June 2026 Observations and Discussion.

[Hoosier]

You almost just have to laugh at some of these forecast soundings for Wed.  Except it's not funny, and may be deadly serious.  For example, I pulled a 3 km NAM one from south of Chicago that has almost 2000 CAPE, 0-1 km helicity of 700 and 0-3 km helicity of 1000.  That's more like an April 17 storm environment, but that kind of shear would even do April 17 proud.

[Hoosier]

Obviously don't take the details verbatim, but in general, look how fast the temps try to recover in IL/IN after the first round of activity.  Besides the strong low level flow to promote recovery, we'll also have nearly max diurnal assistance as we approach the longest day of the year. 

[Jaycee_CHI]

1 hour ago, Hoosier said:

Obviously don't take the details verbatim, but in general, look how fast the temps try to recover in IL/IN after the first round of activity.  Besides the strong low level flow to promote recovery, we'll also have nearly max diurnal assistance as we approach the longest day of the year. 

Hoosenstein!!!

I knew you’d be all over this too lol, this setup is actually so intense it’s kinda eerie almost. 

I feel like our area is a bit too far north though? The morning convection looks like it’ll do what it always does and keep the worst to the south, but also, we both got added to the enhanced risk this afternoon, so idk what to think yet. But also like, this system is so powerful that you’d think if any shift were to happen, it’d be to the north no? 

Also, idk if you’ve looked at StormNet with their tornado forecast but they were pretty accurate last time! This morning we were in the yellow, but now it mirrors a bit what I’m saying, even has it down over STL. Either way, I can’t believe we’re talking about this again one week after a severe wx outbreak to remember, pretty awesome!
 

 

[Hoosier]

15 minutes ago, Jaycee_CHI said:

Hoosenstein!!!

I knew you’d be all over this too lol, this setup is actually so intense it’s kinda eerie almost. 

I feel like our area is a bit too far north though? The morning convection looks like it’ll do what it always does and keep the worst to the south, but also, we both got added to the enhanced risk this afternoon, so idk what to think yet. But also like, this system is so powerful that you’d think if any shift were to happen, it’d be to the north no? 

Also, idk if you’ve looked at StormNet with their tornado forecast but they were pretty accurate last time! This morning we were in the yellow, but now it mirrors a bit what I’m saying, even has it down over STL. Either way, I can’t believe we’re talking about this again one week after a severe wx outbreak to remember, pretty awesome!
 

 

Hey

The morning convection (perhaps even lingering past noon) looks like it's pretty much a given at this point, so the key will be getting a clean break after that for at least a few hours.  Assuming that can happen, the warm front/outflow boundary will want to come north fairly quickly and set the stage for the more intense round of storms later in the day.  

I am almost treating this like an April setup.  We know we're going to have the very strong wind fields/shear... that is a given.  The question will be more in regards to how much temperature/moisture recovery there will be in our area.  Given the very strong shear, we're not going to need to get super warm to cause a problem.  Even temps recovering into the 70s would likely be good enough in this particular setup.

I try to be judicious when communicating severe threats to my family/friends because you don't want to always be hyping something, but I have started to use some pretty strong wording while also acknowledging a scenario that is more tame.  I am really quite concerned for the same general corridor that got hit this past Thursday.  There is a very plausible scenario where we see numerous strong tornadoes and one or more violent tornadoes (EF4+) in the IL/IN area or nearby.  

[Clinton]

I had perfect weather today with a high of 80 with a dewpoints staying in the upper 40s.  Rain is expected in the morning.

[Clinton]

1 hour ago, Hoosier said:

Hey

The morning convection (perhaps even lingering past noon) looks like it's pretty much a given at this point, so the key will be getting a clean break after that for at least a few hours.  Assuming that can happen, the warm front/outflow boundary will want to come north fairly quickly and set the stage for the more intense round of storms later in the day.  

I am almost treating this like an April setup.  We know we're going to have the very strong wind fields/shear... that is a given.  The question will be more in regards to how much temperature/moisture recovery there will be in our area.  Given the very strong shear, we're not going to need to get super warm to cause a problem.  Even temps recovering into the 70s would likely be good enough in this particular setup.

I try to be judicious when communicating severe threats to my family/friends because you don't want to always be hyping something, but I have started to use some pretty strong wording while also acknowledging a scenario that is more tame.  I am really quite concerned for the same general corridor that got hit this past Thursday.  There is a very plausible scenario where we see numerous strong tornadoes and one or more violent tornadoes (EF4+) in the IL/IN area or nearby.  

I think your fine to use some strong wording, you just don't see this type of ingredients in mid June.  I lean more with what Reed is showing, I don't see the warm unstable air being held as far south as the stormNet map shows.  Luckily for me the worst looks to stay to the east. 

 

TORNADO OUTBREAK LIKELY Wednesday again across the Corn Belt from northeastern Missouri through central Illinois into Indiana.

