Sunday May 8th Tornado Forecast

Sunday Day 2 map

Higher end severe weather event and potential tornado outbreak still seems on track for Sunday, with moisture return still looking to be the big question mark with this one. I’m going to keep this short, but the going forecast still seems on track for Sunday, so look back to my previous post from last night for additional details.

There is still a big question mark surrounding how good of moisture we will be able to advect back north ahead of the dryline by tomorrow afternoon. I spent all day working and setting up equipment, so I haven’t forecasted hardly at all. I just glanced at the 12Z NAM and current observations and moisture return into south Texas seems to be lagging behind what the NAM was forecasting. That makes me a little nervous. By 00Z tonight the NAM was showing dewpoints into the low 60’s well into south Texas and nosing into central Texas. Instead we are still looking at upper 50’s across central Texas with mid 60 dewpoints confined to the south Texas coastal areas. That being said, I think the NAM is currently overdoing moisture return. We really need to get dewpoints into the low to mid 60’s across Oklahoma and south central Kansas tomorrow to realize a higher end tornado threat and that’s looking pretty iffy at the moment. I’ll be keeping a close eye on moisture return tonight and tomorrow morning though. I would think that by tomorrow morning we’ll have a much better feel for what type of moisture we’ll be working with Sunday afternoon.

Discrete supercells should develop along a dryline tomorrow afternoon (see map for rough dryline location around the time storms should develop). Storms will quickly track off to the northeast (storm motions will be fairly fast tomorrow, making chasing a little difficult). As storms move off to the northeast they should rapidly become severe with 50-60kts of deep layer shear and moderate instability. Low level shear will improve markedly through the late afternoon and with it the tornado threat should increase. It looks like the 6-10pm or so time frame is when the greatest tornado threat will occur. The tornado threat will be greatest across Oklahoma and south central Kansas where the upper/mid level jet axis crosses over the dryline and has the best overlap with a strong low level jet. Across this area, hodographs are characterized by good length and curvature with 0-1km SRH intensifying to around 300 after 7pm. Below is a forecast sounding for the KS/OK border area at 03Z. That is a very impressive hodograph and with the thermodynamics the NAM is showing it would be extremely favorable for strong tornadic supercells.

KS OK hodograph

With strong speed shear in the lowest 1km and the critical angle near 90 degrees, hodographs look very favorable for strong tornadoes across the area I outlined in hatched red on my map. We just need the thermodynamics. I have a really hard time believing the upper 60 degree dewpoints the NAM is showing will verify, but if it does I think any storm coming off the dryline will pose a strong if not violent tornado threat. However, I think dewpoints will be in the lower 60’s, which will bring that tornado potential back down a bit from what the NAM is showing. With low 60 dewpoints I still think we’re looking at a strong tornado threat though (for non-weather nerds strong references EF2-3 tornadoes and violent is EF4-5 tornadoes in forecast speak).

I am going out tonight so I have to leave it at that and get ready to go. I already got my equipment setup though so my morning will be largely free for forecasting and posting on my blog. I may update again after I see the 00Z run tonight, but it will be brief and likely related to moisture return. That’s the big question mark with this one. Everything else is there for a tornado outbreak. Oh I almost forgot the other big question mark which is convective coverage. The models haven’t been showing many storms coming off the dryline and the NAM is pretty much dry across Oklahoma and far north Texas, but I’m not buying that. With the upper level jet nosing in and good clearing through the afternoon, I expect several supercells to come off the dryline from south central Kansas all the way down to north central Texas. You can’t trust the NAM will convective coverage. More times than not it’s full of shit and good storm coverage (although they’ll be discrete and widely scattered) seems logical along the dryline. Also the veer, back, veer trend to hodographs has subsided to a large degree, especially over the northern half of the threat area. It may still be an issue closer to the Red River (which btw I’ve been saying the south area was the biggest concern with VBV hodographs for several days now, just want to pat myself on the back a bit there lol).

Alright, that’s all I have time for. Sorry for not really breaking down the forecast, but I’m tight on time. Also I typed this in one straight shot without proofreading so forgive the rambling/repetitive nature of my post and likely grammar errors lol. Really my thoughts haven’t changed since my last post so you can scroll back for more information. Check back later tonight for a quick update and tomorrow morning for a full forecast update. My plan as of now is to head out of Wichita around 11-noon’ish and I’ll target NW Oklahoma into far southern Kansas. I’d consider targeting I40 along the dryline, but with the KWCH viewing area looking like it will have a strong tornado threat I need to keep this chase close to home to help with coverage. I’ll post my exact target in the morning.

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