June 22-23 Severe Weather Outbreak

[Powerball]

any other time of year that could be pretty damning... But given that we would still have close to 12 hours of possible daylight and very strong WAA into the area, I wouldn't throw in the towel completely... That would almost definitely leave some type of OFB over at least N IL and E IA as well.

 

With a scenario the HRRR is laying out, you'd want the MCS east of you BEFORE peak heating and also to be located on the southern edge of the MCS to have a legit shot of severe weather with the main shortwave. 

 

Otherwise, the moisture/instability transport will be disrupted as you'll be caught under its outflow bubble (and how fast it dissipates depends on how fast the convective debris burns off) and there will be less time to recover.

 

None of the aforementioned is to say the HRRR will be right of course.

[cyclone77]

DVN did a great job with their AFD.  Mentions the possibility for very large hail.

 

 

FORECAST FOCUS ON POTENTIAL FOR A VERY SIGNIFICANT SEVERE WEATHER
EVENT MONDAY EVENING WITH A CONTINUED ACTIVE PATTERN THROUGH MOST OF
THE EXTENDED. THERE IS A THREAT OF SEVERE WEATHER AND HEAVY RAINFALL
AND POSSIBLE FLASH FLOODING THIS UPCOMING NEW WORK WEEK.

MONDAY EVENING...ANOTHER VOLATILE SITUATION AS SBCAPES WILL BE
EXTREME (IN EXCESS OF 5000 J/KG) ALONG WITH VERY STRONG DEEP LAYER
SHEAR (50-60 KNOTS). LOW PRESSURE WILL BE DEEPENING AS IT TRACKS
FROM THE DAKOTAS TO THE NORTHERN GREAT LAKES WITH MID LEVEL WINDS
STRENGTHENING TO 70 KNOTS (500 MB). A DECENT CAP WILL BE IN PLACE
UNTIL LATE AFTERNOON OR EARLY EVENING WHEN COOLER AIR ALOFT ARRIVES
ALONG WITH LARGE SCALE ASCENT FROM A SHORT WAVE. THIS WILL TRIGGER
EXPLOSIVE THUNDERSTORM DEVELOPMENT AS A COLD FRONT ARRIVES FROM THE
NORTHWEST. INITIALLY SUPERCELLS WILL DEVELOP WITH THE POTENTIAL FOR
VERY LARGE HAIL AND ISOLATED TORNADOES THEN TRANSITIONING TO BOWING
SEGMENTS WITH DAMAGING WINDS IN EXCESS OF 70 MPH. PRECIPITABLE WATER
WILL INCREASE TO OVER 2 INCHES SO TORRENTIAL RAINFALL WILL ACCOMPANY
THESE STORMS.

SPC HAS INCLUDED MUCH OF THE DVN CWA IN AN ENHANCED SLIGHT RISK FOR
SEVERE BUT THIS MAY NEED TO BE UPGRADED TO A MODERATE RISK IN LATER
FORECASTS. BEFORE THE STORMS ARRIVE OUR SOUTHERN CWA WILL HAVE HEAT
INDEX VALUES IN THE MID 90S EARLY IN THE EVENING. A COLD FRONT WILL
BE PUSHING ACROSS THE CWA LATER IN THE EVENING AND BY MIDNIGHT MUCH
OF THE THUNDERSTORM ACTIVITY SHOULD BE PUSHING SOUTH AND EAST OF THE
CWA...AS WINDS TURN NORTHWEST BEHIND THE FRONT. MINIMUM TEMPERATURES
WILL RANGE FROM THE LOWER 60S FAR NORTH TO AROUND 70 FAR SOUTH.

[jojo762]

With a scenario the HRRR is laying out, you'd want the MCS east of you BEFORE peak heating and also to be located on the southern edge of the MCS to have a legit shot of severe weather with the main shortwave.

Otherwise, the moisture/instability transport will be disrupted as you'll be caught under its outflow bubble (and how fast it dissipates depends on how fast the convective debris burns off) and there will be less time to recover.

