Active Severe Weather Pattern Beginning Next Week

[pbrussell]

Models have indicated very large CAPE for at least a week now in this timeframe. It's just a matter of strengthening the flow aloft. I can't recall seeing such explosive instability in May for a long stretch like this since 2013 (might have to go back further than that).

 

Wind profiles don't look too shabby either. I know it's early, but at least they're not unidirectional. May have to take a few days off, and might even get to see some action right here in KC.

[andyhb]

Laughing at all the GFS soundings with their moisture depth at 00z for pretty much every day next week. Really needs to improves its PBL scheme in that aspect.

[Jim Martin]

From Norman AFD this morning...

 

An unstable airmass is expected to remain in place this entire

week, with several other mid level shortwave perturbations moving

within the WSW flow ahead of a digging trough. Expect the

possibility of strong to severe storms each day, with storm

organization and intensity likely increasing through the week as

the mid to upper flow does the same. For now it appears Thursday

may have the best potential for producing widespread severe

weather as a signficant 500 mb vort max lifts northeastward with

an accompanying jet max, although it's unclear what will transpire

near the surface.

[andyhb]

Don't often see language like this in the mid/long range section from OUN's AFDs.

 

Monday through late in the week; if there was ever a definition of
an "active pattern," this would be it.

[bjc3395]

GFS trying to delay the end of the enhanced southwest flow regime such that tor potential may continue into the weekend. Incredible.

Edit: mostly Friday. Looks like troughing finally passes through friday/Saturday.

[Chinook]

So weird to see lowercase letters used by the NWS.

[jojo762]

Don't often see language like this in the mid/long range section from OUN's AFDs.

saw that... They are not wrong by any means. Quite impressive given the amount of time this whole thing will encompass, as well as the fact that some days could be pretty big. Still thinking the day(s) with the best high-end potential will be with the final-- and likely strongest-- S/W sometime in the Thursday-Saturday time frame, possibly involving more than one day.

Several WFOs have already been hinting in their AFDs at this time period being likely the most significant as well given that mid/upr level support will be there in a BIG way, unlike most of the other days this coming week that'll see marginal/sufficient shear and nuclear CAPE.

[SluggerWx]

Don't often see language like this in the mid/long range section from OUN's AFDs.

Looks like you picked a great week to chase, Andy! Glad you're flying into Denver - maybe you'll get a chance to see some of our crazy CO weather on the way out to KS.

Here's a grab from the 18z NAM 4K in Yuma, CO - 6:00 PM Sunday evening.

[OUGrad05]

Looks like you picked a great week to chase, Andy! Glad you're flying into Denver - maybe you'll get a chance to see some of our crazy CO weather on the way out to KS.

Here's a grab from the 18z NAM 4K in Yuma, CO - 6:00 PM Sunday evening.

Yuma, CO (05.23.16 00z) (NAM4K 18z 05.20.16).PNG

Wow, thats awesome

[jojo762]

Lots can and will change, but both the GFS and Euro appear to be honing in on Thursday (5/26) being the biggest day. Still some big disagreement as to where exactly the larger threat will be, with the GFS as usual being likely too far east with the dryline. I'd prefer a blend right now between the GFS/EURO on DL location. For about four successive runs, GFS forecast soundings have painted a pretty scary picture up and down and east of the dryline in KS/OK. 

 

Time will tell...

[OUGrad05]

Lots can and will change, but both the GFS and Euro appear to be honing in on Thursday (5/26) being the biggest day. Still some big disagreement as to where exactly the larger threat will be, with the GFS as usual being likely too far east with the dryline. I'd prefer a blend right now between the GFS/EURO on DL location. For about four successive runs, GFS forecast soundings have painted a pretty scary picture up and down and east of the dryline in KS/OK. 

 

Time will tell...

At this point that seems to be the case.  Mon/Tues may turn out ok but SRH is pretty low in OK those days but not bad in KS.  A few minor changes and we could have an active early and late week.  I'd like to get in another chase, unfortunately I'll be traveling to Houston Weds and back Thurs night so that flight may be delayed and I can't chase those two days

[brettjrob]

Andy and wxmann, are you both chasecationing this week? Unreal timing, if so. Even though it would be nice to see a clear-as-day 5/29/04 or 5/23/08 style setup, such a ridiculous string of days with legit potential is the best you can get, failing that. We shall see how everything evolves, but it wouldn't surprise me if this is the best *chasecation* week since May 2013, at least. And even the better weeks that year were so damn honed in on OKC that if we can avoid that this time, it might be better in some respects.