This is a very potent trough ejection and associated jet stream kinematics, with spring-like upper levels with June instability and moisture. Anomalous systems cause anomalous impacts, so we should brace for a high ceiling severe weather outbreak.

All hazards will be possible in this target area, including intense tornadoes, vigorous wind bag, and large destructive hail. 

We will be activating storm chase mode for this event

 

[Hoosier]

7 minutes ago, Clinton said:

I think your fine to use some strong wording, you just don't see this type of ingredients in mid June.  I lean more with what Reed is showing, I don't see the warm unstable air being held as far south as the stormNet map shows.  Luckily for me the worst looks to stay to the east. 

 

TORNADO OUTBREAK LIKELY Wednesday again across the Corn Belt from northeastern Missouri through central Illinois into Indiana.

This is a very potent trough ejection and associated jet stream kinematics, with spring-like upper levels with June instability and moisture. Anomalous systems cause anomalous impacts, so we should brace for a high ceiling severe weather outbreak.

All hazards will be possible in this target area, including intense tornadoes, vigorous wind bag, and large destructive hail. 

We will be activating storm chase mode for this event

 

Agreed about the latest stormnet map looking unrealistic.  The only way I could see something like that would be if the early day stuff comes unexpectedly far south AND crapvection keeps festering all afternoon. 

[Hoosier]

Here's the 00z HRRR for Wednesday afternoon.  It also shows a quick recovery up to Lake Michigan in the wake of the first round of storms.  With such a rapidly evolving environment, very close monitoring will be required as sometimes the models cannot keep up in rapid advection situations.

Something I'm wondering is how realistic is it for temps to be in the 50s in the early afternoon north of the front, but a number of models indicate that so it could very well happen. 

 

[Jaycee_CHI]

4 hours ago, Hoosier said:

Hey

The morning convection (perhaps even lingering past noon) looks like it's pretty much a given at this point, so the key will be getting a clean break after that for at least a few hours.  Assuming that can happen, the warm front/outflow boundary will want to come north fairly quickly and set the stage for the more intense round of storms later in the day.  

I am almost treating this like an April setup.  We know we're going to have the very strong wind fields/shear... that is a given.  The question will be more in regards to how much temperature/moisture recovery there will be in our area.  Given the very strong shear, we're not going to need to get super warm to cause a problem.  Even temps recovering into the 70s would likely be good enough in this particular setup.

I try to be judicious when communicating severe threats to my family/friends because you don't want to always be hyping something, but I have started to use some pretty strong wording while also acknowledging a scenario that is more tame.  I am really quite concerned for the same general corridor that got hit this past Thursday.  There is a very plausible scenario where we see numerous strong tornadoes and one or more violent tornadoes (EF4+) in the IL/IN area or nearby.  

First of all, I love your approach! It’s similar to what I do — a lot of my friends ask me about weather and I always try my best to not be the clickbait bs stuff you see everywhere, it’s genuinely so frustrating. 
 

That said, yeah the system being so powerful almost makes everything else seem like it’ll be minor in terms of impact just due to its insane strength with this system, I feel like I haven’t seen something like this really ever in June!

StormNet is kinda garbage imo in regards to the other trends that are occurring. Idk if you saw this but my god, the significant tornado parameter on the HRRR, but omfg!!!

[Hoosier]

38 minutes ago, Jaycee_CHI said:

First of all, I love your approach! It’s similar to what I do — a lot of my friends ask me about weather and I always try my best to not be the clickbait bs stuff you see everywhere, it’s genuinely so frustrating. 
 

That said, yeah the system being so powerful almost makes everything else seem like it’ll be minor in terms of impact just due to its insane strength with this system, I feel like I haven’t seen something like this really ever in June!

StormNet is kinda garbage imo in regards to the other trends that are occurring. Idk if you saw this but my god, the significant tornado parameter on the HRRR, but omfg!!!

I don't ever remember seeing a system like this in our area in June, and the anomaly maps back it up.  When you look at the 500 mb heights and the surface low pressure, both are record or near record for June.  Very anomalous setups can lead to very anomalous outcomes, so there's a chance we could see something pretty wild... and in this case, the "pretty wild" could end up being an unusually intense tornado outbreak (not just total number of tornadoes) for this time of year.   

[Hoosier]

The day that holds the record for the most tornadoes in a single day in Indiana -- June 2, 1990 -- had a sub 990 mb surface low.  Not saying the tornado record will be broken, but just a general point that such a deep system at this time of year is probably not going to go quietly.

 

[Hoosier]

Moderate Risk on the new outlook for Wednesday.  Once we can better nail down the specifics on the morning convection and where the boundary ultimately ends up, wouldn't completely rule out the possibility of a narrow high risk corridor, imo.

