mimillman Posted January 23, 2021 Share Posted January 23, 2021 Man Iowa. What a winter there 1 1 Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 23, 2021 Author Share Posted January 23, 2021 Yea I guess the question is, do you believe that solution. I know the NAM is not alone It’s definitely a believable scenario.However, I would be cautioned regarding it until the 0z runs tonight. Currently the wave that leads to the increased confluence is well north in Canada, across the Northwest Territories and Nunavut. There is some sampling that occurs up there, but it’s sparse. For the 0z runs tonight the wave will have pushed south into Saskatchewan and Manitoba, which has a bit more RAOB coverage.. 3 1 Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 23, 2021 Author Share Posted January 23, 2021 No matter the solution, hopefully ORD has corrected their recent track record of 2-inches-lower-than-measured-a-block-away snowfall measurement issues.Measuring will be in good hands for this event.. 2 Link to comment Share on other sites More sharing options...
mimillman Posted January 23, 2021 Share Posted January 23, 2021 Wild to me that Chicago’s last 6”+ snowstorm was November 2018, and that at ORD. For the Loop, last 6” storm I can remember was Feb 2018. Has been a horrendous stretch and it is finally coming to an end. 1 Link to comment Share on other sites More sharing options...
SchaumburgStormer Posted January 23, 2021 Share Posted January 23, 2021 9 minutes ago, michsnowfreak said: Event after event, whether it's small or large, it just boggles my mind how often we weenies look at storms that show up on the long range models and even when a threat is legit, until zero hour there are ridiculous swings. Look at that intense snow squall in Chicago the other night, a few days prior to that you thought maybe they would pick up a snow shower at best. Look at our East Side 3 to 4" snowfall on christmas. The news was literally telling people Christmas Eve morning we might see a few flurries but nothing to whiten the ground. Or the surprise downstate IL event where 1-2 was predicted and areas got smoked with 10” 2 Link to comment Share on other sites More sharing options...
purduewx80 Posted January 23, 2021 Share Posted January 23, 2021 What's also interesting about the synoptic light snows into Tuesday, is that we have steady cold air advection in the lowest 3KM or so with a lengthening fetch over the Lake. This 12Z RGEM sounding for Tuesday afternoon would result in a much deeper DGZ, high-ratio snow and the potential for significant additional accumulations. Most other guidance isn't quite as cold though. 1 Link to comment Share on other sites More sharing options...
ILSNOW Posted January 23, 2021 Share Posted January 23, 2021 Even the ICON is coming on board 1 Link to comment Share on other sites More sharing options...
purduewx80 Posted January 23, 2021 Share Posted January 23, 2021 2 hours ago, TheRegionRat said: Where is the energy for the storm, and has it been sampled? The LOT AFD says it's coming ashore this morning. Fully sampled for the 12Zmodel suite? The overnight AFD didn't say that. It's definitely still offshore. The system tomorrow is already well inland now. AFD for reference, it's a doozy: Quote Sunday night through Friday... We continue to focus in on the Sunday night-Tuesday morning timeframe (and moreso specifically Monday afternoon/night therein) for the potential for an impactful winter storm across a large swath of the forecast area. We`ll continue to note that while deterministic and ensemble guidance alike continues to trend towards a general similar solution, the parent wave packet is still just now dropping southward off the central California coast and has some 2,000 miles to traverse before reaching our longitude later Monday afternoon and evening. Thus, while the ensemble envelopes are gradually narrowing, we`d be remiss if we didn`t address the lingering large degree of uncertainty, especially considering somewhat marginal thermal profiles with a likely degree of mixing taking place somewhere in the CWA (near and south of I-80). In addition, we at least have to entertain the idea of dry slot issues impacting parts of the area given the latest 700 mb low track across central/north-central Illinois. Before we get to the "main event," do want to quickly address a low (yet nonzero) potential for freezing drizzle Sunday evening/overnight within the forecast area. Global guidance has held onto a pretty steady signature during this period, squeezing out some very light precipitation amounts (<0.02") in a corridor that`s waffled between I-88 and I-80 and just south. This seems to be in response to a combination of increasing upper jet divergence, and incoming sheared lead shortwave out of the Rockies, and an attendant tightening of the low-level baroclinic zone. Our first wave (addressed in the short term discussion) will have likely scoured out a good deal of our mid and upper-level moisture, leaving behind profiles that are just marginally- supportive of ice nucleation. Depending on the depth of the mid- level dry air, could be a bit of a seeder-feeder type mechanism to drive more in the way of light snow, but the latest look of forecast soundings is one more of drizzle at this time. As a result, we`ve added in some slight chance wording for freezing drizzle, mixed perhaps with a little light snow. This is still somewhat of a conditional threat, but subtle/modest isentropic upglide