8:45 AM Friday 1/18/2008, posted by Dave Longley - Arctic air keeps
piling southward. It'll arrive here in stages. One push of
cooler air moved through this morning. The next one arrives here
midday Saturday. The one Saturday may have a little light snow
with it during the middle of tomorrow. Then the party gets
started. Party if you're a snow-lover.
To get too specific would be fruitless right now, but here's a basic
overview. Winds are pretty southwesterly in the lower atmosphere
through later Saturday, so if there is any lake effect snow, it would
have to be east and northeast of Lake Ontario. There doesn't look
to be any contribution of moisture from the upper lakes yet, so
overall, Saturday doesn't look that bad.
Saturday night the true arctic airmass arrives with 850 mb temperatures
down to -20C over Lake Ontario. This will make the atmosphere
VERY unstable and we should have snow with thunder and lightning
straight east of Lake Ontario Sunday morning. Winds in the lower
atmosphere still look to be pretty west-southwesterly, so no linkage
with the upper lakes is seen yet. The upper level trough axis is
still to our west, so that should ensure some heavy snow remaining
north of Syracuse.
Midday Sunday, the upper trough is forecast to swing through, winds
will veer to a more northwesterly direction, we get moisture
contribution from the upper lakes, and we should have a band of intense
snow east and southeast of Lake Ontario. Preliminarily, this
looks to be a big dump of snow for the Tug Hill from later Saturday
night through Sunday. This is assuming winds are westerly
Sunday. The air will certainly be cold. The one negative
factor we'll have to overcome is dry air in the lower atmosphere.
That's one thing we'll have to keep an eye on.
More later today and through the weekend.
-Dave Longley