 

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1259 AM CDT Tue Jun 16 2026

Valid 171200Z - 181200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF CENTRAL ILLINOIS INTO NORTHWEST INDIANA...

...SUMMARY...
An outbreak of severe thunderstorms is expected across portions of
Illinois and Indiana on Wednesday. Intense tornadoes, swaths of
damaging gusts to 80 mph and hail to 2.5 inch diameter are expected.

...Midwest...

A volatile environment for severe thunderstorms is expected to
develop across portions of the Midwest from IA/MO into IL/IN/OH on
Wednesday, with significant all-hazards severe expected.

A mid/upper level shortwave trough initially over the northern
Plains early Wednesday will pivot southeast across the Upper Midwest
through 00z, and much of the Great Lakes by 12z Thursday. As this
occurs, particularly intense mid and upper level flow, especially by
June standards, if forecast to increase over the region. A 60-80 kt
westerly 500 mb jet stream will overspread much of the Midwest
through the evening, before increasing further during the nighttime
hours. Furthermore, an impressive southwesterly 850 mb low-level jet
around 50-60 kt will be oriented from KS into IA at 12z. This
feature will spread east/northeast across IL/IN/OH through evening.
Interestingly, the core of the low-level jet may be somewhat
displaced to the east of the core warm sector expected to develop
across the Mid-MS Valley vicinity, perhaps tied to an early-day
shortwave impulse ejecting across IA/IL during the morning.
Nevertheless, 40-55 kt 850 mb winds will persist even across the
warm sector even as the core of the low-level jet overspreads the
Ohio Valley toward Lower MI during the afternoon. 

At the surface, an elongated area of low pressure will extend from
ND to the Mid-MO valley Wednesday morning. A warm front will extend
from northwest IA southeastward across central IL, while a cold
front extend from eastern NE into western KS. As this system
progresses east through the day, the warm front will lift northward
into northern IL/IN/OH and upper 60s/near 70 dewpoints are expected.
Aided by steep midlevel lapse rates/cooling aloft, MLCAPE will
approach 2500-3500 J/kg. The latitude of the warm front continues to
be a point of uncertainty. Most forecast guidance depicts morning
convection near and north of the warm front within a strong warm
advection regime moving eastward across IA/northern IL/IN. It is
uncertain if this will suppress the northward advancement of the
warm front. The ultimate position of the warm front will have large
impacts on where particularly concerning strong to intense tornado
potential may eventually develop as storm motion would likely be
along the boundary, rather than across the boundary, allowing for
potentially fast-moving/long-track supercells interacting with the
warm front and remaining within the favorable warm sector.

As the surface cold front develops east, additional convection will
develop along the boundary by late afternoon/early evening from far
southeast IA into northern MO and eastern KS. Initial supercells
along this boundary will pose an all hazards risk -- including very
large hail, strong tornadoes and damaging gusts. With time, this
convection may develop into a line propagating east/southeast. If a
linear MCS develops, swaths of damaging wind gusts will be possible.


In general, given the strength of background flow fields, damaging
wind potential could be significant regardless of storm mode.
Furthermore, even storms developing north of the warm front could
still produce severe gusts given large MUCAPE, fast storm motion and
intense flow just above the surface. Favorable low-level shear will
also support continued tornado potential even within a linear storm
mode via embedded supercell structures and mesovortex generation.
Large to very large hail potential is most likely early in storm
development and where supercells are more likely to remain discrete
(northern MO/far southeast IA/north-central IL).

...Gulf Coast...

Isolated strong gusts are possible in association with a tropical
disturbance moving eastward along the Gulf Coast. See the tropical
weather outlook from the National Hurricane Center for more
information.

..Leitman.. 06/16/2026

 

[westMJim]

With clear skies and a calm wind the temperature is now down to 55. Today it will become cloudy with a good chance of showers and maybe a rumble of thunder. Tonight, and Wednesday will also see a good chance of rain and maybe a storm or two. There is also a chance of some heavy rain.  Friday and Saturday should be dry but it will remain rather cool for mid to late June with highs in the upper 60’s to low 70’s it may reach the mid 70’s on Saturday and Sunday. Lows should stay mostly in the 50’s.

We now have reached the half way point of June 2026 and so far the mean is 69.2 that is a departure of +2.3  but that will go down in the next week.  It looks like 89 will be the highest temperature for the June and the lowest temperature so far is 45. There has been a total of 2.19” of rainfall that is +0.19 above average and looks to go up even further.  While there has been several thunderstorm warnings there has really not been much actual thunderstorm activity in my local area. The official H/L yesterday at Grand Rapids was 72/48 there were 5 Heating Degree Days, no rainfall the highest wind gust was 30 MPH out of the SW. There were no significant weather events. For today the average H/L is 80/59 the record high of 96 was in 1952 the coolest high of 55 was in 1974 the record low of 39 was in 1917 and 1947 the warmest low of 70 was in 2022, 1994 and 1919. The most rainfall of 2.23” was in 1920. Last year the H/L was 84/59.

