Roger Smith

At the end of the day, the weather can let us down, just like politics or life in general, but then we have this: so to the GFS, the Euro, the GEM, NAM and the rest I say Beethoven, Mozart, Bach, Schubert and Mendelsohn ... deal with it. Fix up your craft and reach the stars.

One reason for optimism is that the last storm shifted west relative to much of the guidance and NAM had a better handle on that. So if the same thing happens this time, it's a better outcome than many of these recent model runs would have you believe. I still think that very warm Atlantic is going to play a role and that has to be a factor in favor of a coastward shift.

Predict the temperature anomalies (F deg) relative to 1991-2020 normal values for DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA Contest deadline before late penalties 06z Tuesday Feb 1st 2022.

There's a 1012 mb low in south central NM. Nothing but E-NE winds ahead of it. That is probably a good sign. And wasn't the NAM the best model for the last storm that ended up going a lot further west than many other models were saying it would? Bet the Euro comes in with another rocking solution tonight. That warm Atlantic water is just sitting there waiting for its time to do battle. It argues for a west solution, tuck, and stall potential. http://www.spc.noaa.gov/exper/mesoanalysis/s15/sfcmap.pdf

GGEM snow potential is moderate rather than heavy, but better than GFS. Would say 3-6" DCA, 6-8" BWI-PHL on GGEM. 10-15" NYC and 20-30" New England. It is not a blockbuster storm but solid. However if the Euro-NAM blend proves more accurate then I would double most of those numbers (30-40" NE).

GGEM looks better though. Not following the GFS but closer to the NAM.

You would think with all those submarines the Germans would know about the warm water off the coast? This is why I think the storm will ride as far west as possible, the thermocline. I must hide now.

no more hot dogs for me since that run.

Just amazed at the potential from this storm if it follows the GEM evolution, that much rapid deepening with very cold air interacting with anomalously warm ocean temperatures suggests some very high snowfall totals are possible, perhaps March 1888 needs to be considered as part of analogue set (if there is an outcome like these model runs are suggesting). Think also there was a storm March 1-2 1914 that combined very low pressures, strong winds and heavy snow. That one from historical weather maps was a bit closer to NYC than the track of the Blizzard of 1888. My first call on this would be 18-24 inches NYC metro, 24-48 inches Long Island and parts of CT, 12-18 n NJ. Wind gusts 70-90 mph seem possible. This could create emergency situation for much of the region and most of New England. Still time for models to change but I see the nucleus of the storm already over UT, CO and WY.

It snowed at TLH in the formative stages of the Blizzard of 1899 so that Florida snow is not a bad sign. The only other snow I can recall in FL was in Jan 1977 during an epic cold spell. That being said, I could see this evolution changing run to run for quite some time, none of these moving parts look set, but there is plenty of cold air available and a recent history of deep upper lows tracking through the southeast, so given peak climo and the land-ocean gradient likely to exist, why not this sort of result?

Just about 250 years after the Washington-Jefferson storm and 100 years after the Knickerbocker.

If that 18z GFS is onto something, we have a long way to go yet.

Since you have already compared the DCA data to other U.S. locations I won't bother to crunch the numbers for NYC then. Just thinking about any possible cause for this, especially as it clearly was not a component of the climate before 1980. (it may have been for some interval in the past, will check on that). Also it seems to transfer across the Atlantic or occurs almost simultaneously on both sides of the Atlantic. That would point to an external source, if it were a teleconnection, you would expect a lag of several days. The slightly earlier pulse at Toronto is probably due to that city being further west and the effect likely has to do with waves coming in from the Pacific, so the direction of travel of these signals may be WNW-ESE. Perhaps there is a sympathetic response wave in the eastern Atlantic. I have noted in some of my research that a spike in temperatures in eastern North America often appears either simultaneously or within 3-5 days in the British weather data. There are numerous (non-random in frequency) examples of similar dates of warm and cold records. But it is not a guaranteed 1:1 relationship. For example, the 1936 heat wave in North America never showed any sign of transferring across the Atlantic at all. If it is an external signal, the only plausible place to look would be in the Sun-galaxy interactions. A solar-planetary tidal phenomenon, while plausible for rotating sectors of about this magnitude, would not stay centered on any given part of the calendar year. A Sun-galaxy interaction would do so. January 12-13 is roughly two weeks after the Sun has crossed the galactic equator and there does seem to be a bit of a temperature spike in late December, but what would cause a two week lag for this? Possibly it has some effect on the Pacific circulation which takes some time to organize a response to send downstream. It seems like a process like that should be more spread out at random over 2-3 weeks however. Anyway, continuing to think about this. Something happens in this recent era that did not happen routinely in the past. As you say, it is getting beyond the bounds of being "one of those things" that statistical variability can produce, and more towards a semi-permanent feature.

This is the same graph as above, with the 1840-1980 averages added. Of course that interval was generally a bit colder too due to climate change and urban heat island growth. However, the trends are much different with respect to the 12th spike in temperature: MEAN DAILY TEMPS (TORONTO CITY) red _ 1991-2021 ... blue _ 1981-2021 ... green _ 1840-1980 ... note that the 1840-1980 temperatures show basically a gradual decline interrupted by the "January thaw" signal.

