MAG5035

If not they have a really good chance at beating the next two days daily record min and probably Thursday's record max min. The crazy part about this cold is that with how significant the cold airmass is.. it's pretty likely that the lakes with only about 30% ice coverage (fairly normal actually this time in Jan) are going to save us to a degree with surface temps (along with the core of the PV lifting somewhat north of here). The stuff west of the lakes in Chicago and that region as a whole is amazing. Like that's legitimate -20 to -30ºF air with the wind blowing and not localized radiational cooling. Not an airmass seen very often that far into the heart of the US.

The schools in this county usually at least delay with advisory criteria wind chills, which -15ºF is the threshold for. Warning threshold is -25ºF in all the state, which our temps/wind combo probably won't be enough to achieve the warning criteria outside of the north central and Laurel's where winds will be higher and temps lower. Either way, those wind chills are pretty serious business and it's likely most schools/other organizations are taking the major cold snap seriously. Heck Penn State Main Campus of all places cancelled all afternoon classes last Thursday. Why? Simply because it was supposed to get cold after it rained and things might ice back over. Speaking of wind chills, imagine if we were still using the old wind chill chart that was used prior to 2001. A -5ºF temp and a 20mph wind would have given you an apparent temp of -46ºF, lol.

In case anyone was wondering how my <1” panned out... I got a 2.2” fluff bomb this morning, aka >1”.

Bunch of virga out of this so far here.

The reductions are most notable back here in the central/south central counties, AOO went from 2-3 range to <1 and UNV went from like 4 to maybe 1 or so. Although I'm sporting a nice 6-7" glacier pack as is so I don't expect anyone to feel bad for me haha. No there would be more than that going into generating those products with them having percentile and probability maps to look at. They likely utilize short range ensemble data like the SREF and HREF plus WPC's products.

CTP's map might be a tad conservative back in the central counties when factoring in their own probability products they have plus WPC's products which seem to bullseye UNV/IPT. The SREF's are pretty charged up too. Clearly WPC (as of their late afternoon issuance) favors a more NW axis to this but models have seemed to tend towards the east with the potential enhanced snowfall that would represent an axis of say, 4+. Esp the Euro, which had favored this type of scenario but really shifted east the last couple runs, progressing the front and not really popping the coastal low until to the NE with a less robust shortwave. It's a more progressive look that even alot of the Sus Valley was almost too far west for. I see this event evolving primarily around a several hour period of snow associated with a nice ribbon of forcing along the frontal boundary ushering in the arctic air. Embedded in that could be a intense band of snow with the actual front. The far southern tier may initially be a bit warm at the surface with some mixing at the beginning or snow that may not accumulate immediately. Snow ratios will progressively get better as the arctic air blasts into the column. So with that alone I would foresee a forum-wide 1-3" with scattered higher amounts as the base minimum. Now a negatively tilted trough with some coastal development could linger this enhanced area of precip over a given area, thus the threat for perhaps warning level snows. I would expect patchy upslope snows to linger in the interior counties for a time with the arctic air coming in. Primary worry is the precip hole being portrayed on models in the south central counties. Parent low goes to the lakes with secondary coastal development so some westerly downslope component could be in play, although I think the good dynamics/forcing will mitigate that to a degree.

Geez well that'll be quite the insurance policy if Tuesday's snow doesn't work out. 1.3" down here this morning.

Polar vortex is definitely happening, its just the question of how much it dumps south into PA.. which models have been toying around with the last couple days. 12z models today has the Euro as colder than the GFS. Wed-Fri looks to be the brunt of the arctic air intrusion with Thursday as the absolute coldest. For Thursday GFS had high singles for while Euro looked debatable if it reached 0 in H-burg. Either number for a high is hard to do in the Sus Valley. Interior Central PA was in the -10s on both (Euro colder) on both models for Wed night. Wind and prospective snow on the ground could dictate an even lower bottom to low temperatures.

Have had some upslope snows erupt in western/central PA in the overnight hours. Have about a half inch of new snow with it still snowing.

There continues to be some pretty significant differences in evolution between the GFS and Euro for the next event slated for the early part of next week. The European drops in and phases a robust shortwave on a nice negatively tilted 500mb trough, resulting in coastal development and a swath of moderate snows across most of central PA. GFS is faster, weaker and further north with shortwave and just simply drops in the PV and it's sub 500dm 500mb heights into the northeastern US. Euro actually didn't really drop in the PV with tonights run, keeping it in Canada (still plenty cold). Canadian similar or maybe even more robust than the Euro.

