the afternoon with the 00Z run. I think morning precipitation the NAM has and the dry pocket is geeking with it, so I’m not giving it any thought right now. Plus the 00Z run of the NAM has trended way more towards greater instability/weaker cap relative to the 12Z run. The NAM is catching up, it just needs another run or two I think, but I do think we’ll get storms off the dryline. I’ll get into more detail tomorrow, but basically I think we’ll get a few storms off the dryline with the best tornado potential near the triple point and dryline bulge. That looks to be far NW Oklahoma and SW Kansas and potentially into south central Kansas. The tornado potential looks to be somewhat lower end. Maybe it could nose up into more like a 10% tornado probability type setup if things go right. I did try to make a map tonight btw. No dice though. I’m on may MacBook and I tried opening powerpoint to make a map and apparently my subscription expired. Didn’t know I had one. I thought I had bought microsoft office. Whatever. Renewing that was more work than I was looking for and I did not one to get my old chase laptop to use microsoft paint to make a map. It’s all the way across the room and again too much work lol. I would have circled that area from Woodward to Minneola, KS and points northeast of there downstream as the greatest tornado threat if I did make a map though, so just envision that. I’m real curious to see how SPC handles their map tomorrow. That will say a lot about where they think the triple point will set up. May see a hatched area over that portion of the risk area.

Beyond Wednesday setup, there looks to probably be some lower end localized events peppered through the week, with potentially a more significant trough coming in the following week. Still too far out for details, but I’m more excited about the week after this one than I am about this week’s potential. So good news if you’re chaser. Things seem to be getting active in the plains. I need to get new brake pads this week some time before I really start hitting the road hard in the next two weeks. I’ll get out two or three times this week I bet, but the following two weeks is when I really will be hitting it hard. I have 9 days straight off work at the end of the month so unless we get screwed with a ridge, I’ll be covering a lot of miles in the plains. May hit Colorado and Wyoming during that stretch. I hope I get too. It’ been a while since I’ve chased that far north and I’d like to get back up there.

That’s all for tonight. I’ll check the models tomorrow and try to get a map posted so check back then if you’re interested

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