Some weather history for June 16th, 1987, Temperatures soared above 100 degrees in the Upper Midwest, reaching 104 degrees at Lincoln, NE. Thunderstorms produced wind gusts to 96 mph at Valley City, ND, and baseball size hail near Red Oak, IA. (The National Weather Summary) (Storm Data) Here in Michigan 1974, Cool and cloudy weather prevailed for the middle of June with high temperatures only in the middle 50s across the region on both June 16th and 17th. While it will be cool here this year it is still warmer than it was in 1974.

[WildWisconsinWeather]

We actually had a local meteorologist (on her weather webcast) say there are not a lot of dynamics with tomorrow’s storm.  That kind of exposed her lack of knowledge, even if she was talking locally.

[chescowxman]

Plenty of chilly lows in the 40's across Chesco valley locales this AM. The lowest I could find was the 45.8 low at our typical chilly spot up in Warwick Twp. Another near perfect day on tap today with highs from the mid 70's along the ridges to the upper 70's in the valleys. We warm up with shower chances both Wednesday night and Thursday with highs well into the 80's. We turn cooler again for the weekend with highs remaining in the 70's in the higher spots with lots of sunshine.

[Hoosier]

Gino Izzi's afd from LOT was absolutely fabulous.  Gonna post it.  Notice how he compares it to a cool season outbreak in the South, even though we're now well into June.

 

Wednesday:

An unusually powerful shortwave trough is progged to race
east-southeastward into the upper Midwest and western Great
Lakes Wednesday into Wednesday evening. Model guidance is in
good agreement on the synoptic scale with 500 mb heights
progged to be 3-4 standard deviations below normal for mid June.
At the sfc, an associated low pressure that could threat all-
time monthly record for June is expected to develop across
Wisconsin and eventually move into lower Michigan.
Unsurprisingly, the kinematic fields with such an anomalously
strong system are also nearing the upper echelons of what we
see this time of year in the Midwest. All of this to say that
synoptically, the ingredients are coming together for a
potentially dangerous outbreak of severe thunderstorms and
potentially long-tracked, intense tornadoes.

On the mesoscale, there are naturally greater uncertainties
regarding precisely where (and to a lesser extent, if) the
overlap of exceptionally strong deep and low level shear and
moderately strong instability will take place. SPC`s latest
SWODY2 highlights areas south of I-80 in our CWA with a rare
day 2 moderate risk (level 4 of 5) for Wednesday. The potential
ceiling for bad this severe weather event could get is quite
high, but it is also important to note there are obviously still
failure modes that could materialize on the mesoscale and
prevent the reasonable worst case scenario from unfolding.

The general expectation as it looks now is that a strong low
level jet (increasing to 60kt+ at 850 mb by 12z Wed) will result
in very strong low level theta-e advection and eventually the
development of strong to severe thunderstorms late tonight.
Initially development is expected over eastern IA, but as the
low level jet translates eastward into IL, it should support
this convection developing/moving into northern IL near/after
sunrise Wednesday morning. While this convection will be
elevated, strong effective shear and a reservoir of 1000-2000
J/kg of MUCAPE should allow for elevated supercells. The
greatest severe risk Wednesday morning looks to be over our
western and eventually southern CWA. In addition to the threat
large hail, strong shearing instability near a sharpening
frontal inversion would point to at least some threat for the
development of gravity wave associated convection. Should this
occur, a damaging wind threat could also develop, despite little
or no sfc based instability. In fact, there could even be
pockets of locally significant severe wind gusts (>75 mph) near
or just west/south of our CWA Wednesday morning. This
convection will probably evolve into an MCS as it tracks east
across northern IL and into northwest Indiana Wednesday morning.

The morning convection will likely augment the warm frontal
position and at least initially slow the northward progression
of the composite warm front/outflow boundary, delaying
destabilization north into our CWA. This seems to be the most
obvious potential failure mode: morning convection retarding
the northward surge of the warm front and subsequently the
stronger instability, keeping the extreme wind shear profiles
and strong synoptic forcing somewhat divorced from the more
favorable instability. While that is one potential obvious
failure mode, at this point, it seems unlikely to fully succeed
in completely disrupting the otherwise exceptionally favorable
synoptic set-up from resulting in a high end severe threat.
Though the precise location of the most likely area(s) to see a
high end event, could change some on the mesoscale as the event
nears.

The reason that this morning convection is unlikely to
completely stunt the northward surging warm front is the
extremely strong mass response expected as a result of the near
record deep low pressure system. With a far less intense low
last Thursday, an impressively large footprint of a cold pool
left behind from an MCS that lingered well into the afternoon
was able to be completely overcome in just a matter of a couple
of hours late in the day. Something similar seems plausible
again tomorrow afternoon where a dissipating outflow boundary
from early convection could separate an extremely volatile air
mass from a still sufficiently unstable air mass north of the
boundary could support severe thunderstorms with damaging winds
and isolated tornadoes.

