...Meteorological Fall that is...
Even though the official start of winter begins on the date of the winter solstice, (the 21st of December this year), meteorological winter begins tomorrow, December 1. Meteorological winter is defined by the National Oceanic and Atmospheric Administration as:

The onset of winter-like weather conditions, [and] occurs earlier as one moves northward

So on this last day of meteorological fall, we were treated to nearly average temperatures in the lower to mid 50s. And it seems fitting to introduce "winter" (although I will be re-introducing winter on the 21st) as snow cover is beginning to expand across the Upper Midwest and Rocky Mountain Regions.

Forecast the next 3 days:
The outlook for the next 72 hours remains relatively straight-forward as a weak high pressure cell off to our northwest weakens and slides eastward.

Tomorrow:
A weak low pressure system, aided primarily by upper level energy (aka: vorticity), is spreading light snow showers across a swath of the Midwest, from eastern Nebraska to Iowa. This system, which is moving at a fairly good clip from west to east, should approach the area tomorrow afternoon. Given the limited moisture associated with it, the most we'll see out of this low will be a few more mid-level clouds during the late morning/afternoon hours.

High temperatures will be a bit colder than today and will likely remain in the upper 40s.

Friday:
Winds Friday will be the main 'weather header' to close out the work week. The clipper-like low affecting the Midwest will begin to merge with a developing coastal low off the Northeast Coast during the day, and will likely usher in some breezy northwest winds of 10-20mph.

Temperatures, due to the wind direction/speed and what we call Cold Air Advection, will keep max temps in the mid 40s.

Saturday:
This will be one of those days when you should be inside, maybe next to a warm fire. An approaching low will spread clouds our way, and highs will be a bit on the nippy side as they struggle to touch 43-45. I don't expect any precipitation during the daytime hours of Saturday.

The forecaster's nightmare!
The developing weather pattern past Saturday has the potential to drive even the sane insane. There are so many variables coming together at a specific time, one wrong forecasting move weather features during this timeframe becomes disastrous.

We basically know a low pressure system will develop in the southern part of the US over the weekend and progress eastward towards Georgia and Alabama by Sunday. The problems arise when asking "will we see snow or not," and "when will the precip start?" Both of these questions go in tandem with one another, because if precip begins to fall in the Mid Atlantic late Saturday night, after radiational cooling has allowed surface temps to fall below freezing, precipitation would begin as snow, or possibly a freezing rain/sleet mixture.

The GFS model has been having a fascinatingly horrid time at forecasting this low pressure feature. For that reason, I am still not putting a lot of weight onto this numerical model. At this point, I think precipitation will break out across the metro region between midnight and 5AM as snow, but a changeover to a rain/snow mix will occur during Sunday.

Again, I will use a phrase that seems to be used too many times: this is not written in stone, and a considerable amount of uncertainty still exists regarding Sunday's storm system. If this were to remain all snow (and at this point, the chances are about 3:1 it doesn't) then we could see snowfall accumulations around 1-4 inches. But again, I don't really see support from models that would uphold this event remaining all snow.

Ice Age!
I do not know how reputable this site is, but New Scientist.com has released an article describing how the ocean current (part of the global Thermohaline Circulation pictured at right) that delivers Europe's "relatively balmy climate," is shutting down, and introduce Europe to a "mini-ice age."

Scientists attribute this shut down of the current to global warming, although there is some doubt to that speculation.