is noted within a fully-saturated 10,000 foot lower tropospheric column that will likely be below freezing. Evening model guidance continues to slightly delay the onset of stronger forcing for ascent associated with the main vort max, with the main region of warm-advection/DCVA looking to spread into the region as early as late Monday morning, but more likely now more fully into Monday afternoon and evening. Deterministic GFS has trended notably farther northwest, and seems to now, along with its ensemble counterpart, be on the northwestern periphery of the guidance suite. ECMWF and EPS, while also trending perhaps a smidge northwest, has maintained a remarkable degree of run-to- run consistency, with the rest of the global suite seemingly aligning towards it with time. Categorical PoPs are warranted at this time, and have also smeared PoP chances well into Tuesday as deformation area precipitation now looks to hold on through the day. With the slightly farther northwest movement, mixing with freezing rain and possibly some sleet is becoming a bit more likely as far north as the I-80 corridor Monday afternoon and evening before the thermal profiles cool with the passage of the low to our south. Bourgouin based layer energy grids don`t seem to support an overly high potential for sleet given a lack of deeper near-surface cold air for refreezing, with mainly a snow/freezing rain ptype forecast although could certainly see some sleet working its way into the picture. With the close approach of the 700 mb low, there is some concern that the system`s dryslot may start to come into play, especially south of I-80 Monday afternoon and evening, which would start to toss more drizzle/rain into the equation as well. For now, given the uncertainties here, we won`t be slicing the onion that thin at this point, but something to be aware of. We are showing some ice accumulations nudging up towards 0.10"-- locally a bit higher--but the assumption is that the dearth of more persistent CAA and colder surface temperatures will help temper icing impacts south of I-80. As the system passes to our south and east through Monday evening and overnight, winds will turn more northerly and the column should cool sufficiently to turn most--if not all--of our area over to snow within the deformation axis. This would likely be the period of highest impacts given the potential for fairly high snowfall rates under the core of the 500 mb upper low. Light snow looks to continue through Tuesday morning and may now extend through the afternoon hours, with a transition to some marginal lake effect as precipitation comes to an end. Regarding potential snow-to-liquid ratios: storm track climatology (Southern Plains/Panhandle low) and lack of a colder antecedent airmass (warmed up by preceding disturbances) likely spell an overall lower-than-normal (wetter/heavier) snow when the event is taken as a whole. A somewhat mismatched ascent profile, maximized just above the dendritic growth zone, combined with a fairly deep layer in the 0 to -5 C range atop surface temperatures only around 30 portend sub 10:1 ratios to start Monday afternoon, dryslot issues notwithstanding. Through Monday evening/overnight, guidance suggests we should start to volley sufficient ascent through the DGZ to nudge ratios upwards within the deformation zone. Eyeballing a rough 8-11:1 type ratio with our first stab at amounts here, which overall aligns well with SPC SREF max saturated temperature and Cobb ratio output. We`ve noted tonight that the deterministic ECMWF and GFS are right towards the top end of their corresponding ensemble counterparts regarding QPF amounts. For the first pass at amounts, in coordination with surrounding offices and WPC, elected to maintain more of an ensemble-based flavor to things, which results in a swath of amounts near 5-6" through the heart of our CWA. These amounts will more than likely undergo some re-working with subsequent forecast updates, however, as confidence in storm evolution grows. Do think there is a decent potential for some 8" amounts somewhere in the CWA with this system, with some potential for lake enhancement (although marginal) as well, but it`s still too soon to bite off on totals this high. Finally, strong and gusty northeasterly winds, gusting at times towards 30 to perhaps 40 mph, will likely build wave action into the northeast Illinois and possibly northwest Indiana shore. While lake levels have diminished from last year, still-elevated levels, combined with wave heights building towards 10 ft suggest a decent threat for at least minor lakeshore flooding Monday night into Tuesday. We`ll get into a brief reprieve Tuesday night into Wednesday morning as ephemeral shortwave ridging builds in overhead. Another rather potent, fast-moving disturbance continues to be well-advertised in the extended guidance. Very cold temperatures aloft and steep lapse rates support some threat for some bursts of heavier snowfall with this system, although what appears to be a short residence time and moisture-starved nature should help hold additional snow totals down. Guidance additionally remains split on this feature`s track, so broad-brushed chance PoPs continue to be the way to go at this juncture. Carlaw 1 Link to comment Share on other sites More sharing options...
Sciascia Posted January 23, 2021 Share Posted January 23, 2021 Low looks a few hairs NW on 12z GFS compared to 6z Link to comment Share on other sites More sharing options...
