General Weather Discussion - April 2014

[venture]

I have some preliminary plans to visit the Arts Festival tomorrow in the late afternoon/early evening. I'm hoping if these storms happen here they happen later. That sounds like what you're saying, but I may just be getting hopeful.

That's accurate. Unless the dryline marches east really fast, I don't see anything in here in the afternoon and probably not until late evening.

[Plutonic Panda]

Noted and reported.

Report all you want. I have not seen you do anything but troll. Every post I've seen by you, you have added absolutely nothing to the conversation except attacking and making fun of people.

[venture]

Discussion for Saturday/Sunday

Moisture return kicks in on Friday with dews getting back into the mid 50s. There might be a stray storm on Friday late, but nothing that should amount to much. GFS is flat out insane on moisture return on Saturday. 70 degree dews up into NW OK. 70 degree dews in April? I'm not sold. Dryline setups up by mid afternoon just inside Oklahoma out west, say around the first column of counties. Warm front will be north of the state, so the entire area will be in the warm sector. Surface low will be back over Eastern CO. Most of the positioning is in agreement with ECMWF, but the Euro isn't quite as intense with moisture return in NW OK and is a bit further NW with the low center. The dryline isn't really going to move a ton on Saturday. There might be a bulge on it near the Red River, which can help with focused storm development. GFS has the dryline just west of I-35 by 1PM on Sunday. Euro is faster than this and has the dryline around a Coffeyville/Tulsa/Dallas line by 1PM. We are talking roughly a 100 mile difference in the forecast between the two. So if we split the difference we are looking at it being around a Pawhuska/Stillwater/Norman/Duncan line by 1PM. This is obviously something that has to be resolved in order to determine the main risks for Sunday. I know there is a lot of chatter about Sunday being a major day or even the biggest day in this series, but all too often the previous day can play havoc with the "big day" setup. I'm not as enthused about the prospects of Sunday when it deals with the impacts on the Metro. Now let me also say this could be a nonstop even that continues through Saturday evening and overnight, so there might not be a break in anything.

So those are the boundaries. Looking at the environment itself Saturday has an extremely unstable atmosphere. We are talking LI's in the -9 to -12 range for most of the body of the state except for the SE quarter. Surface based CAPE values are just in the extreme category going by the GFS - up to 4000 j/kg for the around along and to the NW of I-35 and I-44. Euro is a bit further west with the best instability but is still kicking out values at or above 2500 j/kg for much of NW and W OK. Here is a forecast sounding for 4PM near the Weatherford/Clinton area...which is in the middle of the bulk of the instability.



So looking at this the one thing that stands out is not the best directional shear with surface winds mostly South, we normally want to see SE for better directional shear but this really isn't terrible for tornado production. Movement on the storms look good for tracking purposes - only about 30-35 mph heading to the NE - as usual. LCLs are a tad high, but not terrible in the low 800s. Cap is almost nothing. The indices to also look at for severe weather - LI, SI, TT, KI, SW, and EI are well in place for higher end severe weather. So really, the conditions are there - but we know it isn't that simple.

Initiation per GFS has storms starting along the dryline by 4PM generally along US 183 moving to the east slowly and getting into the Metro by early to mid evening. It then settles things down overnight and initiates convection again on Sunday nearly right along or just east of I-35 and keeps it mostly stationary through early evening. If we look at the Euro's solution it has storms popping in NW OK by 4PM and then along 183 by 7PM...so about 3 hours later than GFS. It brings storms in overnight into the early morning over I-35. On Sunday it doesn't have any precip forecast in the state after the morning convection. So this is the confusing part on why people are building up Sunday so much unless they are just going to discount the QPF forecasts of the model. My dilema is that GFS has been such utter crap for the last several runs that now people are all jumping on it. Yes it has come into agree with Euro in many aspects, but does that mean we automatically start dismissing Euro for Sunday now? I'm wouldn't think so. Now if GFS starts to get some consistency, then we'll need to pay attention.

Still a lot of questions on timing in my mind for the weekend. It looks like it could be a pretty big day (or days), but it just isn't there yet to really pinpoint who is getting what and when.

[Plutonic Panda]

Yep, and for whatever reason very few can see that.

Perhaps you just can't see that some people have severe weather anxiety.

[venture]

Thanks Venture. I finally started following this thread. Glad I found it.

Welcome! I'll be cross posting more and more with Facebook/Twitter with these bigger events so I don't miss anyone.

[ultimatesooner]

I'm getting pretty darn excited about Saturday.

I know I sound like a sicko. It's an okie thing.

me too, some of the best moods I'm in all year are on severe weather days. The destruction may suck at times but its a great reminder that mother earth still owns it and we only stay here.

I set up for these storms days like just like I do for sporting events, multiple TVs, radios, cookouts, beer in the cooler and I'm good to go

[bchris02]

Mike Morgan is predicting Sunday to be the biggest day with another shot at storms on Monday. I guess it all depends on where the dryline sets up.

Correct me if I am wrong here. If the dryline is right over the metro or barely west of it, might supercells go up but not be strong enough to do significant damage until they get a little farther east? Likewise, if its far enough west might we look at them converging into a squall line by the time they get here?

[jn1780]

Mike Morgan is predicting Sunday to be the biggest day with another shot at storms on Monday. I guess it all depends on where the dryline sets up.

Correct me if I am wrong here. If the dryline is right over the metro or barely west of it, might supercells go up but not be strong enough to do significant damage until they get a little farther east? Likewise, if its far enough west might we look at them converging into a squall line by the time they get here?

A lot of unknowns about dryline placement Sunday. Plus or minus 50 miles can make a big difference. Storms can become mature supercells in about 30 minutes under the right conditions.

