Yeah these LLLRs could be a major fly in the ointment.
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Severe WX Severe Weather Threat June 6-14
- Thread starter Kds86z
- Start date
US_Highway15
Member
Not to mention, not like looking at the weather models right now is even productive, but no model predicted this MCS in Indiana lasting this long, so you can basically call any previous run unreliable.
jiharris0220
Member
Yes, but LLLR are counted in 1km. In this case the vertical temperature difference in this layer is only a little over 5c.
And this is with surface temps in the mid 80s.
The atmosphere here does not cool off with height much at all.
But this failure mode can be overcome with favorable storm mergers and maybe a slightly drier vertical profile.
jiharris0220
Member
The MCS is pretty much a non factor all things considered. The airmass behind it has completely recovered and is rapidly advecting northward.
If we had a stout cap, actually good LLLR, a favorably mixed/drier vertical profile, and a slightly better positioned 300mb jet, we would’ve been looking at a slam dunk tornado outbreak.
But, it’s the year 2026, the year of “close but never meant to be”
US_Highway15
Member
We basically looking at a squall line, QLCS event at this point?
jiharris0220
Member
Pretty much yea, the deep layer sheer vector is parallel with the cold front, which favors upscale growth, which is already occurring.
The OWS convection won’t start initiation until 4 or 5pm, and that will be the best chance to see anything of significance.
Again though, good luck getting any vertical stretching when your vertical temperature profile in the low levels is a flat as a wash board.
US_Highway15
Member
SPC 4PM update:
"..20Z UPDATE
THE PREVIOUS FORECAST REMAINS MOSTLY ON TRACK WITH ONLY MINOR
ADJUSTMENTS MADE. ACROSS THE MIDWEST, LATEST GOES IMAGERY SHOWS
GRADUAL CLEARING ACROSS SOUTHERN IA/NORTHERN MO/WESTERN IL BEHIND A
DECAYING MCS. SURFACE OBSERVATIONS ACROSS SOUTHERN IA SHOW SOME
DEGREE OF AIR MASS RECOVERY IS ONGOING; HOWEVER, THE QUALITY OF
DESTABILIZATION WITH NORTHEASTWARD EXTENT REMAINS VERY UNCERTAIN
GIVEN MORE EXTENSIVE CLOUD COVER, ADDITIONAL PRECIPITATION, AND THE
RAPID APPROACH OF THE COLD FRONT FROM THE WEST.
NONETHELESS, REGIONAL 18Z RAOBS AND VWPS ARE SAMPLING THE APPROACH
OF A 60-70 KNOT MID-LEVEL JET, WHICH HERALDS THE ONSET OF STRONGER
SYNOPTIC ASCENT ACROSS THE UPPER MS VALLEY. SOUTHERLY LOW-LEVEL FLOW
SHOULD STRENGTHEN THROUGH THE EVENING IN RESPONSE TO INCREASING
ASCENT, WHICH WILL LIKELY HELP ADVECT HIGHER THETA-E AIR
NORTH/NORTHEASTWARD AS WELL AS BEGIN TO AUGMENT LOW-LEVEL SRH.
RECENT MRMS COMPOSITES SHOW THE ONSET OF CONVECTIVE INITIATION ALONG
THE COLD FRONT, WHICH SHOULD MAINTAIN SUFFICIENT RESIDENCE TIME
WITHIN THE RETURNING THETA-E PLUME FOR FURTHER STRENGTHENING OVER
THE COMING HOURS. LATEST HIGH-RES ENSEMBLE GUIDANCE (INCLUDING WOFS
AND TIME-LAGGED HRRR/RRFS SOLUTIONS) APPEAR TO BE CAPTURING THESE
TRENDS WELL AND CONTINUE TO DEPICT THE CORRIDOR OF HIGHEST SEVERE
WIND AND TORNADO THREAT ACROSS THE MODERATE RISK ZONE. AS SUCH,
LITTLE CHANGE WAS MADE TO THE ONGOING PROBABILITY AND INTENSITY
CONTOURS."