This is quite the rabbit hole haha. I actually caught another one.. 11/6-7, 1953 totaled 15.4". Also the 2003 blizzard had 18" on Feb 16-17th (out of a 20.3 4 day total). So that would put one in the 1950 and 2000 decade. I'm really intrigued about 1958, that was a really snowy winter especially in Feb-Mar. I found this out of a Lancaster Online article from right before the March 2017 storm which had a top ten list of snowfalls in Lancaster, and actually Horst was the source of the information. On the list at #6 was Feb 15-16th, 1958 at 20". The data had about 8" at MDT for that. But they also had another storm honorable mentioned. https://lancasteronline.com/news/local/biggest-snowstorms-in-lancaster-county-history/article_582b86b6-014a-57ed-aac7-25a3ae0748e8.html So MDT reported about a 9 inch total from those few days while that apparently was going on in Lancaster County. That's an insane gradient if that was all that Harrisburg had out of that.

We look to be transitioning to a more northern branch dominated regime as we have quite a cold pattern looming. The next event to watch appears to be around the beginning/early part of next week. I think it has the possibility to be some kind of snow event potentially with an arctic front passage. GFS takes parent low into the lakes, and despite thicknesses that would be supportive of snow seems to take surface and low level temps too warm and thus present a mixing or rain potential up front. Euro evolves the system a little differently and would be more of a snow event. Either way both models are currently bringing the house arctic air wise behind this system.

Did some measuring of the glacier pack around the yard and it was a pretty uniform 5.5-6". That's pretty good snowpack retention with all the rain. Then again the station nearby didn't finally crack the 32-33ºF mark until nearly 9am this morning when it briefly spiked to 38ºF and was back below freezing by mid-afternoon. I mentioned to wsptwx yesterday about possible small creek and drainage issues but not bigger problems with the larger waterways as interior counties (that make up West Branch Susquehanna basin) probably weren't going to lose significant snowpack. You think it still would have been at least addressed with a flood advisory if not an areal flood warning. Especially with how much you ended up spiking temp wise and as much rainfall as your neck of the woods ended up with.

Is it smaller streams/creeks type flooding or poor drainage? (Or both)

I only see 4 events total in that spreadsheet that would categorize as 15" or greater. One in the 1983-1987 timeframe (Blizzard of 83), 2 in 1993-1997 (Blizzards of 93' and 96'), and of course the big one in 2013-2018 for the 2016 Blizzard. Clearly that's missing the Feb 2003 storm and then Feb 2010 storms as those events must have been split on multiple days. I feel like MDT probably had more than one event of >15" in the 1948-1992 but I don't really know that for sure, I'm not familiar with H-burg snowstorms back that far and the Gov't shutdown has claimed the site with the archived NESIS storm data. I can tell you that noted major snowstorms in 1958 and 1966 may have delivered such. The other site for Millersville snowfalls by decade that was provided on here showed 15+ snowfalls in 1958,1961, and 1979. I know that's not particularly the Harrisburg region but those are at leas a few other storms that might have done that in that time period. Single day snowfall data is probably not the best way to try to find a trend in frequency of storms of bigger size. Although yes the last especially 10 years has had an uptick in big single event snows in the Sus Valley. It's hard to compare storms or periods of yesteryear to today simply because technology, how connected we are today, and how we're able to monitor and track these things and etc. I often wonder what the narrative might be if we actually had something like a 77-78 type winter, or a hurricane season like 1954 which featured three major hurricanes impacting the eastern seaboard in the same season (including one of the only Cat 4's to ever hit NC). Heck the town I live in had a 15-20inch snowstorm in 1928.. on APRIL 28th. If you look back hard enough you can find plenty of crazy prior to the last 25 years. One thing I do notice in those spreadsheets with how they're broken down, is some of the more recent lousy winter periods we've had. 1998-2002 is clearly the worst of the bunch having only 63 measurable snowfalls (discounting the one counting "T", but it's still the least with that). What did we have in that period? The 97-98 super nino winter, which was one of the least snowy in Harrisburg. Followed by 2 Nina winters and then the 01-02 non-winter. The period 1988-1992 was almost as bad. The 90s as a whole outside of 92-93, 93-94, and 95-96 featured some pretty underwhelming winters. Recent 5 year periods in the 2000s-2010s featured lower totals number of snowfalls until the most recent 5 year period which is back to being more on par with overall higher numbers prior to 1998-2002 period. But 1973-1977 also sticks out for having a low number of total snowfalls. That period, notably, conincides with a very dominant La-Nina ENSO state much as the late 90s (late 98 to early 2001) was.

