Roger Smith

There is some chance of the Tonga eruption having an impact on the winters of 2022-23 and 2023-24. Following Tamboro (Apr 1815) there was a very cold period throughout the northern hemisphere setting in around the winter of 1815-16 and reaching its most anomalous levels in the "year without a summer" of 1816. Winter 1816-17 where records exist was not exceptional, in fact considerable mild weather was experienced in some winters 1817 to 1819, but winter 1820 was harsh. Then after Krakatoa (1883) several years were very cool but what contaminates that is the fact that 1883 was already running very cold before the eruption (March 1883 in particular set many cold records). The greatest effect from Krakatoa looks to be around the winter of 1884-85. Pinatubo (1991) was a less severe volcanic eruption but is widely credited (whether right or wrong) with the cool summer of 1992. Winter 1992-93 was quite a cold one, 1993-94 even colder. For the size of the dust veil it would seem that Pinatubo should not be given all the credit for those cold winters, however. It takes several months for a tropical dust veil to spread out over the mid-latitudes and this one was further south of the equator than the other examples. If the dust veil is comparable to Krakatoa then we should see some effects from it. However, the current La Nina could flip to some kind of El Nino pattern and that might offset, at least for a while. Is the Tonga dust veil considered similar to Krakatoa, or more like Pinatubo? There was also a volcanic connection postulated between eruptions in Iceland in 1783 and the cold winter of 1783-1784.

I also had a look at reports from YYZ and YTO (downtown Toronto) on the EC website. Using the same convention that I have used for any other recent Toronto snowfalls, the total snowfalls on 16th-17th will be recorded as 39.3 cm (from 10:1 conversion of 39.3 mm total precip). The site reports 25 cm snow depth at some point during the storm and tomorrow there will be another snow depth report. If that exceeds 39 cm then I would enter that amount adjusting the two conversions and retaining the precip numbers. I have never found a case like that since 2017, what has been more often the case is that the post-storm snow depth is just a bit below the presumed 10:1 conversion which is acceptable given compaction, but then again, the water equivalent implied from the YYZ obs indicate only about a 9:1 ratio which if applied to the YTO precip would give a slightly smaller snowfall of around 35 cm. As a previous poster indicated, the YYZ total snowfall was 32.4 cm and that came from a total precip of 34.4 mm (ratio then is 324/34.4 or 9.4 to 1). That assumes that none of the precip was rain, if any small amount was, then the ratio would be closer to 10:1. If the final snowfall estimate for downtown is maintained at 39.3 cm (the conversion of the two daily amounts is shown in the table and adds up to 15.5 inches) , then the storm will rank t-18 all time (since 1846 when daily snowfall becomes available), and 4th highest since 1930, highest since Jan 1966. Many of the top thirty storms in this list (first appeared here yesterday) are from the heavy snowfall era of the 1860s and 1870s when Toronto's average winter snowfall was closer to 80" and sometimes exceeded 100". March 1870 alone contributes three of the storms to this list and March 1876 two more. By the way the heaviest Nov storm was in 1950 (12.5") and the heaviest April two-day total from 1975, nearly ten inches. So no Nov or Apr storms make this list. Rank ____ Amount (2d total) ____ Dates (with daily amounts) _ 01 _____ 23.0 __________________ Dec 25-26 1872 (15.0 + 8.0)^ _ 02 _____ 22.5 __________________ Dec 11-12 1944 (19.0 + 3.5) _ 03 _____ 22.0 __________________ Feb 20-21 1846 (18.0 + 4.0) _ 04 _____ 20.0 __________________ Mar 15-16 1870 (10.0 + 10.0) _t05 _____ 19.5 __________________ Mar 26-27 1870 (3.5 + 16.0) _t05 _____ 19.5 __________________ Jan 24-25 1873 (4.2 + 15.3) _t07 _____ 18.0 __________________ Feb 5-6 1863 (16.0 +2.0) (+1.0 4th = 19") _t07 _____ 18.0 __________________ Feb 14, 1850 (18.0) _ one day _t07 _____ 18.0 __________________ Jan 20-21 1867 (15.0 + 3.0) _t07 _____ 18.0 __________________ Feb 24-25 1868 (12.0 + 6.0) (+1.0 23rd = 19") _ 11 _____ 17.8 ___________________Feb 28-Mar 1 1900 (10.0 + 7.8) (1900 not a leap year) _ 12 _____ 16.6 __________________ Jan 22-23 1966 (0.9 + 15.7) _ 13 _____ 16.5 __________________ Mar 21-22 1867 (15.0 + 1.5) _ 14 _____ 16.2 __________________ Mar 28-29 1876 (10.5 + 5.7) _ 15 _____ 16.0 ___________________Dec 4-5 1898 (6.0 + 10.0) _t16 _____ 15.7 ___________________ Jan 8-9 1884 (11.1 + 4.6) _t16 _____ 15.7 ___________________ Jan 21-22 1902 (2.5 + 13.2) _t18 _____ 15.5 ___________________ Mar 20-21 1876 (9.0 + 6.5) _t18 _____ 15.5 ___________________ Mar 8-9 1931 (12.0 + 3.5) _t18 _____ 15.5 _____________ Jan 16-17, 2022 (1.2 + 14.3) (msd 3.1 + 36.2 cm) _ 21 _____ 15.1 (msd 38.4 cm)*___ Jan 2-3 1999 (almost all on 2nd) _t22 _____ 15.0 ___________________ Dec 29 1855 (one day) _t22 _____ 15.0 ___________________ Mar 12-13 1870 (6.0 + 9.0) _ 24 _____ 14.5 ___________________ Feb 2-3 1910 (5.0 + 9.5) _ 25 _____ 14.4 (msd 36.5 cm)*___ Feb 7-8 2013 (8.0 + 6.4) (msd 20.3+16.2 cm) _ 26 _____ 14.3 (msd 36.2 cm)*___ Feb 27-28 1984 (4.7 + 9.6) (msd 12.0 + 24.4 cm) _ 27 _____ 14.2 ___________________ Feb 21-22 1950 (11.0 + 3.2) _ 28 _____ 14.0 ___________________ Jan 18-19 1864 (4.0 + 10.0) _ 29 _____ 13.9 ___________________ Dec 27-28 1968 (2.6 + 11.3) _ 30 _____ 13.5 ___________________ Feb 25-26 1960 (13.0 + 0.5) _ xx _____ 13.0 or more __________ Feb 1845 (upper limit probably 18") ______________________________ * and ^ notes are explained in my previous post almost 24h back in the thread, * basically refers to fact that only four now post-1978 storms were measured in cms and converted, all the rest were originally measured in inches; and ^ the leading storm from Dec 1872 appears to be mostly from localized lake effect as synoptic pattern available suggests a much lower potential total from that component. That was not the case for any of the other old-time storms where the weather maps revealed strong low pressure systems tracking to the south of Lake Ontario usually from southwest. --------------------- So this storm would rank t-18 on the all-time list, but note that it is third highest January total just behind Jan 22-23 1966 which the author recalls as being no more disruptive than this one, and on a weekend, and marginally lower than a storm total from 1902 (Jan 21-22); the Jan 2-3 1999 storm was slightly lower in the table but its disruption increased after subsequent 8-10 inch falls added to the snowpack. Also while ranking t-18, the storm ranks third since 1940 and fifth since 1899. Open to suggestions about any revision of those estimates, I have just finished the update of the data base that you can find over in the climate change forum here (a link to a similar thread on UK net-weather where due to larger download limits I have stored the supporting excel files), and I have not contacted anyone at EC to inform them that this data base exists, but my plan is to do so, and to suggest that they fill in the few missing days from this location (most of which are after 2013) from hourly data which are often almost complete and would give reliable temperature and precip estimates, also it would probably be a good plan to merge the two concurrent reports that exist between 2003 and 2017 where one needs to go from one site to the other to blend temperature, rainfall and snowfall. If the downtown station was then maintained at the current service level (ideally with snowfall restored) then it would continue to provide an unbroken climate record from essentially the same location as at all past times, that is to say, geographically similar, a large city has grown up around the location which was originally near the outskirts of a small town.

