General Weather Discussion - May 2017

[SoonerDave]

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.

Do yourself a favor and banish Mike "Drive South" Morgan from your weather repertoire.

[jn1780]

Do yourself a favor and banish Mike "Drive South" Morgan from your weather repertoire.

While I'm not a fan of Morgan, What he is showing is not that much different from what NWS Norman is showing and I would assume these people talk with the SPC people since they are in the same building? Official day 2 products only come out twice per day and that's by design because they don't want people to overly focus on details a day before. Storms don't care where the red line is drawn across a map or how another guy drew his red line 15 miles closer.

http://www.weather.gov/images/oun/graphicast/image8.png

[SoonerDave]

While I'm not a fan of Morgan, What he is showing is not that much different from what NWS Norman is showing and I would assume these people talk with the SPC people since they are in the same building? Official day 2 products only come out twice per day and that's by design because they don't want people to overly focus on details a day before. Storms don't care where the red line is drawn across a map or how another guy drew his red line 15 miles closer.

http://www.weather.gov/images/oun/graphicast/image8.png

As I understand it, SPC is in Norman, OK. KFOR, KWTV, etc are in far NE OKC. Granted, storms don't know/care about lines on a map. In fairness, most every local met does some variety of their own map and likely uses SPC resources perhaps as a departure point. As far as direct interaction with them goes, I don't know that there's that much formal contact, if any.

Regardless, today is shaping up to be one of those days/evenings in OK, so folks need to just keep track of things...mid/late afternoon for OKC it would seem. Stay safe, everyone....

[John1744]

SPC has upgrade NW OK to a high risk with a 30% hatched tornado risk indicating possibly long strack strong tornadoes likely today in and around that area.

Today definitely is seeming like one of those keep an eye on your apps if you're out and about.

[SoonerDave]

Was reading the SPC summary and they're talking about CAPE values near 4,000. Just a huge amount of instability. Springtime in OK.....

[jn1780]

As I understand it, SPC is in Norman, OK. KFOR, KWTV, etc are in far NE OKC. Granted, storms don't know/care about lines on a map. In fairness, most every local met does some variety of their own map and likely uses SPC resources perhaps as a departure point. As far as direct interaction with them goes, I don't know that there's that much formal contact, if any.

Regardless, today is shaping up to be one of those days/evenings in OK, so folks need to just keep track of things...mid/late afternoon for OKC it would seem. Stay safe, everyone....

I was referring to the local NWS forecast office vs the SPC. They had the moderate going as far out as Canadian county.

[SoonerDave]

I was referring to the local NWS forecast office vs the SPC. They had the moderate going as far out as Canadian county.

Oops - my bad. Sorry 'bout that I should probably learn to read someday....

Your point regarding map boundaries is very well-taken. The whole map issue could stir up a totally separate discussion about whether difference between a 30% risk and a 15% risk really changes how anyone could or should respond to a severe weather forecast.....

[bradh]

Deer Creek Schools cancels after school Antler Care already

[Anonymous.]

This is the 4th High Risk issuance of 2017. And the first that isn't in the southeastern US since 2014. (2017's 4 High Risks are the only 4 High Risks since 2014)


Models are trying to figure out storm initiation today, but can't make up their minds. As it looks right now, we could see development first into SW OK somewhat early (3-4pm). After this early convection, there could be a break (in the clouds) between the initial storms and the dryline. This will allow for a quick burst of heating before the dryline fires the big boys. As it stands, NW OK is nearly guaranteed to have 3-4 monster supercells that will likely track along very similar paths. As far as the southern portion of the dryline, right now models are conflicted about developing nothing at all, or 1-2 big supercells. We could also have a few supercells form out of the earlier convection on the southern end. This would be ahead of the dryline and have a very good chance of becoming right-turn supercells with potential impact into C OK before nightfall. After dark, there will likely be a line of storms trying to backbuild from NW/N OK down toward C OK. It is unclear at this time if it will do as such.

I will keep this updated throughout today and get some maps in here once we get some cumulus fields going.