 

Anyway, speaking of 2013, Bennington called and wants to remind everyone that absolutely no "in between big shortwaves" day can be trusted not to steal the show in this pattern. At least one day in that stretch (5/29/13) probably failed in large part due to drought-induced PBL mixing, so hopefully this period will be more similar to active stretches late in 2008 (aside from the mega outbreak days) and 2010, when drought wasn't a concern.

[bjc3395]

Potential is up there imo to be the most active in recent time.

I feel like we'll see two moderates at the least, perhaps Tuesday and almost certainly the late week trough. Everything else is mesoscale driven.

[bjc3395]

At this point that seems to be the case. Mon/Tues may turn out ok but SRH is pretty low in OK those days but not bad in KS. A few minor changes and we could have an active early and late week. I'd like to get in another chase, unfortunately I'll be traveling to Houston Weds and back Thurs night so that flight may be delayed and I can't chase those two days

Wouldn't worry quite yet, aside from the days where we have sig s/w passing through the day will basically depend on where the s/w/embedded max is.

[jojo762]

Tomorrow could produce a couple nice supercells across SW KS/TX PH... 00z 4KNAM/00Z NAM and 12Z WRF-NMMB agree on a pretty nasty supercell in SW KS tomorrow evening/night. Other models show more of a cluster in SW KS, with some potential sups in TX PH.

[andyhb]

Andy and wxmann, are you both chasecationing this week? Unreal timing, if so. Even though it would be nice to see a clear-as-day 5/29/04 or 5/23/08 style setup, such a ridiculous string of days with legit potential is the best you can get, failing that. We shall see how everything evolves, but it wouldn't surprise me if this is the best *chasecation* week since May 2013, at least. And even the better weeks that year were so damn honed in on OKC that if we can avoid that this time, it might be better in some respects.

 

Anyway, speaking of 2013, Bennington called and wants to remind everyone that absolutely no "in between big shortwaves" day can be trusted not to steal the show in this pattern. At least one day in that stretch (5/29/13) probably failed in large part due to drought-induced PBL mixing, so hopefully this period will be more similar to active stretches late in 2008 (aside from the mega outbreak days) and 2010, when drought wasn't a concern.

 

Yup, was always heading out in this period anyway, but I started looking at flights as soon as I saw that W trough/extended WSW flow over a highly unstable warm sector showing up with some consistency. Hopefully at least one day will deliver here.

 

And yeah, speaking of Bennington, the in-between days seem to have that kind of feel with very high CAPE and some mesoscale enhancement of the wind fields in certain places thanks to persistent lee cyclones (12z/18z GFS had this on full display and the Euro to some degree as well).

[jojo762]

Andy and wxmann, are you both chasecationing this week? Unreal timing, if so. Even though it would be nice to see a clear-as-day 5/29/04 or 5/23/08 style setup, such a ridiculous string of days with legit potential is the best you can get, failing that. We shall see how everything evolves, but it wouldn't surprise me if this is the best *chasecation* week since May 2013, at least. And even the better weeks that year were so damn honed in on OKC that if we can avoid that this time, it might be better in some respects.

 

Anyway, speaking of 2013, Bennington called and wants to remind everyone that absolutely no "in between big shortwaves" day can be trusted not to steal the show in this pattern. At least one day in that stretch (5/29/13) probably failed in large part due to drought-induced PBL mixing, so hopefully this period will be more similar to active stretches late in 2008 (aside from the mega outbreak days) and 2010, when drought wasn't a concern.

Feel like the late-week "end-of-the-event" S/W has outbreak-type potential, if things go currently as progged, especially as shown by the GFS. Likewise, that time period will evolve quite a bit given how far it is out.

[jojo762]

If you like/believe the NAM, you'll like Monday in KS. Not a huge fan of Monday because of meh mid/upr flow, but the low-levels look pretty good, well before 00Z even! Critical angle well over 90-degrees is also eh too.

[nrgjeff]

Potential is up there imo to be the most active in recent time.

I feel like we'll see two moderates at the least, perhaps Tuesday and almost certainly the late week trough. Everything else is mesoscale driven.