Another three snowstorms? Okay.

To give some historical context for Toronto (downtown), these are the top storm total snowfalls (almost all are two-day totals that are dominated by one day out of the two) ... almost all were measured in inches as Canada went to the metric system in June 1978, and almost all are reliable human measurements (the problems with downtown Toronto snow measurement date back mostly to 2017 when daily measurements ceased although morning snow depths remain in place, for the extension of the records in a project you can access here in the climate change forum, I have been taking a 10:1 conversion of reported precip when it appears similar to the snow depths and using some contacts I have both on the forum and in my family, having some contacts who live just two miles northwest of the observing site which has always been within a half mile of the current location, on the U of T campus in mid-town Toronto) ... Rank ____ Amount (2d total) ____ Dates (with daily amounts) _ 01 _____ 23.0 __________________ Dec 25-26 1872 (15.0 + 8.0)^ _ 02 _____ 22.5 __________________ Dec 11-12 1944 (19.0 + 3.5) _ 03 _____ 22.0 __________________ Feb 20-21 1846 (18.0 + 4.0) _ 04 _____ 20.0 __________________ Mar 15-16 1870 (10.0 + 10.0) _t05 _____ 19.5 __________________ Mar 26-27 1870 (3.5 + 16.0) _t05 _____ 19.5 __________________ Jan 24-25 1873 (4.2 + 15.3) _t07 _____ 18.0 __________________ Feb 5-6 1863 (16.0 +2.0) (+1.0 4th = 19") _t07 _____ 18.0 __________________ Feb 14, 1850 (18.0) _ one day _t07 _____ 18.0 __________________ Jan 20-21 1867 (15.0 + 3.0) _t07 _____ 18.0 __________________ Feb 24-25 1868 (12.0 + 6.0) (+1.0 23rd = 19") _ 11 _____ 17.8 ___________________Feb 28-Mar 1 1900 (10.0 + 7.8) (1900 not a leap year) _ 12 _____ 16.6 __________________ Jan 22-23 1966 (0.9 + 15.7) _ 13 _____ 16.5 __________________ Mar 21-22 1867 (15.0 + 1.5) _ 14 _____ 16.2 __________________ Mar 28-29 1876 (10.5 + 5.7) _ 15 _____ 16.0 ___________________Dec 4-5 1898 (6.0 + 10.0) _t16 _____ 15.7 ___________________ Jan 8-9 1884 (11.1 + 4.6) _t16 _____ 15.7 ___________________ Jan 21-22 1902 (2.5 + 13.2) _t18 _____ 15.5 ___________________ Mar 20-21 1876 (9.0 + 6.5) _t18 _____ 15.5 ___________________ Mar 8-9 1931 (12.0 + 3.5) _ 20 _____ 15.1 (msd 38.4 cm)*___ Jan 2-3 1999 (almost all on 2nd) _t21 _____ 15.0 ___________________ Dec 29 1855 (one day) _t21 _____ 15.0 ___________________ Mar 12-13 1870 (6.0 + 9.0) _ 23 _____ 14.5 ___________________ Feb 2-3 1910 (5.0 + 9.5) _ 24 _____ 14.4 (msd 36.5 cm)*___ Feb 7-8 2013 (8.0 + 6.4) (msd 20.3+16.2 cm) _ 25 _____ 14.3 (msd 36.2 cm)*___ Feb 27-28 1984 (4.7 + 9.6) (msd 12.0 + 24.4 cm) _ 26 _____ 14.2 ___________________ Feb 21-22 1950 (11.0 + 3.2) _ 27 _____ 14.0 ___________________ Jan 18-19 1864 (4.0 + 10.0) _ 28 _____ 13.9 ___________________ Dec 27-28 1968 (2.6 + 11.3) _ 29 _____ 13.5 ___________________ Feb 25-26 1960 (13.0 + 0.5) _ 30 _____ 13.0 or more __________ Feb 1845 ========================== ^ from historical weather maps, appears to be largely east-wind lake effect storm during exceptionally cold weather setting low temp records, the associated synoptic scale event shown near NYC was weak. Historical weather maps are available on wetterzentrale.de back as far as 1835 now. From those I discovered an unrecorded snowstorm in Feb 1845 that might have made this list, shown in 30th place, monthly amounts are available and support a 15-20 inch snowstorm as well as a few smaller events during the month. Toronto weather data while excellent in general from early days have gaps in snow and rain daily amounts in the period 1840-45 (not all data is missing and most months have at least totals available). The conversion of snow to liquid equivalent was always 10:1 until April 1962 and only became variable after that (in other words snowfall plus rainfall was always a case of 10:1 snow equivalent, and if no rain fell then the snowfalls equalled 10x precip). For some unknown reason 1984 data are all recorded in 10:1 ratios. This did not occur for any other year in the conversion era 1962-2017. I have had to restore the 10:1 convention backwards to get any snowfall amounts from the data available after Oct 2017. * the 1984, 1999 and 2013 storms that made this list were measured in cm as shown, converted to inches. All the rest were measured in inches. A double conversion may change their values (official records converted from inches to cms then reconverted to inches, can introduce errors). After several more snowfalls in first two weeks of Jan 1999 the snow depth was 65 cm on Jan 15th, the highest value recorded at the location. The author measured 66 cm in Peterborough ON after the Dec 9-10 1992 snowstorm. Amounts much larger than that are known to have accumulated in Jan 1971 and other heavy snow squall events in central Ontario. The Apr 1975 snowstorm left 60-80 cm amounts in Simcoe County north of Toronto that eventually led to drifts (partially frozen by daily freeze-thaw cycles in strong sunshine) of 2-3 metres separated by bare ground. (personal observation near Barrie ON around Apr 4-6 1975).

