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RodneyS

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About RodneyS

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  • Four Letter Airport Code For Weather Obs (Such as KDCA)
    KIAD
  • Gender
    Male
  • Location:
    Oak Hill, VA

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  1. RodneyS

    Mid-Atlantic winter 2018-19 snowfall contest

    Thanks for your voluminous stats work, Roger. By the way, the National Weather Service is currently showing 13.0 inches of snow for Richmond so far this season; see https://w2.weather.gov/climate/index.php?wfo=akq
  2. DCA _ NYC _ BOS __ ORD _ ATL _ IAH ____ DEN _ PHX _ SEA 3.2 3.5 2.8 4.9 3.4 2.2 1.9 -1.5 0.4
  3. RodneyS

    Our region's extreme run

    I can state with a high degree of confidence that the NWS does not smooth outliers in its 1981-2010 monthly and annual precipitation "normals" but rather uses the 1981-2010 averages, albeit with an unconventional rounding methodology. I state this because I have computed the 1981-2010 averages for each month at DCA, and they either match the DCA normals exactly for each month or they are rounded up by 0.01 inches. For example, if you average the January 1981-2010 precipitation totals at DCA, you get 2.803 inches. For some reason, NWS rounds this to 2.81, whereas using a conventional rounding methodology would result in 2.80. The annual 1981-2010 precipitation normal at DCA is shown as 39.74 inches, whereas I calculate 39.71 inches. However, there is no smoothing. So, for example, the August 1981-2010 normal at DCA is only 2.93 inches, which is rounded up from the 1981-2010 2.924 inch average. However, the historical August 1871-2018 DC precipitation average is 4.07 inches, and that is not taken into account. So, the 1981-2010 DCA August normal makes it appear that August is now a relatively dry month at DCA. But is it really, or was the 1981-2010 August average there an aberration? I would guess the latter, because beginning in 2011, August precipitation at DCA has averaged 3.77 inches -- closer to the long-term average than to the 1981-2010 average. In other words, you have to be careful with monthly precipitation normals because they may have little predictive value. Regarding annual precipitation normals, 30-year annual precipitation averages have ranged between 38.62 inches during 1961-1990 to 43.01 inches during 1871-2010, with an 1871-2018 average of 40.92 inches. So, again, using a 30-year annual precipitation "normal" can be misleading, as the most recent 30-years may be too short a period to conclude that anything other than a random variation is occurring.
  4. Congratulations to Roger, wxallannj, and especially overall winner Scotty for their impressive performances.
  5. RodneyS

    Our region's extreme run

    The final 2018 figures are 66.74 inches at IAD and 66.28 inches at DCA. The IAD total broke the 2003 record by 1.07 inches and the DCA total broke the 1889 record by 4.95 inches.
  6. RodneyS

    Our region's extreme run

    I've been away for a few days, but I just discovered that IAD broke the annual precipitation record on Friday, with 1.08 inches. It has now added 0.52 inches today, and so the current total is 66.73 inches, which exceeds the previous record by 1.06 inches. Both IAD and DCA figure to get a little more rain before midnight, and so I'll post the final 2018 totals tomorrow morning.
  7. RodneyS

    Our region's extreme run

    That's correct. And nothing all that promising on the immediate horizon -- AccuWeather is now projecting only 0.2 inches at Dulles through year end.
  8. RodneyS

    Our region's extreme run

    Again, for what little it may be worth, AccuWeather is currently projecting 1.53 inches of precipitation through year's end at Dulles, which would exceed the annual record there by 0.21 inches.
  9. RodneyS

    Our region's extreme run

    Timely question, as the IAD record is 65.67 inches, set in 2003. The total through today for 2018 is 64.36 inches. So, IAD is closing in on the record, but still needs 1.32 inches to break it.
  10. RodneyS

    Our region's extreme run

    AccuWeather's shorter term forecast was too low, and DCA broke the all-time DC record between 5:52-6:52 this morning. We now (as of 7:52 AM) are up to 61.40 inches of precipitation for the year vs the previous record of 61.33 inches set in 1889.
  11. RodneyS

    Our region's extreme run

    That's right -- not a done deal yet, especially with the big southern snowstorm staying to the south of DC. For what it's worth, AccuWeather is currently projecting 1.23 inches at DCA through month's end. However, only 0.28 inches is projected there through December 19th, and long-range precipitation forecasts are not exactly sure things.
  12. RodneyS

    Our region's extreme run

    November 2018 precipitation at DCA appears to be finalized at 7.57 inches, leaving the annual total of 60.46 inches there just 0.87 inches shy of the 1877 DC annual record. As 138 of 147 previous Decembers in the official precipitation history of DC have exceeded 0.87 inches, the odds of breaking the record are about 94%. Also, the second half of 2018 (July-December) DCA precipitation total of 35.28 inches has already broken the second half record of 33.55 inches set in 1878. Additionally, November 2018 average temperature at DCA appears finalized at 46.5 degrees, which is 3.1 degrees below the 1981-2010 normal, and the lowest average November temperature there since 1997.
  13. DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA 0.0 0.0 -0.6 0.7 -0.5 0.2 0.7 1.0 0.3
  14. RodneyS

    Our region's extreme run

    Not sure whether we're done for the day, but DCA already has recorded 0.44 inches of precipitation, bringing the November total to a DC record 7.55 inches. So, one record down, one to go -- DCA needs just 0.9 inches between now and the end of the year to break the annual record. Every December except nine in DC weather history has seen at least that much.
  15. RodneyS

    Our region's extreme run

    With today's 1.42 inches at DCA, the yearly total now stands at an even 60 inches -- still 4th all-time in DC, but now a strong likelihood to break the record. Even assuming no more precipitation in November, DCA would need only 1.34 inches in December to do so. In the previous 147 Decembers in official DC precipitation history, only 17 times has precipitation been less than that. Moreover, should DCA record only 0.08 inches more this month, that would break the all-time DC November record of 7.18 inches, set in 1877.
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