Our region's extreme run

[RodneyS]

Same here- such a cool July and yet it still managed to burn up my lawn.

 

I think BWI is gonna break another record low tomorrow morning. Forecasted low is 56, which is also the record for tomorrow.

BWI got down to 55 this morning (July 30th) to beat the old record low by a degree. Dulles made it all the way down to 48 this morning to beat the old record low by 3 degrees. 

[RodneyS]

Pretty ho-hum historical average July 2014 temperature at DCA at just 0.4 degrees below the 1981-2010 normal.  IAD, however, was 2.5 degrees below that normal, and for the first seven months of the year its average temperature is 51.4 degrees -- fifth coldest of 52 years, and the coldest since 1984.  1970 was the coldest first seven months at IAD, averaging 50.5 degrees.

[RodneyS]

Pretty ho-hum historical average July 2014 temperature at DCA at just 0.4 degrees below the 1981-2010 normal.  IAD, however, was 2.5 degrees below that normal, and for the first seven months of the year its average temperature is 51.4 degrees -- fifth coldest of 52 years, and the coldest since 1984.  1970 was the coldest first seven months at IAD, averaging 50.5 degrees.

The first seven months at DCA this year averaged 56.5 degrees -- 5.1 degrees higher than IAD. That makes January-July 2014 at DCA only the 20th coldest during the 52 years of IAD's existence. In fact, the coldest first seven months at DCA during that period was just 11 years ago -- 2003 averaged 54.0 degrees there.  

[MN Transplant]

Great stats. Thanks! Has this departure from normal more or less replayed itself along the east coast?

 

[MN Transplant]

Thanks. Wow, those look like huge departures from normal. I would imagine anything over .5 to 1 degree either way is significant. One hell of a year. 

 

Yeah, we've had this awesome persistent negative anomaly over most of the continuous 48. (Dec-Feb followed by Mar-May)

 

 

 

 

[RodneyS]

Thanks. Wow, those look like huge departures from normal. I would imagine anything over .5 to 1 degree either way is significant. One hell of a year. 

DCA is an outlier for the mid-Atlantic, with a 2014 average monthly departure from the 1981-2010 January-July normals of only -0.6 degrees.  IAD's average monthly departure is -2.9 degrees.

[Bob Chill]

How does the conus anom map look since Feb 2013? It seems like there was a flip from a warm east since then. The upper mw has been really cool for a while now as well.

I don't miss the being in a microwave. It lasted long enough to think it was the "new normal". Nice to see a longer term trend of "evening sh!t out"

[RodneyS]

The first seven months at DCA this year averaged 56.5 degrees -- 5.1 degrees higher than IAD. 

 

This temperature differential to this point in the year is the 4th greatest between the two airports.  The greatest was 6.6 in 1976, followed by 5.33 in 1981, and 5.26 in 1975.  The smallest was 1.4 in 2009.  For the year as a whole, the greatest was 5.9 in 1976 and the smallest was 1.7 in 2009.

[PrinceFrederickWx]

July 2014 at BWI broke or tied more record lows than any other July (5 total), but still only finished tied for 17th coldest (along with 1904 and 2003). By comparison, the other recent cool July everyone remembers (2009), finished tied for 10th coldest, but only broke one record low.

 

The period from Jan-July 2014 was tied for the 10th coldest Jan-Jul period ever at BWI, along with 1888 and 1912.

[PrinceFrederickWx]

How does the conus anom map look since Feb 2013? It seems like there was a flip from a warm east since then. The upper mw has been really cool for a while now as well.

I don't miss the being in a microwave. It lasted long enough to think it was the "new normal". Nice to see a longer term trend of "evening sh!t out"

 

It seems like we were in a historically warm pattern (with occasional negative departures) from March 2010 to January 2013. Starting in Feb 2013 its been the other way around. I have no idea why though. It doesn't seem like its stopping anytime soon either.

[PrinceFrederickWx]

Interesting is the disparity in temps between BWI and DCA this year.

 

Normal (1981-2010) for calendar year is 55.1 at BWI and 58.2 at DCA, so BWI on average has been about 3.1 degrees colder. Top five years are below.

 

1981 - 4.4 degrees colder at BWI

2014 (so far)  - 4.3 

1980 - 4.2

1959 - 4.2

1973 - 3.6 

 

So its a very good chance that this will end up being the year where the average temps at BWI and DCA were the farthest apart ever.

[PrinceFrederickWx]

I'm all in for tracking cold records on my webpage now (never thought I'd be saying that in this region). I think we're going negative for August so a top 10 coldest year is still alive...

[PrinceFrederickWx]

6.14 inches of rain for BWI so far, making it the 2nd rainiest day so far. Previous 2nd place holder was 9/30/2010 with 6.02 inches. The all time recordholder is 7.62 inches on 8/23/1933

[PrinceFrederickWx]

BWI has not had a single above average day this month yet.

 

Coldest August on record watch (currently in 4th place).

[Ian]

Two recent climate pieces for CWG. The DC one isn't terribly notable to date other than last few yrs.

