Monday, March 12, 2012

Fun with Variance: If Record Warmth Were Record Cold

Yes, it takes an odd mind to think this way... but, if the shoe were on the other foot, and this record March warmth were instead record cold, what might it look like? Based on a nonsystematic, haphazard look at variance from average and extent to which records have been broken (and as they are expected to continue for this week), here’s one way the current record warmth and forecast might look. (Note: No statistical discipline has been applied to this purely fun, hypothetical forecast.)

Saturday, March 10: 14/-34
Sunday, March 11: 16/-13
Monday, March 12: 24/0
Tuesday, March 13: 20/-8
Wednesday, March 14: 16/-18
Thursday, March 15: 14/-3
Friday, March 16: 9/-10
Saturday, March 17: 12/-8
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18 comments:

  1. BillMarch 12, 2012 at 8:36 PM

    @Rigil Kent Wonder how you could cook up a statics-based random forecast based on our current and expected variance from average and records. (Obviously, this is an amateur's work!)

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    1. Rigil KentMarch 12, 2012 at 10:56 PM

      Would probably look at the standard deviation from the mean (the record that is the max of the distribution is incorporated into the std dev) so:
      we look at the distribution of all minimum temperatures for the date, calculate mean ( which we know from NWS although I would use all records and not just the last 30 years as NWS does) and std dev. we do the same for maxima.
      then we look at the actual temperature and if it is a record it will be by definition above average, we calculate how many st dev that record is from the mean, and we apply it in reverse subtracting the same amount from the mean. ( we do this for both min and max temp).
      Then we can apply a random fluctuation from the function that best matches the actual distribution of min and max temperature.
      repeat for each day...
      because of course the average temp of a date are not equidistant from the record, a record warm may not translate into a record cold and viceversa.
      but this approachis technically more appropriate than simply looking at the absolute difference in degrees from a mean or record because temperature is not a ratio measure. 0 degrees does not mean no cold at all, and 20 degrees is not twice as cold/warm than 40/10 degrees.
      I can do that... but I am out of town for a few days but i can doover the weekend, with the actual data available...

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    2. BillMarch 12, 2012 at 11:27 PM

      No doubt my approach was very crude (as well as inconsistent) and that yours is proper for all those reasons. If you're really bored, it might fun to see how it would play out in a proper statistical sense but unless you're curious, it's not worth bothering. What I'm more curious about is after this next week runs its course (and assuming several more records are broken), at what point can we consider this time frame as one of the unusual of all time. I guess that would be defined as how many standard deviations from the mean over whatever period of time we consider (perhaps from this past Saturday to next Saturday or Sunday, or however long the extreme weather lasts). I assume we won't tie the record for number of consecutive record-breaking days, but with a sustained period of way above normal, it could reach some truly rarified air.

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  2. Plymouth Weather LoverMarch 12, 2012 at 11:36 PM

    A late winter snowstorm would be nice. Anyone see one possible looking way out into late march?

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  3. MWMarch 13, 2012 at 10:05 AM

    Give it up,Plymouth Weather Lover,spring has sprung,don't you have spring fever with all this heat coming,nothing on the maps remotely close to flurries let alone a snowstorm.

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    1. AnonymousMarch 16, 2012 at 3:25 PM

      MW is right... I see where he's going. 130 degrees every day just around the corner!

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  4. bemakiMarch 13, 2012 at 11:42 AM

    @MW-

    Don't forget, this IS Minnesota. Crazier things have happened

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  5. Disco80March 13, 2012 at 4:11 PM

    Paul Douglas asked today about highs 70 or above in March, and whether it had happened three or more times in the month. This is what I found:

    Year,Month,Day,Hi,Lo

    1910 3 19 72 48
    1910 3 21 71 42
    1910 3 23 83 48
    1910 3 28 76 45
    1910 3 29 76 57

    1939 3 23 75 32
    1939 3 24 76 48
    1939 3 25 78 46

    1945 3 22 71 38
    1945 3 23 70 43
    1945 3 24 70 52

    1963 3 24 70 38
    1963 3 30 77 30
    1963 3 31 73 42

    1968 3 25 70 44
    1968 3 28 74 37
    1968 3 30 83 41

    1986 3 28 74 38
    1986 3 29 83 40
    1986 3 31 82 46


    By far the record is 1910 with five days of highs 70 or greater.

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  6. Plymouth Weather LoverMarch 13, 2012 at 4:26 PM

    I do love the warm air--it is awesome. But a quick change and then a big snowstorm--that is what makes Minnesota weather so awesome. It can change so quickly. There are more than me out there that would get a kick out of that. It would melt right away anyway. Just a hope and a prayer--bring it!

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  7. BillMarch 13, 2012 at 4:32 PM

    @Disco80 Good stuff! What would be amazing about this year vs. 1910 is that we could do it earlier in the month.

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  8. ABMarch 13, 2012 at 7:49 PM

    I can't believe it's technically still WINTER. I hit the trails in shorts today.

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  9. bemakiMarch 13, 2012 at 11:39 PM

    Here is the stuff (from SPC) regarding the severe potentials for this weekend into next week:

    ZCZC SPCSWOD48 ALL
    ACUS48 KWNS 130825
    SPC AC 130825

    DAY 4-8 CONVECTIVE OUTLOOK
    NWS STORM PREDICTION CENTER NORMAN OK
    0325 AM CDT TUE MAR 13 2012

    VALID 161200Z - 211200Z

    ...DISCUSSION...

    LATEST GFS AND ECMWF BOTH AGREE THAT A WRN U.S. TROUGH WILL EVOLVE
    THIS WEEKEND IN RESPONSE TO A FAIRLY STRONG BLOCKING HIGH THAT WILL
    DEVELOP OVER THE ERN U.S. HOWEVER...THERE IS CONSIDERABLE
    DISAGREEMENT REGARDING THE EWD MOVEMENT OF STRONGER MID-HIGH LEVEL
    FLOW INTO THE PLAINS WHERE STRONGER SHEAR WOULD NOT ONLY SUPPORT BUT
    ENHANCE THE PROSPECT FOR SEVERE STORMS GIVEN THE EXPECTED
    MOISTURE/INSTABILITY. THE ECMWF IS CONSIDERABLY SLOWER WITH HEIGHT
    FALLS ACROSS THE ROCKIES AND THUS STRONGER FLOW IS EXPECTED TO
    ADVANCE NO FARTHER THAN WY/CO/NM BY THE END OF THE PERIOD. FOR THIS
    REASON WILL NOT INTRODUCE A SEVERE RISK UNTIL TIMING IS RESOLVED
    WITHIN THE MODEL GUIDANCE.

    ..DARROW.. 03/13/2012

    CLICK TO GET WUUS48 PTSD48 PRODUCT

    I will be very interested in how this shapes out.

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  10. Disco80March 14, 2012 at 11:00 AM

    Today's record high of 64 is only two years old!

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  11. Disco80March 14, 2012 at 5:15 PM

    Well, it looks like we'll blow away the two-year-old record by 9 degrees. The forecast looks like a nice week in June.

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  12. bemakiMarch 15, 2012 at 10:17 PM

    There appears to be a conflict within the NWS right now(for tommorrow). The SPC places us within the thunder line, which would mean T-storms tommorrow, and the NWS at the Twin Cities calls for partly cloudy skies. It will be intersting to see who wins out.

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  13. Disco80March 17, 2012 at 9:31 AM

    Last night's overnight low was 35 degrees above the average low for this date and 18 above the average high!

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  14. BillMarch 17, 2012 at 10:41 AM

    Just set up new thread to discuss current weather.

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