Plains tornado threat Mon 5/27-Fri 5/31

[tornadotony]

The details are still far from being determined, but I think it's about time to start a dedicated thread for the midweek system. I don't want to dive into too many details just yet, but with the intensity of jet coming ashore early in the week and where it's coming ashore, a significant severe threat seems almost inevitable. Tuesday might be a little sketchy in the moisture department, but with well-established return flow in place, Wednesday and Thursday should have no problems in that department. In terms of location, it's a pick your poison right now on the models. The GFS has an extremely potent threat for nrn OK, KS, and srn NE, while the Euro, with its more meridional flow over the plains, would more favor OK and nrn TX, especially for tornadoes. From my experience, to see the Euro verify, I would probably want to see the jet streak come ashore with more of a NW-SE orientation to get a setup more like the Euro. Between that and the Euro's tendency to dig a trough too much in the SW US, I'm probably going to side more with the GFS leading up to this event unless we see evidence of more digging as it comes ashore. The bottom line is that a jet disturbance even stronger than the previous humdinger is coming and has the potential to lead to a series of several significant severe weather days.

[Stebo]

Yeah I have been watching this one for a while, you don't see a jet streak of that intensity this often at this time of year. This could be a very significant potential for this region and extending into the GLOV as well. Also you note the Euro's tendency to dive energy too far into the SW, tonight's run didn't and in turn showed several days of strong potential for a large portion of the Plains. I do think it is a bit early to highlight what areas of the Plains could be under the gun the most with this one, though if I had to pick I would say slightly north of last weekend's area, KS/NE although the dry line would possibly light up all the way down into Texas. Of course it is still early and this could still change.

 

One thing to also note, the low level moisture flow is coming all the way from the Caribbean, I don't think we will be seeing any moisture/instability issues with this one, especially with several days of moist flow like this.

 

 

[My Weather Today]

The details are still far from being determined, but I think it's about time to start a dedicated thread for the midweek system. I don't want to dive into too many details just yet, but with the intensity of jet coming ashore early in the week and where it's coming ashore, a significant severe threat seems almost inevitable. Tuesday might be a little sketchy in the moisture department, but with well-established return flow in place, Wednesday and Thursday should have no problems in that department. In terms of location, it's a pick your poison right now on the models. The GFS has an extremely potent threat for nrn OK, KS, and srn NE, while the GFS, with its more meridional flow over the plains, would more favor OK and nrn TX, especially for tornadoes. From my experience, to see the Euro verify, I would probably want to see the jet streak come ashore with more of a NW-SE orientation to get a setup more like the Euro. Between that and the Euro's tendency to dig a trough too much in the SW US, I'm probably going to side more with the GFS leading up to this event unless we see evidence of more digging as it comes ashore. The bottom line is that a jet disturbance even stronger than the previous humdinger is coming and has the potential to lead to a series of several significant severe weather days.

Did you mean to say the Euro would favor OK and Nrn TX?

[andyhb]

Glad to see a thread started on this, obviously we're still a bit out, but some of the signals, not only across the operational guidance, but the ensembles as well, are rather alarming for this time of year (and probably one of the more threatening potentials suggested for this time of year in a pretty decent amount of time). The apparent tendency for the synoptic scale trough to eject out with an at least decently broad base along with unseasonably strong surface cyclogenesis/LLJ development is certainly a recipe for trouble, especially when adding that low level flow right out of the Caribbean.

 

New D4-8.

