Friday, December 09, 2011

1st Snow on Dec 9th--What About the Other Snowless Decembers of the Past?

Finally our first real, widespread snow and its already December 9th. Most people have finished putting up Christmas lights.

A far cry from last December when we had snow on the ground almost everyday with the average high temperature well below freezing. 
3 inches of snow in Sharon Center, Medina County
How does this overall "winter-less" pattern compare with the least snowiest Decembers going back to the late 1960s? First, here are the least snowiest Decembers in chronological order:

1965: 1.2"
1967: 2.8"
1971: 1.9"
1978: 2.5"
1986: 1.1"
1994: 1.0"
2001: 3.7"

The answers to our pattern lie in the winds aloft. They establish the direction the storms along with the propensity for storm development in certain locations. Often times, these "locations" or dips in the wind field are established/enhanced by the warmer/cooler ocean temperatures. These ocean/atmosphere connections are felt "down stream" here in Ohio as either a cold or warm pattern.

Below is the first year: 1965. The map on the left shows where the HIGHS and LOWS are located. The right map shows the COOL and WARM pool in the Pacific and Atlantic and their positions. Notice the HIGH near the WARM POOL in the PACIFIC and the HIGH over the great lakes. In between lies the WESTERN trough where the LOWS reside. This HIGH kept warmer than normal air over OHIO and the snow amounts small.

Now 1967, 1971, 1978, 1986, 1994 and 2001. Notice that the PACIFIC HIGH is near the WARM POOL in each year and the WESTERN trough sits ahead of it. Also, notice the LOW in the ATLANTIC in varying degrees each of these Decembers. For OHIO, the same RIDGE we have overhead this year suppressed the COLD and SNOW in these past years.

When we average all of these years, we come up with this composite picture. Notice once again, the HIGH over OHIO.  
November this year, featured the strong PACIFIC HIGH which drove COLD AIR into the WESTERN TROUGH which kept the OHIO RIDGE in place keeping us mild and wet. Look at the similarities between  this past November picture below to the Decembers above.  Scary isn't it?
 Now look at the first week of December through the 7th. The HIGH has shifted north into ALASKA shifting the WESTERN TROUGH east into CANADA and the CENTRAL US which has drove the OHIO RIDGE well east.

Does this still mean December will stay below normal in snowfall or are we anticipating a shift to a colder pattern? I have a good feeling that this December will feature more short-lived cold shots and off/on snow. Will it be as snow less as the Decembers above?  Given these pattern shifts and the ATLANTIC shifting cooler, we can expect weather that is more winter-like. Meanwhile, I'm off to cut down a Christmas tree!

Wednesday, December 07, 2011

Dec 7th Snowcover Last 5 Years: Which Year is the Winner?

Our first lake effect event begins Friday.  So far, hardly a flake has fallen this year. Has this year's snowfall country wide more or less than in recent years?  Here are the numbers with these excellent snow maps from the National Snow Analysis site. from this year back to 2007. Last year and this year are dead-even. Notice the snow this year is west whereas last year, it was east.