None of the aforementioned is to say the HRRR will be right of course.

well verbatim the 23Z HRRR at hour 15 is at 9am... And peak heating is ~4-5pm.. Still would want it gone by around 3pm or before... Definitely have time to spare really. Especially given the amount of dynamics that go into this. One concern with the MCS in the morning could possibly be that it continues to back build crapvection over the area due to the stregthening SFC-low and in response the strong LLJ bringing strong WAA directly into the MCS... One caveat against this idea would be the streghthening of the EML in the morning which would instead act to surpress any back building of the MCS and could possibly weaken it significantly. And surpress any convection at all until afternoon when better forcing comes Into play, and in turn lead to our potential ceiling being reached possibly.

[Powerball]

well verbatim the 23Z HRRR at hour 15 is at 9am... And peak heating is ~4-5pm.. Still would want it gone by around 3pm or before... Definitely have time to spare really. Especially given the amount of dynamics that go into this. One concern with the MCS in the morning could possibly be that it continues to back build crapvection over the area due to the stregthening SFC-low and in response the strong LLJ bringing strong WAA directly into the MCS... One caveat against this idea would be the streghthening of the EML in the morning which would instead act to surpress any back building of the MCS and could possibly weaken it significantly. And surpress any convection at all until afternoon when better forcing comes Into play, and in turn lead to our potential ceiling being reached possibly.

 

As far as the bolded, the issue more so will be with areas further north and east (Michigan / Ontario).

 

BTW, 14z Monday is 10am in the eastern time zone. 

[ClicheVortex2014]

23z HRRR has the MCS all over the western portion of the enhanced risk area by 14z... and it looks like it's weakening. I'd guess it would be out of there by 16z or 17z. If this were March or maybe even April, that would be too late... but I think this still leaves plenty of time to destabilize.

 

[andyhb]

We really don't need a play by play of every high res run especially this far out.

[Hoosier]

FWIW, LOT's hwo mentioned gusts of 40 to perhaps 45 mph tomorrow outside of storms, which is entirely believable given the low level wind fields/mixing depth.

[thewxmann]

The HRRR is pretty crappy at these ranges. It's probably better just to watch the convective trends of the Dakotas storms.

[jojo762]

As far as the bolded, the issue more so will be with areas further north and east (Michigan / Ontario).

BTW, 14z Monday is 10am in the eastern time zone.

well I'm more so just considering the afternoon threat to be more so in S WI/N IL and areas around that.. Basically the western risk area. Since it seems more likely that an MCS would be less likely to be thermodynamically detrimental, and since it seems probable that convection in this area will have a better chance at being discrete and pose a more significant tornado risk... Not to say that the threat in Michigan shouldn't be considered significant by any means, just purely talking from more of a discrete supercell threat aspect. And Illinois and Wisconsin is in central time.. But Michigan isn't of course.

[ClicheVortex2014]

The HRRR is pretty crappy at these ranges. It's probably better just to watch the convective trends of the Dakotas storms.

Especially with MCS's. It couldn't even nail down what was happening at hour 1 last night.

[Thundersnow12]

Agree on not picking apart every HRRR detail but will be interesting to watch how much heating and instability we get going ahead of a possible mid-morning MCS..

 

Pretty bullish already by 14z just ahead of it into northwest IL

 

[thewxmann]

Especially with MCS's. It couldn't even nail down what was happening at hour 1 last night.

 

I've noticed that HRRR is pretty bad between hr 0-6 as well. There seems to be a sweet spot (~8 hr out, or morning runs for an afternoon-evening event) that HRRR does fairly well.

[Powerball]

well I'm more so just considering the afternoon threat to be more so in S WI/N IL and areas around that.. Basically the western risk area. Since it seems more likely that an MCS would be less likely to be thermodynamically detrimental, and since it seems probable that convection in this area will have a better chance at being discrete and pose a more significant tornado risk... Not to say that the threat in Michigan shouldn't be considered significant by any means, just purely talking from more of a discrete supercell threat aspect. And Illinois and Wisconsin is in central time.. But Michigan isn't of course.

 

I see your point, and I agree as far as S. Wisconsin and N. Illinois. 

 

But yeah, at least as far as I'm concerned locally, I would prefer that no organized activity makes it into S. Wisconsin / Illinois tomorrow morning. In past occurrences, that typically diminishes the potential locally. But then again, synoptically, this system is fairly anomalous so nothing can be totally ruled out. 

