RodneyS

June 28-July 8, 2012 vs. July 15-20, 2013 Heat Waves June 28-July 8, 2012 Avg Max: 99.5 Avg Min: 76.4 Avg Dly: 88.0 July 15-20, 2013 Avg Max: 95.5 Avg Min: 79.3 Avg Dly: 87.4 So, last year's heat wave lasted five days longer and featured record-breaking average maximum and average daily temperatures for an 11-day period. This year's heat wave's claim to fame was the highest six-day average minimum temperature,* with the last five days each reaching at least 80 -- breaking the record of four consecutive 80+ minimums set July 21-24, 2011. Also, there was one other significant difference: Last year's heat wave featured the derecho on the second day, causing many folks to be without power for one of the hottest stretches in DC history. This year, happily, power outages were minimal. * I just discovered that July 19-24, 2011 averaged almost 2 degrees higher, at 81.2. However, only four of those days featured an 80+ minimum.

Final June total of 9.97 inches at DCA fell well short of record, but did crack top twenty rainiest months in DC history, at # 19.

Correct, and it's interesting to note how much rainfall varies in this area during extreme tropical events. Here are the all-time monthly precipitation records for any month in DC, Baltimore, and Dulles, with the other one or two locations shown for perspective: September 1934: 17.45 inches in DC vs 12.41 in Baltimore August 1955 18.35 inches in Baltimore vs 14.31 in DC June 1972 18.19 inches at IAD vs 11.53 in DC and 9.95 in Baltimore

Probably so, but it's interesting to note that during the first 10 days of June 2006, DCA recorded just 0.24 inches.

It's actually not surprising that, after last year's record warmth, this year would produce sharp declines. This year's May average of 66.7 is still 0.7 degrees above the 1981-2010 May average and 1.4 degrees above the historical (1871-2013) May average. And this year's spring average of 56.5 is only 0.1 degrees below the 1981-2010 spring average and 1.4 degrees above the historical spring average.

May 2013 at DCA is finalized at 66.7 degrees, the 45th warmest of all-time, vs last year's 71.4 degrees, the 3rd warmest. This year's meteorological spring (March, April, and May) at DCA is finalized at 56.5 degrees, the 43rd warmest. That compares with last year's record-breaking spring average of 62.2 degrees. The 5.7 degree decline from one spring to the next is the second greatest in DC history, topped only by the 5.8 degree decline between 1991's 60.0 degrees and 1992's 54.2 degrees.

Interesting contrast between the Reagan and Dulles Airport records today. Reagan hit 91, beating the old DC record by only two degrees, but that was the warmest temperature in DC this early in the season since April 6, 1942, when the old Weather Bureau station at 24th and M Streets recorded that same temperature. Dulles, on the other hand, hit 89, shattering the old record by 11 degrees, but that was the warmest temperature there this early in the season only since April 7, 2010, when 91 was recorded. Further, Dulles recorded 93 on April 6, 2010.

Both DCA and IAD beat their three consecutive season low snow totals. At DCA, the most recent three seasons total 15.2 inches, compared with the previous record of 18.4 inches set in the three seasons ending in 1999. And, at IAD, the most recent three seasons total 29.0 inches, compared with the record of 29.2 inches set in the three seasons ending in 2009. So, at IAD, the previous three-year low total occurred immediately prior to the record 73.2 inches in 2009-10. Therefore, with a new three-year low total established this year, numerology tells us that next year . . . that's correct -- will set a new four-year low.

Slight change this year, with March 2013 at DCA finishing at 43.8 degrees. The 13.0-degree decline equals the record set between 1946 and 1947, when the average temperature fell from 53.0 to 40.0. Perhaps the more interesting fact about March 2013 is that the average temperature was lower than December 2012's average of 45.3. The last time March was colder than the preceding December was 1959-60.

Incorrect assumption, and so here are the revised figures: DC still beat the old record snow minimum for two consecutive seasons, but only by 1.7 inches, and IAD now actually falls short of the two-year record minimum by 1.9 inches. So, at IAD, the record remains 14.5 inches during the winters of 2007-08 and 2008-09. DCA's 2012-13 snow total of 3.1 inches is the sixth lowest of 129 DC snow seasons, whereas IAD's 12.7 inches is the 13th lowest of 51 snow seasons.