 

Dulles Airport just recorded its longest “heart of summer” cool streak on record
http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/08/18/dulles-airport-just-recorded-its-longest-heart-of-summer-cool-streak-on-record/

 

Summer 2014 in D.C.: 90-degree days running 40 percent below normal
http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/08/15/summer-2014-in-d-c-90-degree-days-running-40-percent-below-normal/

 

[PrinceFrederickWx]

Its looking like this Aug. will rank somewhere between 2nd and 4th coldest at BWI.

 

I was surprised to find that there was actually one time at BWI where Sept. was hotter than Aug. (1921) and one time where they were equal (1881). I mention this because I wonder if it will happen this year with the way the longer range forecasts are looking. Although in both the previous cases, it wasn't because Aug. was so cold (like this year) but rather because Sept. was so hot. 1881 was the hottest Sept. ever and 1921 was the 4th hottest.

[PrinceFrederickWx]

4th coldest August and tied for 7th coldest Jan. 1 - Aug. 31 period at BWI.

[RodneyS]

This temperature differential to this point in the year is the 4th greatest between the two airports.  The greatest was 6.6 in 1976, followed by 5.33 in 1981, and 5.26 in 1975.  The smallest was 1.4 in 2009.  For the year as a whole, the greatest was 5.9 in 1976 and the smallest was 1.7 in 2009.

Remarkable August 2014 temperature differential between DCA and IAD.  DCA averaged 77.7 degrees -- warmer than last August and only the 22nd coldest August there since 1963, when records began at Dulles.  IAD, on the other hand, averaged just 71.8 degrees -- the coldest since the record of 70.4 in August 1992, and the third coldest August ever there.  The 5.9 degree August 2014 differential between the airports was the greatest since that same differential in October 1997.  The greatest monthly differential between the airports was December 1975, at 7.3 degrees.

[Ian]

Counting today, 5 of 6 days to start September were 90+ at DC. Hasn't happened since 1980 when all 6 days reached that mark.

 

We may not torch as often anymore but we still torch well.

[RodneyS]

Counting today, 5 of 6 days to start September were 90+ at DC. Hasn't happened since 1980 when all 6 days reached that mark.

 

We may not torch as often anymore but we still torch well.

Also, the week of August 31-September 6 was the hottest seven consecutive day period of the year at DCA, averaging 84.7 degrees.  During the 2014 meteorological summer, the hottest week was June 27-July 3, which averaged just 81.8 degrees.  Eyeballing historical DC temperature records to determine which year had the latest hottest week, 1985 may be the champion.  September 4-10, 1985 averaged 84.3 degrees, which was hotter than the hottest meteorological summer week of August 10-16, 1985, at 82.6 degrees.  Also, in 1881, which is not only the hottest September in DC history, but also the only year in which September was the hottest month of the year in DC, September 3-9, 1881 averaged 82.8 degrees, which was slightly hotter than the hottest meteorological summer week of July 10-16, 1881, at 82.6 degrees.

[uncle W]

Also, the week of August 31-September 6 was the hottest seven consecutive day period of the year at DCA, averaging 84.7 degrees.  During the 2014 meteorological summer, the hottest week was June 27-July 3, which averaged just 81.8 degrees.  Eyeballing historical DC temperature records to determine which year had the latest hottest week, 1985 may be the champion.  September 4-10, 1985 averaged 84.3 degrees, which was hotter than the hottest meteorological summer week of August 10-16, 1985, at 82.6 degrees.  Also, in 1881, which is not only the hottest September in DC history, but also the only year in which September was the hottest month of the year in DC, September 3-9, 1881 averaged 82.8 degrees, which was slightly hotter than the hottest meteorological summer week of July 10-16, 1881, at 82.6 degrees.

 

Also, the week of August 31-September 6 was the hottest seven consecutive day period of the year at DCA, averaging 84.7 degrees.  During the 2014 meteorological summer, the hottest week was June 27-July 3, which averaged just 81.8 degrees.  Eyeballing historical DC temperature records to determine which year had the latest hottest week, 1985 may be the champion.  September 4-10, 1985 averaged 84.3 degrees, which was hotter than the hottest meteorological summer week of August 10-16, 1985, at 82.6 degrees.  Also, in 1881, which is not only the hottest September in DC history, but also the only year in which September was the hottest month of the year in DC, September 3-9, 1881 averaged 82.8 degrees, which was slightly hotter than the hottest meteorological summer week of July 10-16, 1881, at 82.6 degrees.

nice stats...What is DCA's hottest seven day periods of all time?...

[RodneyS]

nice stats...What is DCA's hottest seven day periods of all time?...

I believe that was just three years ago -- July 19-25, 2011 averaged 89.2 degrees at DCA, making it also the hottest week ever in DC history. July 2-8, 2012 gave that week a good run for its money, averaging 89.1 degrees.  July 7, 2012 featured DC's hottest average daily temperature ever at 93.5 degrees, with a high of 105 and a low of 82. 

[RodneyS]

The 2013 astronomical summer (June 21-September 23rd) did not produce as sharp a contrast, but nonetheless the average minimum of 69.7 degrees was good enough for 13th place all-time, versus the average maximum of 85.7 being only 47th warmest.  

