RCNYILWX

A zone of significant icing and sleet to its north certainly plausible in this setup, and severe weather in the warm sector. The sharp baroclinic zone and juiced air mass would still be in play with a weaker system, so given the 1035-1040 mb high pressure sandwiched to the north and northeast, that would bring the freezing rain and sleet zones farther south. As it stands, the 12z ECMWF verbatim showing ice storm criteria ice amounts (including with FRAM estimate) and 1-2" of sleet north of I-88 and into southern Wisconsin even with a fairly deep surface low is a red flag for what could happen with a slightly weaker and farther south low pressure track.

Snowing at ORD and MDW now due to low level lake effect, despite being under the dry slot at the moment. Can best see the echoes streaming in on the terminal dopplers. Edit: Joe/Chicago Storm beat me to it

The HRRR stays deeply saturated enough (-10C or colder) for longer, through about 18 or 19z that would hold onto poorer quality snow. But mid-late afternoon, the cloud temps warm up and then have to wait until toward 00z and beyond to flip back to low quality snow. It's a very tough forecast. Sent from my SM-G998U using Tapatalk

The most recent guidance brings a pronounced dry slot centered around 500 mb pretty far north. If you're in the Chicago area and were excited by the 18z NAM kuchera algorithm output, it's definitely overdone based off what's shown on the forecast soundings. There's still uncertainty with how much of the warm conveyor belt (warm advection) precip gets up into northern IL tomorrow morning, with the NCEP guidance more bullish on that note. After that, the models are in good agreement in loss of cloud ice due to the dry slot and this possibly even causing ptype issues up near the WI border (I'm leaning toward there being just enough saturation to stay as a poor quality snow up there). For much of the Chicago metro and points south, some of the guidance brings the warm nose in, and some is colder, but it's kind of immaterial with the cloud temps around -6C. I'd think we'd still have sleet with the low level wedging and steep lapse rates possibly yielding a convective effect driven flip to sleet at times. However, if the WCB precip misses us, concerned that most of the precip tomorrow is a liquid and some sleet mix, with rain/drizzle vs freezing rain/FZDZ dependent upon surface temps. Eventually, the cloud temps cool off to the -10 to -13C range late afternoon and onward, which would shift ptype to mainly low quality snow through Thursday evening. Lake enhancement prospects also seem likely to be affected by the dry air issues aloft. The snow amounts, even in the WSW within LOT CWA, might be overdone due to the mid-level dry air issues. Roads are probably still gonna be shitty for the Thursday PM commute though.

I'm here this evening - not sure if we'll be able to make any changes this shift, but wouldn't be surprised if there's an expansion by the midnight shift. Sent from my SM-G998U using Tapatalk

They didn't have to issue a warning this morning. Could have waited to make the call on the day shift today. My observation is that they as an office feel like they have to make decisions earlier than they need to and sometimes unnecessarily lock themselves into these situations. Hopefully it works out. Sent from my SM-G998U using Tapatalk

You're better than that.

I buy decent sleet accums on the north end of the warm nose aloft. Good signal for a low level cold wedge and the incoming air mass with this system is legit wintry. The exact location of the heavy snow band remains a challenge because the differences are being driven by variance in the fgen circulation response. Sent from my SM-G998U using Tapatalk

The benchmark for a February torch until it's surpassed is February 2017. 6 days in a row of highs from the mid 60s to around 70 at ORD on 2/17-2/22 and then 2/23 hit 59.

2012-13 is another analog to the current season in terms of low snow to this point. That season ended up with an AN Feb and March to salvage merely slightly below normal for the season at ORD. It also had near misses to prevent an AN seasonal total, and far northern IL did finish above to well above normal. If we don't get a solid event or two the rest of this month, having to rely on March to escape 2011-12 like futility will be a taller order, but not unheard of. 2001-02 is another somewhat recent example that had just under 20" going into March, but had 11.2" in March to finish slightly below normal on the season (I consider ~30" slightly below normal given the year to year volatility of snowfall). Ultimately, ORD often finds a way to get to 30"+, though this season does look to be a challenge to do so.

