May 15th - 20th Plains Storm/Severe disco

[Stebo]

I see numerous slight risks with well placed hatches for all days beginning Sat. None of the progs in any way suggest widespread sig severe given marginal mid level/upper level flow/shear and midsummer like capping across much of the southern plains.

 

Some of the models are far from marginal with respect to midlevel flow, unless you are talking about the dryline only then I would agree there. I do however think it is early to say what type of risk areas end up being the case especially since the mesoscale has yet to be resolved.

[andyhb]

I see numerous slight risks with well placed hatches for all days beginning Sat. None of the progs in any way suggest widespread sig severe given marginal mid level/upper level flow/shear and midsummer like capping across much of the southern plains.

 

I don't know if it is just me, but several of the progs for Sunday and Monday would at least appear to suggest pretty decent potential as the mid/upper level jet rounds the base of the trough and ejects more fully into the warm sector. The GGEM makes Sunday a pretty solid looking day in Central and Eastern OK at the very least, the Euro and GFS are a bit more tame on Sunday, but at least the GFS looks pretty potent on Monday east of the Plains.

[baroclinic_instability]

Some of the models are far from marginal with respect to midlevel flow, unless you are talking about the dryline only then I would agree there. I do however think it is early to say what type of risk areas end up being the case especially since the mesoscale has yet to be resolved.

Weak upper trough/SW ejections do not lend themselves to strong backed low level flow. The mid level flow does indeed ramp up post ejection, but the weak baroclinity will not yield much in the way of a low level isallobaric response. I am not saying the threat potential for something more substantial is not there, but everyday has quite a few asterisks involved, including near unidirectional flow later on.

[baroclinic_instability]

I don't know if it is just me, but several of the progs for Sunday and Monday would at least appear to suggest pretty decent potential as the mid/upper level jet rounds the base of the trough and ejects more fully into the warm sector. The GGEM makes Sunday a pretty solid looking day in Central and Eastern OK at the very least, the Euro and GFS are a bit more tame on Sunday, but at least the GFS looks pretty potent on Monday east of the Plains.

Goodness sakes. Read my response to Thundersnow's post...he was referencing how SPC would possibly deal with the various risk days, and I gave a response. Potential and probability of a severe threat are NOT equal. 

[Stebo]

Weak upper trough/SW ejections do not lend themselves to strong backed low level flow. The mid level flow does indeed ramp up post ejection, but the weak baroclinity will not yield much in the way of a low level isobaric response. I am not saying the threat potential for something more substantial is not there, but everyday has quite a few asterisks involved, including near unidirectional flow later on.

 

 

Sure a strong backed flow would be nice but it is far from a deal breaker like it is being represented, there is still good clockwise shear and substantial instability. I am not seeing near unidirectional flow later on until late on Monday.  I also wouldn't consider this a weak trough ejection unless you are buying the flatter quicker model.

[Ian]

I'm going with see texts on all days. 2013 ftw.

 

(kidding)

[andyhb]

Goodness sakes. Read my response to Thundersnow's post...he was referencing how SPC would possibly deal with the various risk days, and I gave a response. Potential and probability of a severe threat are NOT equal. 

 

This isn't what I was referring to (or criticizing) and I never said you were wrong, I'm just giving my thoughts on what the model guidance is showing, it was not intended to be confrontational.

[Chicago Storm]

I see numerous slight risks with well placed hatches for all days beginning Sat. None of the progs in any way suggest widespread sig severe given marginal mid level/upper level flow/shear and midsummer like capping across much of the southern plains.

Voice of reason.

[thewxmann]

I see numerous slight risks with well placed hatches for all days beginning Sat. None of the progs in any way suggest widespread sig severe given marginal mid level/upper level flow/shear and midsummer like capping across much of the southern plains.

 

Yup. Nothing screams big outbreak but we can still get a few very nice tornadoes here and there. Something akin to 6/9/05, 5/12/04, etc...

[Stebo]

Voice of reason.

Yeah that's right, every system is nothing until it is dropping tornadoes, right?

[Stebo]

Yup. Nothing screams big outbreak but we can still get a few very nice tornadoes here and there. Something akin to 6/9/05, 5/12/04, etc...

Yeah I don't think anyone is calling for a big outbreak, however I could see stuff reach into the mod risk category.

[Ian]

Yeah I don't think anyone is calling for a big outbreak, however I could see stuff reach into the mod risk category.

6/9 was a pretty large outbreak.. I think people get fixated on 100 or something when they think outbreak. 

 

May 12 04 is one of the more notable chase days too.. at least for the house video near Attica. 

