February 23, 2012
The usual, 4 maps of the upcoming 4 weeks off last night’s 00z ECMWF. Trend remains similar to what we saw from Sunday night’s runs: Cool troughing through the next 2 weeks, then more ridging over most of North America with the West Coast on the western edge of that…I interpret that as “warmer rainy weather”. Probably no “near snow” setups beyond mid March if this is correct.
February 23, 2012
Here’s what we are thinking for the lower snow levels this weekend:
As mentioned in the previous post, there’s nothing too exciting coming except that most of us will at least see snow in the air sometime between Saturday evening and Sunday night, but it’ll be tough to see much accumulation to the lowest elevations. I mentioned this type of setup 8 days ago during that “winter is cancelled” diatribe during the 10pm newscast. Sure, we can still get these wet snowfalls that don’t last long, but we’re done with actual snowstorms and cold spells (just barely survived that one).
That said, a -7 to -8 degree 850mb temp and 500-1000mb thickness around 520 is good enough for sticking snow to sea level if you get the moisture at the right time of day. And from late Saturday evening through Monday morning, plus again Tuesday, areas up around 1,500′ will score quite a bit.
So the “threat period” for snow in the lowest elevations is late Saturday night through Sunday evening when the moisture runs out. From 9am-5pm Sunday it’ll be too warm in the lowest elevations too due to the February sunshine unless we get some sort of very heavy showers.
Another thought…here’s the 12z 4km WRF-GFS snowfall forecast from 4pm Saturday to 4pm Sunday. When I start seeing “fingers” of snow moving out into the valley hills as I see here, that’s when we get very close to sticking snow in the lowest elevations.
Chief Meteorologist Mark Nelsen