May 16 - June 4(ish) Severe Weather

[Quincy]

As we move toward the peak of severe weather season, the medium range guidance has come into fair agreement with the potential for an uptick in severe thunderstorm activity across the Central United States. 

The first half of next week has potential, but threats could begin by this weekend (May 18-19). Since we’re near the climatological peak of the severe weather season. I decided to group the time together, as ensemble signals suggest an active stretch may linger through Memorial Day weekend and beyond. 

The synoptic pattern appears to be going through a shift this week. As of now (May 14), upper level ridging is developing across the Pacific Northwest. A series of low amplitude shortwaves will dig toward the Southeast, most notably around the May 16-17 period, before pattern realignment takes place. SPC has outlined a Day 4 risk area across the Lower Mississippi Valley vicinity as this takes place and MRGL/SLGT risk areas precede that over the next 1-3 days.

This weekend, May 18-19, ridging is expected to build across the south-central states, as troughing digs across southwestern Canada. There may be some severe potential around this timeframe across the Central Plains vicinity.

Early next week is when ensemble and analog guidance suggest a broader scale, severe-favorable setup develops across the western/central US. Details are TBD, but the general pattern may support troughing across the West, ridging shifting toward the Lower Mississippi Valley and enhanced upper level flow overspreading the southern/central Plains. 

It’s too soon to speculate about any major trough ejection or individual day that might feature the greatest threat. Operational runs of the Euro and GFS vary with trough amplification and timing. There are some signs that some stubborn troughing across the Great Lakes/Northeast could emerge late in the month. While that’s not necessarily ideal for Plains severe activity, we are moving into the time of the year where that’s still workable. 

The last run of the Euro Weeklies hints at this, but still shows a general pattern that would support severe thunderstorm activity from the Plains into the Midwest. 

Those with trips or “chasecation” prospects should be encouraged by the signals. It’s already been an active year, but another active stretch appears to be in the works. 

[CheeselandSkies]

GFS suggests Sunday/Monday in KS/possibly down the dryline into OK, Tuesday further east somewhere in the MS and/or OH Valley, somewhat more localized potential in the southern Plains Wednesday followed by another potentially big round Thursday-Saturday. All subject to how each day evolves on the mesoscale of course; but can't complain about another string of chances like this if you're out chasing.

[Ed, snow and hurricane fan]

T-Storm watch for Central Texas.  Moderate hail/2 inch hail.  Except Houston traffic, I should be done with a doctor appt. NW Houston (249/FM 1960 area) by 4 pm and HRRR suggests semi-discrete cells with STP AOA 4 and some impressive updraft helicities just a couple of counties NW of Houston.  But I'm not driving US 290 anywhere near rush hour, and, having never chased before, and having to check my cell for radar while driving alone I'd have a decent chance of either destroying my car via hail or rear-ending someone, destroying my car, someone else's car, and possibly seriously injuring myself.  So I'll come home and internet and check YouTube on the TV to see if anybody is chasing.  I don't think I have ever seen anyone chasing near here.  There is a 'Pastor Jaime G' ( @ StormChaserHTX) who gets high wind/heavy rain/lightning shots he shares with local broadcast media via social media.  Maybe some Aggie met students, it may not be that far from CLL.

[Chinook]

The 00z NAM already has a potent setup for the day-4 forecast (72 hours, Sunday night)

[Quincy]

The expected pattern realignment is underway. The derecho across Texas yesterday was partially driven by a cold front surging toward the Gulf of Mexico, effectively scouring seasonably rich moisture out of the Plains. Things will be changing in the coming days. 

Saturday: 
Split upper level flow continues tomorrow with the subtropical jet positioned along the Gulf Coast and the northern branch ejecting out of the Northern Rockies. The result may be a bit of a break in the severe action, largely due to a lack of stronger flow/deep layer shear across the Plains. However, a few marginally severe storms and perhaps a transient supercell or two can’t be ruled out across Kansas, as a front drops through the area. 

Sunday:
It looks like the first potentially active day in what should be a fairly busy stretch for severe weather across the region. The setup appears just a bit disjointed, as a split flow regime hangs on. The southern branch is progged to be ejecting toward the OK/TX panhandles and KS, while the northern branch remains displaced to the north. 

Nonetheless, at least isolated to scattered severe thunderstorms, including a few supercells, seem probable across the central/southern Plains. Forcing will be modest and only weak Lee cyclogenesis is expected over the western Kansas vicinity. Details are still TBD, but it looks like a modest-caliber event for late May standards, but still worthy of storm chasing. 