Glad to see you mentioned that low total, did you notice it tied a record? Maybe the record amount was actually broken but the amount got entered as the value for yesterday as well? I was also expecting to see a value in the 4-5 range, the other three look legit from the reports all around the region.

997 mb low appears to be offshore near NC-SC border, track from pressure falls and upper level winds most likely to run inland between ORF and RIC then up the west side of Ches Bay between DC and BAL by 03z (possibly right over DCA). At the surface I think this cold wedge is trapped for the duration, at least in the DC and noVA regions, BWI may get close to 45F briefly but DCA 35F and IAD 33F with the changeover only coming near end of precip anyway, could be some lightning around by 00z especially over se MD and DE. Would expect final snowfalls in the 3-6" range (with obviously higher totals in mtns) west of Baltimore, around 1.5" in Baltimore.

All-model weighted consensus low track is approx RIC to DCA to ABE, rapid deepening. Think it plays out as 3-6 hour heavy snow front end thump followed by sleet and possible large ice pellet with thunder around 09z in metros, wrap around snow quickly follows. Scour out of cold air is not very complete south of York PA due to rapid development and inland penetration of warm nose mostly north of the Delaware, even there surface residency time of milder air very brief. Partial coastal energy transfer 12-15z pushes occlusion rapidly north across LI, s NE. Think it could result in a better snow outcome than the NWS forecast by almost 2:1 ratio, as that early stage will crank and another 1-2" possible from the wraparound. Note that DC is right under the 500 mb low by 12z Monday. Column is implied to be non-vertical, with 700 mb low displaced to west of 500 mb and southwest of surface low. Seen from above the cylinder looks like the letter C with the upper portion closest to the surface. Such a dynamic evolution, bound to be some thundersnow and thundersleet involved. Don't think temps come up as much as some fear, will do so in NJ-ePA more so. Strongest winds probably follow the warm nose and trailing front, may not be that big a factor in DC or even BAL as a result, perhaps strongest by Mon afternoon in downsloping WNW. Think some will be saying "got more snow than expected" by Monday mid-day, although by how much, perhaps not that much, maybe add 1-2" to expectations.

06z GFS looks like an improvement especially compared to 06z NAM but also to 00z GFS.

If you wanted to lodge a complaint with NAM, I understand this gentleman is Director of Public Relations ...

Recent obs, the low center was southeast of Wichita Falls TX and the closest place with snow was Des Moines IA. There are strong northerly winds blowing into the TX panhandle from CO and w KS but that air is the old stale chinook being pulled out of MT and AB. By this time tomorrow the separation of low center and arctic wave will be about one-fifth as large as it is now. This is going to be an interesting storm to track into the southeast US, whatever it actually ends up doing.

The cycle of optimism-pessimism is actually trending in a good way, next peak of optimism should be late Saturday. At that range the models can't miss. Pros seem a bit suspicious that these model shifts are bogus, not sensing their enthusiasm at this stage. How many cold 500 mb lows form in this particular way? And the offset of the circulation to snow development at present will be replaced overnight by something more normal looking. I wonder if the injection of cold air into the circulation will change the model output, because right now that low in Texas is surrounded by mild air masses, the arctic front is almost a thousand miles northeast of the low. By late Saturday it's making more direct contact in AR-MS. And there's the contact with the Gulf to consider. There are ways these forecasts could bust on the warm side.

I wonder how many analogues there would have been for a storm evolution similar to this. Also before throwing a sheet over this, let's not forget the storm hasn't actually happened yet. What if the models are just as wrong about this as they were in that early March setup a few years ago. In that case the storm ended up missing wide right if I recall, what's to say this doesn't miss wide right and you're back in a good place?

Binghamton snow bus now boarding on platform five.

Not indulging, just a natural high -- but seriously, I have the feeling there's going to be a surprise ending to this story, looking at how cold that high is over n ON today, when it settles into the St Lawrence valley and feeds down through NY, very cold surface temps may make the low decide to follow the path of least resistance. That could translate into extra snow for anywhere in this subforum except east of the Bay, and also same holds true for e PA. I see the forecast nightmare looming for NYC but they could start out with heavy snow before the inevitable mixing. I'm not the only one, SCC also stating similar views. The clash between this frigid high and the amped southerly stream over anomalously warm ocean should lead to a very powerful storm.

Any chance of locally heavy snow squalls in E-NE winds in Chicago, Milwaukee regions? I was just looking at the temps near the high, generally in the -30s. The feed of frigid cold as the low develops to southwest could pull in very cold air over Lake Michigan by this afternoon and overnight.