[Anonymous.]

Mike Morgan is predicting Sunday to be the biggest day with another shot at storms on Monday. I guess it all depends on where the dryline sets up.

Correct me if I am wrong here. If the dryline is right over the metro or barely west of it, might supercells go up but not be strong enough to do significant damage until they get a little farther east? Likewise, if its far enough west might we look at them converging into a squall line by the time they get here?

Impossible to answer due to tons of conditions.

We have seen linear intiation go super cellic and we have seen super cellic go linear.

For example, this is what looks to be an evolving line of storms with embedded supercells. It doesn't take long for them to move into a more favorable environment and become isolated.

[SoonerDave]

Venture, correct me if I'm wrong, but based on your comments and the way things are lining up it looks to me like we could see stuff strong enough overnight Saturday such that the atmosphere wouldn't have a chance to calm down/recpver enough to facilitate the setup some are forecasting for Sunday. Reasonable possibility (amid all the infinite permutations of all the variables )?

[FritterGirl]

Lots of folks concerned about weather for the marathon on Sunday a.m., and rightly so. I know most of the big storms usually pop up late afternoon when temps are cooking at their highest levels, but as we get closer, can you guys let us know how things look to be lining up for the Marathon? About 25,000 plus folks are expected to be outside running in this. Thanks!

[venture]

Venture, correct me if I'm wrong, but based on your comments and the way things are lining up it looks to me like we could see stuff strong enough overnight Saturday such that the atmosphere wouldn't have a chance to calm down/recpver enough to facilitate the setup some are forecasting for Sunday. Reasonable possibility (amid all the infinite permutations of all the variables )?

There is always that possibility.

Lots of folks concerned about weather for the marathon on Sunday a.m., and rightly so. I know most of the big storms usually pop up late afternoon when temps are cooking at their highest levels, but as we get closer, can you guys let us know how things look to be lining up for the Marathon? About 25,000 plus folks are expected to be outside running in this. Thanks!

Honestly, Saturday will impact Sunday. So it very well can come down to a last minute call.

[bchris02]

Lots of folks concerned about weather for the marathon on Sunday a.m., and rightly so. I know most of the big storms usually pop up late afternoon when temps are cooking at their highest levels, but as we get closer, can you guys let us know how things look to be lining up for the Marathon? About 25,000 plus folks are expected to be outside running in this. Thanks!

Mike Morgan just said some wind and hail may be possible Sunday morning but no real tornado threat until Sunday afternoon.

Edit: Good news is his map has Saturday's focal point in western Oklahoma with a moderate risk out there and only a slight risk in the metro.

[FritterGirl]

Mike Morgan just said some wind and hail may be possible Sunday morning but no real tornado threat until Sunday afternoon.

Thanks, bchris! Sadly, I have little faith in MM's prognostications since (to me) he seems a drama-stirrer more than anything, which is why I turn to the fine folks here.

Honestly, Saturday will impact Sunday. So it very well can come down to a last minute call.

Venture, I hear ya on the "Saturday may change everything" call. Will keep checking back. Thanks!

[bchris02]

A lot of unknowns about dryline placement Sunday. Plus or minus 50 miles can make a big difference. Storms can become mature supercells in about 30 minutes under the right conditions.

Agreed. We saw this on May 19, 2013, which was the Edmond and Shawnee tornadoes. Supercells fired but they were able to make it east of the metro area before they did any major damage (unfortunate for the folks in Shawnee). May 20th on the other hand was right at that sweet spot in which the cells were at maximum intensity over densely populated territory.

[venture]

18Z GFS... here is the forecast sounding for Saturday in OKC at 7PM. This latest run breaks storms out along or just east of US 183 now approaching the metro by mid evening. This is what you call directional shear.

[OKCMallen]

Jeez louise, are your little black arrow flag things on the right side supposed to be flying off the graph!?

[jn1780]

Jeez louise, are your little black arrow flag things on the right side supposed to be flying off the graph!?

Yeah, that would be lower level winds heading in the opposite direction of the upper level winds. lol

[OKCMallen]

Yeah, that would be lower level winds heading in the opposite direction of the upper level winds. lol

It's very dramatic. I am a complete beginner with reading these soundings. I sort of get what some of it is a little, but I don't then know what the implications of the data are.

[jn1780]

It's very dramatic. I am a complete beginner with reading these soundings. I sort of get what some of it is a little, but I don't then know what the implications of the data are.

No worries, I don't really understand it either. lol

[SoonerDave]

Jeez louise, are your little black arrow flag things on the right side supposed to be flying off the graph!?

Don't you know 32nd notes when you see them?? All hanging off the Trouble Clef? Indicating Sharp winds across the Flat plains?

[venture]

This may help a little: Weather Spotlight - Upper Air Soundings

I put values on the left hand side in a scale that gives a general idea of when each value starts to get a bit extreme. Keep in mind, just one value in the high category - or further right on the scale - doesn't mean end of the world. It is all relative and everything has to work together.

[bchris02]

18Z GFS... here is the forecast sounding for Saturday in OKC at 7PM. This latest run breaks storms out along or just east of US 183 now approaching the metro by mid evening. This is what you call directional shear.

So has the dryline potentially moved east from where it was originally supposed to be?

[jn1780]

So has the dryline potentially moved east from where it was originally supposed to be?

This is a model of what the environment could be like above OKC at 7:00 Saturday. Doesn't indicate where thunderstorms will fire or be at. It shows what thunderstorms could do if their in the area.

[bchris02]

This is a model of what the environment could be like above OKC at 7:00 Saturday. Doesn't indicate where thunderstorms will fire or be at. It shows what thunderstorms could do if their in the area.

My question was more aimed at his statement about storms firing around Hwy 183.