There is variance in guidance with just how far north the
effective boundary will get, but somewhere generally in the
vicinity of I-80 is where a majority of the models show it
reaching its peak latitude in our CWA. To the south of this
boundary, the environment looks similar to what`s often seen in
the cool season major tornado outbreak in the southeastern
United States. Forecast hodographs are literally off the chart,
with 0-1 environmental SRH >500 m^2/s^2. This sort of extreme
low level shear, coupled with low LCLs and resultant strong
0-3km CAPE, fast storm motion, and favorable downstream
environment is the classic type of set-up long tracked strong-
violent tornadoes.

It`s important stress that while the synoptic set-up is classic
for a tornado outbreak, we are dealing with convection that
often alters the mesoscale environment in ways that cannot be
anticipated 12-24+ hours in advance. As noted above, there are
certainly scenarios where an alteration of the mesoscale
environment could dramatically reduce or shift the area of the
greatest tornado risk. For this reason, it is important to
monitor later forecasts closely. Finally, in addition to the
supercell tornado threat, a fast moving line of severe
thunderstorms/possible derecho may also accompany the front
producing widespread, potentially significant, wind damage as
well as line embedded tornadoes, some possibly strong.

Not to be overlooked, precipitable water values are progged to
get to near or just above 2", meaning that convection will
likely be extremely efficient rain producers. The stronger
convection could easily produce 2"+ of rain in just an hour or
so. Given the antecedent very moist ground and generally above
average streamflow, there is a threat of flash flooding
Wednesday. The greatest threat may be with the first round of
convection, since it will likely be a bit slower moving and
offer a better chance of some training cells than the second
round. When the area most at risk can be better refined, we will
need a flood watch for portions of the area for Wednesday as
well.

After Wednesday:

We should see a break in the active pattern for the rest of the
work week. There are indications that we could get into a more
active northwest flow type pattern heading into the weekend and
beyond.

- Izzi

[Clinton]

21 minutes ago, Hoosier said:

Gino Izzi's afd from LOT was absolutely fabulous.  Gonna post it.  Notice how he compares it to a cool season outbreak in the South, even though we're now well into June.

 

Wednesday:

An unusually powerful shortwave trough is progged to race
east-southeastward into the upper Midwest and western Great
Lakes Wednesday into Wednesday evening. Model guidance is in
good agreement on the synoptic scale with 500 mb heights
progged to be 3-4 standard deviations below normal for mid June.
At the sfc, an associated low pressure that could threat all-
time monthly record for June is expected to develop across
Wisconsin and eventually move into lower Michigan.
Unsurprisingly, the kinematic fields with such an anomalously
strong system are also nearing the upper echelons of what we
see this time of year in the Midwest. All of this to say that
synoptically, the ingredients are coming together for a
potentially dangerous outbreak of severe thunderstorms and
potentially long-tracked, intense tornadoes.

On the mesoscale, there are naturally greater uncertainties
regarding precisely where (and to a lesser extent, if) the
overlap of exceptionally strong deep and low level shear and
moderately strong instability will take place. SPC`s latest
SWODY2 highlights areas south of I-80 in our CWA with a rare
day 2 moderate risk (level 4 of 5) for Wednesday. The potential
ceiling for bad this severe weather event could get is quite
high, but it is also important to note there are obviously still
failure modes that could materialize on the mesoscale and
prevent the reasonable worst case scenario from unfolding.

The general expectation as it looks now is that a strong low
level jet (increasing to 60kt+ at 850 mb by 12z Wed) will result
in very strong low level theta-e advection and eventually the
development of strong to severe thunderstorms late tonight.
Initially development is expected over eastern IA, but as the
low level jet translates eastward into IL, it should support
this convection developing/moving into northern IL near/after
sunrise Wednesday morning. While this convection will be
elevated, strong effective shear and a reservoir of 1000-2000
J/kg of MUCAPE should allow for elevated supercells. The
greatest severe risk Wednesday morning looks to be over our
western and eventually southern CWA. In addition to the threat
large hail, strong shearing instability near a sharpening
frontal inversion would point to at least some threat for the
development of gravity wave associated convection. Should this
occur, a damaging wind threat could also develop, despite little
or no sfc based instability. In fact, there could even be
pockets of locally significant severe wind gusts (>75 mph) near
or just west/south of our CWA Wednesday morning. This
convection will probably evolve into an MCS as it tracks east
across northern IL and into northwest Indiana Wednesday morning.