That trend on the 12z GFS towards more of a coastal low dominance could make the outcome much different if the storm slows down a bit, I read the commentary here before running the loop and saw a somewhat more optimistic potential, mixing looks brief and I could see how this trend might lead to an all-snow outcome. You can follow a center of low pressure up the coast developing offshore and heading for Cape Cod. Halfway house to a much different outcome? Interesting to see if Euro goes in this direction also. My first call would be 3.5" BWI, DCA and 5.5" IAD, 8 to 15 over regions northwest of DC to ROA, about 6-9" CHO. Some sleet and max temps 34-38F, dropping back to low 30s, mixed showers for most with 3-5" upslope in wraparound. Results, some snow left on ground in metros and 3-6 frozen pack further west, slow meltdown Tuesday-Wednesday with a few more passing flurries.

Record highest snowfall totals, weekly intervals The table covers the snowfall season therefore it begins in October and ends in early May. (WEEK) INTERVAL ____ MAX SNOW ___ YEAR(S) _____________ close 2nd or 3rd Oct 4-10 to 6-12 _ Tr _________ 1925, 1979 Oct 7-13,8-14 ___ Tr __________ 1925, 1937, 1979 Oct 9-15 _______ 0.5" _________ 1896 Oct 10-16 ______ 0.5" _________ 1896 Oct 11-17 ______ 0.5" _________ 1896 Oct 12-18 ______ 0.5" _________ 1896 Oct 13-19 ______ 0.5" _________ 1896 Oct 14-20 ______ 0.5" _________ 1896, 1952 Oct 15-21 _______0.5" _________ 1896, 1952 Oct 16-22 ______ 0.5" _________ 1952 Oct 17-23 ______ 0.5" _________ 1952 Oct 18-24 ______ 0.5" _________ 1952 Oct 19-25 ______ 0.5" _________ 1952 Oct 20-26 ______ 0.5" _________ 1952 Oct 21-27 _______ Tr ___________1903, 1944 Oct 22-28 _______ Tr __________ 1903, 1925, 1934, 1944, 1965 Oct 23-29 ______ 2.9" _________ 2011 Oct 24-30 ______ 2.9" _________ 2011 Oct 25-31 ______ 2.9" _________ 2011 Oct 26-Nov 1 ___ 2.9" _________ 2011 Oct 27-Nov 2 ___ 2.9" _________ 2011 Oct 28-Nov 3 ___ 2.9" _________ 2011 Oct 29-Nov 4 ___ 2.9" _________ 2011 Oct 30-Nov 5 ___ 0.8" _________ 1925 Oct 31-Nov 6 ____2.5" _________ 1879 Nov 1-7 _________ 4.3" _________ 2012 Nov 2-8 _________ 4.7" _________ 2012 Nov 3-9 _________ 4.7" _________ 2012 Nov 4-10 ________ 4.7" _________ 2012 Nov 5-11 ________ 4.7" _________ 2012 Nov 6-12________ 4.7" _________ 2012 Nov 7-13________ 4.7" _________ 2012 Nov 8-14 ________2.3" _________ 1892 Nov 9-15 ________6.4" _________ 2018 Nov 10-16 _______6.4" _________ 2018 Nov 11-17 _______ 6.4" _________ 2018 Nov 12-18 _______6.4" _________ 2018 Nov 13-19 _______6.4" _________ 2018 Nov 14-20 _______6.4" _________ 2018 Nov 15-21 _______6.4" _________ 2018 Nov 16-22 ______ 2.0" _________ 1873 Nov 17-23 ______ 4.7" _________ 1989 Nov 18-24 ______ 4.7" _________ 1989 ____ 3.9" 1938 Nov 19-25 ______ 8.8" _________ 1938 Nov 20-26 ______ 9.3" _________ 1938 Nov 21-27 ______13.0" _________ 1898 ____ 12.8" 1938 Nov 22-28 ______13.0" _________ 1898 ____ 12.8" 1938 Nov 23-29 ______14.1" _________ 1898 ____ 12.8" 1938 Nov 24-30 ______19.0" _________ 1898 ____ 13.5" 1882 _ 12.8" 1938 Nov 25-Dec 1 ___16.0" _________ 1898 ____ 13.5" 1882 Nov 26-Dec 2___16.0" _________ 1898 ____ 13.5" 1882 Nov 27-Dec 3___11.0"__________ 1898 _____ 9.0" 1882 Nov 28-Dec 4___ 9.0" _________ 1882 _____ 7.0" 1911 Nov 29-Dec 5___ 9.0" _________ 1882 _____ 8.3" 1926 __ 7.0" 1911 Nov 30-Dec 6___14.0" _________ 2003 _____ 9.0" 1882 __ 8.3" 1926 __ 7.0" 1911 Dec 1-7 ________ 14.0" _________ 2003 _____ 8.3" 1926 __ 7.3" 1886 __ 7.0" 1911 Dec 2-8 ________ 14.0" _________ 2003 _____ 8.3" 1926 __ 7.3" 1886 __ 7.0" 1911 Dec 3-9 ________ 14.0" _________ 2003 _____ 9.3" 2005 __ 8.4" 1926 __ 7.3" 1886 __ 7.0" 1911 Dec 4-10 _______ 14.0" _________ 2003 _____ 9.3" 2005 __ 8.5" 1926 __ 7.3" 1886 __ 7.0" 1911 Dec 5-11________ 14.0" _________ 2003 _____ 9.0" 1926 __ 7.3" 1886 __ 6.8" 2005 Dec 6-12 _______ 15.2" _________ 1960 _____ 6.8" 2005 Dec 7-13 _______ 15.2" _________ 1960 _____ 8.4 1926 __ 8.1" 1904 Dec 8-14 _______ 15.2" _________ 1960 ____ 11.9" 1917 __ 8.4" 1926 Dec 9-15 _______ 15.2" _________ 1960 ____ 13.5" 1916 __ 9.2" 1926 Dec 10-16_______ 15.3" _________ 1960 ____ 13.5" 1916 Dec 11-17 _______ 15.3" _________ 1960 ____ 13.5" 1916 __ 10.5" 2020 Dec 12-18 _______ 