 

a little early to call?

[bjc3395]

a little early to call?

Probs, 0z guidance isn't doing me any favors, haha.

[andyhb]

There is about four different areas that could see significant severe on Thursday with this new GFS run, pretty darn stout. Lead shortwave enhances flow at all levels into the GL/OV, with the broader, primary shortwave ejecting towards the S Plains and Ozarks.

 

Edit: And now Friday showing pretty high potential near I-35 in OK.

[jojo762]

There is about four different areas that could see significant severe on Thursday with this new GFS run, pretty darn stout. Lead shortwave enhances flow at all levels into the GL/OV, with the broader, primary shortwave ejecting towards the S Plains and Ozarks.

Wednesday also looks pretty good across Kansas/Oklahoma and into Texas if CI can occur along the dryline. Cap is pretty decent on wednesday though, so that is probably a big "if," given that there is no obvious S/W, rather just broad SW/W flow aloft.

[jojo762]

There is about four different areas that could see significant severe on Thursday with this new GFS run, pretty darn stout. Lead shortwave enhances flow at all levels into the GL/OV, with the broader, primary shortwave ejecting towards the S Plains and Ozarks.

 

Edit: And now Friday showing pretty high potential near I-35 in OK.

I'll take this GFS run please.    Seems that the GFS has been trending to the end of the week being big, that'll change some/a lot though probably... Late May almost always produces something, but man did you time your chasecation perfectly. Looks like the most "active" period for the plains in a while. "Active" on paper, at least, whether that turns into anything noteworthy is TBD. Been a while since we've seen SW flow atop a very moist/unstable warm sector for this many successive days in the plains-- really anywhere for that matter.

[jojo762]

SPC 06Z D2SWO (Sunday 5/22)

 

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0100 AM CDT SAT MAY 21 2016  
 
VALID 221200Z - 231200Z  
   
..THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE PLAINS  
 
   
..THERE IS A MRGL RISK OF SVR TSTMS ACROSS MUCH OF THE PLAINS  
 
   
..SUMMARY  
 
SEVERE THUNDERSTORMS ARE EXPECTED ACROSS A BROAD PORTION OF THE  
GREAT PLAINS ON SUNDAY.  
   
..SYNOPSIS  
 
AN AMPLIFIED LARGE-SCALE PATTERN WILL EXIST OVER THE CONUS/CANADA  
SUNDAY...HIGHLIGHTED BY A NORTHEASTWARD-PROGRESSIVE UPPER TROUGH  
OVER THE NORTHERN/CENTRAL ROCKIES TO NORTHERN PLAINS. A COLD FRONT  
WILL ADVANCE EASTWARD ACROSS THE NORTHERN PLAINS...WHILE A SOUTHWARD  
EXTENDING DRYLINE WILL BE A FOCUS FOR POTENTIAL SEVERE THUNDERSTORM  
DEVELOPMENT ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS.  
   
..SOUTHERN PLAINS INCLUDING WESTERN OK/TX  
 
ON THE PERIPHERY OF THE CENTRAL/NORTHERN ROCKIES UPPER TROUGH...WEAK  
HEIGHT FALLS/MODEST LARGE-SCALE FORCING FOR ASCENT  
SHOULD OVERSPREAD THE SOUTH-CENTRAL HIGH PLAINS IN CONJUNCTION  
MODESTLY STRENGTHENING MID/HIGH-LEVEL WESTERLIES...WHILE FORCING FOR  
ASCENT WILL TEND TO BE WEAKER SOUTHWARD INTO WEST-CENTRAL/SOUTHWEST  
TX. BENEATH AN ADVECTING ELEVATED MIXED LAYER...INCREASINGLY RICH  
LOW-LEVEL MOISTURE WITH MIDDLE/UPPER 60S F SURFACE DEWPOINTS WILL  
RESULT IN STRONG DESTABILIZATION NEAR/EAST OF THE DRYLINE AS IT  
EXTENDS NORTH-SOUTH ACROSS FAR WESTERN PORTIONS OF KS/OK/TX.  
 