"..20Z UPDATE
THE PREVIOUS FORECAST REMAINS MOSTLY ON TRACK WITH ONLY MINOR
ADJUSTMENTS MADE. ACROSS THE MIDWEST, LATEST GOES IMAGERY SHOWS
GRADUAL CLEARING ACROSS SOUTHERN IA/NORTHERN MO/WESTERN IL BEHIND A
DECAYING MCS. SURFACE OBSERVATIONS ACROSS SOUTHERN IA SHOW SOME
DEGREE OF AIR MASS RECOVERY IS ONGOING; HOWEVER, THE QUALITY OF
DESTABILIZATION WITH NORTHEASTWARD EXTENT REMAINS VERY UNCERTAIN
GIVEN MORE EXTENSIVE CLOUD COVER, ADDITIONAL PRECIPITATION, AND THE
RAPID APPROACH OF THE COLD FRONT FROM THE WEST.
NONETHELESS, REGIONAL 18Z RAOBS AND VWPS ARE SAMPLING THE APPROACH
OF A 60-70 KNOT MID-LEVEL JET, WHICH HERALDS THE ONSET OF STRONGER
SYNOPTIC ASCENT ACROSS THE UPPER MS VALLEY. SOUTHERLY LOW-LEVEL FLOW
SHOULD STRENGTHEN THROUGH THE EVENING IN RESPONSE TO INCREASING
ASCENT, WHICH WILL LIKELY HELP ADVECT HIGHER THETA-E AIR
NORTH/NORTHEASTWARD AS WELL AS BEGIN TO AUGMENT LOW-LEVEL SRH.
RECENT MRMS COMPOSITES SHOW THE ONSET OF CONVECTIVE INITIATION ALONG
THE COLD FRONT, WHICH SHOULD MAINTAIN SUFFICIENT RESIDENCE TIME
WITHIN THE RETURNING THETA-E PLUME FOR FURTHER STRENGTHENING OVER
THE COMING HOURS. LATEST HIGH-RES ENSEMBLE GUIDANCE (INCLUDING WOFS
AND TIME-LAGGED HRRR/RRFS SOLUTIONS) APPEAR TO BE CAPTURING THESE
TRENDS WELL AND CONTINUE TO DEPICT THE CORRIDOR OF HIGHEST SEVERE
WIND AND TORNADO THREAT ACROSS THE MODERATE RISK ZONE. AS SUCH,
LITTLE CHANGE WAS MADE TO THE ONGOING PROBABILITY AND INTENSITY
CONTOURS."
Cell developing E of Edina MO may be the first candidate for a long lived supercell, has that kidney bean shape.
You've got pretty decent lift over there too. Our main threat area is only moderately unstable atm.
You are not reading that temperature profile correctly.
jiharris0220
Member
I clarified this in a later post that Im specifically talking about the 1km increment within this layer, which is what LLLR are based off of. (Obviously you already know this)
I wonder if the higher sheer and instability will make up for the lower lapse rates. It's not like the sharper temperature gradient will be needed for forcing.
Tornado warned now. It's basically on its own with some showers/weak cells for mergers. In an environment of STP 5-7
DanLarsen34
Member
I would say it’s possible, but storm mergers are probably be needed for it to actually occur. This environment has some similarities with the afternoon portion of April 12, 2020 where lapse rates were similarly poor and it took assistance for the two Bassfield cells to take off.
DanLarsen34
Member
There’s OWS underway now near Peoria well ahead of the current tornado warned cell. Those will have to be monitored closely
Kolle
Member
SPC's Evan Bentley has a live discussion on tonight's event:
jiharris0220
Member
This OWS supercell about to cross over into IL is entering an area where the LFC is above 1000meters, expect this storm to rapidly intensify and increase in height.
Whether it produces a long tracker is still in the air.
When you have shear as high as it is today, you really don’t need extremely high vertical instability to produce one.
Whether it produces a long tracker is still in the air.
When you have shear as high as it is today, you really don’t need extremely high vertical instability to produce one.
jiharris0220
Member
Storm merger in progress with this cell now, this is a good thing for it in the long term.
That's a pretty serious looking trough here.
warneagle
Member
we've got a Severe Thunderstorm Watch now. still going to play golf in the 96° heat because I'm, like, a smart person.