The morning convection will likely augment the warm frontal
position and at least initially slow the northward progression
of the composite warm front/outflow boundary, delaying
destabilization north into our CWA. This seems to be the most
obvious potential failure mode: morning convection retarding
the northward surge of the warm front and subsequently the
stronger instability, keeping the extreme wind shear profiles
and strong synoptic forcing somewhat divorced from the more
favorable instability. While that is one potential obvious
failure mode, at this point, it seems unlikely to fully succeed
in completely disrupting the otherwise exceptionally favorable
synoptic set-up from resulting in a high end severe threat.
Though the precise location of the most likely area(s) to see a
high end event, could change some on the mesoscale as the event
nears.

The reason that this morning convection is unlikely to
completely stunt the northward surging warm front is the
extremely strong mass response expected as a result of the near
record deep low pressure system. With a far less intense low
last Thursday, an impressively large footprint of a cold pool
left behind from an MCS that lingered well into the afternoon
was able to be completely overcome in just a matter of a couple
of hours late in the day. Something similar seems plausible
again tomorrow afternoon where a dissipating outflow boundary
from early convection could separate an extremely volatile air
mass from a still sufficiently unstable air mass north of the
boundary could support severe thunderstorms with damaging winds
and isolated tornadoes.

There is variance in guidance with just how far north the
effective boundary will get, but somewhere generally in the
vicinity of I-80 is where a majority of the models show it
reaching its peak latitude in our CWA. To the south of this
boundary, the environment looks similar to what`s often seen in
the cool season major tornado outbreak in the southeastern
United States. Forecast hodographs are literally off the chart,
with 0-1 environmental SRH >500 m^2/s^2. This sort of extreme
low level shear, coupled with low LCLs and resultant strong
0-3km CAPE, fast storm motion, and favorable downstream
environment is the classic type of set-up long tracked strong-
violent tornadoes.

It`s important stress that while the synoptic set-up is classic
for a tornado outbreak, we are dealing with convection that
often alters the mesoscale environment in ways that cannot be
anticipated 12-24+ hours in advance. As noted above, there are
certainly scenarios where an alteration of the mesoscale
environment could dramatically reduce or shift the area of the
greatest tornado risk. For this reason, it is important to
monitor later forecasts closely. Finally, in addition to the
supercell tornado threat, a fast moving line of severe
thunderstorms/possible derecho may also accompany the front
producing widespread, potentially significant, wind damage as
well as line embedded tornadoes, some possibly strong.

Not to be overlooked, precipitable water values are progged to
get to near or just above 2", meaning that convection will
likely be extremely efficient rain producers. The stronger
convection could easily produce 2"+ of rain in just an hour or
so. Given the antecedent very moist ground and generally above
average streamflow, there is a threat of flash flooding
Wednesday. The greatest threat may be with the first round of
convection, since it will likely be a bit slower moving and
offer a better chance of some training cells than the second
round. When the area most at risk can be better refined, we will
need a flood watch for portions of the area for Wednesday as
well.

After Wednesday:

We should see a break in the active pattern for the rest of the
work week. There are indications that we could get into a more
active northwest flow type pattern heading into the weekend and
beyond.

- Izzie

The latest run of the 3km NAM was nasty.  I hope people in your area are paying attention. 

[Hoosier]

22 minutes ago, Clinton said:

The latest run of the 3km NAM was nasty.  I hope people in your area are paying attention. 

I would think that would be less of an issue than usual, considering what just happened around this area last week.  Should make people more likely to take any tornado warnings seriously.

[Hoosier]

LOT has now confirmed 20 tornadoes in their cwa from last Thursday.

This one almost took a right turn right into Midway Airport.  I actually know someone who was at the airport at that time to pick up a friend (that flight turned around and ended up getting diverted to Kansas City... d'oh).

[Jaycee_CHI]

17 minutes ago, Hoosier said:

I would think that would be less of an issue than usual, considering what just happened around this area last week.  Should make people more likely to take any tornado warnings seriously.

Do you still think we’re too far north? I feel like you have a better shot than I do at getting in on the crazy tornado action. 
 

you also beat me to it on that writeup!! That’s the most intense AFD I think I’ve ever read in my life. The tornado parameters aren’t even real atp!!! 
 

[Hoosier]

3 minutes ago, Jaycee_CHI said:

Do you still think we’re too far north? I feel like you have a better shot than I do at getting in on the crazy tornado action. 
 

you also beat me to it on that writeup!! That’s the most intense AFD I think I’ve ever read in my life. The tornado parameters aren’t even real atp!!! 
 

I have a better shot than you, and areas south of here have a better shot than me.  

The 12z HRRR has very little break in the storms around Chicagoland tomorrow afternoon, limiting recovery, so the better severe parameters end up staying fairly far south of Chicago.  But we're going to have to monitor how things are unfolding on an hourly basis.  A 2 hour break vs a 4 hour break could make a big difference in how far north the better severe threat can get.

