RodneyS

Looks as though DCA's snow total yesterday was revised up to 0.9 from 0.8.

Tough sledding today for LittleVillageWx, with IUsedToHateCold now in command but WEATHER53 and Rest of Field lurking.

It looks like LittleVillageWx is going to hold on in Richmond, leaving WEATHER53 as his biggest challenger. If on Saturday BWI gets 0.6 inches, DCA gets 0.2 inches, IAD an inch or so, and RIC 0.1 inch, that puts WEATHER53 into the lead, with limited chances for any more snow this season. I would handicap the win probability as follows: LittleVillageWx 40% WEATHER53 35% IUsedToHateCold 15% Rest of Field: 10%

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ____ DEN _ PHX _ SEA 1.9 1.4 1.0 0.2 4.2 1.3 -0.6 0.3 -1.4

February 2022 at DCA did not come close to matching March 2014 in either of the above categories, but did manage to tie for 20th in official DC weather history in the first one, with 1802 months now in the books. That's still quite impressive, especially since it's the second highest in the last 35 years. You wil note that all of these months are in either January (4), February (6), March (8), or April (3): Highest Average Daily Change in Maximum Temperature March 2014, 12.42 February 1900, 12.11 March 1934, 11.94 March 1923, 11.71 March 1911, 11.58 January 1950, 11.32 March 1935, 11.29 February 1893, 11.04 February 1917, 10.96 March 1907, 10.90 February 1918, 10.89 March 1987, 10.87 April 1965, 10.83 April 1926, 10.77 January 1937, 10.74 March 1890, 10.74 April 1936, 10.70 January 1885, 10.65 January 1890, 10.65 February 1883 10.64 February 2022, 10.64

Thanks. In doing the search for largest daily average temperature declines, I found some inconsistencies in the data. At first, I thought the largest decline occurred on January 13, 1895, as the average temperature that day is listed as 9.0 degrees, with January 12, 1895 listed as 37.5 degrees. However, I then saw that the listed range on the 12th is 27 to 48, whereas the listed range on the 13th is 4 to 14. So, presumably what happened is that the Weather Bureau employee was at his station for a good portion of the day on the 12th, but left well before midnight with the temperature falling. By midnight, it may have been say, 20, but no one was there to record it. By the time he arrived on the 13th, the temperature was between 4 and 14, and so that's what he recorded, but the true range on the 12th would have been 20 to 48 (average 34), and the true range on the 13th would have been 4 to 20 (average of 12), and so the actual decline would have been only 22 degrees. I'm not sure when an automated temperature recorder was used in DC, but I believe all those anomalies occur prior to 1900.

I just posted this on the Capital Weather Gang page: Yesterday, DCA recorded the largest decline in daily high temperature this century. The high on Wednesday was 77, but it plummeted to 42 yesterday, for a decline of 35 degrees. That was the largest since December 23, 1998, when the high temperature declined by 39 degrees -- from 67 on December 22nd to 28 on December 23rd. The largest daily high temperature decline in DC history occurred on March 19, 1934, when the decline was 41 degrees -- from 78 on March 18th to 37 on March 19th. Also, yesterday's decline in daily average temperature of 22 degrees at DCA -- from 59.5 on Wednesday to 37.5 yesterday -- was the largest since February 9, 2017, when average temperature declined by 23.5 degrees -- from 62.5 on February 8th to 39 on February 9th. The largest daily average temperature decline in DC history occurred on January 29, 1934, when the decline was 28 degrees -- from 49.5 on January 28th to 21.5 on January 29th.

No, I was not up until after the snow had stopped. But the snow that had drifted over my car was amazing, particularly since nothing of that magniture had been forecast.

Since today is the 43rd anniversary of PD 1 (it actually began on Sunday afternoon and evening, February 18, 1979 with 4.7 inches of snow at DCA, but 14.0 inches fell on the morning of February 19th), I thought I would weigh in with my memory of that event. When I went to bed on Sunday evening in my apartment in Reston, Virginia, the forecast was for about 6 inches total. When I first looked out the window Monday morning at my apartment parking lot, I wondered if my eyes were deceiving me because I could not see my car! It was an electrifying moment that is still frozen in my mind. Many huge storms have come and gone since, but none have come close to matching that moment.

I thought you might jump into the lead and close out LittleVillageWx, based on RIC receiving 0.2 inches of snow with 0.04 inches of precipitation. But RIC reported only a trace of snow, and so LVWx is still the leader in the clubhouse.

January 2022 at DCA averaged 34.6 degrees, which was 2.9 degrees below the new 1991-2020 normal and 0.7 degrees below the 1871-2022 DC historical January average. It was also the coldest month at DCA since February 2015, which averaged only 30.3 degrees. Perhaps the most unusual aspect ot January 2022 at DCA was that the temperature there was 13.0 degrees below December 2021 -- the 5th largest decline in DC history for those two months, with December 2015 to January 2016 being the largest, at 16.3 degrees.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 0.7 0.3 0.7 -0.9 2.1 -0.7 -1.2 0.4 -0.8

RIC has now been revised to 4.3 inches.

It looks as if your hope was realized, assuming the latest snow totals are not revised. They show the following: BWI 13.3, DCA 12.3, IAD 11.4, and RIC 3.6. According to my calculation, that puts Little Village Wx in the lead with 8.0 vs 8.9 for you. However, the best you can do is finish with 5.1 and if you do, Little Village Wx will have 5.0.

I agree with your numbers and analysis. I still think something is wrong with last Sunday's IAD snow report, but I inquired of the lwx webmaster and never heard back.

Interesting analysis, Roger. I think this would be a great topic for a research-oriented meteorologist or PhD candidate to investigate.