[jn1780]

Oops - my bad. Sorry 'bout that I should probably learn to read someday....

Your point regarding map boundaries is very well-taken. The whole map issue could stir up a totally separate discussion about whether difference between a 30% risk and a 15% risk really changes how anyone could or should respond to a severe weather forecast.....

Yeah, especially when your east of the bullseye. The stronger longer lived right turners can find themselves east of the higher risk area and they still take awhile to spend down even after moving out of the most favorable conditions.

[riflesforwatie]

This is the 4th High Risk issuance of 2017. And the first that isn't in the southeastern US since 2014. (2017's 4 High Risks are the only 4 High Risks since 2014)

This is also the first High Risk in the initial Day 1 forecast since Nov 2013. In other words, all the Highs since then have been Day 1 upgrades at the end of the overnight shift or during the subsequent day shift.

For the Plains this is the first tornado-driven High (i.e., instead of a wind-driven High) since the Woodward OK tornado day (14 Apr 2012).

[riflesforwatie]

Your point regarding map boundaries is very well-taken. The whole map issue could stir up a totally separate discussion about whether difference between a 30% risk and a 15% risk really changes how anyone could or should respond to a severe weather forecast.....

More to the point, the true probability of any of the severe hazards exists on a continuous scale. It's not truly a stair-step of (for tor) 2-5-10-15-30-45-60, but it's drawn that way for technical reasons. So the closer you are to the 15% line, the closer the real forecast probability is to 15%. Just outside that line, it doesn't immediately drop to 10%, but instead drops gradually as you move orthogonally away from the line.

[jn1780]

The local nws office has now included all of the metro in the moderate risk. This probably means they are more confident the southern storms will actually form.

[riflesforwatie]

Official day 2 products only come out twice per day and that's by design because they don't want people to overly focus on details a day before.

It also takes people, time, and effort to issue a Convective Outlook. Given the available resources, five Day 1 outlooks and two Day 2 outlooks are appropriate, in my view.

[5alive]

[5alive]

^^^ Click for hi-res image

[OkiePoke]

Can I get a ELI5 for right-turn storms?

[baralheia]

Can I get a ELI5 for right-turn storms?

In general, springtime thunderstorms tend to move from the southwest to the northeast. Rotating supercell thunderstorms sometimes make a "right turn", where they began moving in a more easterly direction; often, when this happens, it signals intense rotation and a strong tornado. The storm on May 20th, 2013 that produced the Moore tornado did exactly that.

That's my understanding from a non-meteorology background; someone like Anonymous could likely explain better than I could, however!

[bchris02]

In general, springtime thunderstorms tend to move from the southwest to the northeast. Rotating supercell thunderstorms sometimes make a "right turn", where they began moving in a more easterly direction; often, when this happens, it signals intense rotation and a strong tornado. The storm on May 20th, 2013 that produced the Moore tornado did exactly that.

That's my understanding from a non-meteorology background; someone like Anonymous could likely explain better than I could, however!

The 5/31/13 storm that produced the El Reno tornado did that also. That was one part of why Mike Morgan's "drive south" was so irresponsible because people were driving right into the path of the storm since it didn't take the usual southwest/northeast path.

[Anonymous.]

Supercells are powerful counter-clockwise spinning storms. This spin can be strong enough to possess ability to alter entire boundaries. The same spin often [if strong enough] can make the storm want to collapse/close onto/into itself (think of it as a big ocean wave beginning to 'break'). This will allow the storm to basically move more easterly from its original north/northeasterly desire. What we often see, is a supercell that is varying between northeast movement and east movements. This is a type of "jogging" pattern by the storm. And each time it moves east, is a good indicator of stronger and more intense rotation. Often times meteorologists and chasers talk about storms "ramping up" - this is the ELI5 of rotation appearing to increase, thus an east (or right) move is likely occurring or about to occur.

[Bunty]

FLOOD WATCH OUT FOR NEARLY ALL WESTERN TWO THIRDS OF THE STATE. INCLUDES OKC.

