Hoosier Posted July 8, 2017 Share Posted July 8, 2017 As of now, we have a marginal risk area for Sunday and Monday. It's a pretty classic summer pattern that will feature a big reservoir of heat/high dewpoints with the potential for multiple disturbances (sometimes hard to pinpoint very well in advance) passing through the region, resulting in periodic MCS activity capable of severe weather and possibly flooding. Quite possible this pattern will still be around beyond the 14th, but running the thread through then for now. Link to comment Share on other sites More sharing options...
Hoosier Posted July 8, 2017 Author Share Posted July 8, 2017 Some signal that the boundary may try to shift north around midweek, so some areas that get missed to the south early on may have a better shot then. Subject to change of course. Link to comment Share on other sites More sharing options...
Paulie21 Posted July 8, 2017 Share Posted July 8, 2017 Surface low and boundary locations have been jumping around on recent model runs, however, looks like the type of environment looks to stay consistent on the 12km NAM. Moisture clearly not being an issue, and in turn big CAPE with healthy lapse rates in place. Sunday will probably be a semi-organized MCS type day, but Monday and now Tuesday definitely raise some eyebrows. Wind fields and storm motions in respect to boundary could be favorable for initial sups. A right mover would have plenty of streamwise vorticity to work with as well. Link to comment Share on other sites More sharing options...
Stebo Posted July 8, 2017 Share Posted July 8, 2017 1 hour ago, Hoosier said: Some signal that the boundary may try to shift north around midweek, so some areas that get missed to the south early on may have a better shot then. Subject to change of course. Interestingly enough the 4km NAM is further north with Monday's potential as well. Even the GFS is further north than the 12km NAM. I do know that you have to be cautious in these potentials as cold pools can modulate the progression of the warm front but if Sunday isn't impressive, things shift north from there. Link to comment Share on other sites More sharing options...
cyclone77 Posted July 8, 2017 Share Posted July 8, 2017 Looks like a potent MCS is in store for late tomorrow night into Monday morning from IA/WI down into parts of IL/IN. Globals are in pretty good agreement on that. Could be a pretty decent wind event given the mid-level support, and over 2000J/kg ML cape feeding into it from IA. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted July 8, 2017 Share Posted July 8, 2017 23 minutes ago, cyclone77 said: Looks like a potent MCS is in store for late tomorrow night into Monday morning from IA/WI down into parts of IL/IN. Globals are in pretty good agreement on that. Could be a pretty decent wind event given the mid-level support, and over 2000J/kg ML cape feeding into it from IA. There may be a pretty sharp sw edge of the rain around here. Link to comment Share on other sites More sharing options...
Jim Martin Posted July 8, 2017 Share Posted July 8, 2017 There is also the risk for Flash Flooding, especially across Northern Illinois, Northern Indiana, Northern Ohio, and far southern lower Michigan. Link to comment Share on other sites More sharing options...
Hoosier Posted July 9, 2017 Author Share Posted July 9, 2017 Tis the season for big boy CAPE Link to comment Share on other sites More sharing options...