 

Also, with respect to the 1998 event referenced by APX, things were 100% clear ahead of those storms (which are setups that we do best in locally). 

[andyhb]

MCD for convective trends this evening: http://www.spc.noaa.gov/products/md/md1110.html

[Superstorm93]

Just for posterity. 

 

SCP up to 71 units and a ridiculously curvy hodograph 

 

90 knots 0-6km shear lol 

 

[RCNYILWX]

I think just as there's always potential failure modes in this region, ultimately it'll be hard to get by without fairly widespread severe weather with this magnitude of deep and low level shear in late June. Even considering the time of year, the amount of instability that will be in place is not exactly common for here. I'm favoring at least part of the current ENH area in the DVN and LOT, and possibly IWX CWAs being included in a day 1 MDT. I'd say more than morning/mid-day convection, (which could also be severe) significantly reducing the threat, the cap with southward extent could still be an issue, though I'm buying into the consensus that it will break. 18z 12km NAM was very concerning in that it breaks the cap over northern IL in the late afternoon in an environment that will be even slightly more favorable for sig. severe than the early evening. The forecast hodo and soundings are as high end as it gets for this area.

[Chargers09]

I think just as there's always potential failure modes in this region, ultimately it'll be hard to get by without fairly widespread severe weather with this magnitude of deep and low level shear in late June. Even considering the time of year, the amount of instability that will be in place is not exactly common for here. I'm favoring at least part of the current ENH area in the DVN and LOT, and possibly IWX CWAs being included in a day 1 MDT. I'd say more than morning/mid-day convection, (which could also be severe) significantly reducing the threat, the cap with southward extent could still be an issue, though I'm buying into the consensus that it will break. 18z 12km NAM was very concerning in that it breaks the cap over northern IL in the late afternoon in an environment that will be even slightly more favorable for sig. severe than the early evening. The forecast hodo and soundings are as high end as it gets for this area.

Are these areas in addition to Michigan and Wisconsin being in the mod or are those left out?

[Powerball]

I was just reminded that Detroit's Freedom Festival fireworks are scheduled for tomorrow night.

 

So we'll see if that's impacted.

[andyhb]

00z NAM looks like a bit of a shift south, still incredible soundings showing up in E WI and Lower MI in the 21z-00z timeframe.

[Powerball]

Are these areas in addition to Michigan and Wisconsin being in the mod or are those left out?

 

Did you read his entire post?

[Chargers09]

Did you read his entire post?

Yes I did. I wanted clarification and wanted to ask him a question. Thanks.

[RCNYILWX]

Are these areas in addition to Michigan and Wisconsin being in the mod or are those left out?

I was focused on the southern areas because I think WI and MI are a slam dunk.

[Thundersnow12]

Question will be do we get storms in this environment and are they discrete? 

 

[Powerball]

Yes I did. I wanted clarification and wanted to ask him a question. Thanks.

 

I thought this part addressed your question:

 

I'd say more than morning/mid-day convection, (which could also be severe) significantly reducing the threat

 

But I could be wrong.

[MidwestChaser]

 

[ClicheVortex2014]

NAM has high STP values lingering into the night... even some new semi-discrete cell initiation at 09z behind a squall-like feature that came from Michigan. These cells might even be surface-based, based on the soundings.

 

The latest SREF has some decent parameters for Wednesday... possibly even Thursday. 

[Chargers09]

I was focused on the southern areas because I think WI and MI are a slam dunk.

 

 

I thought this part addressed your question:

 

 

 

But I could be wrong.

 Interesting. 

[homedis]

 

wowowowowowowow that's dangerous... heading straight downtown

[Chargers09]

I was focused on the southern areas because I think WI and MI are a slam dunk.

Thank you for the clarification. Much appreciated. 

[Hoosier]

Question will be do we get storms in this environment and are they discrete? 

 

sig tor here.gif

 

This version of the NAM has a strange lack of coverage in much of N IL during the late afternoon/early evening.  Not really sure why...can't blame it on lack of instability as MLCAPE of 4000+ is being progged.