Looks like DCA is finalized today at 1.4 inches, and so the 2-inch storm streak remains alive. However, the 1-inch or less in a single day streak ended today at 789 days.

Quite a difference between this year's and last year's astronomical winters (December 21st through March 20th) at DCA. Last year's average temperature of 45.9 degrees shattered the high record by 2.2 degrees. This year's average was only 40.4 degrees, still good enough for a tie for 29th on the all-time list, but 5.4 degrees below last year.

Thanks for the link, which inspired me to check the last three snow seasons at DCA and IAD. And, yes (again assuming that we're done for this season), they also easily broke the record low snow totals for three consecutive seasons: The new DC record for that period is 13.8 inches vs. the old record of 18.4 inches set 14 years ago, and the new IAD record is 24.9 inches vs. 29.2 inches set four years ago.

Assuming that we've seen the last of snow for this season, DC beat the old record snow minimum for two consecutive seasons by 3.1 inches, and IAD (at 8.6 inches this season and 3.7 inches last season) beat the old record (set four years ago) by 2.2 inches. There is nonetheless a big difference between DCA's and IAD's 2012-13 snow seasons: DCA's displaces last season's as the third lowest of 129 DC snow seasons, whereas IAD's is only the ninth lowest of 51 snow seasons there.

Much wetter, but only slightly colder. The two consecutive meteorological winters 1996-97 and 1997-98 at DCA averaged 42.0 degrees and 11.45 inches of precipitation. The two most recent meteorological winters there averaged 42.3 degrees and 8.32 inches of precipitation.

February 2013 appears to be finalized at 38.3 at DCA, making it 0.7 degrees below the 1981-2010 normal, and tied for the 56th warmest all-time. Quite a change from last February's 44.3, and enough to bring down the average 2012-13 meteorological winter temperature to 41.3, the 13th warmest. Last year's average meteorological winter temperature of 43.3 was the third warmest all-time, but DCA still managed to record half an inch more snow during December 2011 to February 2012 than during the last three months. Contrary to what you may think, however, the snow total of 3.5 inches during the last two meteorological winters does not break the all-time record. That honor still belongs to 1997-98 and 1998-99, which saw a total of only 3.0 inches of snow. Further, the meteorological winters of 1930-31 and 1931-32 also saw a total of only 3.5 inches of snow. However, March 1999 saw 8.7 inches of snow and March 1932 saw 4.0 inches. The two-year seasonal record minimum amount of snow in DC is actually 1996-97 and 1997-98, which saw 6.8 inches of snow. So, DCA must receive at least 3.3 inches of snow during the rest of this season to avoid the last two seasons setting the all-time record for snow futility.

January 2013 at DCA averaged 40.3 degrees, making it the 22nd warmest January in DC, compared with 40.7 last year (17th warmest). The December-January average was 42.8 degrees, making those first two months of the meteorological winter the 6th warmest, just behind last year's 42.9 for those two months (5th warmest).