Paulie21 Posted July 9, 2017 Share Posted July 9, 2017 Monday has a reminiscent look of June last year if anyone recalls, however, a lot less flow aloft this time around. Main shortwave initiates morning convection and quickly exits the area, leaving anemic flow at mid levels, however, rich moisture and healthy lapse rates will advect into N IL and IA by the evening. With mid to high 70 degree dew points pooling along the front and 3500-5000 J/kg of CAPE, I don't see recovery being an issue. Surface low and boundary placement has been a bit variable among the models but as of now, area of concern appears to stretch from E IA to N IL (trying not to ride the 00Z NAM too hard). LLJ @ ~40 kts will probably out-do the mid-levels on Monday which will probably only have 30 kts or so by initiation. Not much pressure falls to work with so not a large area of backed surface flow, but along the front or any outflow boundary that may occur from morning convection could serve as a focal point for greater low-level helicity. NAM has been hinting at initial discrete convection in a pretty impressive environment. Storm motion ESE to SE depending if we get a right mover (which could increase the amount of streamwise vorticity parallel to the storm relative inflow wind). Storm motion also nearly orthogonal to the 0-1km vorticity vector on forecast hodographs. Tuesday... Placement has been more consistent for this day among models than Monday actually, however, it has shifted closer to Illinois again (from Iowa (thank god)). Rather potent shortwave approaches from the west with better flow aloft in comparison to Monday. Bulk shear vectors (unlike 35 kts on Monday) look to be 40+kts along an area of 4000-5000 J/kg of CAPE. Values here aren't critical I suppose. Big CAPE, we get it, it's July...pretty common... Bunker's method says a right mover would move due east on Tuesday. The rest is pretty much same as Monday, plenty of helicity...both days have over 200 m2/s2 0-1km, large area of eff. inflow layer 400+ m2/s2, mid to high 70 dews. I'm wondering if a large column of northwesterly flow on Monday would cause rain to fall primarily into the storm motion, therefore in the inflow, causing storms to be more HP in nature, as opposed to westerly flow aloft on Tuesday. Guess we will find out. Using H7 UVV's to show possible initial discrete nature of convection on the NAM. Soundings taken from timeframe before initiation in that area. Link to comment Share on other sites More sharing options...
HillsdaleMIWeather Posted July 9, 2017 Share Posted July 9, 2017 1 hour ago, Paulie21 said: Monday has a reminiscent look of June last year if anyone recalls, however, a lot less flow aloft this time around. Main shortwave initiates morning convection and quickly exits the area, leaving anemic flow at mid levels, however, rich moisture and healthy lapse rates will advect into N IL and IA by the evening. With mid to high 70 degree dew points pooling along the front and 3500-5000 J/kg of CAPE, I don't see recovery being an issue. Surface low and boundary placement has been a bit variable among the models but as of now, area of concern appears to stretch from E IA to N IL (trying not to ride the 00Z NAM too hard). LLJ @ ~40 kts will probably out-do the mid-levels on Monday which will probably only have 30 kts or so by initiation. Not much pressure falls to work with so not a large area of backed surface flow, but along the front or any outflow boundary that may occur from morning convection could serve as a focal point for greater low-level helicity. NAM has been hinting at initial discrete convection in a pretty impressive environment. Storm motion ESE to SE depending if we get a right mover (which could increase the amount of streamwise vorticity parallel to the storm relative inflow wind). Storm motion also nearly orthogonal to the 0-1km vorticity vector on forecast hodographs. Tuesday... Placement has been more consistent for this day among models than Monday actually, however, it has shifted closer to Illinois again (from Iowa (thank god)). Rather potent shortwave approaches from the west with better flow aloft in comparison to Monday. Bulk shear vectors (unlike 35 kts on Monday) look to be 40+kts along an area of 4000-5000 J/kg of CAPE. Values here aren't critical I suppose. Big CAPE, we get it, it's July...pretty common... Bunker's method says a right mover would move due east on Tuesday. The rest is pretty much same as Monday, plenty of helicity...both days have over 200 m2/s2 0-1km, large area of eff. inflow layer 400+ m2/s2, mid to high 70 dews. I'm wondering if a large column of northwesterly flow on Monday would cause rain to fall primarily into the storm motion, therefore in the inflow, causing storms to be more HP in nature, as opposed to westerly flow aloft on Tuesday. Guess we will find out. Using H7 UVV's to show possible initial discrete nature of convection on the NAM. Soundings taken from timeframe before initiation in that area. Will say based on the models, the SPC outlook feels a little lax. Link to comment Share on other sites More sharing options...
cyclone77 Posted July 9, 2017 Share Posted July 9, 2017 SPC be like meh when it comes to 8000J/kg forecast soundings in the midst of 40kt shear and subtle NW flow shortwaves. Marginal oughta do it. The ongoing MCS on Monday morning should alone be enough to warrant at least a slight over parts of IA/IL/IN. I suspect the update at 1730z will have some major changes. Link to comment Share on other sites More sharing options...
