RodneyS

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.

We also shattered the low maximum record for October 8th at IAD by five degrees -- 51 today vs 56 in 2000. We just missed the record low maximum in DC, with a 55 degree reading at DCA. The DC record is 54, last recorded in 1910.

I just calculated that for the average 2012 temperature at DCA to fall to 1991's average of 60.2 degrees would require a negative departure averaging four degrees in October, November, and December. That, in turn, would make those three months the 22nd coldest fourth quarter of all time in DC, and the coldest since 1989, which featured a December that averaged 27.9 degrees -- tied for the second coldest all-time.

The beat goes on: January-September 2012 checks in at an average 65.0 degrees, breaking the 1991 first nine months record by 1.6 degrees.

To further update, January-August 2012 checks in at an average 64.1 degrees, breaking the 1991 first eight months record by 1.6 degrees.

And January-July 2012 checks in at an average 61.7 degrees, breaking the 1991 first seven months record by 1.7 degrees.

Not exactly breaking news, but the DCA 2012 First Half average temperature of 58.0 degrees easily broke the previous DC record of 56.4 set in 1991. June 2012 finished at 76.2, placing it in a tie for 23rd warmest on the all-time list. First Half precipitation, on the other hand, was the 7th lowest all-time, at only 13.12 inches. June 2012 finished at 2.38 inches, marking the 6th consecutive month of below normal precipitation at DCA.

Thanks. 71.6 for May 1944 is indeed consistent with the daily figures that I have for that month. I would guess that the difference between the old 70.8 figure and the new 71.6 figure for May 1944 is the difference between using the old Weather Bureau at 24th and M Streets NW or (Reagan) National Airport for the official numbers. Weather records have been kept at National Airport since July 1, 1942, but the last I knew it was not the official source until July 1, 1945. Has that now changed?

I think things are now finalized: May 2012 in DC checks in with an average temperature of 71.4 degrees, third on the all-time list behind 1991 (73.0) and 2004 (71.8). However, spring (March-May) 2012 easily shatters the all-time record, with an average temperature of 62.2 degrees, beating the 1977 record of 60.7 degrees by 1.5 degrees. Further, the first five months of 2012 averaged 54.3 degrees, beating the 1991 record of 52.3 degrees by 2.0 degrees. Finally, the most recent 12 months (June 2011 to May 2012) averaged 61.8 degrees, beating the two-month-old warmest 12 consecutive months record of 61.6 degrees set during April 2011 to March 2012.

At least for the last decade in DC. However, precipitation at DCA was below the 1871-2011 DC averages 12 out of 14 months during August 2001 to September 2002, with only 27.70 inches recorded during that period, versus an 1871-2011 average amount for those 14 months of 48.59 inches -- a deficit of 20.89 inches, or 43%. Further, there was a more significant drought in DC during November 1929 to April 1931. During those 18 consecutive months, precipitation was below the 1871-2011 averages in each month. During that period, a total of only 34.85 inches of precipitation were recorded, versus an 1871-2011 average amount of 59.29 inches -- a deficit of 24.44 inches, or 41%.

And now the warmest January-April average: 2012: 50.0 1990: 49.0 1976: 48.0 On the other hand, the March-April temperature increase of 1.5 degrees at DCA was the second smallest change on record in DC history and the smallest since 1907, when the temperature actually declined by 0.4 degrees between March and April. Also, assuming no rain before midnight at DCA, January-April 2012 precipitation will be only 7.46 inches -- the sixth lowest on record and the lowest since 1985's 7.09 inches. The all-time low was 6.28 inches in 1872. But then again, if you measure precipitation at DCA over the last nine months, it is 35.69 inches -- the 19th most on record from August to April. The record for those nine months was 44.88 inches from August 1934 to April 1935.

It's also worth noting that March 2012 was the third largest temperature anomaly relative to monthly historical DC averages, which date to 1871. The champ is still January 1950, which at 48.0 degrees was 12.8 degrees above the 1871-2012 January average of 35.2 degrees. Second is still February 1934, which at 24.6 degrees was 12.3 degrees below the 1871-2012 February average of 36.9 degrees. March 2012 checked in at 56.8 degrees, or 11.8 degrees above the 1871-2012 March average of 45.0 degrees. In doing so, it displaced January 1932 as third on the all-time list. January 1932 averaged 46.8 degrees, or 11.6 degrees above the 1871-2012 January average of 35.2 degrees.

That's a good one (although I don't think those airports existed then -- the temperatures were for the official measuring points in DC and Baltimore). I remember May 31,1991, when we almost broke the DC record for the earliest 100 degree reading, but came up a degree short.

I think a while back NOAA corrected the March 1945 average to 56.2, but we still broke the record.