Thanks, Roger. You will note above that in my post of February 20, 2020 I found a similar differential for six other cities in the Mid-Atlantic and Northeast US. There are other temperature differentials in that region during the course of the year, but the January 12-14 to January 20-22 differentials seem to be the most extreme by far.

Yes, although the differences are not quite as extreme. See below table, showing the average daily temperatures for January 12-14 combined and January 20-22 combined for the periods 1872-1983, 1984-2022, 1984-2013, 1991-2020, and 2014-2022: Period Jan 12-14 Jan 20-22 Difference 1872-1983 33.8 36.4 +2.6 1984-2022 39.3 33.6 -5.7 1984-2013 38.6 33.0 -5.6 1991-2020 40.5 33.7 -6.8 2014-2022 41.4 35.6 -5.8

Recent DCA temperatures offer more support for the "January 13th thaw-January 21st freeze" hypothesis, with the former day in 2022 averaging 41.5 degrees and the latter day averaging 23.0 degrees. The new NCDC 1991-2020 DCA normals now reflect a bottoming out of yearly temperatures in the January 18th-22nd time frame (at 37.0 degrees), with January 13th 0.2 degrees higher. The previous 1981-2020 normals showed a bottoming out right around January 13th (at 35.7 degrees), with January 21st 0.2 degrees higher. While this update is a step in the right direction by NCDC, it does not come close to reflecting the reality that during 1991-2020 at DCA January 13th temperatures averaged 9.0 degrees higher than January 21st (41.6 vs. 32.6). What convinces me that this differential is not merely a weird aberration, but rather an unexplained phenomenon, is that I first noticed it nine years ago, and it has continued. Specifically, during the last nine years (2014-2022), January 13th temperatures at DCA have averaged 6.7 degrees higher than January 21st (40.4 vs. 33.7). While this differential is not quite as high as during 1991-2020, my first calculation of the differential was for the period 1984-2013, when it averaged 8.2 degrees (40.3 vs. 32.1). So, the differential actually increased when that 30 year period was moved forward by seven years to 1991-2020, and while it has been somewhat lower during the most recent nine years, it is still for those nine years way beyond what would be expected if 1984-2013 had been an aberration. What is particularly interesting about all of this is that for the first 112 years of official daily temperature recordkeeping in DC (1872-1983), there tended to be a January 13th freeze and a January 21st thaw. Specifically, during that time frame, January 13th averaged 3.5 degrees cooler than January 21st. So, while for the most recent 39 years in DC, January 13th has averaged 7.0 degrees warmer than for the first 112 years (40.3 vs 33.3), January 21st has averaged 4.3 degrees cooler (32.5 vs 36.8). Why the big shift? Inquiring minds want to know.

I did not notice that the IAD snow amount tied a record yesterday, but something seems amiss if the reported hourly precipitation totals are accurate. By the way, today's IAD report shows an additional 0.2 inches of snow on 0.07 inches of precipitation, but that seems reasonable as the temperature was above freezing while that snow was falling. I just made an inquiry of the lwx webmaster, asking someone to look into yesterday's reported snow total.

Yes -- three times, including the first winter IAD was open. 1) 1962-63: DCA 21.4, BWI 19.6, IAD 20.6 (and RIC 16.9) 2) 1987-88: DCA 25.0, BWI 20.4, IAD 16.7 (and RIC 12.6) 3) 2001-02: DCA 3.2, BWI 2.3, IAD 2.6 (and RIC the champ at 8.7) By the way, I'm suspicious of the report of only 2.3 inches of snow at IAD yesterday. I live near there and there was quite a bit of light, flaky snow through late afternoon. IAD reported 0.42 inches of precipitation as of 6:52 PM, and I would have thought that the snow-precipitation ratio would have been at least 10-1, which would mean at least 4.2 inches of snow.

The temperature this morning at DCA made it down to 17 degrees, the lowest there since the 10 degree low of January 31, 2019.

Today's average temperature of 26 at DCA (high of 30, low of 22) was the lowest since February 1, 2019's average of 22 (high of 24, low of 20). The 30 degree high was also the lowest since Feb 1, 2019's high of 24.

It appears that the National Weather Service has reduced yesterday's snowfall at DCA from 2.7 to 2.6 inches and at IAD from 4.5 to 4.0 inches. If those revised figures hold, the current Top Three would be: olafminesaw 7.3, Rickin Baltimore 8.8, and WxWatcher007 and MN Transplant tied at 9.8. Unfortunately for WxWatcher007, he is still closed out by olafminesaw, but olafminesaw now has a little more of a cushion over MN Transplant. The latter would now need BWI to receive an additional 0.2 inches or more, IAD to receive an additional 4.1 inches or more, and RIC to receive an additional 0.5 inches or more to close out olfaminesaw. Alternatively, however, if RIC were to receive 1.6 inches more, olafminesaw would be closed out even if no more snow falls in the Washington-Baltimore area this season.

Another way of looking at this is that if snow at each of the four locations averaged about 85% of George BM's forecasts, snow would total 44.6 inches at BWI, 28.5 inches at DCA, 47.6 inches at IAD, and 24.6 inches at RIC. That would result in George BM's total departure being 26.0 and Idub23's total departure being 26.3. That would close out Idub23 because all of his departures would be negative, whereas all of George BM's departures would be positive. By the way, as good as olafminesaw has been in your contest over the years, he is on shaky ground this year because he already has negative departures at both BWI and DCA. If during the rest of the winter, BWI were to receive an additional 0.2 inches or more, IAD were to receive an additional 3.6 inches or more, and RIC were to receive an additional 0.5 inches or more, MN Transplant would close out olafminesaw.