hlcater Posted July 9, 2017 Share Posted July 9, 2017 2 minutes ago, cyclone77 said: SPC be like meh when it comes to 8000J/kg forecast soundings in the midst of 40kt shear and subtle NW flow shortwaves. Marginal oughta do it. The ongoing MCS on Monday morning should alone be enough to warrant at least a slight over parts of IA/IL/IN. I suspect the update at 1730z will have some major changes. Surprised as well, since Cohen doesn't normally tend to be super conservative on outlooks, expected a slight on the D2 outlook from him. Marginal just a tad undermining for MCS potential I would say. Link to comment Share on other sites More sharing options...
Hoosier Posted July 9, 2017 Author Share Posted July 9, 2017 Seems quite likely that this will be one of those stretches where the outlooks will be prone to ramping up, perhaps rather quickly. I could easily envision multiple ENH days and wouldn't even be shocked with a MDT at some point. Link to comment Share on other sites More sharing options...
Stebo Posted July 9, 2017 Share Posted July 9, 2017 46 minutes ago, Hoosier said: Seems quite likely that this will be one of those stretches where the outlooks will be prone to ramping up, perhaps rather quickly. I could easily envision multiple ENH days and wouldn't even be shocked with a MDT at some point. Agreed, though I do think Monday should be a SLGT at this point. All models have convection and big instability/decent shear over E IA/S WI/N IL. Link to comment Share on other sites More sharing options...
IllinoisWedges Posted July 9, 2017 Share Posted July 9, 2017 Day 4 outlook for NE IL, N IN, and all of S and C MI. Link to comment Share on other sites More sharing options...
cyclone77 Posted July 9, 2017 Share Posted July 9, 2017 HRRR looks to maintain the MCS all night long tonight, which would bring severe prospects well south of I-80. Showing over 2000J/kg ML and surface cape well ahead of the ongoing MCS at the end of the run (08z). Places as far south as Champaign and Lafayette IN may be at risk if HRRR is correct. Juicy 850 jet pointing at it as well. Wouldn't be surprised to see an enhanced area pop up from around MSP down into northeast IA/southwest WI. Could be some widespread wind reports in those areas later this evening. Link to comment Share on other sites More sharing options...
homedis Posted July 9, 2017 Share Posted July 9, 2017 New D1 Link to comment Share on other sites More sharing options...
Hoosier Posted July 9, 2017 Author Share Posted July 9, 2017 Trying not to get too excited yet for tomorrow until it's clear how tonight plays out, but talk about a powderkeg being progged for tomorrow in N IL/N IN etc. Link to comment Share on other sites More sharing options...
Stebo Posted July 9, 2017 Share Posted July 9, 2017 17 minutes ago, Hoosier said: Trying not to get too excited yet for tomorrow until it's clear how tonight plays out, but talk about a powderkeg being progged for tomorrow in N IL/N IN etc. Yeah, even extends into Southern MI and NW OH. Not to look too far ahead but Wednesday is catching my eye as well especially with the NAM/GFS. Link to comment Share on other sites More sharing options...
cyclone77 Posted July 9, 2017 Share Posted July 9, 2017 18 minutes ago, Hoosier said: Trying not to get too excited yet for tomorrow until it's clear how tonight plays out, but talk about a powderkeg being progged for tomorrow in N IL/N IN etc. HRRRx looks pretty nice for you later tomorrow. Initiation just to your north. This area looking more and more out of play for tomorrow after looking pretty good the last few days. Looks like initiation will take place south of I-80 in the DVN area. Late tonight will be our main show in the next 36hrs. Link to comment Share on other sites More sharing options...
