Chicago: Warm December=Warm January?

[Chicago WX]

So with this December being a blow torch, I went back through the records at O'Hare Airport to look at what happened the following January. I just used the data from O'Hare, to try to make it one site specific. Records began there in 1958.

The chart below shows the 25 warmest Decembers at ORD, in order from warmest on down. For kicks, I also added the average numbers for 3 indices (AO, NAO, and PNA) for that December. As you can see, it's not always clear cut when looking at those stats (see Dec 2001 which at first glance looks like a good set up, but was a very warm month). The seemingly consistent theme with those Januaries that turned cold was an improving AO...either late in December or the first part of January.

The averages highlighted in yellow are longterm values. I used the range -1.0 to 1.0 for "normal" for January and February. Otherwise, blue highlighted is -1.1 or cooler...red highlighted is +1.1 or warmer. Also the years on the left side are highlighted with ENSO state (red=Nino, blue=Nina).

14 of the Januaries were warmer than normal

9 of the Januaries were cooler than normal

2 of the Januaries were within normal

11 of the Februaries were warmer than normal

9 of the Februaries were cooler than normal

5 of the Februaries were within normal

Conclusions...well odds favor a warm January, but of course there are exceptions. At least it looks like February has better shot to be cooler than normal or normal. This isn't a forecast, but just a look at the statistical angle of things.

[Geos]

Nicely done!

[dmc76]

ChicagoWX your the MAN!

[michsnowfreak]

good work as always. I dont see it on there, but I know one of Mr. Deedlers fav analog, 1964-65, had a mild December followed by more seasonable temps but some good snowstorms in Jan/Feb/Mar (Mar actually was very cold). In fact, one thing that sticks out to me from many of the years you posted, a lot of very cold March/Aprils with meaningful spring snowstorms. Will be interesting to see how this winter shapes up.

[Chicago WX]

good work as always. I dont see it on there, but I know one of Mr. Deedlers fav analog, 1964-65, had a mild December followed by more seasonable temps but some good snowstorms in Jan/Feb/Mar (Mar actually was very cold). In fact, one thing that sticks out to me from many of the years you posted, a lot of very cold March/Aprils with meaningful spring snowstorms. Will be interesting to see how this winter shapes up.

December 1964 was cooler than normal at O'Hare, -2.7º versus the longterm average. Looking at the map for Dec 1964, it looks like the OV up to the SE corner of MI was average to above. A very Nina-ish looking map with a SE ridge and cold in the northern Plains.

And thanks to all for the kind words.

[michsnowfreak]

December 1964 was cooler than normal at O'Hare, -2.7º versus the longterm average. Looking at the map for Dec 1964, it looks like the OV up to the SE corner of MI was average to above. A very Nina-ish looking map with a SE ridge and cold in the northern Plains.

And thanks to all for the kind words.

Interesting.

Here are Detroits top 20 warmest Decembers and the remainder of that winter.

81-10 norm: D- 30.1...J- 25.6...F- 28.1...M- 37.2

I highlighted any JFM that was more than 1F above or below the current normal in either red (warm) or blue (cold). majority of the time, a warm December was indeed followed by at least 1 colder than normal month.

Its hard to tell where Dec 2011 will rank with 10 days to go, but I think the chances of it making the top 10 are very slim (avg temp through 12/19 is 35.4)

..............DEC.........JAN....FEB....MAR

1881-82...40.6......31.0...39.5...39.7

1889-90...39.2......33.6...32.4...30.4

1877-78...38.1......27.3...29.2...41.4

1923-24...37.7......21.8...25.5...33.7

2006-07...37.4......29.6...19.3...40.1

1982-83...37.3......28.7...31.6...38.4

1931-32...37.2......36.7...33.0...29.8

1918-19...36.3......31.1...29.4...36.3

1965-66...35.9......21.4...28.3...38.3

2001-02...35.8......32.7...32.9...34.8

1891-92...35.6......20.7...29.1...30.8

1941-42...35.5......25.8...22.7...38.5

1994-95...35.4......28.4...24.9...39.2

1998-99...35.3......23.1...32.7...34.8

1956-57...34.8......21.1...30.6...36.9

1959-60...34.6......29.0...27.5...26.3

1913-14...34.3......29.4...17.6...33.1

1957-58...34.1......26.6...22.8...36.4

1952-53...34.1......30.6...32.2...37.9

1984-85...34.0......20.3...23.4...38.4