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Our region's extreme run


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No trace of snow yet (through end of December) in DC. Only has happened in 01-02.

And that season DCA recorded a trace on January 6th.  Looking at the forecasts for next week, I would venture that record is about to fall.  However, DCA did manage to record 3.2 inches of measurable snow after that in January and February, which was 0.6 inches more than IAD.  :)  

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I can't believe DCA's only had a zero in Dec. only once. Its happened five times at BWI.

For some reason, in the late 1880s there was a gap in recording December snow in DC, but in all of those years at least a trace of November snow was recorded.  More recently, neither December 1972 nor December 1991 saw even a trace of snow at DCA, but traces were recorded there in November 1972 and November 1991.

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We need to get Sep.. 1881. That one should be next. :P

September 1881 was a pretty remarkable month, even though the average temperature of 78.2 was just 8.4 degrees above the 1871-2015 average of 69.8. For one thing, it was the warmest month of the year -- the only time in DC history that September has been warmer than June, July,and August.  Second, the maximum was 104 on September 7th -- tied for the 6th highest maximum in DC history, with the top five all occurring much earlier (between July 7-August 17).  It's also interesting to note that New Year's Day 1881 featured a minimum of minus 14 -- the second lowest in DC history.  So, the 1881 DC temperature range was 118 degrees -- greatest yearly range in DC history.  

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I just did the same thing with AccuWeather's DC projections and got 50.9 degrees.  That would not only shatter the December record of 45.6 degrees set in 1889 and tied in 1984, but also the all-time winter monthly record of 48.0 degrees set in January 1950.  

 

 

Weather.com now has forecasts through December 30th, and they're even warmer:  Average DC temperature Dec 1-30, 2015 = 51.3 degrees.

 

Impressive performance by Weather.com and AccuWeather in mid-December to pretty much nail the final December 2015 DCA average of 51.2.  That was 11.5 degrees above normal.  IAD, at 48.7, was 12.1 degrees above normal; and BWI, at 49.0, was 12.3 degrees above normal. 

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Looks like this should go down as the third warmest year on record for DC*.

 

2012    61.5
1991    60.2
2015    60.1
1998    60
1990    60

 

 

*you know the story

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Looks like this should go down as the third warmest year on record for DC*.

 

2012    61.5

1991    60.2

2015    60.1

1998    60

1990    60

 

 

*you know the story

When the DCA temperature sensor was replaced on August 10th, the psychro-dyne indicated that it was reading 1.7 degrees too high.  From that date forward,  the 2015 DCA-IAD average temperature differential shrunk from 5.06 degrees through August 9th to 3.45 degrees thereafter -- a reduction of 1.61 degrees.  So, I think that's a pretty good indication that the old sensor was reading about 1.7 degrees too high for many months.  If it was doing so beginning no later than New Year's Day 2015, the official yearly average temperature at DCA was inflated by a full degree by the faulty sensor.

 

However, there have very likely been past sensor issues at many sites -- including  DCA and IAD -- that received little attention or even went undetected.  For example, in 1976, the DCA-IAD annual temperature differential was 5.9 degrees, whereas in 2009 it was only 1.7 degrees.  Were the DCA and IAD sensors both accurate in those years?  So, I think the bottom line is that there was a problem with the DCA sensor for much of 2015, but attempting to adjust the numbers would open up a new can of worms.        

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When the DCA temperature sensor was replaced on August 10th, the psychro-dyne indicated that it was reading 1.7 degrees too high.  From that date forward,  the 2015 DCA-IAD average temperature differential shrunk from 5.06 degrees through August 9th to 3.45 degrees thereafter -- a reduction of 1.61 degrees.  So, I think that's a pretty good indication that the old sensor was reading about 1.7 degrees too high for many months.  If it was doing so beginning no later than New Year's Day 2015, the official yearly average temperature at DCA was inflated by a full degree by the faulty sensor.

 

However, there have very likely been past sensor issues at many sites -- including  DCA and IAD -- that received little attention or even went undetected.  For example, in 1976, the DCA-IAD annual temperature differential was 5.9 degrees, whereas in 2009 it was only 1.7 degrees.  Were the DCA and IAD sensors both accurate in those years?  So, I think the bottom line is that there was a problem with the DCA sensor for much of 2015, but attempting to adjust the numbers would open up a new can of worms.        

I agree with you on that, it is what it is. Just glad that they did a 'repair'. 

