RCNYILWX

I had 8.8" or 8.9" in the grids so that's a good line. Sent from my SM-G965U using Tapatalk

I think your location should be okay (maybe NW McHenry an exception to that) and you'd also be in the trajectory for lake enhancement tomorrow. Regarding that part of the AFD, it's something we noted on some of the CAMs that the heaviest sim ref seems to hit a wall and those 35-40 dbz echoes don't get all the way north. With it so close I wouldn't want to bank on that actually happening but it's an item to watch. Highest likelihood of being in that snow minima is out by Rockford, so Winnebago, Boone and Ogle. Western portion of Ogle and Lee look to have mixing issues through 5pm to as late as 7pm. Sent from my SM-G965U using Tapatalk

As a special storm day deal, until I go to bed later this morning, if anyone has any LOT CWA specific snow forecast questions, feel free to ask away and I'll do my best to answer. The overnight forecast that I put together in collab with WPC and surrounding offices attempted to toe the line between playing it slightly conservative vs what potential higher end outcome could be and giving an idea of the areas where we think have the best chance to end up in the 8-9" range or even higher. Those are the areas in the 8-12" range on our snow map. Note that even though the snow map range is 8-12" I think the highest point amount I have anywhere is a bit over 9". Enjoy the tracking today and I'll be up to enjoy the ++SN this evening! Sent from my SM-G965U using Tapatalk

You should be higher than that now in the updated storm total. Your area looks good. Sent from my SM-G965U using Tapatalk

Accounting for the above described feature we're bringing mixing into our west and southwest 1/4 to 1/3, which will eat into snow totals some there. East of wherever mixing makes it looks all systems go. 00z EPS 6+ probs actually beefed up for the LOT CWA. Sent from my SM-G965U using Tapatalk

I'd gladly be wrong on my calls on this one. So much time for this one but the changes we've seen on the operational run are good ones to end up with a snow event a few days after northern stream dominant frontal passage. Sent from my SM-G965U using Tapatalk

Noteworthy uptick in the mean QPF. Have been looking at 00z soundings from TX and vicinity and the moisture quality is legit. Also on mid level w/v can see our burgeoning synoptic system has a deep layer feed from the Pacific from southwest of the Baja. So we're getting Pacific and Gulf moisture involved. Sent from my SM-G965U using Tapatalk

We all look at the RGEM/RDPS on here but I don't think I've ever seen it referenced in a WPC model preference discussion. Sent from my SM-G965U using Tapatalk

I'll get a chance to look much more in depth when I get to the office in a couple hours. Initial reaction is that the NAM always seems to be like a windshield wiper for our area. Until we see model support for that depiction, I don't see putting a ton of stock in it at this time since as @Chicago Storm noted the PWATs were actually up on this run. WPC likes to lean on the ensemble means for QPF forecasting since those are usually more stable and they add in details from some of the high res stuff. Interested in seeing their thoughts when I get in. Sent from my SM-G965U using Tapatalk

I'll take what the 18z GFS runs are selling. Pass on snowpack nuking and hydro issues. Lots of time to go. Sent from my SM-G965U using Tapatalk

I'm back tonight with MTF so we'll both be diving into stuff. Can't say much about the slight drop in forecast totals since I recently woke up lol. I'll defer to those who have been closely following the data all day for now and probably chime in later when I've looked at more stuff. Sent from my SM-G965U using Tapatalk

It'll take some pretty wholesale changes to avoid rain in northern IL with this setup. I continue to hope that the operational ECMWF is too amped and to slow to swing the occluding cold front through. 00z Euro was slower than the ensemble mean and a good deal slower than the GFS's and the GEM. Sent from my SM-G965U using Tapatalk

This is one of the "under the hood" items I was mentioning, and I overlooked it last night. It's very easy to get caught up on model run QPF, but when you have this caliber of jet divergence, excellent moisture transport, top of the chart PWAT, and there's a disconnect with QPF, probably safe to side on the higher QPF guidance. With the pretty decent difference between the 12km and 3km NAM, I was wondering if the 12km's BMJ convective parameterization scheme could be messing with the output some and the 3km explicitly forecasting the embedded convective elements could do a better job in this case. Sent from my SM-G965U using Tapatalk

