General Weather Discussion - May 2018

[Anonymous.]

Starting May thread early to avoid discussion of the early month storm potential being in two different places.

As I mentioned in the April thread, this weekend is going to be fantastic weather-wise. Probably one of the best of the season. 70s and 80s with light winds.


SPC has outlined risks for at least three future days in Oklahoma. The first two days being Monday and Tuesday with 15% chance of severe storms mainly out in western and northwestern OK. Wednesday they have outlined a 30% risk that covers essentially the northwestern half of OK, with 15% in the remaining.

What this means: Usually when SPC is outlaying risks this far ahead, the potential for abnormally severe weather is high. These days usually lead to at least moderate risk outlines in the 3-day SPC outlook, and sometimes are upgraded to high risk outlines somewhere in the same outlook window.

As we are obviously many days out from the event(s) - accurately predicting storm mode is difficult. But as of right now storms look to be supercell in nature developing off of a dryline. Just stay tuned into the local weather sources in the next 3-5 days.

[SoonerDave]

Anon, help me with something. I surely get the general setup for this week, but one thing that puzzles me a bit is that usually the biggest area of focus is closer to the triple point near the low, which is well north into Kansas. But they seem in the discussion to be focusing more on NW/NC OK for the threat area of concern into day 5 (Weds). Is something mitigating the KS threat some, despite that 30% region?

[Anonymous.]

I am not sure what you're asking, but SPC has made updates since you posted a couple days ago obviously. But right now we have slight risks for western OK today and tomorrow with Wednesday being the larger area of risk with the storm ejecting. Currently 30% probability with NW OK being hashed for significance.

NAM has supercells developing along the dryline late Wednesday and moving into central parts of the state overnight.

[SoonerDave]

Anon, the hatched area in NW OK essentially what I missed or was newly added. That addresses what I clumsily tried to ask before. That hatched region is much closer to the triple point, which is where I would have expected the 30% region to be focused (rather than as broadly as it is now).

[Anonymous.]

Yea the SPC is very keen on updates! Day 2 slight risk has now been mostly removed from OK in the latest update.

[bchris02]

Do you think the local TV meteorologists are overhyping this? I guess since it's the first event of the season they are trying to get people into that severe weather mindset but I'm not thinking that Wednesday will be particularly high-end. There will probably be a few tornadoes in the state but it isn't going to be one of those classic PDS-type days. Am I wrong?

[Ginkasa]

Do you think the local TV meteorologists are overhyping this? I guess since it's the first event of the season they are trying to get people into that severe weather mindset but I'm not thinking that Wednesday will be particularly high-end. There will probably be a few tornadoes in the state but it isn't going to be one of those classic PDS-type days. Am I wrong?

I haven't been particularly watching the TV meteorologists much, but I'm personally of the opinion that if there is a chance for tornadoes and severe weather they should ensure the public is made aware of it. It just takes one tornado to ruin someone's day; it doesn't have to be a "classic PDS-type" day for storms to have an impact.

[Anonymous.]

SPC maintaining generally same risk areas. There is uncertainty building across the dryline area of storm formation and timing. Development looks like very likely across C KS and W TX. While remains more questionable in the middle east of the OK/TX border.

In the current forecast, I would say it could likely be an event that is non-widespread and we could just have 1 or 2 areas of very localized impacts.

Here is a couple snapshots of various shorter-range models showing development:

WRF showing linear development near the OK/KS border with more discrete-in-nature development across W/SW OK.



NAM showing development in KS and down into W TX, but gapping all of OK until late overnight when some development occurs in W OK and moves NE.

[Ian Drake]

Thank you, those graphics bring a sense of relief... better than the gloom and doom that the weather channel and the Storm prediction center have painted over the region. I’m still a nervous wreck though, my work productivity is suffering quite a bit.

[Dessert Fox]

Do you think the local TV meteorologists are overhyping this? I guess since it's the first event of the season they are trying to get people into that severe weather mindset but I'm not thinking that Wednesday will be particularly high-end. There will probably be a few tornadoes in the state but it isn't going to be one of those classic PDS-type days. Am I wrong?

David Payne is anything but hype these days, generally. He livestreams nearly every day on facebook at around 11 am.

[SoonerDave]

David Payne is anything but hype these days, generally. He livestreams nearly every day on facebook at around 11 am.

Yeah for those of us who remember, he's ratcheted it down quite a bit.

The entirety of this forecast, however, is pulling me back to my question from earlier in the week: Why was there so much emphasis beyond the area immediately near the triple point? This setup has favored stronger weather in KS for some time now, but SPC pushed out the 30% region early in the game. The region itself wasn't so much the problem as was its *size*. And now it seems to be unfolding that, sure enough, we could have strong storms here, the better potential is where it's always been. I think SPC could have kept a lot more of OK in a slight risk zone and accomplished the same level of warning. Even their forecast discussions implied their expansion of the enhanced risk was more discretionary. They added an odd hatched region later - near the triple point - which probably should have been the 30% or enhanced region to begin with IMHO...

And I've also noticed a distinct trend among all local TV to move the hype away from the weather guy and toward the news folks. Every station was doing a "clean out your shelters" type of story this morning. I actually heard one story where the reporter actually said, "If you hear sirens, go to a shelter." Seriously?