13.4" _________ 1916 ____ 13.0" 1904 __ 10.5" 2020 Dec 13-19 _______ 12.9" _________ 1916 ____ 10.5" 2020 Dec 14-20 _______ 21.1" _________ 1948 ____ 13.0" 1916 __ 10.9" 2009 __ 10.5" 2020 Dec 15-21 ________21.3" _________ 1948 ____ 13.7" 1916 __ 10.9" 2009 __ 10.5" 2020 Dec 16-22 _______ 21.3" _________ 1948 ____ 13.7" 1959 __ 10.9" 2009 __ 10.5" 2020 Dec 17-23 _______ 16.0" _________ 1948 ____ 13.7" 1959 __ 10.9" 2009 Dec 18-24 _______ 16.0" _________ 1948 ____ 13.7" 1959 __ 11.4" 1912 __ 10.9" 2009 Dec 19-25 _______ 20.1"__________ 1883 ____ 13.7" 1959 __ 11.4" 1912 __ 10.9" 2009 Dec 20-26 _______ 28.6" _________ 1947 ____ 20.0" 1872 ___ 13.7" 1959 __ 11.4" 1912 __ 11.2" 1933 Dec 21-27 _______ 28.9" _________ 1947 ____ 20.0" 2010 ___ 18.0" 1872 __ 13.7" 1959 __ 11.4" 1912 Dec 22-28 _______ 29.2" _________ 1947 ____ 20.0" 2010 ___ 18.0" 1872 __ 11.4" 1912 __ 11.2" 1933 Dec 23-29 _______ 29.2" _________ 1947 ____ 20.0" 2010 ___ 18.0" 1872 __ 11.4" 1912 __ 11.2" 1933 Dec 24-30 _______ 26.7" _________ 1947 ____ 20.0" 2010 ___ 19.6" 1872 __ 12.0" 2000-01 __11.4" 1912 Dec 25-31 _______ 26.7" _________ 1947 _____20.0" 2010 ___ 19.6" 1872 __ 12.0" 2000-01 __11.2" 1933 Dec 26-Jan 1 ____ 26.8" _________ 1947-48____ 20.0" 2010-11 __ 12.0" 2000-2001 Dec 27-Jan 2 ____ 14.5" _________ 1876-77_____12.0" 2000-2001 __ 11.5" 1924-25 Dec 28-Jan 3 ____ 14.5" _________ 1876-77____ 12.0" 2000-2001 __ 11.5" 1924-25 __ 11.0" 1922-23 Dec 29-Jan 4 ____ 14.5" _________ 1876-77 ____ 12.0" 2000-2001 __ 11.5" 1924-25 __ 10.9" 1922-23 10.5" 2017-18 Dec 30-Jan 5 ____ 13.8" _________ 2000-2001 __13.0" 1876-77 __ 11.5" 1924-25 __ 10.5" 2017-18 Dec 31-Jan 6 ____ 13.0" _________ 1876-77 _____11.5" 1924-25 __ 9.8" 2017-18 Jan 1-7 __________ 15.9" _________ 1996 _______ 13.0" 1877 __ 11.5" 1925 __ 9.8" 2017-18 Jan 2-8 __________22.5" _________ 1996 _______ 11.5" 1925 __ 11.0" 1988 __ 10.7" 1923 __ 9.8" 2018 Jan 3-9 __________ 21.1" __________1996 _______ 11.2" 1988 __ 10.7" 1923 __ 9.8" 2018 Jan 4-10 _________ 20.5" _________ 1996 _______ 9.8" 2018 __ 9.4" 1988 Jan 5-11__________ 20.5" _________ 1996 _______ 9.8" 1881 Jan 6-12 _________ 22.9" _________ 1996 _______ 10.8" 2011 Jan 7-13 _________ 22.9" _________ 1996 _______ 12.5" 1964 __ 10.8" 2011 Jan 8-14 _________ 12.5" _________ 1964 _______ 10.5" 1954 Jan 9-15 _________ 12.5" _________ 1964 _______ 10.7" 1954 __ 10.0" 1910 Jan 10-16 ________ 13.0" _________ 1879 _______ 12.5" 1954, 64 __ 10.0" 1910 Jan 11-17 _________13.0" _________ 1879 _______ 12.5" 1964 __ 10.0" 1910 Jan 12-18 ________ 13.3" _________ 1879 _______ 12.5" 1964 __ 10.0" 1910 Jan 13-19 _________13.3" _________ 1879 _______ 11.5" 1964 __ 10.0" 1910 Jan 14-20 ________ 15.3" _________ 1978 _______ 13.3" 1879 __ 11.9" 1961 __ 10.0" 1910 Jan 15-21 ________ 15.3" _________ 1978 _______ 13.3" 1879 __ 11.9" 1961 __ 11.0" 2014 Jan 16-22 ________ 15.3" _________ 1978 _______ 13.3" 1879 __ 11.5" 2014 __ 10.9" 1961 Jan 17-23 ________ 27.9" _________ 2016 _______ 15.3" 1978 __ 11.5" 2014 __ 10.4" 1961 Jan 18-24 ________ 27.5" _________ 2016 _______ 13.6" 1978 __ 11.5" 2014 Jan 19-25 ________ 27.5" _________ 2016 _______ 13.6" 1978 __ 12.5" 2014 __ 11.3" 1905 Jan 20-26 ________ 27.5" _________ 2016 _______ 17.5" 2011 __ 12.5" 2014 __ 11.3" 1905 Jan 21-27 ________ 27.5" _________ 2016 _______ 24.2" 2011 __ 13.4" 2015 __ 12.5" 2014 __ 12.4" 1871 __ 11.3" 1905 Jan 22-28 ________ 27.5" _________ 2016 _______ 20.0" 2011 __ 15.0" 1871 __ 13.4" 2015 __ 11.0" 1905 __ 10.8" 1897 Jan 23-29 ________ 27.3" _________ 2016 _______ 20.0" 2011 __ 15.5" 1871 __ 13.4" 2015 __ 11.0" 1905 __ 10.5" 1897 Jan 24-30 ________ 20.0" _________ 2011 _______ 15.5" 1871 __ 14.4" 2015 __ 11.0" 1905 __ 10.5" 1897 Jan 25-31 ________ 20.0" _________ 2011 _______ 12.5" 1871 __ 10.5" 1882 __ 10.0" 1897 and 1905 Jan 26-Feb 1 _____ 20.1" _________ 2011 _______ 12.5" 1871 __ 10.5" 1882 __ 10.0" 1897 Jan 27-Feb 2 _____ 17.2" _________ 2021 _______ 12.5" 1871 __ 11.5" 1897 __ 11.0" 1966 __ 10.5" 1882 Jan 28-Feb 3 _____ 17.4" _________ 2021 ________ 10.5" 1882 __ 9.9" 1966 Jan 29-Feb 4 _____ 17.4" ________ 1961, 2021 ___ 16.0" 1882 __ 11.7" 1907 __ 11.1" 1926 __ 11.0" 1876 Jan 30-Feb 5 _____ 17.4" ________ 1961, 2021 ___ 17.2" 1907 __ 17.0" 