In the Central England Temperature data, the period 12th to 14th Jan has become milder in recent decades while the 19th to 21st have become colder. For 1991-2020 averages, the 12th-14th were 5.2 C, 5.4 C and 5.2 C then the coldest day of the month is the 22nd (3.9 C). This is similar although less amplified than the signal you found. However for 1981-2010 the warmest interval was 19th-21st. This has disappeared from the data, and since the two intervals have twenty shared years (1991-2010), the differential represents a shift from the 1980s to the 2010s. This also seems in line with your findings if not directly overlapping them. For Toronto, which has data from 1840 to present, I found that averages in January followed a similar trend to what you've described. Will post this and edit in a graph as it's on a different device. This is a graph of mean daily temps (in C) for Toronto for both 1981-2021 and 1991-2021. It can be seen that there is a spike in mean temperature around the 12th, and considerably lower values around the 21st. So this phenomenon is not confined to DCA. I would expect that I will find it also in the NYC data that I have (looking at that next). Will speculate on a cause after thinking about it for a while. This 12th to 21st drop in mean temperature does not show up very prominently before 1980 and there was a "January thaw" signal in earlier decades that has a remnant in that smaller spike around the 23rd.

I will look at some of my data sets to see what happens at other locations in this time frame. Did you spot any other similar anomalies during the rest of the year? I will post my findings in a few minutes, I already have the averages available for various periods, just need to check them.

Final scoring for January 2022 Scoring in this table is based on final anomalies as shown. FORECASTER ____________DCA_NYC_BOS__east__ORD_ATL_IAH__cent_ c/e__DEN_PHX_SEA__west___ TOTAL Confirmed anomalies ___ -2.9 _-3.4 _-2.5 _______-4.6 _-0.3 _-1.0 ___________ -0.8 _+0.9 _-1.8 wxdude64 _______________ 58 _ 58 _ 92 __ 208 __ 62 _100_ 64__ 226 __ 434 __ 76 _ 84 _ 88 __ 248 ____ 682 Stormchaser Chuck ______ 92 _ 92 _80 __264 __ 58 _ 86 _ 80 __ 224 __ 488 __ 94 _ 68 _ 24 __ 186 ____ 674 wxallannj _________________54 _ 46 _ 66 __ 166 __ 52 _ 86 _ 68 __ 206 __ 372 __ 98 _ 88 _ 92 __ 278 ____ 650 so_whats_happening _____52 _ 44 _ 68 __ 164 __ 70 _ 82 _ 56 __ 208 __ 372 __ 88 _ 90 _100 __ 278 ____ 650 Tom ______________________40 _ 26 _ 42 __ 108 __ 46 _ 84 _ 98 __ 228 __ 336 __ 94 _ 96 _ 46 __ 236 ____ 572 hudsonvalley21 __________ 36 _ 30 _ 50 __ 116 ___64 _ 64 _ 38 __ 166 ___282 __ 98 _ 92 _ 88 __ 278 ____ 560 ____ Consensus __________ 36 _ 28 _ 46 __ 110 ___52 _ 72 _ 44 __ 168 __ 278 __ 94 _ 88 _ 82 __ 264 ____ 542 _____ Normal _____________ 42 _ 32 _ 50 __ 124 __ 08 _ 94 _ 80 __ 182 __ 306 __ 84 _ 82 _ 64 __ 230 ____ 536 BKViking _________________ 20 _ 14 _ 34 __ 068 __ 40 _ 70 _ 24 __ 134 __202 __ 98 _ 88 _ 70 __ 256 ____ 458 Roger Smith ______________36 _ 30 _ 40 __ 106 __ 28 _ 70 _ 30 __ 128 __ 234 __ 54 _ 70 _ 78 __ 202 ____ 436 DonSutherland1 __________ 30 _ 24 _ 52 __ 106 __ 60 _ 34 _ 30 __ 124 __ 230 __ 94 _ 76 _ 36 __ 206 ____ 436 RodneyS _________________ 22 _ 02 _ 22 __ 046 __ 18 _ 64 _ 40 __ 122 ___168 __ 86 _ 84 _ 94 __ 264 ____ 432 Scotty Lightning _________ 22 _ 12 _ 40 __ 074 __ 00 _ 64 _ 50 __ 114 ___ 188 __ 74 _ 92 _ 74 ___240 ____ 428 RJay _____________________ 22 _ 12 _ 30 __ 064 __ 38 _ 74 _ 20 __ 132 ___ 196 __ 84 _ 68 _ 64 __ 216 ____ 412 =========================================== EXTREME FORECAST REPORT _ DCA (-2.9) and NYC (-3.4) are wins for Stormchaser Chuck with lowest forecasts (-2.5, -3.0). _ BOS (-2.5) has ended up with a win for wxdude64 (-2.1) and a loss for Stormchaser Chuck (-3.5). _ ORD (-4.6) is confirmed to be a win for so_whats_happening (-3.1) with low forecast. _ ATL (-0.3) does not qualify as fourth coldest forecast has highest score. _ IAH (-1.0) is a win for Tom with coldest forecast (-0.9). _ DEN (-0.8) did not qualify with third and fourth coldest forecasts tied for highest scores. _ PHX (+0.9) did not qualify with fifth coldest forecast the highest score. _ SEA (-1.8) did not qualify for an extreme forecast as fourth coldest forecast is the highest score. Scoring summary after one month __ Stormchaser Chuck___ 2-1 so_whats_happening__ 1-0 Tom __________________ 1-0 wxdude64 ____________ 1-0 Five locations qualified for coldest and none for warmest. Best forecasts will appear in tabulated format next month You can check them in the scoring table (bold highlighted). Congrats to wxdude64 with top score for January.

Could over-perform, lots of cold air ready to undercut, good rates likely (12-15 : 1 ?), absence of actual low pressure may be putting some off, but 3-4" potential for all three airports and 5" locally southeast MD and parts of se VA. The trend is your friend.

I mentioned to some weather weenies in Toronto that this thread was open, and a sort of glazed look of delight mingled with apprehension came upon them.

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.