That Euro run is basically textbook on how it can work and is the probable best case scenario. Mild antecedent air mass and a ~980 mb low taking a favorable track for us are a precarious position to be in. I buy the signal at this point (997 mb low over IND on the EPS mean) that there's more likely than not to be a follow up system to the Tuesday rainer and it's probably our only chance until the last week of February. Sent from my SM-G998U using Tapatalk

Beavis is next level lol. Would probably find a way to complain if he lived in the mountains in Utah where one of the ski resorts has had almost 500" this winter already. Sent from my SM-G998U using Tapatalk

The CFS stuff on their crappy in house site never looks like the output on WxBell and Tropical Tidbits. Progression on that output looks pretty similar to the other ensemble data. Not sure why there's such a large discrepancy. Might be worth emailing CPC. I will say that I personally rarely go to the CPC page for the CFSv2, and don't really look at it much even on the other sites.

Looking at the upcoming pattern, given the MJO influence likely playing a role in flexing the SE ridge, certainly not a cold look and some outright torch days will be in play. That said, the fact that there will be cold air into Canada, northern Plains, northern Lakes, means it's not a pattern not necessarily devoid of snow threats farther south (still would be better farther west you go given the southeast ridge). While the favored corridor overall should be similar to what we've seen this winter, shorter wavelengths this time of year with an already active wave train is how it can work. There have been some operational runs showing this, with a lead warmer cutter and then follow up wave interacting with a temporarily shunted baroclinic zone post fro-pa. It's thread the needle amidst more wet than white threats, but not zero (though pessimism is not unreasonable). After the mild and wet southeast ridge regime, still looking at a possible transition to a better pattern beyond mid month with positive height anomalies in the western part of the EPO domain and potentially -WPO as well forcing the TPV a bit farther south. This may be related to MJO wave propagation and stratospheric evolution. In the last few runs, the EPS has been a bit quicker to go into a colder look, so certainly not a lock yet. Sent from my SM-G998U using Tapatalk

The zonal winds becoming negative are indicative of a SSW, though tropospheric coupling and/or the split or displacement causing effects like 2018 (2013 another somewhat recent example) are far from a given. My post was a little tongue in cheek because of our luck in springs being the one thing we're good at ruining haha.

This is not what you want to see if you want a warm March-April. Sent from my SM-G998U using Tapatalk

The outcome of that run was actually a pretty sizable shift south in the (more meh) snow swath, though to your point, another example of a system with a decent track and much less cold air to work with for the time of year than there typically would be. It's going to be another thread the needle situation where it can work out in a narrow swath if the system is deep enough. Sent from my SM-G998U using Tapatalk

I look at that snow season as one that wasn't far off from a big total at ORD (ended up just slightly below the current normal). Had the big February stretch, but didn't get into the max swath in any of the events in that stretch. Also had several near misses, including the December clippers that favored WI to lower MI, a whiff west and south with the big late March event, and a miss north with the April blizzard. Sent from my SM-G998U using Tapatalk

By February, the pattern finally resembled a more classic La Niña look with amplifying southeastern ridging. It was decidedly un Niña-like most of the time prior to that. I believe the SSW and subsequent blocking disrupted what might have been a mild and active spring. The SPV has had times of being strong this winter, but lack of NAO and AO blocking hasn't been the main driver of the warmth since January. I wouldn't rule out stratospheric effects causing issues in March-April this year because January was warm. This December had a period of pretty strong NAO blocking. 2011-2012 isn't a good analog either because it had a huge PV lobe parked on top of Alaska November onward. Sent from my SM-G998U using Tapatalk

Out here, we had by far our snowiest month of that winter in February and a record tying 9 days in a row of measurable snow. The 2nd half of the month was mild and wet (with a big river flooding event in Indiana and east central IL), but finished exactly normal at ORD following the cold and snowy start. Biggest factor in the cold March-April 2018 was a poorly timed SSW event in the latter part of February that set up an extended period of deep -NAO blocking. April was particularly brutal because it was essentially another month of winter when almost everyone but beavis are craving warmer temps by then. If you want something to ruin spring, a prolonged late season blocking episode is one of the common ways to do it. Sent from my SM-G998U using Tapatalk