1882 __ 11.6" 1920 __ 11.1" 1926 __ 11.0" 1876 Jan 31-Feb 6 _____ 17.4" ________ 1961, 2021 ___ 17.0" 1882, 1920 __ 16.0" 1907 __ 15.5" 1978 __ 11.2" 1926 __ 11.0" 1876 __ 10.8" 1985 Feb 1-7 ___________19.9" _________ 2021 _______ 17.7" 1978 __ 17.5" 1920 __ 17.4" 1961 __ 15.2" 1967 __ 15.0" 1907 __ 11.5" 1874 __ 11.2" 1876, 1926 Feb 2-8 __________ 17.7" _________ 1978 _______ 17.5" 1920 __ 17.4" 1961 __ 15.2" 1967 __ 11.5" 1874 __ 11.0" 1876 and 1907 Feb 3-9 __________ 17.7" _________ 1978 _______ 17.5" 1920 __ 17.4" 1961 __ 15.2" 1967 __ 12.1" 1926 __ 11.5" 1874 __ 11.4" 1961 _ 11.0" 1876 and 1907 Feb 4-10 _________ 20.7" ________ 1926 _______ 19.1" 1920 __ 17.7" 1978 __ 17.2" 1967 __ 11.8" 1907 __ 11.0" 1876 Feb 5-11 _________ 21.8" _________ 1994 _______ 17.7" 1978 __ 17.2" 1967 __ 16.4" 1983 __ 13.4" 1920 __ 12.6" 1923 __ 12.1" 1926 __ 11.0" 1933 Feb 6-12 _________26.9" _________ 2006 _______ 21.8" 1994 __ 21.5" 1983 __ 17.7" 1978 __ 17.2" 1967 __ 15.7" 1923 __ 12.6" 1899 __ 12.1" 1926 Feb 7-13 _________26.9" _________ 2006 _______ 22.5" 1899 __ 21.8" 1994 __ 19.0" 1983 __ 14.5" 1967 __ 12.5" 1926 Feb 8-14 _________26.9" _________ 2006 _______ 21.8" 1994 __ 19.9" 1899 __ 17.6" 1983 __ 12.6" 1926 __ 12.1" 1871 Feb 9-15 _________26.9" _________ 2006 _______ 17.6" 1983 __ 16.0" 1899 __ 15.3" 2014 __ 14.6" 1994 __ 12.6" 1926 __ 12.0" 1871 __ 11.0" 1894 Feb 10-16 ________26.9" _________ 2006 _______ 17.6" 1983 __ 16.0" 1899 __ 15.4" 1914 __ 15.0" 2010 __ 14.1" 2014 __ 12.8" 1994 __ 12.0" 1871 __ 11.9" 1996 __ 11.0" 1894,1926 Feb 11-17 ________ 26.9" _________ 2006 _______ 19.8" 2003 __ 17.6" 1983 __ 16.0" 1899 __ 15.0" 1914 __ 14.1" 2014 __ 12.8" 1994 __ 12.7" 1996 __ 12.0" 1871 __ 11.0" 1894 Feb 12-18 ________ 24.1" _________ 2006 _______ 19.8" 2003 __ 16.0" 1899 __ 15.6" 2014 __ 15.0" 1914 __ 12.0" 1871 __ 12.7" 1996 __ 12.6" 1893 __ 11.0" 1894 Feb 13-19 _________19.8" _________ 2003 _______ 15.8" 1914 __ 15.6" 2014 __ 13.4" 1979 __ 12.7" 1893 and 1996 __ 10.6" 1873 __ 10.0" 1902 Feb 14-20 _________19.8" _________2003 _______ 14.2" 1914 __ 13.4" 1979 __ 12.7" 1996 __ 10.0" 1902 Feb 15-21 _________19.8" _________ 2003 _______ 13.5" 1902 __ 13.4" 1979 __ 10.7" 1947 and 1996 Feb 16-22 _________19.8" _________2003 _______ 14.0" 1902 __ 13.4" 1979 __ 10.7" 1947 and 1996 Feb 17-23 _________16.3" _________ 2003 _______ 14.0" 1902 __ 12.7" 1979 __ 10.7" 1947 Feb 18-24 _________12.9" _________ 1921 _______ 12.7" 1979 __ 10.7" 1947 Feb 19-25 _________12.9" _________ 1921 _______ 12.7" 1979 __ 11.3" 1934 __ 11.0" 2005 __ 10.7" 1947 Feb 20-26 ________ 20.9" _________2010 _______ 12.0" 1934 __ 11.0" 2005 __ 10.7" 1947 Feb 21-27 ________ 20.9" _________ 2010 ________ 9.5" 2005 __ Feb 22-28 ________ 20.9" _________ 2010 ______ 10.8" 2005 __ Feb 23-29 _________ 5.2" __________1972 Feb 23-Mar 1 _____ 20.9" _________ 2010 (Feb 24-Mar 1 leap years only 6.6" 1968) ___ 14.6" 1914 __ 13.7" 2005 Feb 24-Mar 2 _____ 20.9" _________ 2010 (Feb 25-Mar 2 leap years only 11.5" 1896) ___ 14.6" 1914 __ 13.7" 2005 _ 11.5" 1896 Feb 25-Mar 3 _____ 20.9" _________ 2010 (Feb 26-Mar 3 leap years only 13.0" 1960 __ 11.5" 1896) ___ 14.5" 1914 Feb 27-Mar 4 _____ 15.0" _________ 1960 (Feb 26-Mar 4 non leap years 14.5" 1914 __ 13.2" 1917 __ 11.5" 2010 __ 10.5" 2019) ___ 10.0" 1896 Feb 28-Mar 5 _____ 15.1" _________ 1960 (Feb 27-Mar 5 non leap years 14.5" 1914 __ 14.1" 2015 __ 13.9" 1917 __ 10.5" 2019) ___ 10.0" 1896 Feb 28-Mar 6 _____ 17.4" _________ 1914 (Feb 29-Mar 6 leap years only 15.1" 1960 __ 10.8" 1916 __ 10.0" 1896) __ 14.1" 2015 __ 13.9" 1917 __ 10.5" 2019 Mar 1-7 ___________ 17.8" _________ 1914 _____ 14.1" 2015 __ 10.8" 1916 __ 10.4" 2019 __ 10.0" 1896 Mar 2-8 ___________ 18.1" _________ 1941 _____ 14.8" 1916 __ 10.0" 1896 Mar 3-9 ___________ 18.1" _________ 1941 _____ 11.6" 1916 Mar 4-10 __________ 18.1" _________ 1941 _____ 13.0" 1916 __ 12.5" 1907 Mar 5-11 __________ 18.1" _________ 1941 _____ 13.0" 1916 __ 12.5" 1907 Mar 6-12 __________ 18.4" _________ 1941 ____ 16.5" 1888 __ 13.0" 1916 __ 12.5" 1907 Mar 7-13 __________ 19.5" _________ 1888 ____ 18.4" 1941 Mar 8-14 __________ 20.9" _________ 1888 ____ 16.0" 1941 __ 9.7" 2017 Mar 9-15 __________ 20.9" _________ 1888 _____ 9.7" 2017 Mar 10-16 __________20.9" _________ 1888 _____ 16.0" 1896 __ 9.7" 2017 Mar 11-17 __________ 20.9" _________ 1888 _____ 16.0" 1896 Mar 12-18 __________20.9" _________ 1888 _____ 12.2" 1896 __ 12.1" 1956 __ 10.0" 1892 Mar 13-19 _________ 19.0" __________ 1956 _____ 12.0" 1896 __ 11.5" 1906 __ 10.0" 1892 Mar 14-20 _________ 18.3" __________ 1956 _____ 12.0" 1896 __ 11.5" 1906 __ 10.0" 1892 Mar 15-21 _________ 18.3" __________ 1956 _____ 12.0" 1896 __ 11.8" 1958 __ 11.0" 1906 __ 10.0" 1892 Mar 16-22 _________ 18.3" __________ 1956 _____ 11.8" 1958 __ 10.0" 1892 __ 8.4" 2018 Mar 17-23 _________ 12.8" __________ 1967 ______ 12.1" 1956 __11.8" 1958 __ 8.4" 2018 __ 8.0" 1892 Mar 18-24 _________ 12.8" __________ 1956 _____ 11.8" 1958 __ 9.8" 1967 __ 8.4" 2018 Mar 19-25 _________ 11.8"___________ 1958 _____ 9.8" 1967 __ 9.0" 1956 __ 8.4" 2018 Mar 20-26 _________ 11.8"___________ 1958 _____ 9.8" 1967 __ 8.4" 2018 Mar 21-27 __________ 9.8" ___________ 1967 _____ 8.4" 2018 __ 7.1" 1958 Mar 22-28 __________ 9.0" ___________1967 ______ 5.0" 1998 __ 4.5" 1896 Mar 23-29 __________ 4.5" ___________1896 _____ 3.0" 1885 Mar 24-30 __________ 4.5" ___________1883 _____ 3.0" 1885 Mar 25-31 __________ 4.5" ___________1883 _____ 3.0" 1885 Mar 26-Apr 1 _______ 9.7" ___________ 1924 _____ 4.5" 1883 __ 3.0" 1885 Mar 27-Apr 2 _______ 8.5" ___________ 1924 _____ 5.5" 2018 __ 4.5" 1883 __ 3.0" 1885 Mar 28-Apr 3 ______ 10.0" ___________ 1915 _____ 8.5" 1924 __ 5.5" 2018 __ 4.5" 1883 __ 3.0" 1885 Mar 29-Apr 4 ______ 10.2" ___________ 1915 _____ 8.5" 1924 __ 5.5" 2018 __ 4.5" 1883 __ 3.0" 1885 Mar 30-Apr 5 ______ 10.2" ___________ 1915 _____ 8.5" 1924 __ 6.5" 1944 __ 5.5" 2018 __ 4.5" 1883 Mar 31-Apr 6 _______10.2" ___________ 1915 _____ 8.5" 1924 __ 6.5" 1944 __ 5.5" 2018 __ 3.3" 1938 Apr 1-7 _____________10.2" ___________ 1915 _____ 8.5" 1924 __ 6.5" 1944 __ 6.4" 1938 __ 5.5" 2018 __ 4.0" 2003 __ 3.0" 1896 Apr 2-8 _____________10.2" ___________ 1915 _____ 6.5" 1944 __ 6.4" 1938 __ 5.5" 2018 __ 4.0" 2003 __ 3.0" 1896 Apr 3-9 _____________10.2" ___________ 1915 _____ 6.5" 1917,1944 __ 6.4" 1938 __ 5.0" 1907 __ 4.0" 2003 __ 3.3" 1916 __ 3.0" 1896 Apr 4-10 ____________ 9.6" ___________ 1982 _____ 6.5" 1917,1944 __ 6.4" 1938 __ 5.0" 1907 __ 4.0" 2003 __ 3.3" 1916 __ 3.0" 1896 Apr 5-11_____________ 9.6" ___________ 1982 _____ 6.5" 1917,1944 __ 6.4" 1938 __ 5.0" 1907 __ 4.0" 2003 __ 3.3" 1916 __ 3.0" 1896 Apr 6-12 ____________ 9.6" ___________ 1982 _____ 6.5" 1917 __ 6.4" 1938 __ 5.0" 1907 __ 4.0" 2003 __ 3.3" 1916 __ 3.0" 1896 __ 2.5" 1918 Apr 7-13 ____________ 9.2" ___________ 1875 _____ 6.5" 1917 __ 5.0" 1907 __ 4.0" 2003 __ 3.3" 1916 __ 3.1" 1938 __ 2.6" 1918 __ 2.5" 1896 Apr 8-14 ___________ 10.0" ___________ 1875 _____ 6.5" 1917 __ 5.0" 1907 __ 3.3" 1916 __ 2.6" 1918 Apr 9-15 ___________ 10.0" ___________ 1875 _____ 6.4" 1917 __ 5.0" 1907 __ 2.6" 1918 Apr 10-16 __________ 10.0" ___________ 1875 _____ 2.6" 1918 Apr 11-17 __________ 10.0" ___________ 1875 _____ 2.6" 1918 Apr 12-18 __________ 10.0" ___________ 1875 _____ 3.0" 1887 __ 2.2" 1918 Apr 13-19 __________ 10.0" ___________ 1875 _____ 3.0" 1887 Apr 14-20 ___________ 3.0" ___________ 1887 _____ Apr 15-21 ___________ 3.0" ___________ 1887 _____ Apr 16-22 ___________ 3.0" ___________ 1887 Apr 17-23 ___________ 3.0" ___________ 1887 Apr 18-24 ___________ 3.0" ___________ 1887 _____ 0.5" 1883 Apr 19-25 ___________ 3.0" ___________ 1875 _____ 0.5" 1883 Apr 20-26 ___________ 3.0" ___________ 1875 _____ 0.5" 1883 Apr 21-27 ___________ 3.0" ___________ 1875 _____ 0.5" 1883 Apr 22-28 ___________ 3.0" ___________ 1875 _____ 0.5" 1883 Apr 23-29 ___________ 3.0" ___________ 1875 _____ 0.5" 1883 Apr 24-30 ___________ 3.0" ___________ 1875 _____ 0.5" 1883 Apr 25-May 1 ________ 3.0" ___________ 1875 Apr 26-May 2 ________ 0.5" ___________ 1874 Apr 27-May 3 ________ 0.5" ___________ 1874 Apr 28-May 4 ________ 0.5" ___________ 1874 Apr 29-May 5 ________ 0.5" ___________ 1874 Apr 30-May 6 ________ Tr _____________ 1946, 1956 May 1-7 ______________ Tr _____________ 1946, 1956 May 2-8 ______________ Tr _____________ 1946 May 3-9 ______________ Tr _____________ 1946, 1977, 2020 May 4-10 _____________ Tr _____________ 1946, 1977, 2020 May 5-11 to 9-15 _____ Tr ______________ 1977, 2020

