RodneyS

Here is an interesting historical fact about two prior DC winters. According to https://www.stormfax.com/elnino.htm, both 1913-14 and 1959-60 were ENSO neutral, just as this winter is. In the winter of 1913-14, no measurable snow fell in DC until February 13, 1914. Then a Valentine's Eve/Valentine's Day storm dropped 4.5 inches. That seemed to open the snow gates, as after that snow fell on an additional nine days through March 22, 1914, resulting in 28.6 inches of total snow for the season, of which a record 19.3 inches fell in March. In the winter of 1959-60, once again no measurable snow fell in DC until February 13th, and once again a Valentine's Eve/Valentine's Day storm dropped significant snow -- this time, 6.2 inches. And once again, that seemed to open the snow gates, as after that snow fell on an additional seven days through March 16, 1960, resulting in 24.3 inches of total snow for the season, of which 17.1 inches fell in March -- the second most ever -- second only to March 1914.

Time for another update. Once again this year at DCA, January 13th was much warmer than January 21st (48.5 degrees vs 31.5). So, for the most recent 30 years (1991-2020) at DCA, January 13th has averaged 41.6 degrees vs. 32.6 degrees on January 21st. A two-tailed T-Test shows that the odds of this being a random variation are less than 1 in 18,500. So, how will the NCDC handle this inconvenient fact when it calculates its new daily 30-year January temperature normals at DCA? The 1981-2010 January temperature normals there show temperatures bottoming out in mid-January, not January 21st. Further, even if the new DCA normals were to reflect a bottoming out on January 21st, the January 13th normal would likely be calculated using standard methodology as only 0.2-0.3 degrees higher than January 21st, and not the actual 9 degrees higher. Could someone at NCDC think way outside of the box and develop a radically new January temperature model, showing an annual thaw at DCA occurring around January 13th? And if s/he did, would s/he be given an award or fired? A thorny problem for NCDC, it seems to me.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 4.3 3.5 3.5 4.2 4.0 3.5 0.2 -1.7 0.3

Basically, but as Al Gore can tell you, there is a big difference between narrowly winning and narrowly losing.

Congratulations to wxdude64, who appears to have caught me at the wire when I bobbed my head. As always, the great majority of the credit belongs to Roger for organizing the contest and doing the bookkeeping. I'll give it another try in 2020, as long as Roger continues to do the heavy lifting.

It's remarkable how the early rainy DCA weekend pattern reversed during the last 31 weeks of 2019. During the first 21 weeks, 54% of weekend (Friday-Sunday) days had measurable precipitation vs. only 23% of weekdays. However, during the last 31 weeks, only 17% of weekend days had measurable precipitation vs. 41% of weekdays. Overall, 32% of weekend days had measurable precipitation vs. 34% of weekdays.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 0.7 -0.3 -0.3 2.6 0.7 2.4 0.3 0.4 0.6

Snowfall (11/23): DCA: 14.4" NYC: 25.1" BOS: 40.0" ORD: 35.0" DTW: 38.0" BUF: 100.0" DEN: 80.0" BTV: 88.0" SEA: 4.0"

BWI: 18.9" DCA: 14.4" IAD: 22.3" RIC: 10.4" Tiebreaker SBY: 6.4"

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA -1.3 -1.5 -0.8 -2.2 -2.1 0.1 -3.0 0.8 0.2

October 2, 2019 is in the record books for the hottest October maximum in DC, Baltimore, and Dulles. The respective maximums today were 98, 98, and 96. The previous record for DC and Baltimore was set on October 5, 1941, with respective maximums of 96 and 97. The previous record for Dulles was set October 9, 2007, at 94.

Minor correction for DCA: According to the Capital Weather Gang, September 2019 was the 3rd warmest and 4th driest September in DC history; see https://www.washingtonpost.com/weather/2019/10/01/washington-just-posted-its-rd-warmest-th-driest-september-record

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 2.3 1.2 0.3 2.3 2.6 2.9 0.7 0.6 -0.1

DCA _ NYC _ BOS _ ORD _ ATL _ IAH _ DEN _ PHX _ SEA 0.5 0.3 0.3 0.6 0.2 2.7 2.6 1.2 2.1

DCA _ NYC _ BOS __ ORD _ ATL _ IAH __ DEN _ PHX _ SEA 0.6 1.1 1.5 0.6 -0.3 0.6 1.0 1.0 0.8

You're looking good right now, while I'm headed from first to worst. By the way, I think Richmond hit 99 a couple of weeks ago, but that may look cool by the time the weekend ends.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH __ DEN _ PHX _ SEA 1.7 1.2 1.0 0.2 1.1 0.3 -0.6 0.4 1.8

Another DC precipitation record has just fallen. The previous DC record precipitation from the second half of one year to the first half of the following year was 62.16 inches, set during July 1885 to June 1886. With 0.62 inches already recorded at DCA tonight, the July 2018-June 2019 total there is 62.53 inches and counting.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH __ DEN _ PHX _ SEA 1.6 -0.1 0.4 -2.2 1.8 1.1 -0.9 -1.3 0.9 

BWI: 97 DCA: 98 IAD: 97 RIC: 98 HGR: 97

Most of us have complained at some point about rainy days seeming to occur more often on weekends than on weekdays. However, as the Capital Weather Gang recently noted, that has actually been the case this year in this area, assuming that the weekend is defined to include Friday; see https://www.washingtonpost.com/weather/2019/05/13/washingtons-wettest-days-history-inches-precipitation-have-fallen-past-year/?utm_term=.2bb2b4bf05c4. Specifically, through the first 19 weeks of 2019 at DCA, there have been 32 weekend days on which measurable precipitation has fallen vs. only 17 weekdays on which measurable precipitation has fallen. Moreover, because there are more weekdays than weekend days, the percentage of weekend days that have received measurable precipitation is 56% (32 of 57 days) vs. only 22% for weekdays (17 of 76 days). I just ran a two-tailed T-Test to determine the probability of this pattern occurring randomly, and it works out to be about one chance in 730. So, is this rainy weekend pattern here just a fluke, or is there more to it than that?

You're right that last April was relatively cool at DCA -- 54.9 degree average, which was 1.9 degrees below the 1981-2010 normal, and 7.5 degrees cooler than this year.

April 2019 averaged 62.4 degrees at DCA, second all-time in DC to the 63.8 recorded in April 2017. However, precipitation was only 2.24 inches -- the first below normal month at DCA since October 2018.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH __ DEN _ PHX _ SEA 3.2 0.0 -1.0 -1.5 3.1 1.1 -2.1 0.0 2.7 99 98 96 95 99 101 98 116 92

Congratulations to Olaf for his razor-thin victory over Stormpc, and many thanks to PFDKWx and Roger for doing the heavy lifting. As of late February, this contest could have gone a dozen different ways, as many pre-season forecasts were for a snowy March. However, the Snow Gods had other ideas, as they usually do.