December 1, 2005
Well, another year has begun for SNUWW and right on cue with the first discussion of the season since December 1 is considered the start to meteorological winter. This will be a relatively short discussion as time is of the essence and there are still many differences in both short and long term with the computer models.
Let me begin by saying that between Saturday December 3 and Friday December 9, our area has the chance to see 3 separate wintry events to start off the very young season. A weak impulse will be pressing Eastward from the Rockies on Friday and will spread light precipitation over the region Saturday night and into Sunday. Temperatures seem a bit warm to keep everything as all snow, especially South and East of the city, but should at least begin as snow or a light mix. This is event #1 and should have minimal impact on the region. Best case scenario (if you like snow) would be a max of 2", though we are going with little, if any accumulation at this time in regards to the Saturday night and Sunday system.
As this system pulls away, cold air will be left in it's wake as the disturbance quickly gets absorbed into a Polar Vortex over Eastern Canada. All the while, a high latitude blocking pattern is developing as ridging just West of Greenland links up with an upper level ridge over Central Canada. This will force another piece of energy Southward later in the day on Sunday. Things get iffy as event #2 approaches on Monday, though we think guidance is keying in on a solution. A storm system (Miller A) will be emerging out of the Gulf of Mexico and will pull Northeastward through the Tennessee Valley and Southeast. Precip looks to overspread the region during the day on Monday. As of now, all signs are that precip will begin as all snow for our area, though there are conflicts in regards to whether or not we stay all snow as the storm redevelops off the Carolina Coastline and roars Northeastward to the 40/70 lat/lon proximity (aka, the Benchmark). It is looking less likely that the storm will remain unphased and go directly out to sea, though this is still a possibility at this time. It will all depend on how the upper energy from event #1 reacts as it encounters the PV in Eastern Canada. Bottom line, possible snow on Monday turning to rain and then back to snow. Accumulations are possible, but the system will be a quick mover.
Finally, a piece of the Arctic Vortex currently in Alaska will drop down and ride the Southern branch of the jet as a very vigorous wave of low pressure, both at the surface and aloft around mid week. All signs are that this storm will track along the Gulf Coast picking up ALOT of moisture along the way. Meanwhile, an Arctic high pressure area will be locked on place over the Northeast (thanks to a 50/50 low ala ECMWF) with cold air damming nosing it's way all the way Southward into Georgia along leeside of the mountains. In short, cold air will be entrenched in the Northeast and in favored 'damming' spots just East of the Appalachians. It is way too far out to get any more specific, suffice to say, yes, there is a big storm in the Gulf midweek with cold air in place in the East. That's all we need to know at this point since we have 2 other players to move through before this gyre lumbers eastward along the Gulf Coast.
That's is for now. Some mixed precip Saturday night into Sunday which could accumulate but looks unlikely at this point. A second system comes out the Gulf on Monday and redevelops along the Carolina coast. This system, in prefect setup, could yield accumulating snows for our area, but there is a 50/50 split among guidance as to precip type and exact track. Finally, another storm tracks East along the Gulf Coast midweek with cold air entrenched in the East. So, 3 chances for snow in our area in less than one week's time, and it's only the first week of December! Going to be a long winter in my opinion (apologies on the lack of a winter outlook this year). Take care!!
S.B.