NAM placed on free agent waiver list, can't phase the levels like most other players.

A stronger 500mb low on the same trajectory would probably work, giving the coastal more of a dominant role, and the NAM was hinting at that outcome. Its later onset time would also mean slightly lower surface temps at p onset. There is plenty of time left for trends in the right direction. The actual outcome of the Atlantic storm will play a role, I would only consider the current 48h depictions for that to be moderately reliable. Also thinking CHO likely to be all or nearly all snow, the warm intrusion seems more likely to flow into the Potomac and MD than noVA.

Looks incrementally better, capture is just about over DCA, 500 mb low track has shifted slightly southeast. Good signs.

06z NAM ends at 84h position se GA while 90h 00z GFS was on SC coast. Slower by at least six hours, similar intensity. Not a lot of difference in high positions, both near ALB, both about 1030 mbs. Implications for M/A outcome not all that clear. Lots of time left for possible improvements to track, no time for panic yet.

Snow to sleet, briefly rain (possible thunderstorms), back to sleet and blowing snow to end, snow gradient from 4-6" southern Queens to 8-12" Yonkers-White Plains area, heavier further up the Hudson valley and into n NJ. Or just all snow if this goes back to a full coastal scenario. Strong east winds during snow and sleet, later strong west to northwest winds during wrap-around blowing snow. Brief temp spike to 40 F possible.

At a minimum this storm will probably add 3" to BWI and DCA, 6" to IAD and 1-2" to RIC but median of possible outcomes more like 5-6" at BWI, 4-5" at DCA, 8-10" at IAD, and top end would be 12-15 inches at all three in which case RIC would likely have 5" -- and that's going to eliminate three quarters of the field. With all of Feb and Mar to go. Which means add another inch

That 18z GFS run has very fast occlusion over central NJ which could mean a wild ride for NYC - I wonder if eventually this will turn into a very dynamic system with a deeper center than currently advertised, and still thinking it could be double centered, with features of a wintry nature that might mirror some of those late summer rainstorm features of locally intense bands oriented NW-SE near the Hudson valley. Potential for some very high snowfall totals in parts of PA and NY state, right now it seems like NYC could see a bit of everything but even so, a strong gradient of snow totals across the northern portions of the metro region. For a location like JFK, perhaps 5-8 inches snow, followed by sleet, brief rain back to sleet and then blowing snow as wrap around hits, another inch or two with that. Temps 25-28 during the initial snow, 30-33 mid-storm, spike to 42 then back down into low 30s. But I suspect this may evolve into more of a classic coastal as the GFS backtracks further. Maybe ICON had the best solution after all. Would not be surprised to see this into the 970s by event time.

I wouldn't say the low tracks northwest, it may be more that it explodes into a stacked low over PA and remnants of the coastal are shattered along the occlusion, that PA low is the weak inland component exploding due to the energy peak hitting the circulation. This could be another big snowfall event for BGM as well as anything else it does, remember last winter's 40" storm up there? And Albany had almost three feet as well. Think it was around a week before Xmas. Not implying the storm will be diminished for M/A region just another thing it does. If we combine the NAM further south at 84h, the ICON's history of a strong coastal, and this, we start to see how the eventual solution could be a more dynamic storm. I'm actually sitting in the midst of its developmental stage here and it is far from impressive, but diving energy that rounds a trough can do a lot to overcome that. Anyway, this looks high impact for noVA, w MD and much of PA into upstate NY, could be very hard to forecast around NYC as it looks like the thermals will spike rapidly and fall back just as fast.