6/18/10 FCST: WI

[Tim Balassie]

Looking at the GFS and WRF models this evening I am currently thinking about W WI tomorrow (18 June), assuming that enough CAPE can be generated by 0z.

Winds will be strong across all levels, with an interesting 850mb SW jet in place by 0z. Temps look OK, although 700mb looks a little high. CINH contours don’t seem to support that, however. Looks to be some low level turning with surface winds S to SSW.

Could be another interesting day if insolation can get going, CAPES can top 2500 j/kg and LI’s up to -10. Timing probably isn’t great, and the chase terrain leaves a lot to be desired. It would be nice to get the upper air dynamics further S, and the cold front/wind shift convergence axis pushed thru a little sooner than after 0z.

I guess I would look at starting in Eau Claire, but not sure the trip will be worth it given the above.

TMB

 

[J West]

I would not make any major decisions until it's clear what happens with the on-going convection tonight. Once an outflow boundary or two are laid down in the wee hours tomorrow morning, you can make a better decision on nailing down a target. The typical "Day 2" event for WI is never clear until the Day 1 convection is out of the state. As such, I don't even look at data until the day of, in the morning. Timing is everything with sunlight, cloud cover and boundaries.

That said, it looks like a Janesville-Tomah line is a safe place to start the day. If the area can recover, I will be making a play on it with a noon departure from the SE corner. If anyone is going to come up and play, please check the 511 link in my sig for current construction info.

 

[Colin Davis]

As of the 0z NAM, absolutely can't rule out IA. In fact, it looks like perhaps the better of the two targets, all things considered.

Now if only the other models would agree.

EDIT: Did I really just say I want the other models to agree to an Iowa target? Good god. Now, northeast Iowa near Dubuque or southern Iowa near Osceola? God this will be fun. Watch for me on SpotterNetwork...whichever one lures me, head to the other one.

 

[Tim Marquis]

The 12z GRB sounding is a bit disappointing but I'm thinking that it isn't entirely representative due to the MCS last night. I have a feeling an 18z release will probably be happening today and it should offer a better glimpse to what the set up is. My only concern for convection breaking out is the northern fringe of the MCS in Iowa interfering with day time heating. Other then that, if the RUC is right we could see CAPE values in the 2000-3500 range across central wisconsin. What I find interesting is in the new 12z SPC discussion, they seem to focus on wisconsin for the tornado threat, even go as far as mentioning strong tornadoes yet kept WI out of the moderate risk. I guess we didn't meet thresholds for moderate but with a 10% prob. for tornadoes, this may be upgraded in the 1730 outlook.

 

[Jason Fideler]

What I find interesting is in the new 12z SPC discussion, they seem to focus on wisconsin for the tornado threat, even go as far as mentioning strong tornadoes yet kept WI out of the moderate risk. I guess we didn't meet thresholds for moderate but with a 10% prob. for tornadoes, this may be upgraded in the 1730 outlook.

I was wondering the same thing. Don't understand it either. I'm definitely liking the 10% probability for tornadoes though. Sucks that that area is kind of hard to chase. Too many trees and so-on....

 

[Joe Zagrodnik]

It's been a slow year in Wisconsin, so it's about time that we got some action--and time for my first post (have been doing lots of reading this year). I will be driving from Madison to Milwaukee this evening, but I will detour to see any storms that might be in the vicinity.

Judging by the bright sunny skies outside, destabilization shouldn't be a problem today. Shear is a little weak, but still good for this time of year. This is peak Wisconsin tornado season, after all.

I do think the best target area is Central to North Central Wisconsin, where the shear is better and there is additional lift due to the right entrance region of the jet.

 

[Tim Balassie]

Took a look at the morning sounding data and surface obs. Seems to be a low in Canada and a low in NC KS, linked with a wind shift/convergence line within the trof axis. Well defined trof on upper level obs across the Dakotas. Greatest wind speeds appear to be across Nrn MN and WI.

Compared this to RUC model, and upper dynamics look to be confined to MN and WI. My initial thoughts seem to align with SPC, as they place a 10% tornado prob across C to NE WI. Thus I would stick to my initial target of Eau Claire for now.