Winter Man Posted January 23, 2021 Share Posted January 23, 2021 21 minutes ago, mimillman said: Wild to me that Chicago’s last 6”+ snowstorm was November 2018, and that at ORD. For the Loop, last 6” storm I can remember was Feb 2018. Has been a horrendous stretch and it is finally coming to an end. It's been longer than that for me personally because of college. https://www.weather.gov/lot/21Nov2015snowfall Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 23, 2021 Author Share Posted January 23, 2021 12z GFS a bit south. Link to comment Share on other sites More sharing options...
mimillman Posted January 23, 2021 Share Posted January 23, 2021 1 minute ago, Chicago Storm said: 12z GFS a bit south, but just about noise level. . It’s beautiful. Any further north than 6z was getting cringeworthy for the metro Link to comment Share on other sites More sharing options...
mimillman Posted January 23, 2021 Share Posted January 23, 2021 Lake showers still going in NE Illinois Link to comment Share on other sites More sharing options...
Sciascia Posted January 23, 2021 Share Posted January 23, 2021 Snow numbers around Chicago & lakeside just keep slowing ticking upward as the run goes on Link to comment Share on other sites More sharing options...
hawkeye_wx Posted January 23, 2021 Share Posted January 23, 2021 GFSv16 Link to comment Share on other sites More sharing options...
ChiTownSnow Posted January 23, 2021 Share Posted January 23, 2021 9 minutes ago, hawkeye_wx said: GFSv16 Rockford would cash in again on that run When would we expected watches to go up? Link to comment Share on other sites More sharing options...
mimillman Posted January 23, 2021 Share Posted January 23, 2021 GEFS similar trend, slightly further south and weaker. Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 23, 2021 Author Share Posted January 23, 2021 12z GEM bumped north, to the current consensus. . Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 23, 2021 Author Share Posted January 23, 2021 GEM has 30” in parts of IA.. 1 Link to comment Share on other sites More sharing options...
Cary67 Posted January 23, 2021 Share Posted January 23, 2021 11 minutes ago, ChiTownSnow said: Rockford would cash in again on that run When would we expected watches to go up? Rfd doing well this year with respect to being a bit further east. Most years the Lake influence pushes ORD past RFD later in the winter for season totals Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 23, 2021 Author Share Posted January 23, 2021 12z GEM Link to comment Share on other sites More sharing options...
ChiTownSnow Posted January 23, 2021 Share Posted January 23, 2021 All models seem to be In relative agreement now? With track at least? Link to comment Share on other sites More sharing options...
mimillman Posted January 23, 2021 Share Posted January 23, 2021 Should start seeing the watches hoisted with evening AFDs. Going to need blizzard warnings in Iowa 1 Link to comment Share on other sites More sharing options...
Cary67 Posted January 23, 2021 Share Posted January 23, 2021 7 minutes ago, mimillman said: Should start seeing the watches hoisted with evening AFDs. Going to need blizzard warnings in Iowa Would LOT need to issue watches before tomorrow evening? Another 24hrs to see if short range models agree? Link to comment Share on other sites More sharing options...
Sciascia Posted January 23, 2021 Share Posted January 23, 2021 I start work in 10 minutes. Not sure when I’ll be able to check in again, but please don’t get to a part 3 without me. 1 Link to comment Share on other sites More sharing options...
RogueWaves Posted January 23, 2021 Share Posted January 23, 2021 2 hours ago, dmc76 said: 3-6” for SEMI. Traditional 5-9 incher incoming. 1 Link to comment Share on other sites More sharing options...
RCNYILWX Posted January 23, 2021 Share Posted January 23, 2021 Would LOT need to issue watches before tomorrow evening? Another 24hrs to see if short range models agree?I could see waiting until tomorrow morning for the watch.Sent from my SM-G965U using Tapatalk 1 Link to comment Share on other sites More sharing options...
hawkeye_wx Posted January 23, 2021 Share Posted January 23, 2021 UK is a bit south and more progressive. Link to comment Share on other sites More sharing options...
mimillman Posted January 23, 2021 Share Posted January 23, 2021 4 minutes ago, RCNYILWX said: I could see waiting until tomorrow morning for the watch. Sent from my SM-G965U using Tapatalk Interesting. I’d have thought there’s enough consensus now you can be reasonably confident issuing a watch. Link to comment Share on other sites More sharing options...
RCNYILWX Posted January 23, 2021 Share Posted January 23, 2021 Interesting. I’d have thought there’s enough consensus now you can be reasonably confident issuing a watch.I could go either way, there's enough supporting evidence to issue today but sometimes it's not the worst to wait. My guess is DVN issues today. So it would be up to our forecasters whether to hoist a watch too because MKX would have too much uncertainty. Link to comment Share on other sites More sharing options...
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