Monday:
Medium range models show some phasing of the upper level jet, as a trough digs from California toward the Desert Southwest. Due to westward placement and “late” timing, it does not look like a major event, but at least some severe potential should exist, once again around the central/southern Plains vicinity. 

Tuesday: 
It’s several days out, but there’s good model agreement that the next notable trough ejection will take place. Models show a robust, broad upper level jet across the central states. Confidence appears highest for severe potential around the lower Missouri Valley vicinity, somewhere around Iowa/eastern Kansas/Missouri. Details will need to be ironed out, but the synoptic pattern favors a heightened severe threat. This may extend as far east as portions of the Mississippi Valley, but we’ll see. 

Midweek and beyond look generally active, but moisture may be scoured out of most of the plains on Wednesday, behind Tuesday’s system. Even if that is true, moisture recovery seems likely by late week, along with ensemble guidance favoring enhanced upper level flow across the Plains. The result should be continued severe threats most days, right through Memorial Day weekend. 

[andyhb]

Tomorrow is looking pretty interesting on the southern periphery of the mid level wave ejecting into KS. Multiple 12z CAMs with supercells on the nose of the higher theta-e in W OK. Got that mothership look to it with a tornado chance as the LLJ cranks towards sundown.

[Quincy]

9 hours ago, andyhb said:

Tomorrow is looking pretty interesting on the southern periphery of the mid level wave ejecting into KS. Multiple 12z CAMs with supercells on the nose of the higher theta-e in W OK. Got that mothership look to it with a tornado chance as the LLJ cranks towards sundown.

Having reviewed 00z guidance, it certainly looks interesting near western Oklahoma early Sunday evening. 

Models show troughing across the High Plains with subtle lee cyclogenesis over southwestern Kansas. A belt of enhanced upper level flow should reside from New Mexico across the OK/TX panhandles and into Kansas as the mid level wave ejects. Convective initiation seems likely by mid afternoon near an effective triple point over SW Kansas and with warm advection farther north in central/northern Kansas near a pseudo warmth front.

 Capping and initially larger T/Td dew point spreads along the dryline over the eastern Texas panhandle will delay convective initiation until late afternoon. With that said, most 00z CAMs show at least one or two isolated storms going up ahead of the dryline by 22-00z. If sustained convection is realized, any storm would move eastward, into western Oklahoma, where increasingly richer moisture will reside. This along with an increasing low level jet would conditionally favor intense supercell development and an associated tornado threat.

Given that messy storm modes are more likely across Kansas, the southern target certainly has my attention. Especially given a southern stream perturbation pointing right at the dryline, just south of the surface low.

[Gobucks15]

That could be one hell of a derecho later today in that environment

[Chinook]

SPC says MODERATE risk, including 45% hatched for hail and wind in similar areas. The 45% risk for wind is about twice the size of the 45% risk for hail. (but not extensive)

[Quincy]

PDS severe thunderstorm watch for northwestern Oklahoma and much of Kansas. 50/20 tornado probabilities too. 

Recent WoFS runs show expected storm modes nicely: clustered, bowing segments in Kansas with isolated supercells in northwestern Oklahoma. 

Low level moisture is over performing some progs. Upper 60s dew points are common across western Oklahoma with lower 70s not far downstream with a 25-30 knot low level jet already in place. 15-25 knot, backed near-surface winds will keep moisture streaming NW. 
Live updating dew point map:

18z NAM is very bullish, showing several supercells along the dryline from western Oklahoma, even down to western north Texas by early evening. I’m not sure I buy that, but regardless, any sustained convection in western Oklahoma will have the potential to produce significant severe. 

Edit: Now the 19z HRRR initiates a tail end supercell just south of I-40 in western Oklahoma. 

[brianc33710]

95/90 wind & 95/80 hail, SPC warned for 75-100 mph winds when they raised to MOD.

@Gobucks15 That’s what the SPC fears is happening & why they went with a rare PDS Severe Thunderstorm Watch. 

[Chinook]

This supercell had the rear flank downdraft wrap all the way around, now there is an unconfirmed tornado warning.

[DDweatherman]

Kansas, look out 

613 PM CDT Sun May 19 2024

The National Weather Service in Wichita has issued a

* Severe Thunderstorm Warning for...
  Eastern Saline County in central Kansas...

* Until 645 PM CDT.

* At 612 PM CDT, severe thunderstorms were located along a line
  extending from near Niles to near New Cambria to Assaria, moving
  east at 30 mph.

  THESE ARE DESTRUCTIVE STORMS FOR EASTERN SALINE COUNTY

  HAZARD...100 mph wind gusts and golf ball size hail.

  SOURCE...Radar indicated.