If the 1981-2010 temperature normals for Reagan National Airport are taken at face value, DCA temperatures on average bottom out during January 12th-17th (at a mean of 35.7 degrees), then rise gradually (to 35.9 degrees on January 21st, 37.2 degrees on February 5th, and peak between July 12th-21st at 80.0 degrees). However, January daily temperatures during this period -- and even more so during the most recent 30 years, 1984-2013 -- appear inconsistent with those normals. During the past 30 years, the first 14 days of January at DCA have each averaged above the 1981-2010 normals, whereas January 19th-23rd have each averaged below those normals. This may be illustrated by comparing January 13th to January 21st average temperatures during the past 30 years at DCA, as well as looking at the historical DC temperature record for those two days and the coldest average day of the year. For the first 112 years of official DC daily temperature history -- 1872-1983 -- January 13th was the coldest January day, at 33.3 degrees on average; and January 21st was the second warmest January day, at 36.8 degrees on average. The January temperature peaked on the 22nd at 37.2 degrees on average during 1872-1983, with the annual mean temperature bottoming out on February 5th at 32.6 degrees on average. However, during 1981-2010, the mean temperature at DCA on January 13th was 38.7 degree on average, decreased sharply to an annual minimum of 32.2 degrees on average on the 21st, and rose about halfway back to 35.3 degrees on average on February 5th. Further, the disparity with 1872-1983 has widened during 1984-2013, with January 13th the warmest January day of this most recent 30-year period at 40.3 degrees on average, January 21st the coldest day of the year at 32.1 degrees on average, and February 5th the coldest February day (29 years through 2012) at 35.9 degrees on average. To recap, January 13th has gone from being the coldest January day at 33.3 degrees on average during 1872-1983 to the warmest January day at 40.3 degrees on average during 1984-2013 -- an increase of 7.0 degrees. January 21st has been the mirror image of January 13th -- going from the second warmest January day at 36.8 degrees on average during 1872-1983 to the coldest day of the year at 32.1 degrees on average during 1984-2013 -- a decrease of 4.7 degrees. Finally, February 5th has gone from being the coldest day of the year at 32.6 degrees on average during 1872-1983 to merely the coldest February day at 35.9 degrees on average during 1984-2012 -- an increase of 3.3 degrees. The increase in temperature on February 5th between these two periods has been pretty clearly within the range of what would be expected in an era of warming temperatures, as February temperatures 1984-2012 have been 2.9 degrees warmer on average than during 1872-1983. But what about the January temperature record, and in particular, the contrast between January 13th and 21st during these two periods? Is that merely an aberration, or is a more fundamental change taking place that is not reflected in the current temperature normals?

It was on just a few minutes ago (about 6:15 P.M.), complete with the erroneous graphic that claimed the drought is now 780 days. I'm guessing it will be on again this evening.

You just made the big-time, with the DC snow drought featured on the Weather Channel. Of course, they managed to transpose a digit, claiming it's now 780 days, rather than 708. And they didn't credit your research, the way Ian did in his Capital Weather Gang story. But, if Al Roker picks up the story tomorrow morning, can fame and fortune be far behind?

Interesting Capital Weather Gang article about how unrepresentative of the DC area DCA's minimum temperature are -- http://www.washingto...weather_latest. Nonetheless, when apples to apples comparisons are made for DCA, average temperatures there have been generally increasing since National Airport became the official DC measuring station in 1945, and minimum temperatures have been increasing faster than maximums. For example, 2012's average minimum of 52.9 F beat 1991's average minimum of 51.2 F by 1.7 degrees, whereas 2012's average maximum of 70.2 F beat 1991's average maximum of 69.4 F by only 0.8 degrees. Prior to National Airport becoming the official DC measuring station, the warmest year on record in DC was 1921, with an average minimum of 48.6 F and an average maximum of 67.5 F. So, relative to that year, 2012's average minimum was 4.3 degrees warmer and 2012's average maximum was 2.7 degrees warmer. Does anyone care to speculate on what those increases would be if the official measuring station had not changed in 1945?

December was nearly as warm as November at DCA, at 45.3 degrees. That made it the sixth warmest December in DC (warmest was 45.6 in both 1889 and 1984), and the 1.3 degree decline from November was the seventh smallest (smallest was 0.1 decline in 1923 from 45.1 in November to 45.0 in December). Needless to say, the annual average warmest record of 60.19 degrees in 1991 was shattered, at 61.49 degrees in 2012.

With November now finalized at a below normal 46.6 degrees at DCA, the January-November 2012 average is 63.0, breaking the 2010 first eleven warmest months record by 1.0 degree. To break the annual average warmest record of 60.19 degrees set in 1991 requires a December DCA average temperature of 29.5 degrees or higher. Based on forecasts, that looks to be a sure thing, although as recently as 1989 the December DCA average was only 27.9. The all-time coldest December average temperature in DC is 27.1 in 1876.

I don't have the complete list, but I posted on the Hurricane Sandy thread that the highest wind gust ever recorded at DCA was 98 miles per hour during Hurricane Hazel on (Friday) October 15, 1954; see http://www.washingto...1ZtdJ_blog.html

January-October 2012 averaged 64.6 degrees at DCA, breaking the 2010 first ten warmest months record by 1.4 degrees. Further, the most recent 12 months, November 2011 to October 2012, broke the five-month-old twelve consecutive warmest months record of 61.8 set during June 2011 to May 2012 by 0.2 degrees, averaging 62.0 degrees.