Area Affected In Green:


Alfalfa - Atoka - Beckham - Blaine - Bryan - Caddo - Canadian - Carter - Cleveland - Coal - Comanche - Cotton - Custer - Dewey - Ellis - Garfield - Garvin - Grady - Grant - Greer - Harmon - Hughes - Jackson - Jefferson - Johnston - Kay - Kingfisher - Kiowa - Lincoln - Logan - Love - Major - Marshall - McClain - Murray - Noble - Oklahoma - Payne - Pontotoc - Pottawatomie - Roger Mills - Seminole - Stephens - Tillman - Wa****a - Woods - Woodward.

Effective: Thu, 5/18 11:06am Updated: Thu, 5/18 11:27am Urgency: Future
Expires: Tue, 5/23 7:00am Severity: Moderate Certainty: Possible

Details:

...Periods of Heavy Rainfall Expected Through Saturday Morning...
...FLOOD WATCH IN EFFECT FROM 7 PM CDT THIS EVENING THROUGH
SATURDAY MORNING...
The National Weather Service in Norman has issued a
* Flood Watch for flash flooding...flooding of creeks and
rivers...and flooding of low lying areas for portions of
Oklahoma and northern Texas, including the following areas, in
Oklahoma, Alfalfa, Atoka, Beckham, Blaine, Bryan, Caddo,
Canadian, Carter, Cleveland, Coal, Comanche, Cotton, Custer,
Dewey, Ellis, Garfield, Garvin, Grady, Grant, Greer, Harmon,
Hughes, Jackson, Jefferson, Johnston, Kay, Kingfisher, Kiowa,
Lincoln, Logan, Love, Major, Marshall, McClain, Murray, Noble,
Oklahoma, Payne, Pontotoc, Pottawatomie, Roger Mills,
Seminole, Stephens, Tillman, Wa****a, Woods, and Woodward. In
northern Texas, Archer, Baylor, Clay, Foard, Hardeman, Knox,
Wichita, and Wilbarger.

* From 7 PM CDT this evening through Saturday morning
* Areas of 3 to 5 inches of rain are expected by Saturday morning
with higher amounts possible in some locations.
Precautionary/preparedness actions...
A Flood Watch means there is a potential for flooding based on
current forecasts.

You should monitor later forecasts and be alert for possible
Flood Warnings. Those living in areas prone to flooding should be
prepared to take action should flooding develop.

[Bunty]

Do yourself a favor and banish Mike "Drive South" Morgan from your weather repertoire.

He said "drive south" in response to a F-5 tornado. Such tornadoes can easily destroy everything, leaving only the slab foundation. Would you be brave enough to stay in your house when it's in the path of a F5 tornado, especially if there was no storm shelter?

[SoonerDave]

He said "drive south" in response to a F-5 tornado. Such tornadoes can easily destroy everything, leaving only the slab foundation. Would you be brave enough to stay in your house when it's in the path of a F5 tornado, especially if there was no storm shelter?

And a car is so much *better* a choice.....especially when driving into the jam he had no small hand in creating, and making them all sitting ducks. It was one of the singularly most irresponsible things ever spewed by an OKC weatherman.

[OkiePoke]

Thanks for the explanation. So, only really strong storms/tornadoes will turn east. The tornado dictates this, not the atmosphere?

The CAPE is pretty high from my understanding. From the traditional set up of a dryline & cold front, does the CAPE determine the severity/intensity? So, the CAPE is high which correlates to a potential strong tornado therefore could change the boundary cuasing the storm to move east? I am assuming there are a lot of other factors including shear.

[Bellaboo]

And a car is so much *better* a choice.....especially when driving into the jam he had no small hand in creating, and making them all sitting ducks. It was one of the singularly most irresponsible things ever spewed by an OKC weatherman.

Yes and the station had him out on a 2 week leave after that. He also said to get under ground if possible. Resulting in several deaths from residents choosing to hide under a bridge that later flooded.