[Stebo]

6/9 was a pretty large outbreak.. I think people get fixated on 100 or something when they think outbreak. 

 

May 12 04 is one of the more notable chase days too.. at least for the house video near Attica. 

 

Yeah 20 is an outbreak to me, anyone who thinks this is going to have 100 tornadoes need to get their head out of the sand.

[Ian]

Yeah 20 is an outbreak to me, anyone who thinks this is going to have 100 tornadoes need to get their head out of the sand.

 

everyone seems pretty reasonable here so far. tho chicago storm seems to think it's nothing at all.

[Stebo]

everyone seems pretty reasonable here so far. tho chicago storm seems to think it's nothing at all.

Yeah nothing to see here right? Might as well shut down the thread.

[brettjrob]

Yup. Nothing screams big outbreak but we can still get a few very nice tornadoes here and there. Something akin to 6/9/05, 5/12/04, etc...

 

This might be one of the rare moments you're on the optimistic side of the spectrum relative to me. Given the available data right now, I'd be beyond elated if something along those lines transpired. Between monstrous capping and weak sauce flow thru Sat, then all sorts of timing and veering issues afterward, I almost think a KO punch to chasers' 2013 hopes is the most likely outcome of this whole period -- if only by a small margin. Of course, there's a reason for the saying: "when it's May, you chase." Days like 5/19 last year prove that the atmosphere often finds a way to overcome many obstacles this time of year, even if only in a very localized, fluke fashion. And that's my fear at this point: we may face a situation in which it takes a fluke to get a good tube, making for very difficult and stressful forecasting.

[jojo762]

Just wonder, does OUN always keep their AFD this short? With relatively few details about much of anything.

.DISCUSSION...

A SMALL UPPER-LEVEL WAVE WILL PASS OVER THE SOUTHWESTERN PART OF

OUR FORECAST AREA THIS EVENING...BRINGING A SMALL CHANCE OF SHOWER

AND THUNDERSTORMS TO THE WICHITA FALLS/VERNON AREAS. THIS WAVE

WILL CONTINUE TO MOVE NORTHEAST OVERNIGHT...AND RAIN CHANCES WILL

SPREAD EAST.

LOW-LEVEL MOISTURE WILL MAKE A SUBSTANTIAL RETURN OVERNIGHT INTO

TOMORROW...BRINGING CLOUDS AND RAIN CHANCES TO MOST OF THE

FORECAST AREA. A RATHER MESSY PATTERN WILL REMAIN OVER THE AREA

INTO THE FIRST PART OF NEXT WEEK...MEANING LOW RAIN CHANCES EACH

DAY...BUT NO CLEAR-CUT MAIN EVENT.

A DRYLINE THAT WILL TAKE UP RESIDENCE OVER WEST TEXAS MAY INVADE

OUR FAR SOUTHWEST COUNTIES FRIDAY...BRINGING EXCESSIVELY HOT

WEATHER INTO THAT AREA.

[andyhb]

Just wonder, does OUN always keep their AFD this short? With relatively few details about much of anything.

 

In this case (with the most recent outlook), they appear to be waiting until more timing differences are resolved before delving further into the severe potential this weekend and thereafter.

[jojo762]

Figured they were waiting for the differences to be resolved. So that they don't say something that would be a false alarm.

[brettjrob]

Figured they were waiting for the differences to be resolved. So that they don't say something that would be a false alarm.

 

In general, I think many offices don't bother getting into the nitty gritty of severe weather setups in the extended periods. Even when a significant event may be in the offing, they're focused a lot more on nailing the short range than dissecting every possibility on day 5. Since the gridded forecasts only address temperatures and POPs, there's not necessarily any incentive to worry about storm mode, intensity, etc. on D5-7 since it doesn't directly affect those parameters. By comparison, something like a snowstorm in the extended does seem to get more attention in AFDs a lot, probably because it does heavily affect the numbers they plug into GFE.

[jojo762]

In general, I think many offices don't bother getting into the nitty gritty of severe weather setups in the extended periods. Even when a significant event may be in the offing, they're focused a lot more on nailing the short range than dissecting every possibility on day 5. Since the gridded forecasts only address temperatures and POPs, there's not necessarily any incentive to worry about storm mode, intensity, etc. on D5-7 since it doesn't directly affect those parameters. By comparison, something like a snowstorm in the extended does seem to get more attention in AFDs a lot, probably because it does heavily affect the numbers they plug into GFE.

That makes sense now.... I've noticed that they rarely ever get into specifics in relation to Svr weather, if they even mention it at all in the long term, but almost always mention winter storms.