THAT SAID...A POINT OF CURRENT UNCERTAINTY RELATES TO THE POSSIBLE  
PERSISTENCE/EXTENSIVENESS OF EARLY-DAY CONVECTION ACROSS PARTS OF  
NORTHWEST TX SUNDAY MORNING. THERE IS AT LEAST SOME POTENTIAL THAT  
THIS CONVECTION COULD PERSIST AND FORWARD PROPAGATE AS A  
SLOW-MOVING/LOOSELY ORGANIZED MCS EAST-SOUTHEASTWARD TOWARD CENTRAL  
TX /AND POSSIBLY EVEN THE TX COAST/...WITH AT LEAST SOME DAMAGING  
WIND RISK SHOULD THIS OCCUR. EARLY-DAY CONVECTION-ASSOCIATED  
DIFFERENTIAL HEATING COULD ALSO REFOCUS A LATE-AFTERNOON SEVERE RISK  
SOMEWHERE ACROSS NORTHWEST TX INCLUDING THE CAPROCK VICINITY/TX  
SOUTH PLAINS/LOW ROLLING PLAINS.  
 
REGARDLESS...GIVEN MODERATE INSTABILITY IN THE PRESENCE OF 35-45 KT  
OF EFFECTIVE SHEAR...SUPERCELLS CAPABLE OF VERY LARGE HAIL AND A FEW  
TORNADOES WILL BE POSSIBLE SUNDAY AFTERNOON/EVENING... PARTICULARLY  
ACROSS FAR WESTERN OK AND MUCH OF NORTHWEST/WEST TX NEAR/EAST OF THE  
DRYLINE. SOMEWHAT HIGHER SEVERE PROBABILITIES /ENHANCED RISK/ MAY BE  
WARRANTED ACROSS PARTS OF THE REGION AS MESOSCALE UNCERTAINTIES ARE  
BETTER RESOLVED.  
   
..NORTHERN/CENTRAL PLAINS  
 
INITIALLY...ASSOCIATED WITH WARM ADVECTION ON THE EDGE OF STRONGER  
CAPPING ALOFT...A COUPLE OF STRONGER STORMS COULD DEVELOP AS EARLY  
AS SUNDAY MID/LATE MORNING ACROSS PARTS OF NORTHEAST KS/EASTERN NEB  
INTO SOUTHEAST SD. WHILE STEEP MID-LEVEL LAPSE RATES/MODERATE  
ELEVATED INSTABILITY COULD SUPPORT SOME HAIL POTENTIAL IF/WHERE  
STORMS FORM...THE OVERALL RISK SHOULD BE MITIGATED BY WEAK  
CLOUD-BEARING SHEAR GIVEN THE PROXIMITY OF THE UPPER RIDGE.  
 
AS THE UPPER TROUGH SHIFTS NORTHEASTWARD OVER THE NORTHERN HIGH  
PLAINS...STRONG FORCING FOR ASCENT WILL OVERSPREAD AN INCREASINGLY  
MOIST BOUNDARY LAYER /UPPER 50S AND LOWER 60S F SURFACE DEWPOINTS/  
AHEAD OF AN EASTWARD-MOVING COLD FRONT. WHILE CAPPING WILL INITIALLY  
PREVAIL...SEVERE THUNDERSTORM DEVELOPMENT IS LIKELY TO OCCUR BY LATE  
SUNDAY AFTERNOON/EARLY EVENING IN A NNE-SSW CORRIDOR ACROSS THE  
DAKOTAS/WESTERN NEB AND POSSIBLY FAR SOUTHEAST WY/NORTHEAST CO IN  
VICINITY OF THE FRONT/NORTH OF A SURFACE LOW. SUPERCELLS CAPABLE OF  
SEVERE HAIL/DAMAGING WINDS WILL INITIALLY BE POSSIBLE. WHILE THE  
DEGREE OF FORCING/COLD FRONT...NEARLY UNIDIRECTIONAL WINDS ABOVE THE  
SURFACE...AND RELATIVELY MODEST BOUNDARY-LAYER MOISTURE SHOULD LIMIT  
THE OVERALL TORNADO RISK...A COUPLE OF TORNADOES WILL BE  
POSSIBLE...WITH PARTS OF WESTERN/NORTHWEST NEB MOST LIKELY TO HAVE A  
TORNADO RISK/LARGER HAIL POTENTIAL GIVEN SOMEWHAT GREATER  
MOISTURE/INSTABILITY AND MORE OF A WESTERLY COMPONENT ALOFT. AS THE  
COLD FRONT CONTINUES EAST-SOUTHEASTWARD...STORMS ARE LIKELY TO  
EVENTUALLY MERGE/GROW UPSCALE AND INCREASE IN OVERALL COVERAGE  
SUNDAY EVENING/NIGHT AS THEY SPREAD EAST-SOUTHEASTWARD ACROSS THE  
EASTERN DAKOTAS AND NEB INTO NORTHERN/WESTERN KS...WITH AT LEAST  
SEVERE WIND/HAIL POTENTIAL CONTINUING.  