  IMPACT...You are in a life-threatening situation. Flying debris
           may be deadly to those caught without shelter. Mobile
           homes will be destroyed. Expect considerable damage to
           homes and businesses. Expect extensive tree damage and
           power outages.

[Chinook]

So far there have been many wind reports and hail reports, a 100mph wind at Salina Kansas, flood reports, one tornado warning in Oklahoma

[Gobucks15]

Kansas, look out 

613 PM CDT Sun May 19 2024The National Weather Service in Wichita has issued a* Severe Thunderstorm Warning for... Eastern Saline County in central Kansas...* Until 645 PM CDT.* At 612 PM CDT, severe thunderstorms were located along a line extending from near Niles to near New Cambria to Assaria, moving east at 30 mph. THESE ARE DESTRUCTIVE STORMS FOR EASTERN SALINE COUNTY HAZARD...100 mph wind gusts and golf ball size hail. SOURCE...Radar indicated. IMPACT...You are in a life-threatening situation. Flying debris          may be deadly to those caught without shelter. Mobile          homes will be destroyed. Expect considerable damage to          homes and businesses. Expect extensive tree damage and          power outages.

It’s been awhile since I’ve seen 100 MPH winds in an actual warning

[mob1]

Confirmed large tornado with that cell well west of OKC. 

[Chinook]

Quote

* Tornado Warning for...
  Northeastern Custer County in western Oklahoma...

* Until 830 PM CDT.

* At 738 PM CDT, a confirmed large and destructive tornado was
  observed 4 miles west of Custer City, moving east at 30 mph.

  TORNADO EMERGENCY for Custer City. This is a PARTICULARLY
DANGEROUS SITUATION. TAKE COVER NOW!

 

[Powerball]

1 minute ago, mob1 said:

Confirmed large tornado with that cell well west of OKC. 

 

Definitely wasn't on my bingo card for today...

[Gobucks15]

That’s a big one for sure

[Chinook]

here's the view from KFDR

[mob1]

After it cycled, there's a new PDS warning with that cell now. If it holds together, it's going to move over a more populated area soon. 

[Chinook]

75mph wind measured near Wichita city limits, I assume that was quite possibly the same with some of the power outage areas mentioned

Radar said up to 3" hail with the big tornado storm

[Quincy]

Chased the long lived supercell in western Oklahoma and it’s heading in the general direction of Oklahoma City. Hopefully it weakens. 

 

[Chinook]

storm chaser seeing a tornado near Mustang

Quote

At 935 PM CDT, a confirmed large and extremely dangerous tornado was
located over western Oklahoma City, or 6 miles southwest of Yukon,
moving east at 30 mph.

This is a PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW!

HAZARD...Damaging tornado.

SOURCE...Radar confirmed tornado

[AlexD1990]

storm chaser seeing a tornado near Mustang

At 935 PM CDT, a confirmed large and extremely dangerous tornado was
located over western Oklahoma City, or 6 miles southwest of Yukon,
moving east at 30 mph.
This is a PARTICULARLY DANGEROUS SITUATION. TAKE COVER NOW!
HAZARD...Damaging tornado.
SOURCE...Radar confirmed tornado

Watched it from live on KFOR Livestream

Sent from my SM-F711U using Tapatalk

[mob1]

What is it about this general area?

[mob1]

Looks like the circulation is occluding and another one setting up to its southwest. 

[brianc33710]

Day Two Moderate

Storm Prediction Center May 20, 2024 1730 UTC Day 2 Convective Outlook (noaa.gov)

 

[Windspeed]

Day Two Moderate
Storm Prediction Center May 20, 2024 1730 UTC Day 2 Convective Outlook (noaa.gov)
 

Probably needs its own thread at this point. The MDT coverage area increased for Day 1/tomorrow now with larger hatched and 15% TOR probs.

[nrgjeff]

Southern Iowa convection appears to have spit out a differential heating boundary into northern Missouri. 10:30 am Central visible showed it through Kansas City, but the target will be farther northeast. 10:15 surface chart shows differential heating around I-70 in Missouri. 

Hard as it is for this Jayhawk to say, Missouri has some things going for it. 

The mid-level and upper-level flow crosses the surface front and pre-frontal trough better than farther north. Yes a subtle wind shift is forecast in Missouri ahead of the main front. Next storm motion will be slower in Missouri. CAMs keep some cells discrete in Mizzou likely related to the cross boundary flow aloft. 

Key is for the little outflow along I-70 to stay intact as it lifts north. It will lift north in this strong synoptic pattern and no rain in northern Missouri. I would chase the intersection of the lifting boundary and any pre-frontal trough. While it's a mess south of I-70, Missouri terrain is chasable north of I-70.