Hoosier Posted July 9, 2017 Author Share Posted July 9, 2017 Slight risk for tomorrow. I would've thought a bit farther north than where they placed it though. Link to comment Share on other sites More sharing options...
hawkeye_wx Posted July 9, 2017 Share Posted July 9, 2017 1 hour ago, cyclone77 said: HRRRx looks pretty nice for you later tomorrow. Initiation just to your north. This area looking more and more out of play for tomorrow after looking pretty good the last few days. Looks like initiation will take place south of I-80 in the DVN area. Late tonight will be our main show in the next 36hrs. I still like my chances, but models continue to put Cedar Rapids right on the edge tonight. Between CR and Dubuque looks to be a hot spot, while heading sw from CR the action may drop off quickly. The HRRR drops the rainfall off to nothing just one county sw of CR. It does appear tonight may be the main show of the entire week for eastern Iowa. The next couple days' action may be well southeast or northeast of my area. Link to comment Share on other sites More sharing options...
cyclone77 Posted July 9, 2017 Share Posted July 9, 2017 39 minutes ago, hawkeye_wx said: I still like my chances, but models continue to put Cedar Rapids right on the edge tonight. Between CR and Dubuque looks to be a hot spot, while heading sw from CR the action may drop off quickly. The HRRR drops the rainfall off to nothing just one county sw of CR. It does appear tonight may be the main show of the entire week for eastern Iowa. The next couple days' action may be well southeast or northeast of my area. Yeah the multi-day potential has backed off a bit for our backyards. After tonight's late show we still have a decent shot for the Wednesday event though. Link to comment Share on other sites More sharing options...
OceanStWx Posted July 9, 2017 Share Posted July 9, 2017 12 hours ago, Stebo said: Agreed, though I do think Monday should be a SLGT at this point. All models have convection and big instability/decent shear over E IA/S WI/N IL. You know how it goes, more often than not they "wait and see" with nocturnal convection before getting too bullish on the next day. Link to comment Share on other sites More sharing options...
OceanStWx Posted July 9, 2017 Share Posted July 9, 2017 As for tonight, HRRR really favoring ARX to get the brunt of the MCS. Link to comment Share on other sites More sharing options...
Stebo Posted July 9, 2017 Share Posted July 9, 2017 34 minutes ago, OceanStWx said: You know how it goes, more often than not they "wait and see" with nocturnal convection before getting too bullish on the next day. Yeah which I do understand. Link to comment Share on other sites More sharing options...
OceanStWx Posted July 9, 2017 Share Posted July 9, 2017 3 minutes ago, Stebo said: Yeah which I do understand. Sometimes I do wish they would just cut to the chase though. Doesn't do me much good when I'm already 5 warnings in before the upgrade to slight comes. We certainly don't get the lapse rate killing MCSs that the Midwest does though. Those can really make a good forecast at t-12 hours look silly at t-6 hours. Link to comment Share on other sites More sharing options...
Hoosier Posted July 9, 2017 Author Share Posted July 9, 2017 DVN will be doing a special off-hour balloon launch at 05z. Not something you see very often, as far as that time of night. Link to comment Share on other sites More sharing options...
OceanStWx Posted July 9, 2017 Share Posted July 9, 2017 1 minute ago, Hoosier said: DVN will be doing a special off-hour balloon launch at 05z. Not something you see very often, as far as that time of night. That's not great, but not too terrible. I'm not sure who is and isn't certified there anymore, but you could hold the evening balloon shift over an extra couple of hours to launch (430z release time). Even staying to the end of the flight would probably get them in bed by 2 AM (unless a severe MCS is headed their way ) not having to be in until 2 PM that afternoon. Those near 06z launches get easier and easier the farther west you are. Link to comment Share on other sites More sharing options...
Chinook Posted July 9, 2017 Share Posted July 9, 2017 Likely severe thunderstorm watch for southern Minnesota. Thunderstorms may form sooner than I thought. Mesoscale discussion by the SPC --- SUMMARY...Thunderstorms are expected to develop by 22-23Z across central MN and possibly as far west as northeast south Dakota and rapidly become severe. Link to comment Share on other sites More sharing options...
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