Temps still hovering around freezing. The 32ºF ob on mesowest in Altoona is only several blocks away from my house. KAOO and KJST down toward the bottom of the obs map are both at 46ºF.

Temps continue to hover right around freezing and there's still some ice accrual ongoing on cold surfaces. Had to resalt the driveway cuz ice was starting to take it over again. There's still patchy ice and slushy areas on even some of the more travelled roads. We had started the day early this morning in the upper teens so it's going to take a bigger spike in temps to completely end the ice issues. Pretty big difference between Altoona city and KAOO (Blair County Airport). Most meso obs around town are 32-33ºF while KAOO 15 miles south all the way up to 42ºF.

I think any flooding issues would be of the smaller stream and especially poor drainage variety. Good bit of rain incoming but it probably isn't going warm up enough in the interior counties to wipe out what was already an icy snowpack. NWS Pit put watches up for their counties but they're west of the Alleghenies where warm air via SW flow will get to the surface more easily

The situation here so far today:

Analogs are a useful tool for overall pattern recognition when comparing with similar pattern alignments in the past and expecting reasonable similarities and potential with an upcoming pattern. But using analogs is always risky if one expects a current or forecast pattern analogged to a previous one to deliver the same finite result be it a big storm, a cold or warm air mass with the same magnitude/length or affecting the same region, said big storm (if one materializes) taking the same track or having the same strength and effects, and etc. No two patterns are ever truly the same, there's just too many variables that make up any given pattern to consider. This is especially risky when taking a lot of stock into an analog on a big winter, such as 78 which has come up a good bit with analogs for this winter. There's a reason why analogged big hitter winters like 77-78,93-94, 95-96 don't often rematerialize. Because they were truly anomalous winters in their own right. With regards to model performance, computer models have SST data incorporated into them. They have to.. water covers 70% of the earth's surface and water is a much better retainer of heat than land. There's a lot of behind the scenes work always going on (except for certain shut down governments) to update and tweak these computer models and there's a ton of data that gets incorporated into them to initialize a model run. So when your talking operational models making an up to 10-15 day forecast vs climatic changes over years or decades, those aforementioned numerous pattern variables would come into play into erratic performance. Variables I speak of are things such as blocking patterns and their positioning (NAO/PNA), ENSO/SOI state, Stratwarm events, tropical forcing that makes up the MJO, etc. I really haven't noticed any recent model performance to be any more erratic than it typically is, especially at range. They're always erratic getting out past day 7 unless there's an especially strong signal for something. If there's an imminent pattern change in the mid-long range computer models are always all over the place in the transition period. Look what just happened this month. Some were punting January practically before cleaning up the New Years confetti.

Alot of leftover black ice on some of the back roads around here today. It'll be interesting to see how far temps drop in the regions with a decent snowpack if the winds calm later tonight as the high pressure moves overhead. First order of business this week is going to be Tues Night/Wednesday. Pretty strong signal for a front end ice threat so would expect advisories for the morning rush on Wednesday. With the magnitude of the preceding cold air currently in place, it could be one of those situations you could get icy patches on untreated cold surfaces even if the air temp is a tick or two above freezing. Temps eventually warm some Wednesday and then we'll have to keep an eye on the evolution of the secondary frontal wave that rides up that could provide some back end snow Wed Night.

It finally cleared all the way out down here just in time after some clouds and flurries earlier. Really nice view of it right now, although it is down to 5ºF outside haha.

Yea it's still the same thread I just tweaked the name. We only did about 10 pages of obs yesterday.

Best conditions I ever snowboarded in up there was right after the late March snowstorm this past winter. They got like 20+ inches of snow and had every trail open for a few days. Whichever number is correct is still a pretty impressive precip amount for the Tamaqua Desert.

Already back to 24ºF here. 7.3" was the storm total which compacted to about 4-5" and it's already frozen solid. Trees have pretty much all the snow and ice still on them.