On that note, what are your thoughts on blowing/drifting potential? It's a good point about the actual air temperatures. The moisture content of the snow and overall density will be high but maybe it can still be blown around when temps are 28-30 instead of 31-33. Sent from my SM-G965U using Tapatalk

I didn't look closely specifically at your area, but for our far southern areas, without even looking at wet bulb, the 0C line just sneaking in there near southern Ford to me pointed toward evaporative and dynamic cooling doing a lot of work. The winds will be pulling from the departing high, so that'll help from an evaporative cooling sense and support for heavy precip maxes out dynamic cooling. Certainly uncomfortably close down there. Wish I could stay up to diagnose all the 12z guidance with everyone lol, but gotta get some sleep for another busy shift tonight. Sent from my SM-G965U using Tapatalk

When the convective allowing nested model seems to be handling things well in a pretty convective setup given such steep lapse rates, if anything can give it more weight than the parent model. Liquid equivalent QPF amounts on the NAM aren't too far off what the consensus has been, I guess we'll have to watch for an earlier weakening of the warm advection burst for far northern areas, but like@McHenrySnow said, that seems to be an outlier depiction in there. Not overly concerned with a slightly off looking run of the NAM. If both NAMs came in drier, would have been a bit more concerned. Another thing is with QPF so fickle, a look under the hood at the soundings and other aspects to support the heavy snow rates would help.

06z EPS expanded the areal coverage of 6"+ probs versus its previous 3 runs. Higher than normal confidence continues at this lead. Barring any last minute surprises, which seems unlikely, we'll be going with a warning this afternoon. While our far southern CWA could have ptype issue and less snow, think chances are decreasing that they don't get several hours of heavy snow with the intense warm advection burst. Regarding our snow forecast, felt pretty comfortable with it, even limited WPC QPF slightly 00z-06z in our grids and kept ratio mostly 7-9:1 range, with spots near 10:1. Unlike the last system, it does look like unimpeded Gulf trajectories and very strong moisture transport this time with extreme PWATs for a snow system. Sent from my SM-G965U using Tapatalk

Got the technical discussion out. We've been trying out a shorter initial AFD and then doubling back later. Sent from my SM-G965U using Tapatalk

The #1 CIPS analog tonight is March 8-9, 1999, which produced 9" at ORD. March 5, 2013 is #6 analog and GHDII is #11. Sent from my SM-G965U using Tapatalk

The last recent winter event for the CONUS that had this good agreement in the models at a longer lead time was the December 17th eastern big dog. And wouldn't you know the outlier model for that event was the operational GFS and it was dead wrong. The GFS v16 was right in line with the consensus that ended up being pretty spot on. Sent from my SM-G965U using Tapatalk

That's a good point. Even out by me the stuff on the ground really dried out. Sent from my SM-G965U using Tapatalk

We didn't verify blizzard conditions on Nov 25-26 2018 storm with much higher winds than this one has progged even taking the top end guidance (the NAMs). We'll probably work it into our messaging the potential for brief whiteout conditions out in open rural areas given the rates and wind, but don't think this will reach blizzard warning criteria. Sent from my SM-G965U using Tapatalk

In 10 years or so of posting here I've never been insulted by anyone. Criticism of the forecast comes with the territory; at times can it be slightly unfair? Yes. But other than that we're judged by the content we provide to help others learn and it's important to consider that as a red tagger. We don't get or deserve a pass for too many Banter type posts in a serious forecast discussion.

I can post the 18z Euro WeatherBell WeenieVision Kuchera map in Banter. Edit: In seriousness, I do see the possibility of higher ratios something along the lines of what the WxBell map shows for the whole area in a much narrower swath. You don't get that kind of support for heavy rates and big QPF in a short amount of time without having fgen driven mesoscale banding where everything aligns perfectly. In that swath could see ratios let's say in 12-14:1 range. I don't want to make definitive statements until I see everything in depth tonight.

Re. our (LOT) snow map, spoke to dayshift forecaster and he toned it down slightly for this issuance because it was a big increase from the midnight shift. Internally, WPC went bigger than the WFOs did. The forecaster (KJB) is one our best with winter weather and he wanted to trend instead of jump with today's issuance. I'm good with that approach. Sent from my SM-G965U using Tapatalk