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June 1st-6th Severe Events


Quincy

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With some troughing expected to return to the Pacific Northwest to start June and pieces of energy rotating across the Rockies and into the central/northern Plains, severe threats are expected to ramp up. Although there may not be a particularly significant day between the 1st and 3rd, moderate to strong instability is projected, coupled with wind shear at least marginally supportive of supercells. Add local enhancement via upslope flow and one or more subtle surface lows ejecting from the eastern slopes and each day should feature at least isolated severe thunderstorms. All severe threats should be on the table.

Additional severe potential exists later in the week as the western trough digs, but with details far from resolved, this thread will focus on the first three days of June. However, if trough ejection (occurs, rather than a cut-off or wash-out scenario) is strong enough and occurs far enough east, more impressive mid/upper level winds could possibly create a more robust setup.

The High Plains is continuing to have one of their most consistently active severe seasons in a while. This should continue into early June, although following climo and shifting a bit north than previous events in May.

Edit: Thread extended to include June 4th.

Edit: Extended to include the 5th for the High Plains and 6th for central Plains.

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The NAM forecasts some 3000 J/kg CAPE values in NE Colorado on Wednesday, with over 2000 J/kg near Denver and Fort Collins. I suppose this is worth watching.

The Euro progs at least 2500 J/kg CAPE over portions of eastern Colorado for each of the next three days. It's certainly an area to watch, although the greatest severe potential may actually be a bit north to northeast of Colorado. This is something we haven't said much yet this season.

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Wednesday and Thursday both looking better on all 12Z guidance. 40-50 knots of deep layer shear are now poking out into Nebraska and Kansas both days. LLJ is robust both days. Low level turning is good on and near the boundary. Morning convection is shown exiting the boundary area. EML is depicted. Capping delays afternoon precip. Been a while since we've seen it but very light qpf on the boundary at 00z is actually favorable for chasers. One would expect to see more qpf on hi-res guidance when the time comes.

 

In contrast to Tuesday ENH for large hail I infer from the Day 3, reading between the lines, that tornado probability at least plays a part in the Wednesday ENH. Thursday does not have an outlook yet, but I'd expect it to be ENH tomorrow. if everything comes together right one of those days could become MDT Day 1. The big change I see in 12Z data is better shortwaves promoting new convection away from the morning junk. Time will tell. Cheers!

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Wednesday and Thursday both looking better on all 12Z guidance. 40-50 knots of deep layer shear are now poking out into Nebraska and Kansas both days. LLJ is robust both days. Low level turning is good on and near the boundary. Morning convection is shown exiting the boundary area. EML is depicted. Capping delays afternoon precip. Been a while since we've seen it but very light qpf on the boundary at 00z is actually favorable for chasers. One would expect to see more qpf on hi-res guidance when the time comes.

In contrast to Tuesday ENH for large hail I infer from the Day 3, reading between the lines, that tornado probability at least plays a part in the Wednesday ENH. Thursday does not have an outlook yet, but I'd expect it to be ENH tomorrow. if everything comes together right one of those days could become MDT Day 1. The big change I see in 12Z data is better shortwaves promoting new convection away from the morning junk. Time will tell. Cheers!

Thursday looks impressive in NC KS/SC NE, per both the 12Z NAM (end of run) and 12Z GFS at 7pm Thursday.. Very impressive parameter space in place it appears along the boundary/triple point area. 0-3KM EHI values approaching 12 on both models in a very similar area, strong to extreme instability 3000-5000J/KG MUCAPE, juxtaposed to 30-50kts of 0-6KM shear... Extremely backed SFC flow (essentially easterly), 25-35kts of backed Low-level shear, and modest, but turning wind fields with height (which leads to an impressive curved hodograph)... Only problem is a WEAK upper level wind profile with about 30kts at H25. Both the NAM/GFS also show some CI in this area as well, and possibly along the dryline further south into KS.
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Beautiful supercell near Rapid City tonight. Oddly it backed itself into the hills. Can't recall seeing that before.

You guys had a better vantage point for most of the storm cycle. I was late to the game, but yes, the storm was drifting south and then backed up west before a northward-moving outflow boundary seemingly knocked the supercell out.