[SoonerDave]

Thank you, those graphics bring a sense of relief... better than the gloom and doom that the weather channel and the Storm prediction center have painted over the region. I’m still a nervous wreck though, my work productivity is suffering quite a bit.

I think the SPC got a little aggressive on this one. Yes, it's a bit complicated, lots of moving parts, but they did get a bit edgy on this one for whatever reason.

[Anonymous.]

HRRR model becoming more bullish for storm development for this afternoon across NW OK. I am sure everyone up there is welcome to any potential rain. Main severe threat in this part of the state will be hail as supercell structure is the likely mode. Movement of storms will be off to the NE toward KS.

[soonerguru]

Queston: is Wednesday setting up for an overnight event in Central OK?

[SoonerDave]

Queston: is Wednesday setting up for an overnight event in Central OK?

Sure seems like that's the emerging wisdom. Lots can change though...

[jonny d]

Is this going to be another mother nature fake out? Because the west half of the state being as dry as it is, I don't think it can take another one?

[Anonymous.]

Tornado watch coming for C and SW KS soon with an upgrade to moderate from SPC to the area.


For tomorrow, the enhanced risk has been trimmed down across SW OK, and remains for most of WC , NW, and C OK. The hatched significant severe zone has been expanded to include essentially the NW 1/2 of OK with inclusion of OKC metro. Emphasizing hail size with cells that are able to develop.

[baralheia]

I actually heard one story where the reporter actually said, "If you hear sirens, go to a shelter." Seriously?

Keep in mind that this is because the City of Oklahoma City recently (last year, if I remember right) changed their siren activation policy; previously, all sirens in Oklahoma City would sound if a tornado warning impacted any part of the city. Now, only the sirens in the area covered by the warning will sound. As a result, it's much, much more important to take shelter if you hear sirens now, because you're only going to hear them if you're in immediate danger.

[SoonerDave]

Keep in mind that this is because the City of Oklahoma City recently (last year, if I remember right) changed their siren activation policy; previously, all sirens in Oklahoma City would sound if a tornado warning impacted any part of the city. Now, only the sirens in the area covered by the warning will sound. As a result, it's much, much more important to take shelter if you hear sirens now, because you're only going to hear them if you're in immediate danger.

I'd love to think that was the motivation for the story, but the broader presentation of the story didn't imply nearly that much sophistication.

[Easy180]

Norman Weather Center now has central OK in slight risk as of their 4:20AM hazardous discussion. Reads as if western OK gets the nasty afternoon storms then we get overnight with wind gusts the main threat.

[Anonymous.]

Some big time tornadoes yesterday in central KS, monster storms. Luckily very rural areas in and around those parts.


So far for Oklahoma we have slight risk across large area of state and enhanced up in NW OK just like yesterday. However, the tornado chance parameters have been increased in the area with a focus across the above mentioned enhanced risk zone. I will post in a few hours after some fresh data, and get some graphics posted for what we can expect for this afternoon. Some of these high clouds will likely burn off as we head toward afternoon and that will become a player in destabilization across the region.

[Bobby821]

Some big time tornadoes yesterday in central KS, monster storms. Luckily very rural areas in and around those parts.


So far for Oklahoma we have slight risk across large area of state and enhanced up in NW OK just like yesterday. However, the tornado chance parameters have been increased in the area with a focus across the above mentioned enhanced risk zone. I will post in a few hours after some fresh data, and get some graphics posted for what we can expect for this afternoon. Some of these high clouds will likely burn off as we head toward afternoon and that will become a player in destabilization across the region.

I doubt the way things are trending if OKC metro area will even see storms later this evening or overnight. Looks like all the action will be up north along the OK/KS border and down south into Texas for the overnight.

[Anonymous.]

I think we could see an upgrade to the risk across W and C OK for this afternoon. Atmosphere conditions are priming for an active evening across the state. Right now we have dewpoint temperatures in the upper 60s across the entire body of the state with clearing occurring along and ahead of the dryline.

Short-range models are coming around to producing multiple storms around 4pm along and just east of the TX/OK border. Storms will post an immediate hail threat as updrafts will be very high. Storms will likely merge and become clustes with embedded supercell structures. We could see 3-4 dominant cells/clusters carrying very large hail threats and tornado potentials as the storms move off the dryline and race northeast. After the early evening storms blow through, we will have another round late overnight that develops down in far western TX and rushes across the state. These will be a rain and wind threat, maybe small hail. The main show is the early evening stuff.


Snapshot of HRRR showing development occurring between 4-5pm:


Current dewpoints (this map will continue to update):

[Bobby821]

Starting to see more sun peeking through the clouds here in Moore. The dry line is way farther west than I would have expected it to be with the ongoing drought conditions. we will see how far east the storms that fire off it make it before the cap starts to strengthen after sunset this evening if they can sustain themselves long enough to make it to central Oklahoma to give us some action.

[Anonymous.]

As I expected. SPC has upgraded NW OK to Moderate with Enhanced being expanded across all of the western half of OK, including the OKC metro.

I want to point out the significance of this due to what we saw yesterday leading up to the central KS storms, is occurring again like clockwork across OK. Major destabilization ahead of a sharp dryline is becoming a very strong possibility.

10% hatched tornado parameters are expanded across essentially the western 1/2 of OK.