[Hoosier]

A couple runs of the HRRR have been putting a massive updraft helicity swath through here.  This is a bit north of where the better tornado parameters are progged though.

[Hoosier]

I think there was some coordination on messaging by the NWS offices today.

Chicago:

Final Takeaway Message:

Given the severe weather parameters in play tomorrow, as well
as the threat for potentially significant flash flooding (even
outside of the higher severe threat areas), it is important to
continue to monitor later forecast updates closely. Review (and
practice) severe weather safety plans. Have multiple redundant
means to receive warning information, and keep mobile devices
charged in the event of power outages.

 

Northern IN:

So this is a potentially very dangerous situation
and one would be wise to use caution and stay very weather aware
tomorrow. Make sure to have multiple means of receiving
warnings and keep your cell phones charged up and a fresh set of
batteries in your weather radios in case of power outages.

[Jaycee_CHI]

2 hours ago, Hoosier said:

I think there was some coordination on messaging by the NWS offices today.

Chicago:

Final Takeaway Message:

Given the severe weather parameters in play tomorrow, as well
as the threat for potentially significant flash flooding (even
outside of the higher severe threat areas), it is important to
continue to monitor later forecast updates closely. Review (and
practice) severe weather safety plans. Have multiple redundant
means to receive warning information, and keep mobile devices
charged in the event of power outages.

 

Northern IN:

So this is a potentially very dangerous situation
and one would be wise to use caution and stay very weather aware
tomorrow. Make sure to have multiple means of receiving
warnings and keep your cell phones charged up and a fresh set of
batteries in your weather radios in case of power outages.

We got upgraded to a moderate risk of flash flooding and rightfully so! Looks like training thunderstorms over our area for hours on end — flash flooding in the city is brutal too so hopefully it doesn’t get too insane. 
 

im thinking of going storm chasing tomorrow, I actually got invited to join a well known chaser from the area and im tempted to change my work plans so I can join but im actually really nervous tbh we’ll see though. I’d love to also not miss a chance at catching my favorite tornado sirens ever if somehow we can pull something off in the city. 
 

I’m almost certain they’re going to go high risk tomorrow. There’s just no way they can’t at this point. I wonder if your area gets added to the moderate risk actually! 

[Hoosier]

Sent this out to my people a short time ago.  Obviously have to try to keep it simple for the masses, lol

 

Update on tomorrow's storms.  Maybe a little more clarity, but still plenty of uncertainty...

There will be a round of rain/storms in the morning and into the afternoon.  This round has a very low (almost zero) chance of producing severe weather in our area, but it will keep the temperatures on the cool side.  In fact, it may only be around 60 (or perhaps even in the 50s) into at least the early afternoon, which is quite remarkable for June 17!  This stuff will act to hold the warm front well south of us (down in central IL/IN) into the afternoon.  

Then the big question is what happens after early afternoon.  There are a few possible scenarios:
Scenario 1:  There is little to no break in the rain (0-2 hours long).  This would greatly lower the chances of severe weather later in the day, though the chance may not be zero.

Scenario 2:  There is a 2-4 hour long break in the rain in the afternoon.  This scenario would give the warm front more of a chance to lift into our area and our chances of severe weather (including tornadoes) would be substantial... probably more substantial in the event of a 4 hour break instead of a 2 hour break.

Scenario 3:  There is a longer than 4 hour break in the rain in the afternoon. This scenario would be most concerning of all and would almost guarantee very nasty storms for the area, including a substantial possibility of big, destructive tornadoes.

As of now, scenario 3 looks least likely.  Scenario 1 or scenario 2 look most likely, but I can't say which one yet.  It will require careful hour by hour monitoring tomorrow because that warm front will want to get pushed north quickly from central IL/IN during any breaks in the rain.

[Hoosier]

8 minutes ago, Jaycee_CHI said:

We got upgraded to a moderate risk of flash flooding and rightfully so! Looks like training thunderstorms over our area for hours on end — flash flooding in the city is brutal too so hopefully it doesn’t get too insane. 
 

im thinking of going storm chasing tomorrow, I actually got invited to join a well known chaser from the area and im tempted to change my work plans so I can join but im actually really nervous tbh we’ll see though. I’d love to also not miss a chance at catching my favorite tornado sirens ever if somehow we can pull something off in the city. 
 

I’m almost certain they’re going to go high risk tomorrow. There’s just no way they can’t at this point. I wonder if your area gets added to the moderate risk actually! 

Just go... unless it was Reed Timmer.   

The Chicago sirens kinda creep me out (unless they have changed).  They are like those old school air raid sirens and don't sound like a normal tornado siren.

[Black Hole]

Models looking flatter but probably a little rain here Thursday, with another chance towards Saturday and again late Sunday to Monday. In other words, frequent rain chances remain on track. 

[Hoosier]

The better environment expanded north on the 00z HRRR.  So as said earlier, very close monitoring of observational trends will be needed tomorrow.  