With respect to overall temperatures, the 2014 astronomical summer at DCA was a virtual carbon copy of 2013, averaging a minimum of 69.5 degrees and a maximum of 85.8 degrees.  And, believe it or not, the overall average was identical no matter how many decimal points you carry it out -- 77.66 degrees to two decimal points, which is the 26th warmest in DC history.

[RodneyS]

Remarkable August 2014 temperature differential between DCA and IAD.  DCA averaged 77.7 degrees -- warmer than last August and only the 22nd coldest August there since 1963, when records began at Dulles.  IAD, on the other hand, averaged just 71.8 degrees -- the coldest since the record of 70.4 in August 1992, and the third coldest August ever there.  The 5.9 degree August 2014 differential between the airports was the greatest since that same differential in October 1997.  The greatest monthly differential between the airports was December 1975, at 7.3 degrees.

The beat goes on -- September 2014 averaged 73.9 degrees at DCA (2.9 degrees above the 1981-2010 normal), but only 67.5 at IAD (0.4 degrees below the 1981-2010 normal).  The 6.4 degree monthly differential is the greatest since that same differential in January 1984.

[Bob Chill]

Rodney, is DCA mostly widening the gap because lows? The location is at a serious disadvantage for radiational cooling. We had an unusual amount of good radiational cooling nights in Jul-Aug. Sept usually has them every year. 

 

The high temp differential in August and Sept was 3.68 and 4.5 respectively but the low temp differential was 7.98 and 8.27. I have no idea if this spread is historically normal. 

 

DCA also went through several large expansions in the late 90's and early 2000's. More buildings and more planes certainly doesn't help with temps. No matter which way you shake it, the location is almost perfect to be one of the warmest locales in the area (river, UHI on all sides, elevation). 

 

It would be interesting to compare some recent notoriously humid months in the area. Logic would say the gap would narrow. 

[PrinceFrederickWx]

Despite Sept. finishing 0.9 degrees above average, the period from Jan 1-Sept 30 was tied for 8th coldest at BWI.

[RodneyS]

Rodney, is DCA mostly widening the gap because lows? The location is at a serious disadvantage for radiational cooling. We had an unusual amount of good radiational cooling nights in Jul-Aug. Sept usually has them every year. 

 

The high temp differential in August and Sept was 3.68 and 4.5 respectively but the low temp differential was 7.98 and 8.27. I have no idea if this spread is historically normal. 

 

DCA also went through several large expansions in the late 90's and early 2000's. More buildings and more planes certainly doesn't help with temps. No matter which way you shake it, the location is almost perfect to be one of the warmest locales in the area (river, UHI on all sides, elevation). 

 

It would be interesting to compare some recent notoriously humid months in the area. Logic would say the gap would narrow. 

I don't have monthly minimum/maximum temperatures at Dulles at my fingertips, but I'll try and dig some out.   I do know that some recent months have not featured such extreme minimum and maximum temperature differentials between the two airports.  For example, in September 2011 the high temperature differential was 0.8 degrees and the low temperature differential was 3.6 degrees. Still 2.8 degrees greater on the low side, but that compares with 3.8 degrees greater on the low side this September.  

[RodneyS]

I don't have monthly minimum/maximum temperatures at Dulles at my fingertips, but I'll try and dig some out.   I do know that some recent months have not featured such extreme minimum and maximum temperature differentials between the two airports.  For example, in September 2011 the high temperature differential was 0.8 degrees and the low temperature differential was 3.6 degrees. Still 2.8 degrees greater on the low side, but that compares with 3.8 degrees greater on the low side this September.  

I have put together a decade-by-decade comparison of the average daily difference in maximum and minimum temperatures at Reagan and Dulles Airports.  Overall, since IAD opened in November 1962, DCA has averaged 1.4 degrees higher in maximum temperature and 5.8 degrees higher in minimum temperature.  Decade by decade it looks like this, with the first number the degrees by which the DCA average maximum has exceeded IAD's, and the second number the degrees by which the DCA average minimum has exceeded IAD's:

 

11-17-62/12-31-70:     2.1/5.3

1-1-71/12-31-80:         2.1/6.9

1-1-81/12-31-90:         0.8/6.4

1-1-91/12-31-2000:     1.0/5.7

1-1-2001/12-31-2010:  0.7/4.6

1-1-2011/09-30-2014:  1.9/5.6

[MN Transplant]

Good stuff, Rodney.

[RodneyS]

The beat goes on -- September 2014 averaged 73.9 degrees at DCA (2.9 degrees above the 1981-2010 normal), but only 67.5 at IAD (0.4 degrees below the 1981-2010 normal).  The 6.4 degree monthly differential is the greatest since that same differential in January 1984.

October 2014 averaged 62.9 degrees at DCA (3.4 degrees above the 1981-2010 normal), but only 57.0 at IAD (1.0 degree above the 1981-2010 normal). The 5.9 degree monthly differential brings the 10-month average differential to 5.4 degrees -- the second largest ever.  The largest differential was in 1976, which averaged 6.2 degrees through October and 5.9 degrees for the year as a whole.