RodneyS

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 0.2 0.4 1.0 0.9 0.0 0.7 1.8 2.0 1.5

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 1.0 1.3 2.0 1.5 0.1 1.2 1.4 3.0 3.6

Time for an update. Not much has happened to change the picture during the last two years. In 2019, August 12th had no precipitation at DCA, whereas August 15th had 0.20 inches. This year, August 12th had 0.26, whereas August 15th had 0.21. So the updated 150-year totals for DC, 1871-2020, are: August 12: 43.69 inches total; 21 days with a trace, 55 days with measurable, 12 days with at least an inch, 5 days with 2+ inches. August 15: 12.86 inches total; 16 days with a trace, 49 days with measurable, 5 days with at least an inch, no days with 2+ inches.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 0.9 1.3 2.2 0.9 0.0 -0.4 1.5 2.7 0.3

DCA recorded 28 90-degree-plus days this month, breaking the DC record of 25 set in July 2011. However, the longest streak at 20 days fell one-day short of the 1980 and 1988 record streaks of 21 days. Also, the July 2020 average temperature of 83.9 at DCA fell short of the July 2011 record average monthly temperature of 84.8, as well as the July 2012 average of 84.0.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 1.8 2.2 1.2 2.8 -0.8 1.2 3.1 0.7 -0.8

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 1.1 0.7 1.3 1.9 0.6 1.0 3.9 2.2 -0.5 99 98 97 96 99 103 98 118 93

Based on the metric I was using, 1917 wasn't quite as cold as this year in DC, with an average maximum temperature of 63.8 during April 14-May 13. However, May 1917 maximums averaged only 68.8, 4th coldest of all time. And the overall average May 1917 temperature was only 59.6, just 0.4 degrees above the all-time coldest DC May, which was 1907.

In response to a comment on the Capital Weather Gang webpage arguing that we had a normal Spring, I posted this reply at https://www.washingtonpost.com/weather/2020/05/13/warm-weather-arrive-abruptly-east-this-week-may-just-be-tease-some: I wouldn't exactly call this Spring normal, particularly for the last 30 days. The maximum temperature at DCA during April 14-May 13 averaged 63.6 degrees, the 6th coldest all-time in DC for that period and the coldest since 1882, which averaged 62.2. The coldest all-time was 1875, which averaged 60.8; and the warmest was 1985, which averaged 79.0.

April 2020 at DCA averaged 55.3 degrees -- the same as the 1871-2019 historical average. However, precipitation at 6.30 inches was double the DC April historical average of 3.15 inches. In fact, it was the 7th rainiest April in DC history, with the rainiest being 9.13 inches in 1889.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA -1.7 -1.7 -1.2 -2.4 -0.3 1.6 3.0 3.4 1.4

I just posted this on the Capital Weather Gang webpage, in response to Ian Livingston's article at https://www.washingtonpost.com/weather/2020/04/28/pm-update-some-more-showers-tonight-much-warmer-wednesday Today marked the 15th consecutive day at DCA without a 70+ degree reading. The only other April 14-28 period where that happened in DC weather history was 1875. However, as Ian notes, the current run appears over, as tomorrow is forecast to be at least 70. In 1875, the run ended one day later, on April 30th, with a reading of 72. Still, there is a big difference between these two Aprils. April 1875 averaged only 48.0 degrees, the second coldest April in DC history, whereas this April has averaged 54.8 so far, only slightly below the 1871-2019 historical April average of 55.3. By the way, 1874 was the coldest April in DC history, at 47.1, and the only April day that reached 70+ that year was the 15th, at 72 degrees.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 1.8 1.5 1.2 0.7 2.8 4.5 -0.2 -0.2 -1.9

If anyone had gone with zeroes across the board, they would finished second, with a 6.8 inch departure, compared to Prestige's 3.6. Congratulations to him for leading wire-to-wire. I'm afraid that I am not available to run any contests, but look forward to participating in this contest again next season.

Eight years ago today, I posted on this thread -- http://www.americanw...h-on-record-dca: "The final numbers for the 2011/12 astronomical and composite winters are 45.9 and 45.6 degrees, respectively. Thus, the record for the warmest astronomical winter was broken by 2.2 degrees and the record for the warmest composite winter was broken by 1.6 degrees. When the astronomical winter warm record was last broken (in 1989-90), it was only by 0.2 degrees, and when the composite winter warm record was last broken (in 2001-02), it was only by 0.9 degrees." This season, the astronomical winter (December 21-March 20, on average) averaged 45.5 at DCA , and so it fell only 0.4 degrees short of 2011/12. And the composite winter (December 1-March 20, on average) averaged 44.6 at DCA, and so it fell 1.0 degree short of 2011/12. Both averages are good enough for second warmest in DC history.

Congratulations to you and the rest of the Top Five, as there was a big gap between the Top Five and the rest of the field.

Barring a Palm Sunday 1942 type of event -- https://instaweatherinsights.wordpress.com/2007/03/28/palm-sunday-snowstorm-of-1942 -- it appears that only Dr. Dews was conservative enough (for Richmond) to nail the snow total at any of the four locations. Even our 99% certain winner, Prestige Worldwide, went too high at each location.

February 2020 averaged 43.8 degrees at DCA, with the meteorological winter there at 42.8 degrees, each 7th on the all-time DC list, although February 1984 also averaged 43.8.

DCA_NYC_BOS __ ORD_ATL_IAH ___ DEN_PHX_SEA 4.6 3.7 4.0 4.2 2.2 3.0 2.6 1.8 0.0

I have now done some additional analysis that shows that in several other eastern cities January temperatures during the most recent 30 years have peaked on or about January 13th and bottomed on or about January 21st: Raleigh-Durham: 46.9 vs 37.7 degrees Richmond: 43.6 vs 34.0 degrees Philadelphia: 38.4 vs 29.3 degrees New York: 37.3 vs 28.9 degrees Boston: 34.1 vs 26.2 degrees Portland: 26.4 vs 19.5 degrees

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 4.6 4.2 4.0 2.7 3.8 3.4 -2.5 -1.7 0.8

I don' t know about the deep low on March 1-2, 1914, but DC recorded only a trace of snow on each of those days. However, it recorded 0.3 inches on March 5th, 4.0 on March 6th, 0.7 on March 7th, 5.3 on March 11th, 5.2 on March 20th, and 3.8 on March 22nd. What is remarkable is how similar that winter was to 1959-60 in terms of no measurable snow falling until February 13th, and then way above average after that. This year, DCA has recorded on a percentage basis infinitely more snow so far than those two seasons: 0.6 inches divided by zero.

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.