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Some more stats for BWI- this was the 2nd hottest November-December period. The top ten are listed below (in degrees). We came close to beating 1931, and there's a huge gap between 2nd and 3rd. You'll see some familiar recent years in this list too:

 

1931: 50.2 

2015: 50.0 

1946: 47.4 

1994 & 1941: 47.3 

1948: 46.9

1881: 46.6

1889 & 2011: 46.5

2001: 46.4

 

 

This was also the 10th wettest December at BWI, with 5.85"

 

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Some more stats for BWI- this was the 2nd hottest November-December period. The top ten are listed below (in degrees). We came close to beating 1931, and there's a huge gap between 2nd and 3rd. You'll see some familiar recent years in this list too:

 

1931: 50.2 

2015: 50.0 

1946: 47.4 

1994 & 1941: 47.3 

1948: 46.9

1881: 46.6

1889 & 2011: 46.5

2001: 46.4

 

 

This was also the 10th wettest December at BWI, with 5.85"

At DCA, it was no contest.  The November-December 2015 average temperature there was 52.5 degrees, which broke the 2001 record by 2.3 degrees.   In fact, starting in March 2015, I believe that DCA broke every composite DC monthly record ending in December 2015 -- ten records in all.  

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BWI already had a T in December, but if you're looking to track snow futility, the only January that ever had a 0 (not even a T) was 1937. Its still early, but we're at zero so far and no snow in sight.

 

Should probably mention that 1937 really delivered in February and March and was an above average winter though. :snowing:

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This is something else I've been thinking about but don't have enough info- how often do we go through an entire winter without at least one subfreezing high? Looking at some of BWI's hottest winters I can't find any that didn't have at least one for DJF except 31/32 (and even that winter had several in March). So I can't find any for DJFM at all. Although not having any subfreezing highs may not correlate to an overall torch winter, so I could be looking in the wrong places. I'd assume DCA has had several without.

 

Still early though- and BWI might get one next week?

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This is something else I've been thinking about but don't have enough info- how often do we go through an entire winter without at least one subfreezing high? Looking at some of BWI's hottest winters I can't find any that didn't have at least one for DJF except 31/32 (and even that winter had several in March). So I can't find any for DJFM at all. Although not having any subfreezing highs may not correlate to an overall torch winter, so I could be looking in the wrong places. I'd assume DCA has had several without.

 

Still early though- and BWI might get one next week?

If you define subfreezing as 31 degrees and below, such a failure last happened at DCA four winters ago. During the winter of 2011-12 (Weak La Nina), the low maximum was 32 on January 22, 2012.  The last winter at DCA in which the maximum exceeded 32 every day was the prior very strong El Nino in 1997-98, when the low maximum was 34 on March 11, 1998.    

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I figured not getting a subfreezing high in DJF (yes, I mean 31 and under) would be more common at DCA than BWI. Other than 31/32, the only other one I found was 97/98 (which was tied for 8th hottest winter overall). But there may be others, I can't check them all.

 

Some of BWI's hottest winters and the first subfreezing high they had (also included the super nino of 72/73 out of curiosity, even though its way down on the list at 25th hottest):

 

32/33 - 12/16 (23 degrees)

48/49 - 12/26 (25 degrees)

49/50 - 2/26 (31 degrees)

72/73 - 12/17 (30 degrees)

01/02 - 12/30 (30 degrees)

11/12 - 1/4 (31 degrees)

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Play around with this it has basically everything once you figure out how to pull it http://xmacis.rcc-acis.org

 

Will be adding this to my bookmarks, thanks!

 

I use this page a lot- you guys probably already have this, but if you don't, its got a lot of good data:

http://www.ncdc.noaa.gov/IPS/lcd/lcd.html

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  • 2 weeks later...

December wasn't hot.  It was warm.

And January wasn't cold.  It was cool.  However the 34.9 degree average temperature at DCA, while only 0.3 degrees below the January 1871-2016 DC average of 35.2 degrees, was 16.3 degrees below the December 2015 average DCA temperature of 51.2 degrees.  That decline represented the greatest one-month change from December in DC history.  The previous record-holder was January 1912, which declined 16.0 degrees from December 1911. (The largest increase was January 1990, which was up 15.7 degrees from December 1989.)

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  • 3 weeks later...

At 2:52 PM today, there was a temperature difference of 21 degrees between DCA (65) and IAD (44).  Not a record, as on both January 21, 1984 and January 28, 1987, the daily DCA/IAD minimums differed by 24 degrees (8 and minus 16, and 7 and minus 17, respectively). However, both of those occurred with significant snow on the ground at IAD and a clear night, and so radiational cooling was the source of the extreme difference in morning lows. Does anyone know what the record is for the largest afternoon difference, both at the same time and for the entire afternoon?  (IAD is still forecast to reach about 60 later today.)

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