Haha thanks! It's been cold but otherwise very quiet out here this week, so I have been lurking on this thread. January 2021 definitely ended up being a good snow month in Chicago after a quiet start that ended up kicking off an even bigger month for the city. And I know you were on the thread for the pre-Christmas storm. Re. Boston data, I completely understand frustration if it's not addressed. Only speaking for our two primary climate sites, unfortunately there's less we can do than we'd like at times. We can guess a persistent bias is sensor related, change in built environment (ie. new runways at airports, interstates built nearby and relatively near the sensor, etc) related, or a combination of factors. As one example, I firmly believe Chicago-O'Hare having the city's (entire PoR) warmest summer on record in 2020 was mostly if not entirely related to new highways being built near the west side of the airport. We couldn't do anything to fix that. That construction wound down and the warm bias seemed to ease, though overall more urbanization around ORD has contributed to it being warmer than it was back in the 80s and 90s (on top of background warming). For another example, Midway Airport was running persistently a degree or two warm for a good chunk of 2022, especially with highs. MDW isn't the official climate site but being an important city ob site with a long period of record and relatively close to the office, the ETs get out there often. They checked the sensor and it cleared calibration multiple times. But they ended up finally replacing the temp sensor (think it was part of a larger issue and not bc we/the forecasters asked) and sure enough, the warm bias went away immediately. I'm not saying BOS couldn't have been fixed sooner and it's likely that the issue was well known with the ops staff. However, sometimes it's not as simple or easy as doing what our hardcore weather enthusiast selves (as many of my coworkers are) would fix immediately, and it probably wasn't ignored. Those who can better speak to the issue can correct me if there's already information on this, but if I were to guess, the issue, if it was sensor related, was known and checked multiple times and the ETs kept checking calibration and it passed. I'm not sure if our Observational Program Leader and even the MIC have the authority to order the ESA (in charge of the el techs) to order the ETs to replace a temperature sensor if it passes their calibration checks, even if we tell them we think the sensor is still off. It's possible that something similar to our recent situation with the MDW temperature sensor played out at Boston. Sent from my SM-G998U using Tapatalk

I work at NWS Chicago (originally from Queens in NYC). Don't want to speak for anyone from NWS BTV and [mention=44]OceanStWx[/mention] can comment but wanted to mention our usual protocol. Also for us, we are much more rigid in making sure the data is as good as possible for our 2 primary climate sites (Chicago-O'Hare and Rockford, IL) vs. the non primary climate ASOS sites in our area. Re. the MPV error, for that noticeable and sudden a temperature error, we might be contacted first by AOMC, who oversees sensor errors and opens trouble tickets for the electronics techs to perform the maintenance and then clear the tickets. If they don't contact us, we would contact them to open a trouble ticket and then probably set the data to missing if there's no observer to take manual obs as backup. The problem with the sites without observers is that there's no form of backup that can be substituted in for that data, so it unfortunately would probably have to stay as missing data. For the MPV data, if it's not fixed over the next few days (we do almost always notice and discuss errors like these), there would be nothing wrong with emailing the BTV public email account to let them know. Since it appears the low temp was way off, that data can at least be set to missing and not stand as official for that site for the date, if it's found to be erroneous. For a persistent seeming warm bias like ORH, that one is tougher. ORH is I assume a long running primary climate site like BOS and is probably routinely checked for calibration by the ETs. There's a rather large error bar (+/- 2F) for passing calibration checks, so if the sensor passes and has no other known issues, it's less likely to be "fixable". We have seen cases in which a sensor routinely passed calibration checks, still seemed too warm or cold, but then the issue went away when the temperature sensor was fully replaced. Full replacement is I believe done on an amount of time since installation or on a routine replacement schedule vs the sensor being persistently slightly warm or cold.

4th coldest since 1936, when obs started at Logan Airport. Mount Washington got down to -47, which tied the record low set in 1934 for the observatory.

We should have some chances in the back 1/2 or 2/3 of Feb. Need to cash in with a warning level event farther south, otherwise chances of challenging 2011-12-like futility will certainly go up. If you're looking for good news, it doesn't currently look torchy on the ensembles around mid month (especially with westward extent) and should be fairly active. We'll see how things trend as we get closer to the possible decent period. Can't sugarcoat things prior to that though.

Incorrect on the cloud cover. It was clear everywhere until basically sunrise. And I wouldn't say the cold underperformed. We were slightly too cold at RPJ, we had ORD at -1 to -2, and we never had RFD tagging 10 below. We went below MOS guidance. The Euro was overdone with the coverage of teens below zero (and the GEMs are always overdone), but getting 7 sites to -10F or colder in our late AM updated RTP is not really underperforming imo. https://forecast.weather.gov/product.php?issuedby=LOT&product=RTP&site=lot Sent from my SM-G998U using Tapatalk