General Weather Discussion - May 2017

[bchris02]

Will do a more detailed update tomorrow. But it looks like supercells will develop across the TX PH and and SW OK and move north and east. Large hail will be primary threat out here along the dryline. Then as night falls, the storms will likely evolve into a cluster or line and pose a damaging wind threat to C OK.

It definitely seems like damaging wind has been the thing this year for C OK. It's starting to look like Thursday might be that way as well. I'll take it over tornadoes. This kind of reminds me of the 2002 season.

[Bobby821]

It definitely seems like damaging wind has been the thing this year for C OK. It's starting to look like Thursday might be that way as well. I'll take it over tornadoes. This kind of reminds me of the 2002 season.

Depends on how strong the winds are when they come through. If the are 80+ then that is like having a small tornado go through an area but the winds are more spread out across a larger area and therefore cause more damage in most cases then a small end tornado would in it relatively small area it goes through. At this point I am thinking as far as the metro goes by the time the storms reach OKC area they will be dying down pretty quickly as the encounter a stronger cap over central Oklahoma tonight. Maybe a rumble or two of thunder and some lightning and rain but will be on the weaker side. As for Thursday that seems to be the big day for OKC storms right now but is still a complicated forecast to nail down at this time. Friday we could see storms in and close to OKC as well. But as far as tonights storms go it will really be a non event for okc I am thinking now.

[Anonymous.]

Should see storms firing in the TX panhandle around 4pm. These initial cells ahead of the dryline will likely be supercell in nature and have capabilities of very large hail and isolated tornado potential. These cells will likely die off as they push northeast as we head into the night. More storms will fire just behind these on the actual dryline and will conglomerate into a line of storms that will push east overnight and into C OK. Damaging winds and heavy rainfall are the main threat for OKC.

[Roger S]

Upgrade to Moderate for Western OK and OKC is now riding the edge of Enhanced it looks like.

[SoonerDave]

That graphic makes it a little hard to discern just where OKC is relative to the eastern boundary of the Enhanced risk region. SPC has released a Public Weather Statement with a more detailed map that shows that the Enhanced risk region extends to the western edge of Canadian county. Things appear to be mixing up in the panhandle area for potentially a really rough later afternoon. I'm guessing some of the newer models may be showing some more rapid or intense initiation in the area this afternoon.

http://www.spc.noaa.gov/products/outlook/pwo.html

[SoonerDave]

Here's the excerpt from the latest SPC discussion that includes the new Moderate risk area. (emphasis mine)

Low level moisture continues to stream rapidly northward into the TX
Panhandle and western OK, with dewpoints now in the mid 60s across
the region. Model forecast soundings by mid-late afternoon suggest
strong instability will be present with MLCAPE values over 3500 J/kg
and 8 C/km lapse rates. Isolated and discrete convection is
expected to form along the dryline in the TX Panhandle and track
northeastward through the mid-evening. A pocket of strong low-level
shear is forecast to develop in this region, resulting in favorable
hodograph structures for supercells capable of very large hail and
strong tornadoes. Therefore have upgraded this area to MDT risk.

When they start talking about CAPE values in the 3,500 range, that's a TON of energy available for strong storms to build up. Normally things are set up for strong storms even at 2,500. Combine that with the shear they are predicting and that's just a classic setup for big, rotating storms that will probably pop severe very quickly and toss around a bunch of hail. Folks in western OK just need to keep an eye out for how things develop as the day progresses.

Edit: CAPE is a number that expresses how much energy is in the atmosphere that's available to support lift - the ability for an airmass to climb (which is exactly what thunderstorms do). The higher the number, the more unstable the air is, and the more conducive that air is to thunderstorm development.

[Anonymous.]

PDS watch is out for TX PH and extreme western OK. 80% probability for an EF2 or greater tornado.

[SoonerDave]

Western OK just got upgraded to a PDS Tornado Watch within just the last few minutes.

[OOPS: Sorry anon ]

[Anonymous.]

The dryline is slightly bulging in the center part of the TX PH, this is particularly concerning with models showing at least 1 large supercell coming across the border. If you have friends/family in places such as Elk City, make sure they are paying attention this evening.

Supercells already going north of Amarillo, but here is a snapshot in a couple hours showing the rest of the panhandle lighting up:

[jn1780]

I wonder if people in Elk City think this year is a "boring" season? Just goes to show how fast things can change.

[Anonymous.]

