6/21/06 FCST: IL / IN / MI / OH

[Robert Dewey]

Was quite surprised to see the MDT across MI... SPC has 60% probability lined up, which would have been a HIGH if it was hatched.

Airmass will be quite unstable when the shortwave moves in, with the mid level jet ramping up to +65KNTS from the west or wnw, depending on your location. SFC winds across MI stay backed for quite awhile at southerly or sse'erly, which keeps 0-3km helicity around 350m2/s2. Speed shear is also excellent...

12Z NAM rolls the morning system through by 12Z-15Z, with redevelopment around 21Z across lower MI.

 

[Jeremy Lemanski]

Was quite surprised to see the MDT across MI... SPC has 60% probability lined up, which would have been a HIGH if it was hatched.

Airmass will be quite unstable when the shortwave moves in, with the mid level jet ramping up to +65KNTS from the west or wnw, depending on your location. SFC winds across MI stay backed for quite awhile at southerly or sse'erly, which keeps 0-3km helicity around 350m2/s2. Speed shear is also excellent...

12Z NAM rolls the morning system through by 12Z-15Z, with redevelopment around 21Z across lower MI.
[/b]

I'm very surprised also, mainly because i have my doubts that there will be much in the way of daytime heating. To me, this looks like one of the classic cases where all the dynamics are in place, but with no heating. I will say this, if the MCS is out of the area by about noon, and we can get at least 2-3 hours of sun, to warm into the low to mid 80s, then it could be a very good day for michigan. Also, the clouds might not all bad, temps in the low-mid 80s would give nice capes, yet keep fairly low LCL heights.

The 12z nam keeps temps in the upper 70s-low 80s, with SB capes by 21z of 1500-2500 across most of the mod. risk area, i wish there was just a little more, around 3000, but as it stands, it still doesn't look bad at all.

 

[rdale]

Winds look pretty darn good on the 12Z NAM valid 21Z tomorrow in LAN along with upper-70's giving us 2500CAPE. I agree it's all about post-AM-MCS cloud cover, I have a hard time getting excited about these events this far out. Nonetheless I'll have the chase van readied up for tonight and try to get a little nap in today in case of extended ops ;>

Hopefully a little better than my pea-sized chase yesterday...

 

[tom hanlon]

So much can go wrong with a great lakes event.

Let me count the ways..
<blockquote>stratus deck
</blockquote>squall line

Well I guess that is not soo many ways.

I am chasing tomorrow and will hopefully be in the right place at the right time. Not placing too much hope on today's forecast (see above) but getting into position just the same. Will spend the night near the IN/OH/MI border and see what happens in the AM.

So much can happen and we can be surprised. For example an event in IL last year surprised everyone with a serious tornado, I forget the location, near Danville perhaps. The mystery input was plenty of shear, low level shear and plenty of cape. We seem like we will have that tomorrow. Pinpoint accuracy in terms of a target.. well that is gonna be tough. I hope the more experienced forecasters will add some input regarding that.

Hoping for the best, any tors will be during the early convection and may or may not be long lasting so luck will have a lot to do with it. Can't get lucky unless you are in position so so off to MI/IN/OH I go.

*note* my secret hope is for some Lake breeze bounday interaction. Storms moving into the effect of the lake/coast interaction can be strengthened or weakened.

Storm movement is likely going to be a little fast.

--
Tom Hanlon

 

[Robert Dewey]

Oh man, I seriously hope the lake breeze doesn't startup. With low and mid level winds being so strong, I don't suspect that it will. The lake breeze completely choked off a nice squall line here a few weeks ago as the system ingested cooler marine air.

I'm actually hoping for a nice long squall line or derecho-type system tomorrow... I don't have the equipment to find Michigan supercells, and it would be easier to intercept a squall line given storm motion and terrain. Of course, embedded supercells with landspout-ish tornadoes are always welcome...

 

[Eric Graham]

Doing some late night check of things for chase day tomorrow and noticed SPC has downgraded the MOD area to 45% from ealier-in-the-day 60%. Thinking about heading north up to Logansport, IN area and pitching camp there and wait to see what happens. Considering what happened two weeks ago with the gustnado/landspout fest we had here in central/northern IN; I won't be suprised to see some more tomorrow. Car is gassed up and ready to roll tomorrow. Good luck to all who will be out.

Eric

 

[Robert Dewey]

Latest 00Z NAM is in... It's actually stronger than the previous 00Z run, which lead to the 60% area. I think SPC dropped the 60% so that they could go hatched without upgrading to a HIGH given the uncertainy.

Anyway, the 500MB jet is about 5KNTS stronger on the latest run with a nice shortwave swinging through the IN/MI/OH area between 21Z and 00Z... Haven't been able to see any soundings or instability parameters, but if there isn't too much clouds and the expected moisture arrives, I still imagine MLCAPE values in excess of 2500J/KG...

I'm really thinking that there will be a pretty intense squall line - perhaps reaching "derecho" status. The boundary looks quasi-stationary, so I don't suspect we'll see a massive line of supercells like what was seen on July 2nd, 1997 (Michigan)... But who knows.

 

[Robert Dewey]

All of that stuff that was supposed to materialize over IA/WI/MN never really did, and the RUC keeps delaying it with each run. The northern edge of that stuff in SD/northern NE also seems to be falling apart... I do see a hint of development in central IA on the IR loop, and the stuff in southern NE/northern KS does have me a bit concerned (the RUC doesn't show this activity at all). NAM shows it, but weakens it by 06-12Z...