DAY 4-8 CONVECTIVE OUTLOOK     NWS STORM PREDICTION CENTER NORMAN OK   0352 AM CDT SAT MAY 25 2013   VALID 281200Z - 021200Z   ...DISCUSSION...   THE GFS/ECMWF ARE IN GENERAL AGREEMENT ON TUESDAY /DAY 4/ IN SHOWING   STRONG SWLY FLOW OVER THE SRN HIGH PLAINS NEWD INTO THE   MIDWEST...SUPPORTING AT LEAST ISOLD SEVERE WITHIN THIS CORRIDOR   AHEAD OF THE AMPLIFYING WRN U.S. UPPER TROUGH.  MODELS DIVERGE   SUBSTANTIALLY BY WEDNESDAY /DAY 5/ IN THE EVOLUTION OF THE WRN U.S.   UPPER TROUGH AS IT MOVES INTO THE CNTRL U.S.  THE 00Z/25 GFS SHOWS A   LESS AMPLIFIED SOLUTION VS. THE 00Z/25 ECMWF EXHIBITING A MORE   MERIDIONAL/HIGHER AMPLITUDE SCENARIO AS A NEGATIVELY-TILTED TROUGH   EJECTS INTO THE CNTRL STATES.  ALTHOUGH IT SEEMS PROBABLE AN   ELONGATED MID LEVEL LOW WILL BECOME CENTERED OVER THE NWRN CONUS BY   MID-LATE WEEK...CONSIDERABLE SPREAD IS NOTED IN THE ECMWF/GEFS   ENSEMBLE MEMBERS IN THE EVOLUTION OF EJECTING SHORTWAVE FEATURES.    AS A RESULT...CONSIDERABLE UNCERTAINTY EXISTS FROM WEDNESDAY /DAY 5/   INTO NEXT WEEKEND AND PRECLUDES THE HIGHLIGHT OF POSSIBLE 30 PERCENT   SEVERE PROBABILITY AREAS AT THIS TIME.  DESPITE THE AFOREMENTIONED   MODEL PREDICTABILITY CONCERNS AND PRIOR DAY/S STORM ACTIVITY   EXERTING INFLUENCE ON SUBSEQUENT DAY/S...A POTENTIALLY ACTIVE   SEVERAL DAY PERIOD FOR SEVERE WEATHER IS POSSIBLE.  THEREFORE...AN   INCREASED RISK FOR ORGANIZED SEVERE STORMS SEEMS PLAUSIBLE FOR PARTS   OF THE PLAINS AND MIDWEST ON TUESDAY /DAY 4/...OVER A LARGER PORTION   OF THE PLAINS ON WEDNESDAY /DAY 5/ AND THEN POSSIBLY IN PARTS OF THE   PLAINS AND UPPER MIDWEST ON THURSDAY /DAY 6/.   ..SMITH.. 05/25/2013

[tornadotony]

Did you mean to say the Euro would favor OK and Nrn TX?

Yeah, that's what I get for starting a thread at 2am. Fixed.

[Hoosier]

FWIW, I share your concern. Too early for exact details but this pattern certainly has the look, and residents across the Plains/Midwest will need to be on guard next week.

[brettjrob]

Looks like karma is paying us back for the anomalously quiet March 1-May 15 period. The pattern this upcoming work week reminds me somewhat of 22-25 May 2010. That was an incredible stretch for chasers with continuous southwest flow, but because there were no major cohesive disturbances ejecting out on any given day, the fireworks were relatively localized and caused minimal harm to life and property. If we're lucky, the same may be true next week. The potential is there for a more widespread, significant event around mid-week, but at the moment, no one day screams "HIGH risk material" to me. However, I could see every day from Mon-Thu being MDT, with portions of KS and NE getting in on the action repeatedly.

[OUGrad05]

I am keeping a close eye on this system. Right now not a lot of agreement for weds/Thurs. But frankly the potential looks really impressive for a moderate to high impact event.

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[Ground Scouring]

With a tendency for blocking to bridge in the polar N Hemisphere over the next five days, I would also favor the less-amplified solution of the GFS relative to that of the ECMWF. The GFS solution would tend to maintain most of the PVA with the main vortex off the Pacific NW, thereby allowing a series of impulses to eject into the N Plains and rotate around the base of a very broad trough axis. This would tend to limit the extent of any single severe event, but clearly the kinematics will be favorable over at least part of the warm sector, which is certainly going to be broad based upon the pattern's favoring persistent SSE flow from the Gulf. Mesoscale factors will thus play a significant role again as it did in the recent events. Given the much stronger jet in the upcoming days, I do think that any lee surface low that develops is likely to be deeper than in the last event--very likely 995 mb or lower.

[TropicalAnalystwx13]

Does the 300mb jet usually move north across the region where significant severe weather is occurring like forecast?

 

[Indystorm]

Not necessarily north (meridional flow), but as the jet rounds the base of the trough the upper level divergence with the jet is a signal to watch and I've noticed many times that tornadoes often form somewhat to the sw of the greatest low and mid level helicity. The incoming system does need to be monitored carefully in coming days.

[Minnesota Meso]

MPX  over the last 2 or 3 days has been banging the drum slowly for severe potential next week.  Here is a portion of their AFD that was issued the afternoon of 05/25.

 

"A THREAT FOR ORGANIZED SEVERE WEATHER WILL ENTER THE
PICTURE...ESPECIALLY ON THURSDAY AND FRIDAY AS THE SURFACE LOW
NEARS THE AREA AND DEEP LAYER SHEAR INCREASES. IN FACT...THE CIPS
ANALOGS FOR SEVERE WEATHER INDICATE THERE ARE SEVERAL MATCHES TO
HISTORICAL OUTBREAK EVENTS...INCLUDING JUNE 17TH OF 2010."