00z run:

 

18z run: 

[Black Hole]

10 minutes ago, Hoosier said:

The better environment expanded north on the 00z HRRR.  So as said earlier, very close monitoring of observational trends will be needed tomorrow.  

00z run:

 

18z run: 

It seems like a lot of these times, and more often than the CAMSs think, it grows upscale into a mess early on. This typically prevents the high end setups from reaching the full potential. But it is a trade. You can then end up with a line of high winds and QLCS tornadoes instead of the truly big time supercells. 

[Hoosier]

Was looking at the 03z RAP, and it's pretty interesting to watch how the instability axis comes into northern IL/IN despite it raining virtually the entire time.  Really goes to show the power of the advection/mass response.  Imagine if there is more of a break in the precip than shown.

 

[Hoosier]

SPC maintains a moderate risk and mentions that linear mode is unlikely for most of the event.  Buckle up.

[Hoosier]

The June surface low pressure record of 992.9 mb has stood for the past 90 years in Chicago.  There is a pretty good chance of it being broken.  

[westMJim]

The current temperature and overnight low here in my yard is 57 at 7AM.  Yesterday afternoon there was a heavy shower in my general area. I recorded 0.17” of rainfall, there was some very small hail. Not much in the way of wind and I did not see or hear any thunder. Today looks to have a chance of some severe weather most of that should stay just south of the Michigan state line. There is a chance of some heavy rain and there is a flood watch for areas south of the Grand Rapids metro area. There will be a very deep low for June in the area so we shall see how this all plays out. Highs in the low 70’s will be about 10 degrees below average until Saturday lows will be in the mid 50’s Saturday and beyond will continue to see highs below average in the mid to upper 70’s  and lows still in the mid 50’s

The official H/L yesterday at Grand Rapids was 74/56 there no Heating or Cooling Degree Days. There was  0.02” of rainfall at the airport. The highest wind gust was 39 MPH out of the SW. Some weather events were thunderstorm, light rain. For today the average H/L is 80/59 the record high of 95 was in 1992 the coldest high of 54 was in 1974 the record low of 40 was in 1980 the warmest low of 73 was in 1957 the most rainfall of 2.01” was in 1996. Last year the H/L was 89/65.

Some weather history for June 17^th 1882, A tornado traveled more than 200 miles across the state of Iowa killing 130 persons. The tornado touched down about ninety miles west of Grinnell, and struck the town and college around sunset, killing sixty persons, and causing more than half a million dollars damage. Traveling at nearly 60 mph, the tornado hit Mount Pleasant about 11 PM causing another half a million dollars damage. (David Ludlum) 1989, Unseasonably cool air, responsible for 37 record lows in the central U.S. on the 15th and 16th, including a low of 33 degrees at Valentine NE on the 15th, overspread the eastern U.S. ending a three day seige of severe weather. (The National Weather Summary) Here in Michigan 1975, A tornado struck two miles northeast of Newaygo. A tree fell on and killed a 14 year old girl who was camping with her parents. Tornadoes also hit Roscommon County, where damage was done to some boats on the southwest shore of Houghton Lake. Another tornado damaged several farm buildings north of Zeeland in Ottawa County.  1992. Over a dozen, mostly weak tornadoes struck across Lower Michigan, including south of Coopersville in Ottawa County, near Cedar Springs in Kent County, Harrison in Clare County and Pewamo in Ionia County.

 

[Grizzcoat]

And it's starting in IA--- 

[metallica470]

Did the models overestimate the southern extent of this morning's convection? Just looking at the current radar and comparing, one would think that means the opportunity exists for the warm front to surge further north?

[Clinton]

The HRRR is showing a quick but well timed shot at some supercells over mby.  The storms will occur at peak heating.

 

[Hawkeye]

The severe wind (75+ mph) missed me just a hair south.  I got 50+ mph.  However, we continue to get clobbered with heavy rain as another comma head moved over us.  I've received another 2+ inches this morning, boosting my June total to over 8 inches.

[Tom]

@OttumwaSnomow, you got hit on the southern end?  That was a close call or a direct hit...either way, looks like some nasty weather for a lot of our IA folks and now the attn turns into IL/IN.

 

[OttumwaSnomow]

9 minutes ago, Tom said:

@OttumwaSnomow, you got hit on the southern end?  That was a close call or a direct hit...either way, looks like some nasty weather for a lot of our IA folks and now the attn turns into IL/IN.

 

Yes sir! Just got .75" on tail end of mcs! 

Almost 5" for June.

[chescowxman]

With the exception of tomorrow temperatures over the next week should be near normal for late June with highs in the upper 70's to lower 80's. Thursday will be our warmest day of the week along with a chance of some showers. Lows over the weekend will return to the comfortable 50's for most spots across the area. Shower chances increase by Sunday night and through Monday.