Record December Warmth, Snow and Cold Returns…
Wednesday, December 5th, 2012
Record warmth across much of the nation to start off meteorological winter has really put a damper on the actual start to winter across the nation… “Where’s winter” is a question that many are probably asking as we continue through this early December.
December of 2010 was an exceptional year for many across the far north. For those who lived in Minneapolis, we had the snowiest December on record with 33.6″ of snow. Half of that nearly came in one storm… the same storm that collapsed the Metrodome! This is what it looked like after after the 17.1″ snowstorm on December 10th-11th of 2010.
National Snow Cover on 12/5/10
38.6% of the nation was covered in snow on this date 2 years ago.
National Snow Cover on 12/5/11
Even the fairly dismal winter of 2011 yielded a 32% national snowpack on this date.
2012 US Snow Cover
The extremely warm start to meteorological winter has put a huge dent in the US snow cover this year. As of 12/5/12, only 7.2% of the nation was covered in snow!
Record December Warmth
Look at the number of record highs that were either tied or broken across the nation over the last 7 days… that’s remarkable, no?
Arctic Alaskan Temperatures
As a general rule of thumb, when the Lower 48 is warm, Alaska tends to be quite cold. That certainly has been true as of late. Take a look at the HIGH temperatures across the far north on Tuesday.
First -50s in Alaska
This was a Facebook post from the National Weather Service out of Fairbanks, AK on December 1st:
“Clear skies and high pressure resulted in another cold morning across the eastern interior of Alaska. Many locations reported temperatures colder than 40 and 50 below zero. Temperatures have remained cold during the day as well, with most valley locations unable to climb above 40 below zero in the afternoon. The community of Chicken once again reported the coldest official temperature in the US this morning with a low temperature of 56 degrees below zero. This morning marks the 3rd day in a row that the NWS observer in Chicken has reported temperatures colder than 50 below zero. Clouds moving into the interior on Sunday will provide some temporary moderation in temperatures, but readings will remain well below zero into the upcoming week.”
BIG Changes Coming??
This is interesting… take a look at the NAO forecast through mid December. Note how the red (forecast lines) dip below the zero line. This indicates a predicted “Negative Phase” which would indicate the potential for colder air across the Lower 48. The information below is from NOAA’s CPC and explains the difference between positive and negative phases in the North Atlantic Oscillation:
“Strong positive phases of the NAO tend to be associated with above-averagel temperatures in the eastern United States and across northern Europe and below-average temperatures in Greenland and oftentimes across southern Europe and the Middle East. They are also associated with above-average precipitation over northern Europe and Scandinavia in winter, and below-average precipitation over southern and central Europe. Opposite patterns of temperature and precipitation anomalies are typically observed during strong negative phases of the NAO. During particularly prolonged periods dominated by one particular phase of the NAO, anomalous height and temperature patterns are also often seen extending well into central Russia and north-central Siberia.”
Pacific Low Breaks Loose
It appears that the persistent Pacific low that was churning in the Gulf of Alaska (keeping cold air locked up north and triggering record highs in the Lower 48) will break loose from its position. The energy for that storm will settle into the Lower 48 by the end of the week/weekend ahead.
Here Comes the Cold…
Well, this is more like it… Forecast models continue to indicate a larger, more robust storm, developing this weekend/early next week from the chunk of energy that was sitting in the Gulf of Alaska for so long. Note how this larger storm tugs down colder air from the north. This will bring temperatures to near and even below normal levels by mid December.
Not only will this feature bring back colder temperatures, but it will also be capable of bringing shovelable snow to parts of the nation through early next week. It’s still a bit uncertain on where and how much snow may develop, but more importantly, the potential is there! That’s something that we haven’t seen for quite some time. The image below suggests the placement of the low pressure system at the surface along with snow potential into the weekend based on the ECMWF (European) model run.
GFS Snow Potential
Here is the longer term GFS (American model) solution through AM Monday. Keep in mind that this forecast CAN & WILL CHANGE… Don’t take this literally just yet. There are still several unseen variables that will come into play as this ‘potential’ snow event(s) take place. What I take away from the extended model runs is that we can expect a return to more ‘normal’ December weather across the entire nation rather than the extremely and absurdly warm December conditions that encompassed much of the nation over the last few days.
Hey, thanks for checking in on this Wednesday… Have a great rest of the week!
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