Old Man Winter Strikes Again!
Matt, our weather intern for the season, has put together a blog for you today. Have a great Wednesday! -joe
Old Man Winter is believed to be on vacation, but the big mystery is where, and is he really on vacation or not just on the run for holding the arctic air mass hostage? Given the upper air zonal flow (a pattern in which upper air flows primarily from west to east) it’s fair to assume Old Man Winter isn’t on vacation and isn’t hiding out anywhere down south. This can be proven by taking a quick look at the Sierra, Nevada region current snow cover plot compared to the snow cover plot at this time last year.
Simple illustrations such as the above easily prove that indeed Old Man Winter is definitely not in the Sierra, Nevada region. Only a small fraction of last years snow cover can be found at this time in the Sierra mountains. In this area little to no snow accumulation has been experienced primarily due to the same reason the rest of the US is having a snow-less winter, strong zonal flow resulting in a blocking of cold air from Canada. But does this mean that Old Man Winter is in Canada or closer towards the North Pole? Perhaps holding the arctic air mass hostage? Let’s take a closer look.
As briefly touched on by the FOX 4 weather team, this year the position of the upper level low over cooler than average sea surface temperatures (SST) is closer to the NW US than in previous years. This acts as a mechanism to strengthen zonal (west to east) flow throughout the US, therefore, blocking any cold air masses from dropping down into the lower 48. In addition, the US also has warmer than average north Atlantic SST’s that enhances the upper level high. This high off the NE US acts to accelerate the upper level flow and move any arctic blast that may be trying to drop into the US off to the east. What does this mean to the US?
Simple. Without cold air in place our chances of producing snow drop dramatically. The setup we currently have is vastly different than years in recent history. Over the last few years we have traditionally had cold arctic air in place coupled with the transport of warm-moist air into our region. These conditions act as a perfect setup for aiding large snowfall events, or even just snow in general as the warm-moist air acts to create instability and encourage the lifting of moist air. Thus, producing snow. It can be noted that the warmer the temperature, the less efficient a snow producing storm will be. Another region of interest that has seen a major snow drought this winter is also the Great Lakes region. This leads us to believe Old Man Winter isn’t circling the wagons in Buffalo, or anywhere else in that region for that matter.
The Great Lakes Region is widely know as lake effect snow capitol of the US.
Averaging over 30 inches of snow in years past by this time (Jan 3) in winter, Buffalo has only accumulated 5.2 inches thus far. This can be primarily attributed to upper air frontal blocking by the zonal flow as described above. Lake effect snow in the Great Lakes region is produced by a simple set of conditions:
- Great Lakes cannot be frozen over. The warmer the water temperature the greater the evaporation rate, therefore, the more snowfall.
- Sufficient cold air aloft over the warm lake water which will help create instability via warming of the air above the lake and evaporation of warm water.
- As previously stated, cold air must move over the Great Lakes with ideal wind speeds. Ideally the wind should be between 15-20 knots for maximum snow band formation. For maximum snow totals, winds should travel parallel (and over) to the longest axis of the lake.
Given the information on how lake effect snow is created it is easy to see why area’s such as Buffalo are in a extreme snow drought. However, the Great Lake region is expected to have major lake effect snowfall events…just much later in the winter than normal. Recent history has proven that large scale lake effect snowfall events tend to occur earlier in the winter, however, that will not be the case this year. Again, naming Old Man Winter the culprit for holding the cold air hostage north of the Great Lakes. Without sufficiently cold air, lake effect snow cannot be produced. Which raises the question, where is Old Man Winter and the cold air likely to be found? The million dollar answer is between Canada and the Arctic Circle. With Old Man Winter safely behind bars it looks as if the cold air will make its comeback to our region in the middle or latter part of January. Stay tuned into the FOX 4 Weather Team, as they bring you the most accurate and up to date forecasts.