10-29-04 FCST: Midwest & Plains

[Robert Dewey]

Re: Any comments on the SWODY3?

Got mildly excited by the SWODY3 this morning, with all of WI in a slight risk, much of it within the 25% line (which if everything pans out as expected should turn into at least a MDT risk by Day 1). However I've seen the SWODY3 bust so many times that I no longer put a whole lot of stock in it. I'm not much for interpreting forecast models yet so does anyone have any comments? On the money? Way off? Or is Day 3 just too far off to tell and everybody (including SPC) might as well not even try?

While one can certainly look at the synoptic setup and say it's favorable for severe weather across the Midwest/Great Lakes, it would be hard to focus in on any specific area this far out... But, looking at the latest 12Z ETA coming in, I would say that the WI/IL/Eastern IA look good for FRI, but that will probably change, and it's too far to get any more specific than that...

 

[David Draun]

The area of WI/IL and eastern IA is in an area where with the right amount of insolation, the high temperatures may break the 80 degree mark in the warm sector. Wtih dewpoints in the 60's and maybe even 70's this far north, this late in the season, you'd have to feel pretty good about a sevwx chance on Friday. That is if the morning convection dissipates and doesn't leave debris clouds all over. Just hope the cap inversion isn't too strong.

 

[Andrew Pritchard]

Im big on the eastern half of iowa, nw Illinois, and southern and western Wisconsin. Temps should reach near 80 in the warm sector...with dp's in the upper 60s. On the Day 3...yes, there is a 25%...but lets also remember, that the 22nd was also a 25% on the day 3...and not a thing happened. However, I think this day does also have a lot more potential that the 22nd did. I dont see very many problems with previous period convection or anything. Most of the precip and cloud cover should remain north of the warm front, over Minnesota, and northern Wisconsin.

 

[Andy Wehrle]

Andrew Pritchard wrote:
but let's also remember, that the 22nd was also a 25% on the day 3...and not a thing happened.
That's why I said I've seen the SWODY3 bust too many times to put much stock in it.
It'd be nice if the front would make it north of GRB and put us in the warm sector. GRB is forecasting a high of 65 on Friday with mostly cloudy skies and a south wind. Hmmm...

 

[Glen Romine]

I would make a considerable adjustment to the forecast temps in the warm sector of this storm The ETA has consistently over-forecast the temps - I'd shave at least 5-10 degrees off of the forecast highs. Unfortunately, that doesn't leave much instability even if the dews were to verify. GFS temps look much more reasonable - as does the forecast instability - which is pretty bleak, and would then preclude widespread severe weather. However, a few breaks in the cloud cover are likely to occur in some places - and that should allow for a few small regions where conditions could be favorable given the current model forecast guidance. Of course, these will be tough to identify prior to the day of the event. I'd also make a westward jog in the forecast positions of the front - the 00Z prog is after dark now - and is probably too far east to boot.

The upper level system is making landfall in So. Cal. today, so tonight's model runs should start to have a better handle on the forecast (still large differences between the ETA and GFS forecasts).

Glen

 

[Robert Dewey]

Yeah, and taking a full look at model data, convergence along the front doesn't look all that strong, so it's looking like a weaker forcing event, which would require more instability - I'm gonna go with Glen on this one...

Still time for things to change, but at this point, it looks like a SLGT risk day...

 

[Andrew Pritchard]

Well, I just learned I cant chase on Friday anyways. It looks ok, but either way, it doesnt really look good enough to make a long drive to. Our best bet for now is to just save our time and energy for spring.

Yeah, there is quite a bit of a discrepancy between the eta and gfs. ETA being the more optomistic of the two, which had been showing CAPE upwards of 1500-2000 in the warm sector across Iowa, however the gfs speeds it up and cuts the CAPE about in half, also placing the highest areas over central Illinois. But like I said, I wont be chasing unless something comes very close to Champaign. Maybe keep an eye on next weeks system...but even with that, darkness comes around 530 PM starting next week. March is only 4 months away...

 

[Joel Wright]

I'm sitting here along the Mississippi River in nothtwest Illinois, right where they're saying everything will happen. So that makes me believe the forcast will change by then. :wink:

I do think there will be less cloudiness this time around so maybe we'll have a better chance to get some good surface based convection going along the front somewhere. I think the best chance for tornadoes though would be north closer to the warmfront in Minnesota and Wisconsin.

 

[Joel Wright]

This event will be leading a MUCH more significant event early next week, at least on the models.

A bit off topic but that storm is currently forecasted to be a bomb. 974mb just north of Michigan by Tuesday morning. I look for that to migrate further west in future runs. We're getting into Witch of November season now, where these huge low pressure bombs can develop....

 

[Robert Dewey]

This event will be leading a MUCH more significant event early next week, at least on the models.

A bit off topic but that storm is currently forecasted to be a bomb. 974mb just north of Michigan by Tuesday morning. I look for that to migrate further west in future runs. We're getting into Witch of November season now, where these huge low pressure bombs can develop....

Started a forum for that topic just now: http://www.stormtrack.org/forum/viewtopic.php?t=3998

If you could please delete your post and put it in there instead...

Thanks

 

[Dan Cook]

http://www.wxcaster2.com/CENTRAL_ETA_SVR_C...HSWEAT_42HR.gif

http://www.wxcaster.com/modelskewt.php3?mo...&STATIONID=kmqb

looking decent. Supercell potential's 90, shear 52kts. HWO and AFD from Davenport's not mentioning anything other than rain, possible thunderstorms, however; so we'll see what goes.

 

[David Draun]

http://www.wxcaster.com/modelskewt.php3?mo...STATIONID=_KLOT

Yeah! Chicago looks good too. Supercell potential is 87.8. 47kts of directional shear. We should definitely get something. Enough sunlight and the high will shoot into the 80's easily. If these ETA models verify, I would not be surprised to see a MDT risk forecast on Friday morning.

But, mostly cloudy skies are expected, we'll see. Try to keep the hype down.

 

[Scott Olson]

Eta showing cape upwards of 3k around 18z. Even by 00z still showing about 2800k from SE Iowa into Central Illinois and a rather large area of at least moderate instability. The ensemble seems to favor a southern WI down through Illinois and SE Iowa/N MO for tornadic activity, keeping in mind there is a rather large dry slot in Iowa. Still skeptical of instability with amount of low level RH. But even with less heating this seems like a decent setup.

 

[Glen Romine]

Forecast from the ETA model showing that shortwave rounding base of trough after 00Z - and convergence along the front is fairly weak, so it may be tough to initiate storms during the day. Shear vector orientation relative to the pacific front would support rapid transition to a slow moving squall line, so only apparent area of interest might be along the warm front, which is forecast to reach northern WI by 00Z by the ETA, and even further north by the GFS.

Glen

 

[Andy Wehrle]

NWS in GRB has raised the forecast high temps for FRI from 65 yesterday to 70 today. I'm likin' that, however they also mention almost continuous rain and extensive cloud cover which makes me wonder how they expect that to verify. Their AFD also makes no mention of SVR WX despite the SPC now including most of their CWA in a 25% line including (now) the Green Bay metro area.