Saturday, December 26, 2015
The U.S. snow depth analysis shows a dramatic picture this morning: huge amounts of snow over the Northwest U.S., but virtually nothing over the Northeast U.S. (see below). Washington State has greater depths than any other state (mainly in the Cascades), with amounts exceeded only by British Columbia, the Saudi Arabia of water resources. British Columbia snow is a big positive for us, of course, since the Columbia drains southward and many of us head to Whistler or other south BC ski areas.
Serious folks in the snow business like to look at snow water equivalent (SWE) instead of snow depth. SWE tells us the liquid water equivalent (the depth of water if the snowpack was melted) of the frozen water in the snowpack and is a better measure of the water availability when the snowpack melts during the spring. The SWE for this AM (see below) shows massive amounts in our area, with substantial SWE in the northern and central Rockies. Bad news over the eastern U.S., where preternatural warmth--reaching the lower 70s was enjoyed during Christmas Eve and Christmas Day.
The temperatures back east were simply startling and opposite of the severe cold they experienced the last two winters. Take a look at the max temperatures on Christmas Eve Day. 72F in New York City and Albany. 69F in Boston.
Saturday, December 26, 2015
The Pacific Northwest: Snow Capital of the U.S.
The U.S. snow depth analysis shows a dramatic picture this morning: huge amounts of snow over the Northwest U.S., but virtually nothing over the Northeast U.S. (see below). Washington State has greater depths than any other state (mainly in the Cascades), with amounts exceeded only by British Columbia, the Saudi Arabia of water resources. British Columbia snow is a big positive for us, of course, since the Columbia drains southward and many of us head to Whistler or other south BC ski areas.
Serious folks in the snow business like to look at snow water equivalent (SWE) instead of snow depth. SWE tells us the liquid water equivalent (the depth of water if the snowpack was melted) of the frozen water in the snowpack and is a better measure of the water availability when the snowpack melts during the spring. The SWE for this AM (see below) shows massive amounts in our area, with substantial SWE in the northern and central Rockies. Bad news over the eastern U.S., where preternatural warmth--reaching the lower 70s was enjoyed during Christmas Eve and Christmas Day.
The temperatures back east were simply startling and opposite of the severe cold they experienced the last two winters. Take a look at the max temperatures on Christmas Eve Day. 72F in New York City and Albany. 69F in Boston.
Eastern U.S temperatures have been much warmer than normal all fall. Here is the anomaly (difference from normal) of max temperature for the past 90 days. Western WA has actually been a bit below normal.
Why? The proximate reason is unusually persistent high pressure over the eastern U.S.. Here is the anomaly (in tens of meters) of the heights at a mid-level of the atmosphere (500hPa) for the past 90 days. . Red means higher heights (pressure) than normal. High heights are associated with warmer temperatures below.
This is probably the result of natural variability, no reason to expect it is connected with global warming. What about El Nino? Probably not at this point. We have yet to see the normal El Nino circulation changes, which generally are most profound after January 1st and certainly our recent weather in the Northwest is not El Nino-like.
Finally, some folks in the lowlands may enjoy some snow tomorrow: those on the Kitsap and SE of the Olympics. Here is the 24 snowfall ending 4 AM Monday. Some snow extending over the the Hood Canal area and over parts of Kitsap. Light snow in the Cascades (few inches). None over Seattle, so our mayor can relax.
Most of the Kitsap snow will fall tomorrow morning as a modest front crosses our region
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