However, I’m just not too keen on a C WI chase. I think the terrain is too difficult to get good views of the lower part of storms. WI chasers can correct me here, but for some areas near Eau Claire on I94 most of the terrain is wooded, with only pockets of broad views.

So I’ll turn my attention to areas where I think I can see storm structure – SW WI and NE IA. Wind fields are not progged to be impressive here, but certainly instability will be present. In addition, I have a growing affinity for strong 850mb jets, and there appears to be 40kt flow over SW WI by 0z which coincidentally, is where the RUC places bulls-eyes of 3 and 1km helicity, albeit modest

I guess then that I would target NE IA today, prepared to cross the River into SW WI if need be. It looks like late afternoon to early evening if I read the model right. I did have an interest in the KS low, but the RUC seems to wash it out over N MO by 0z. Plus wind fields are rather anemic.

TMB

 

[Andy Wehrle]

I'm looking to hedge northwest from my area, to the southern fringe of the 10% area. It looks like the cells on the northern end of the Iowa squall line may actually be becoming more discrete, and out ahead of the rest of the line.

Anyone PM me if you're interested in meeting up somewhere on the road.

 

[Tim Balassie]

My impression is that the squall line could mess things up in IA. The cold front/wind shift is still in E NE and W MN, based on my interpretation of surface charts. It looks from the satellite photo that convection is beginning along the front in NE NE. That MCS could leave clouds around to retard instability.

My hope is that the N pat of that line dies, skies clear, winds remain S with warm moist advection in preparation for the advancing cold front later today.

Am I off?

TMB
(KC9JIB)

 

[Dan Thompson]

The highway 29 corridor between Chippewa Falls and Wausau may be decent today, as it is south of the heavily forested areas of northern WI and nearer to the upper jet than southern WI.

 

[Tim Marquis]

This MCS complex in Iowa has become a huge problem. Seeing storms develop in NW Iowa in 50 dew points really puts a bleak chaser outlook on north central wisconsin. It continues to block moisture transport to the north. Most of the operational models had dew points in the 70s across central wisconsin still at 1730z there isn't even a 70 dew point in the state. With SW flow, the rain cooled air would help stabilize the air mass even further to the north. There is some potential in SW Wisconsin however. This first MCS will move out of the area and the caps 4km WRF which has handled this mornings convection the best redevelops in that area when the front comes through in the late afternoon evening.

 

[ericjkelly]

Tim,

The more I look the more I tend to agree with you...

Looking at the RUC....Helicity, Shear, and Cape look really good along the Wisconsin Iowa Border. That also should allow the crap to get through and some heating to take place...

I am sitting this one out at home in Indiana but I would aim for Cuba City, WI

 

[Jason Fideler]

Looks as though the outlook has moved a bit more to the east. I'm right in the middle of 10% tornado risk. I'm going to sit closer to home. Maybe to the Markesan area since it offers good chasing terain. The MCS moving through Iowa has unfortunately moved up the timing. Guess we'll see what happens.....

 

[John Vandehei]

However, I’m just not too keen on a C WI chase. I think the terrain is too difficult to get good views of the lower part of storms. WI chasers can correct me here, but for some areas near Eau Claire on I94 most of the terrain is wooded, with only pockets of broad views.

So I’ll turn my attention to areas where I think I can see storm structure – SW WI and NE IA.

Tim, as a former Madison resident, I think I should point out the topography of SW Wisconsin and NE Iowa. That area is called the driftless area. It's the area where the last glacier didn't reach. As such, it's very hilly. Yes, there are trees in central Wisconsin, but in SW Wisconsin, you get lots of hills and trees. If given the choice, I'd take central Wisconsin. Personally, I think a corridor from Beloit up to Madison and then up to Wausau would be OK. North of Wausau, it gets hilly and the woods thicken up. East central Wisconsin, around Oshkosh and Appleton isn't bad either.

 

[Jeff Duda]

Has anyone else noticed the nice boundary that has set up along the IA-MO border and into SE NE? Pretty good CAPE building there with good backed winds to the north. As long as it moves north and can get out of the way of the capping to the southwest and under the better 500 mb flow, things could kick there soon. I'm planning on heading out with a few chase partners towards SW IA here soon.