 

 

I have problems with my photo sharing site so I hope this stays up, as I'm using a direct link, it will probably change with the next 12z run.  The following shows the tornado reports based off the 05/25/2013 12z run of the GFS at 132hrs compared with the top 15 analog storm systems. Of course this will change many times during the next couple of days, but it does show the potential of what may transpire from the Upper Mississippi Valley south all the way to Texas.  This comes from the CIPS site.

 

[andyhb]

MPX  over the last 2 or 3 days has been banging the drum slowly for severe potential next week.  Here is a portion of their AFD that was issued the afternoon of 05/25.

 

"A THREAT FOR ORGANIZED SEVERE WEATHER WILL ENTER THE

PICTURE...ESPECIALLY ON THURSDAY AND FRIDAY AS THE SURFACE LOW

NEARS THE AREA AND DEEP LAYER SHEAR INCREASES. IN FACT...THE CIPS

ANALOGS FOR SEVERE WEATHER INDICATE THERE ARE SEVERAL MATCHES TO

HISTORICAL OUTBREAK EVENTS...INCLUDING JUNE 17TH OF 2010."

 

Another potential event I have seen popping up rather consistently once the trough fully ejects is June 7th-8th, 1984, which of course was the Barneveld, WI event.

[Minnesota Meso]

Another potential event I have seen popping up rather consistently once the trough fully ejects is June 7th-8th, 1984, which of course was the Barneveld, WI event.

 I find it strange that with the high amplitude pattern we will be seeing next week that this thread is as quite as it has been.  I suspect the reason for that is that most think the out break will further north and not affect the TX, OK,NE area.

[David Reimer]

 I find it strange that with the high amplitude pattern we will be seeing next week that this thread is as quite as it has been.  I suspect the reason for that is that most think the out break will further north and not affect the TX, OK,NE area.

 

Well most of us are busy still recovering from this past week and catching up on life. Also, we're used to so much model inconsistency that most of us don't pay much attention until we're into the 2-3 day range. 

[andyhb]

 I find it strange that with the high amplitude pattern we will be seeing next week that this thread is as quite as it has been.  I suspect the reason for that is that most think the out break will further north and not affect the TX, OK,NE area.

 

I have my doubts about this, I think it may be that we are still analyzing the previous events, among other things. I will say that Ian, Mark and wxmeddler picked a great time to head out there, and although Dsnow didn't catch the events of May 15th-20th, he also looks to have made a choice that should put him in good position.

[brettjrob]

 I find it strange that with the high amplitude pattern we will be seeing next week that this thread is as quite as it has been.  I suspect the reason for that is that most think the out break will further north and not affect the TX, OK,NE area.

 

Maybe not so much TX/OK, but I'd say KS/NE look like the bullseye this week, so I doubt that's the reason. It's probably a combination of fatigue from last week and the murkiness of the picture in terms of specifics at this stage. As I mentioned earlier, this is more of a prolonged southwest flow event than a single, pronounced disturbance ejecting in spectacular fashion (at least until closer to next weekend). It may be difficult to determine the location and severity of the threat even as late as the night before, in some cases. Again using the 22-25 May 2010 period as a point of reference, the Bowdle (5/22), Texline (5/23), and Faith (5/24) significant tornadoes were all localized setups whose specifics couldn't possibly have been pinned down more than 24 hours in advance.

[Minnesota Meso]

I have my doubts about this, I think it may be that we are still analyzing the previous events, among other things. I will say that Ian, Mark and wxmeddler picked a great time to head out there, and although Dsnow didn't catch the events of May 15th-20th, he also looks to have made a choice that should put him in good position.

 

ok, as far as the chaser's go, I get it.  Most of them have made great decisions, and many of were successful...kudos to them.  If they are still out in the field, I hope they move north. 

[Stebo]

Maybe not so much TX/OK, but I'd say KS/NE look like the bullseye this week, so I doubt that's the reason. It's probably a combination of fatigue from last week and the murkiness of the picture in terms of specifics at this stage. As I mentioned earlier, this is more of a prolonged southwest flow event than a single, pronounced disturbance ejecting in spectacular fashion (at least until closer to next weekend). It may be difficult to determine the location and severity of the threat even as late as the night before, in some cases. Again using the 22-25 May 2010 period as a point of reference, the Bowdle (5/22), Texline (5/23), and Faith (5/24) significant tornadoes were all localized setups whose specifics couldn't possibly have been pinned down more than 24 hours in advance.