I did notice in the last few issued AFD's, that at least TOP/DDC/ICT have paid a decent amount of attention to this upcoming threat haven't really looked at any other WFO's besides those three though.

[Ian]

I'm not really sold on anything, and the 0z GFS isn't amazing maybe (cursory look) but it looks good to me. I think the shear will probably end up enough on Sat tho it might be a late and local show. Sunday is convoluted but shifted west a bit on this run.. that dance is tricky but with a 500 low pinching off and that big broad base to the trough .. you never know.

[Thundersnow12]

I'm not really sold on anything, and the 0z GFS isn't amazing maybe (cursory look) but it looks good to me. I think the shear will probably end up enough on Sat tho it might be a late and local show. Sunday is convoluted but shifted west a bit on this run.. that dance is tricky but with a 500 low pinching off and that big broad base to the trough .. you never know.

 

Sunday on the GFS now looks pretty darn good along and west of I-35 in OK. Westerly flow aloft over the dryline with now a strong southerly LLJ.

[brettjrob]

Slowing trend continues on the GFS. Surprisingly, we seem to be on the precipice of Sunday becoming a significant event in the eastern part of the Plains, possibly focused from C OK up through E KS/NE. The general pattern, with the negative-tilt trough axis swinging through during the afternoon, is not one of my favorites. But it's something that tends to be less devastating as you get later into the season with more and deeper moisture. There are plenty of potential failure modes, and if the trend reverses back to a slightly-faster s/w, we really just screw both days. But unlike last night, I'm starting to warm up to Sunday.

 

At this point, it seems safe to say Saturday is no longer a headliner threat, but a high-risk/high-reward chase opportunity should exist in the general vicinity of the KS/NE/CO corner.

[andyhb]

Near OKC, 00z Sunday evening...there's your good Plains look with primarily speed shear in the lowest km and then strong veering above it.

 

[Ian]

Slowing trend continues on the GFS. Surprisingly, we seem to be on the precipice of Sunday becoming a significant event in the eastern part of the Plains, possibly focused from C OK up through E KS/NE. The general pattern, with the negative-tilt trough axis swinging through during the afternoon, is not one of my favorites. But it's something that tends to be less devastating as you get later into the season with more and deeper moisture. There are plenty of potential failure modes, and if the trend reverses back to a slightly-faster s/w, we really just screw both days. But unlike last night, I'm starting to warm up to Sunday.

 

At this point, it seems safe to say Saturday is no longer a headliner threat, but a high-risk/high-reward chase opportunity should exist in the general vicinity of the KS/NE/CO corner.

 

2,000 chasers on one cell. The most photographed landspout ever.

[brettjrob]

2,000 chasers on one cell. The most photographed landspout ever.

 

Sad but true.

 

Man, look at that second s/w dive in for Monday with more robust upper flow. Such a complex evolution, as HM has covered well. I imagine the whole Sunday-Tuesday sequence will flail wildly on the modeling for a few more days, but ultimately the pattern seems conducive for one day to emerge as the best day of the season thus far (lolz). Only downside is it heavily favors mediocre chase terrain rather than W of I-35.

[andyhb]

Sad but true.

 

Man, look at that second s/w dive in for Monday with more robust upper flow. Such a complex evolution, as HM has covered well. I imagine the whole Sunday-Tuesday sequence will flail wildly on the modeling for a few more days, but ultimately the pattern seems conducive for one day to emerge as the best day of the season thus far (lolz). Only downside is it heavily favors mediocre chase terrain rather than W of I-35.

 

Yeah, I just noticed that as well, there is some very strong backing of the sfc winds east of the dryline as well.

 

[thewxmann]

This might be one of the rare moments you're on the optimistic side of the spectrum relative to me. Given the available data right now, I'd be beyond elated if something along those lines transpired. Between monstrous capping and weak sauce flow thru Sat, then all sorts of timing and veering issues afterward, I almost think a KO punch to chasers' 2013 hopes is the most likely outcome of this whole period -- if only by a small margin. Of course, there's a reason for the saying: "when it's May, you chase." Days like 5/19 last year prove that the atmosphere often finds a way to overcome many obstacles this time of year, even if only in a very localized, fluke fashion. And that's my fear at this point: we may face a situation in which it takes a fluke to get a good tube, making for very difficult and stressful forecasting.

 

Haha, maybe the dates I used were a little too extreme. Agree with you about Sat and the veering issues. At this point I think the biggest issue is moisture/LCLs -- the GFS is clueless about boundary layer moisture.

[Ed Lizard]

A day early, but is anyone heading to SPS today?  (We have employees South of Electra, near Iowa Park)

 

 

(New NAM looks better a bit further South, just as far as big QPF).