[andyhb]

Man the 00z Euro tries everything it can to screw up that later week system, so many nebulous ripples initiating junk convection in TX on Thursday and also looks like a bit of a slow/late ejection. Then the upper level flow becomes highly backed on Friday.

[thewxmann]

Andy and wxmann, are you both chasecationing this week? Unreal timing, if so. Even though it would be nice to see a clear-as-day 5/29/04 or 5/23/08 style setup, such a ridiculous string of days with legit potential is the best you can get, failing that. We shall see how everything evolves, but it wouldn't surprise me if this is the best *chasecation* week since May 2013, at least. And even the better weeks that year were so damn honed in on OKC that if we can avoid that this time, it might be better in some respects.

 

Anyway, speaking of 2013, Bennington called and wants to remind everyone that absolutely no "in between big shortwaves" day can be trusted not to steal the show in this pattern. At least one day in that stretch (5/29/13) probably failed in large part due to drought-induced PBL mixing, so hopefully this period will be more similar to active stretches late in 2008 (aside from the mega outbreak days) and 2010, when drought wasn't a concern.

 

Yep, booked this several months in advance. Cannot believe how lucky I am.

[David Reimer]

Leaving OUN in the next hour and heading to Garden City, KS.

[Ian]

Andy and wxmann, are you both chasecationing this week? Unreal timing, if so. Even though it would be nice to see a clear-as-day 5/29/04 or 5/23/08 style setup, such a ridiculous string of days with legit potential is the best you can get, failing that. We shall see how everything evolves, but it wouldn't surprise me if this is the best *chasecation* week since May 2013, at least. And even the better weeks that year were so damn honed in on OKC that if we can avoid that this time, it might be better in some respects.

Anyway, speaking of 2013, Bennington called and wants to remind everyone that absolutely no "in between big shortwaves" day can be trusted not to steal the show in this pattern. At least one day in that stretch (5/29/13) probably failed in large part due to drought-induced PBL mixing, so hopefully this period will be more similar to active stretches late in 2008 (aside from the mega outbreak days) and 2010, when drought wasn't a concern.

Interestingly late May 2004 was all over LR analogs a few weeks ago. As were some other years not quite as big but rather consistent. I was going to take this year off then I was going to do June given post Nino climo but by late April this period was starting to seem to be highlighted. I mean it's hard to turn down late May anyway but there was a strong signal that we could end up in a prolonged SW flow pattern much of the past few weeks. For a while last week it looked a little questionable but guess that's to be expected. Could still fall flat I guess but if you are visiting you can't ask for too much more really. In many ways this is preferable to a huge outbreak that scours the air mass for days after.

[capbreak]

Yep, booked this several months in advance. Cannot believe how lucky I am.

 

Statistically speaking, it's never really a bad idea to book a chasecation for the week leading up to Memorial Day. In the absence of a death ridge, it's almost always got a few days here and there. I seem to remember crunching the numbers and coming up with May 22nd as the best day for sig tors - Hallam, Windsor, Bowdle, Joplin, etc. seem to validate that date as being a common day, if not the statistical peak.

[jojo762]

FWIW (which really isnt much), 12Z 4KM NAM at hour 60 (monday at 7pm) is targeting the OKC metro area for having a pretty sweet supercell. Even shows a hook on simulated reflectivity! 

The environment in front of this thing is pretty volatile too if it were to occur, at least in the low-levels, minus the critical angle well over 90-degrees. (Picked a sounding from 23Z to try to avoid CC.) Remember this environment is probably overdone to an extent because this is the 4NAM, but still would likely have an impressive environment given what other models indicate.. Some weird stuff going on with the 4NAM above 350mb, not sure what it is really doing there, but it shows this same weird upper-level profile on several hours.