BY JOHN FELDT
BLUE WATER OUTLOOK
Unusually High North American Snow Cover
A Cold Late Fall / Early Winter?
The Accumulated Winter Season Severity Index (below) is indicting an “extreme” or “severe” start to the AWSSI winter season over the Upper Midwest and Great Lakes regions. And, there are signs that unusually cold weather could persist the latter half of November over a large part of the central and eastern corn belt.
Probabilities of a White Thanksgiving
With unusually cold air over a large part of the eastern U.S., you might be wondering about the prospects of a White Thanksgiving (defined as either a snow depth of 1 inch or greater on Thanksgiving or no snow depth on Thanksgiving but measurable snow on that date).
The following image provides a statistical overview of the chances of a White Thanksgiving. Statistical odds of 50% or greater are limited to mountainous regions and the far Upper Midwest, Great Lakes, and Northeast.
Source: Data NOAA, Analysis Brian Brettschneider
Here is a weather model showing anticipated snow depth on Thanksgiving. Looking pretty normal as to snow cover right now.
An Active Start To Winter?
The Accumulated Winter Season Severity Index (AWSSI) is based on temperature, snowfall, and snow depth thresholds.
The following AWSSI update indicates an “extreme” (purple) or “severe” (blue) start to the winter season (as defined by the AWSSI) over the northern tier of the U.S. as well as parts of the Upper Midwest and Great Lakes.
Unusually High North American Snow Coverage
We are off the a brisk start to the North American snow season. North American snow cover (red trace below) is at a decadal high compared to decadal lows of last year.
October Eurasian Snow – Near Normal
After a rapid late October increase, Eurasian snow cover has held steady so far in November.
Sources: NOAA – observations, AER
Research indicates that an increase in late fall snow cover over Eurasia can point towards a colder-than-normal winter over the eastern U.S.
Also, the current unusually-high amount of snow cover over North America suggest continued intrusions of cold air over the middle and eastern U.S. the remainder of the month of November.