Latest 03Z RUC does break out precipitation across SW lower MI around 12Z, but the cloud products show only thin cirrus at best (actually, quite a few cloudless areas). Actually, I still have doubts that precipitation will break out as strong as what the RUC suggests (0.75 to 1.00 near GRR). The 03Z RUC is also notably stronger with the 500MB jet streak than the 00Z NAM.

With that said, I have been able to view the instability and shear parameters on COD. NAM keeps 300-400m2/s2 of 0-3km SRH available through much of the day (up through 00Z THU), which is in combination with MLCAPE's of +2500j/kg. VV's are quite dramatic and likely the result of the model blowing up convection, which looks quite reasonable.

What I like about tomorrow is that there is a 700MB thermal axis (8-10C) which briefly pokes up into southern MI around 18Z, which will hopefully cap things off... As the shortwave moves in by 00Z, the 700MB thermal ridge flattens out with 6-8C temps moving in. This, in combination with the shortwave dynamics, wind field, and potential instability should lead to explosive severe thunderstorm development.

 

[rdale]

WBZ pretty high on GFS and flow fairly unidirectional across lower MI by 21Z, so not terribly concerned about rotaters but very happy we won't be dealing with an AM MCS.

 

[Jeremy Lemanski]

I do not like what i see as I wake up this morning. This is a ton of junk storms around right now, from michigan to iowa. With these storms showing no signs of weakening, they may prevent the heating needed for a big show this afternoon. Its only 8.15am, so i'm hoping everything is done by around noon to allow for some heating.

 

[Jason Hetzel]

The last of this morning's activity is currently moving east across SE MI in the form of a solid line and should continue east over the lakes. In wake of this activity regional 1Km satellite imagery shows the sun is shining already in SW MI and heating seems to be already taking place. This should continue for the next few hours and spread east into SE MI allowing the area to destabalize rapidly in wake of current activity. Still too early to tell exactly what the situation will be for later this afternoon, but it still looks pretty good for devestating winds and embedded supercells with the threat of isolated tornadoes continuing. CAPEs are still progged to be around 2500-3000J/Kg and should further heating commence then this will only get higher. Helicity in the 0-3Km range still looks nice over lower MI and with a 50-55Kt jet blasting through this afternoon it could easily get things going fairly quickly. Will have to watch and see how much clearing and heating can take place before any better idea of this afternoon's setup can be determined.

 

[Robert Dewey]

Well, looking at things upstream ... This convection really hasn't stifled instability all that much. SPC mesoanalysis already shows >2000j/kg of MLCAPE across northern IL. In southwestern MI, where some sunshine has occured, temps have soared to almost 80F as of the 9AM metar reports.

The 09Z RUC - which has a very good handle on this precipitation - still shows SBCAPE values in excess of 4500j/kg by 21Z across most of southern MI. The latest 12Z RUC (only out to 2 hours right now) shows this current precipitation diminishing as the nocturnal LLJ weakens, putting an end to the strong ascent. Latest VAD from MKX shows almost 55KNTS at 2.5-3K FT, which has been weakening ... So I have a feeling the area of precipitation over IL/WI will be falling apart over the next few hours.

Even with that being said, there will still be quite a bit of debris... But I think temps will still manage to make it to 80-85F.

 

[Jeremy Lemanski]

well, there are some breaks in the cloud cover across Western lower michigan and temps are in the 70s across that area, but low clouds and rain cover the rest of the state. I have a feeling the mod. risk might be shifted southward with the new outlook. It looks like northern indiana and Northern Ill. stand the best chance at widespread severe weather.

BTW, i'm more/less pinpointing my area of discussion central lower michigan, since i won't be able to chase far and need anything of interest to develop or more in to the thumb. Right now, my chances of seeing some severe weather are pretty slim IMO.

 

[rdale]

I don't see any reason to shift south - the warm front is now pushing into SW Mich with dew points to 70 in Coldwater. Most of the clouds from US23 west into WI/IL are thin so heating not an issue. Already seeing temps in the low-80s into SW MI as well.

All eyes on the Iowa stuff to see how it evolves, but I'm not changing my forecast which looks good for a nice squall line after 4p.

 

[Robert Dewey]

I'm not too worried. Temperatures are rebounding nicely, and the instability is already there. I'm waiting to see how that mess over in IA evolves, as that will likely be our action later today (at least here in MI).

NWS DTX states that if that system can organize and become dominated by the cold pool, it will likely reach forward speeds in excess of 60knts with widespread wind damage (aka significant derecho).

WILL HAVE TO CONTINUE TO MONITOR CONVECTIVE TRENDS TO SEE IF COLD POOL DOMINANCE OCCURS WITH THIS DEVELOPING MCS. IF SO...FORWARD PROPAGATING CORFIDI VECTORS STILL SUGGEST THAT FORWARD MOTION COULD EXCEED 60KTS. THEREFORE...STILL EXPECT THAT WIDESPREAD WIND DAMAGE WILL BE THE PRIMARY HAZARD WITH THIS ACTIVITY. PRIMARY TIMING FOR THE FORECAST AREA WILL BE IN THE 4-10PM TIME FRAME...DEPENDING ON HOW THE MCS
PROPAGATION BEARS OUT.[/b]