I completely disagree with the bold part, what ejects out on Wednesday-Thursday is a pronounced disturbance that is also very strong and takes a strong negative tilt. I am not seeing a prolonged SW flow event with no significant trough ejections at all.

[andyhb]

Well alrighty then...

 

 

 

Times of interest include:

00z 6/8/93

00z 5/8/93

00z 6/17/92

00z 5/23/81

00z 5/25/08

00z 4/27/91

00z 6/16/92

00z 6/8/84

00z 5/30/04

06z 5/13/95

18z 5/4/03

[andyhb]

Latest D4-8 has a D4 for SD and NE, although junk convection/convective overturning appears to be a big concern beyond that. I will say that, given the ambient flow fields on Wednesday, the convection should have a tendency to have a rather strong northward component of motion, which may preclude contamination of the boundary layer/lapse rates downstream into the Upper Midwest, unless an eastward propagating MCS develops. Either way, as usual with multi day potentials, the convection on each day could have a detrimental or complementary effect to the next day, be it with aforementioned lapse rate overturning, setting up outflow boundaries and the like, which will likely make this a tricky set of forecasts.

 

DAY 4-8 CONVECTIVE OUTLOOK     NWS STORM PREDICTION CENTER NORMAN OK   0359 AM CDT SUN MAY 26 2013   VALID 291200Z - 031200Z   ...DISCUSSION...   MODELS ARE IN FAIR AGREEMENT DURING THE EARLY PORTION OF THE   EXTENDED PERIOD IN SHOWING A HIGH AMPLITUDE NEGATIVELY-TILTED UPPER   TROUGH EJECTING INTO THE PLAINS WHILE A MID LEVEL ANTICYCLONE   REMAINS SITUATED NEAR THE NC OUTER BANKS.  THE WRN U.S. SYSTEM WILL   LIKELY EVOLVE INTO A CLOSED MID LEVEL LOW OVER THE NRN ROCKIES/NRN   HIGH PLAINS BY LATE IN THE WORK WEEK.    ON WEDNESDAY /DAY 4/...A MERIDIONAL FLOW REGIME OVER THE PLAINS WILL   FAVOR SCTD TO NUMEROUS SHOWERS/STORMS AS STRONG UPPER FORCING FOR   ASCENT/STRONG SHEAR WILL SUPPORT ISOLD SEVERE STORMS POTENTIALLY   OVER A LARGE PORTION OF THE PLAINS/UPPER MIDWEST.  IT APPEARS THE   MOST PROBABLE CONCENTRATION FOR SEVERE --INCLUDING POSSIBLE TORNADIC   STORMS-- WILL BE IN THE ERN PART OF THE HIGH PLAINS.  AT THIS   TIME...CONFIDENCE IS HIGHEST FOR THIS SCENARIO OVER PARTS OF THE WRN   DAKOTAS/NEB...BUT AN EVENTUAL EXTENSION IN 30 PERCENT SEVERE   PROBABILITIES MAY BE WARRANTED IN LATER OUTLOOKS FOR AREAS FARTHER S   IN THE SRN HIGH PLAINS.     BY THURSDAY /DAY 5/...DESPITE STRENGTHENING SHEAR PROFILES FAVORABLE   FOR ORGANIZED SEVERE STORMS CAPABLE OF ALL FACETS OF SEVERE   --FARTHER E IN A CORRIDOR FROM THE SRN PLAINS NWD INTO THE UPPER   MIDWEST-- PRIOR DAY/S SUBSTANTIAL CONVECTIVE OVERTURNING OF STEEP   MID LEVEL LAPSE RATES IS AT LEAST PARTLY EXPECTED OVER THE PLAINS   AND MAY AFFECT THE MAGNITUDE OF DESTABILIZATION DOWNSTREAM OVER THE   UPPER MS RIVER VALLEY.  AS A RESULT...THIS FORECAST SCENARIO LENDS   CONSIDERABLE UNCERTAINTY PRECLUDING A HIGHLIGHT AREA FOR THE TIME   BEING OVER THE UPPER MIDWEST.  FARTHER S...MODELS HINT AT A   REJUVENATION OF STEEP LAPSE RATES PROTRUDING E INTO THE CNTRL-SRN   PLAINS.  COUPLED WITH STRONG FLOW FIELDS AND RICH MOISTURE...A   HIGHER PROBABILITY AREA MAY BE NEEDED FOR PARTS OF THE CNTRL-SRN   PLAINS IF CONFIDENCE IS MAINTAINED/INCREASES FOR LATER OUTLOOK   UPDATES.     FRIDAY /DAY 6/ MAY CONTINUE TO FOSTER EPISODIC BOUTS OF ORGANIZED   SEVERE STORMS IN A GENERAL AREA FROM THE CNTRL-SRN PLAINS NEWD INTO   THE UPPER MS RIVER VALLEY.  AGAIN...THE INGREDIENTS FOR STORMS   CAPABLE OF SEVERE WEATHER MAY JUXTAPOSE IN TIME/SPACE BUT THE   COMBINATION OF UNCERTAINTY/MODEL PREDICTABILITY PRECLUDES AN AREA   HIGHLIGHT THIS DAY AS WELL.   ..SMITH.. 05/26/2013