I'm on the road. But Severe Watch coming for all of C OK. This will go until early morning hours. Flooding threat will be high. Damaging winds will also be possible.

[mugofbeer]

I think Elk City residents are no longer thinking it's anything remotely boring. A sadly ironic post above. My prayers for those folks there.

[John1744]

NWS has already bumped Thursday to a moderate risk in the west.

[SoonerDave]

I think the setup for Friday is giving the SPC folks some headaches. On the one hand, the fundamental setup for storms is very much present; however, the instability remaining after the Thursday storms and the ability of the atmosphere to recover is very much in question.

[Anonymous.]

Elk City, sorry for calling you out yesterday, I swear it was a coincidence!

Thursday is shaping up to be the real deal across all of W OK and eventually into C OK. Groups of supercells will develop in NW OK down through SW OK. All severe risks look possible with these, large hail and tornadoes being the biggest threat.

Here is an early snapshot of cells developing Thursday evening off of and in front of the dryline:

[Roger S]

Elk City, sorry for calling you out yesterday, I swear it was a coincidence!

Yeah... I mentioned that to my wife while we were watching the coverage last night.... One of those times you have to regret being right I guess.

[Bobby821]

Do you think we will see the moderate risk expanded further south and east to include the metro? as far as Friday goes if it ends up like last Tuesday nights storms they have already cleared out and it is sunny this morning so if that's what happends with Thursday evenings storms then Friday is very much in play still.

[LocoAko]

Apparently had some decent winds at the house last night. Nothing too severe, but it blew all of my yard furniture against the fence, broke tons of branches around the neighborhood, and knocked over a potted plant. Most notably though was my neighbor's trampoline, which is no where to be seen (unless they somehow moved it preemptively, which seems unlikely). Surprised I slept completely through it.

[Outhunder]

Well it looks like any hope of this week being of the higher end severe weather event is failing us and it is looking more like a dud now. Only hope is that hopefully Thursday will bring us some good stuff. This has really turned out to be a boring spring so far weather wise.

Was the death and destruction in Elk City good enough "stuff" for you? Or are you hoping for more deaths and more destruction closer to OKC?

[SoonerDave]

Do you think we will see the moderate risk expanded further south and east to include the metro? as far as Friday goes if it ends up like last Tuesday nights storms they have already cleared out and it is sunny this morning so if that's what happends with Thursday evenings storms then Friday is very much in play still.

The whole thrust of the Friday SPC outlook revolves around the atmospheric recovery question from Thursday's storms. I don't think there's any consensus on it at this point, but clearly they're opting to hedge a bit rather than go more aggressive - at least that's how I interpret it.

[bchris02]

Does the primary tornado threat on Thursday appear to still be in northwestern Oklahoma?

Also, it seems the local TV meteorologists are starting to get a little more bullish on Friday. Earlier in the week, it appeared to be primarily east of I-35.

[NikonNurse]

Does the primary tornado threat on Thursday appear to still be in northwestern Oklahoma?

Also, it seems the local TV meteorologists are starting to get a little more bullish on Friday. Earlier in the week, it appeared to be primarily east of I-35.

It depends on what the storms on Thursday do to the atomosphere......

[SoonerDave]

Does the primary tornado threat on Thursday appear to still be in northwestern Oklahoma?

Also, it seems the local TV meteorologists are starting to get a little more bullish on Friday. Earlier in the week, it appeared to be primarily east of I-35.

Structurally, in terms of the location of fronts and airmass boundaries, the setup for Friday isn't that different from Thursday. What is uncertain is how much the atmosphere will be able to "recover" from the beating it will take with the storms that should form on Thursday afternoon/evening. If that convection takes most of the energy even into the following morning, it necessarily limits the amount of energy/instability available for storms to use as "fuel" on the *next* day. On the other hand, if the atmosphere clears up, and lots of morning heating occurs, the atmosphere will destabilize and promote more thunderstorm development.

[bchris02]

Mike Morgan has shifted the moderate risk boundary a little farther east for tomorrow putting it near the metro. SPC still hasn't made this change yet. Is this just Mike Morgan's hyping or is this system looking to be focused a bit farther east than originally expected? Just a few miles will make a difference in terms of whether OKC will see a significant tornado threat.

[Anonymous.]

You can find all of the SPC's risk maps here:

http://www.spc.noaa.gov/products/outlook/

Anything deviating from this is purely from the individual meteorologist.