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Pretty solid looking upslope/central High Plains setup showing up for Wed on recent runs of the NAM and GFS with some really impressive low level backing and strong/potentially extreme instability for CO and western KS/NE standards.

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It looks like there are three targets today, at least based off of my analysis of morning obs and short-term forecasts. 

 

North target: North Dakota. 

  • Pros: Stronger wind fields aloft, better shear, closer proximity to strongest shortwave energy and good backing of low-level winds.
  • Cons: Somewhat lower instability and some residual cloud-cover.

Central target: South Dakota. 

  • Pros: Strong instability (currently clear skies), proximity to an area low pressure and moisture return.
  • Cons: Somewhat weaker wind shear, only modestly backed low-level winds.

Southern target: Far eastern Wyoming into western Nebraska and the panhandle. 

  • Pros: Models tend to locally back surface winds, secondary low pressure area, decent overlay of moderate to strong instability and wind shear.
  • Cons: Area may be displaced from the stronger forcing aloft, dew-points a few degrees lower, currently in the mid to upper 50s.

The HRRR has been favoring south-central North Dakota for several runs now and the 4km NAM fired a cell there too. South Dakota may have some issues with storm initiation. The southern target has been trending a bit better, but there is question about storms quickly merging into line segments or an MCS down there.

 

For the tornado potential, I'd tend to favor the northern target, although I could see an isolated tornado in the southern flank of storms in the Nebraska panhandle vicinity.

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I am going over to Jamestown to play around with any storms that fire. Not too excited about the setup but the HRRR has been fairly robust. That being said, the HRRR has been pretty bad lately. Maybe it's due for a good one. May as well give it a try... It's in my back yard and I don't have to be at the office today.

Sent from my iPhone using Tapatalk

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I am going over to Jamestown to play around with any storms that fire. Not too excited about the setup but the HRRR has been fairly robust. That being said, the HRRR has been pretty bad lately. Maybe it's due for a good one. May as well give it a try... It's in my back yard and I don't have to be at the office today.

Sent from my iPhone

Yup not seeing much of a chance for the best cell dev here at KRDR.

SC to SE ND looks best.

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Nice anvil visible from the distant south to a newly developing thunderstorm in south-central North Dakota. HRRR is showing a fairly impressive environment evolving in the vicinity. This may be the cell to watch.

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Thursday looks pretty great in NE on the NAM and GFS, a few compensations with the GFS having better low levels and NAM having better deep layer shear and upper level flow with the shortwave that ejects in the afternoon. H7 temps do look pretty warm so I would think early initiation isn't too much of an issue although parameters are already fairly robust by 21z (would actually be more concerned about a cap bust vs. the opposite). Regardless, steep mid level lapse rates with a pretty healthy EML present will likely lead to very large CAPE along/south of the boundary with good directional shear.

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Here was the supercell that crossed the Missouri River just west of Linton, ND this evening. Some of the nicest structure I've seen in person. I then cored the storm and was pelted with golf ball size hail... all to end with a full rainbow. Not a bad little chase basically an hour from home.

 

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Dual ENH risks issued at the 06Z D1SWO, one for NE CO/SE WY/ W NE for the risk of very large hail, and tornadoes (includes a 10% TOR from SE WY southward into Denver) and another ENH risk for damaging winds across N/ Northeast KS and S/SE NE.

On a side note, the SPC is still uninterested in tomorrow (Thursday) for the triple point area that depicts an impressive parameter space. Uncertainity caused by the strong cap that'll be in place, and possible residual cloud cover concerns.. Fwiw, 00Z 4KM NAM showed an isolated supercell popping up right on that triple point where impressive low-level backing will be, and instability will be maximized.

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Dual ENH risks issued at the 06Z D1SWO, one for NE CO/SE WY/ W NE for the risk of very large hail, and tornadoes (includes a 10% TOR from SE WY southward toward Denver) and another ENH risk for damaging winds across N/ Northeast KS and S/SE NE.

Just a heads up, 10% includes Denver also.
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