[tornadotony]

Well alrighty then...

 

 

 

Times of interest include:

00z 6/8/93

00z 5/8/93

00z 6/17/92

00z 5/23/81

00z 5/25/08

00z 4/27/91

00z 6/16/92

00z 6/8/84

00z 5/30/04

06z 5/13/95

18z 5/4/03

4 F5s and a bunch of potential ones in there.

[OUGrad05]

Well alrighty then...

 

 

 

Times of interest include:

00z 6/8/93

00z 5/8/93

00z 6/17/92

00z 5/23/81

00z 5/25/08

00z 4/27/91

00z 6/16/92

00z 6/8/84

00z 5/30/04

06z 5/13/95

18z 5/4/03

So is this a simulation for later this week or an ensemble of past events? I would think its an ensemble of the past events you listed?

[Stebo]

So is this a simulation for later this week or an ensemble of past events? I would think its an ensemble of the past events you listed?

 

It is a collection of the top 15 analogs with a similar setup comparing to the GFS's forecast hour 120 centered on the boxes below

 

[tornadotony]

I've never seen CIPS like that ever.  4 events with F5s, an additional 7 events with F4s.  Good grief.

[brettjrob]

Potent setup for supercells tomorrow near the dryline bulge in KS. Despite some capping concerns, a subtle wave looks to traverse the region during the afternoon, and the GFS, NAM and its 4 km nest all convect. Provided convection indeed initiates somewhere near SLN and sustains into the early evening, I'd expect a substantial tornado threat. Here's the 4 km NAM updraft helicity at 03z (unfortunately, the hourly maxima for 01z and 02z aren't available):

 

[nrgjeff]

Event may start tomorrow, Monday, and go through Friday. Mon/Tue look like good isolated supercell chasing days south of WF/DL intersections. Wednesday may be unidirectional - a good rest day? Thu/Fri starting to look similar, but far from identical, to last Sun/Mon. EDIT: What Brett says about Monday while I was typing. I strongly agree!

 

Mon/Tue both feature jet streaks and short waves ejecting out of the digging West trough with moderate, and adequate, speed and directional shear for tornadoes. Looking for a small moderate risk in Kansas Monday where the WF and DL meet. Expect another Tuesday in the Plains. Wednesday may be a rest day except perhaps the northern High Plains per Day 4. Other models came around to the Euro for Wed. Timing is not totally aligned on all the models, but Thursday could feature strong to violent tornadoes based on pattern recognition iff that strong jet streak punches out west to east. Low levels would respond with such a short wave. Some models holding up enough energy for more severe storms Friday. 

 

If time is limited one could argue there are two separate chase set-ups. Mon/Tue photogenic isolated tornadoes are possible - the finesse days. Thu/Fri could be more of a strong/violent tornado set-up. I'm assuming a lot this far out. Just painting possibilities. Be safe and good luck!

[andyhb]

I've never seen CIPS like that ever. 4 events with F5s, an additional 7 events with F4s. Good grief.

You said it. I can't personally remember seeing a more impressive one either. The fact that the wind reports don't vastly outnumber the tornado reports says something about the synoptic setup.

[tornadotony]

I'm going to go ahead and change this to Monday-Thursday.  I'll start new threads as we go along if/when things get out of control.  Huge week ahead.

[David Reimer]

At this point with money considerations into place (new battery and A/C repair), I'll probably sit anything out that isn't in S KS or TX/OK. That likely means I'll start my chaseventure on Wednesday in western Oklahoma. I wish I had the resources to head up north, but it isn't going to happen. Good luck to those heading out. Bag some wedges!