The Final Snow Forecast

February 23, 2011

It’s crunch time…we’ll be entering the critical 24 hour period (to get snow in the lowest elevations) soon.  Here’s our forecast, which will probably the last one for this event.  I think by Thursday evening it’ll all be over as the cold and dry air starts moving in from the north.

Note that I haven’t really changed anything.  Still think 1-3″ is most likely for most of us.  That leaves either a pitiful 1″ or a lucky 3″.  If we don’t get a widespread 1″ across the Metro area, that’ll be considered a BUST to me.  Hope for a cluster of heavy showers tonight or tomorrow!  This forecast is also for Salem, Vancouver, Astoria, Longview…really any area west of the Cascades at the lowest elevations.  A bit more is likely on the hills, but I doubt anyone below 1,500′ would get more than 5″.  More like 3-5″.

Chief Meteorologist Mark Nelsen


Wednesday Morning Update

February 23, 2011

Not a whole lot to talk about this morning.  Things are progressing pretty much as I mentioned in last night’s post with one exception…even less snow than expected around the Metro area this morning.  We forecast a Trace-1″ around town.  A lot of spots didn’t even get the “Trace”.  That’s a bit pathetic…just not enough showers moving inland.

As expected, temps rising up to around 40 the next few hours with the late February “daytime heating”.  I really wish there was not a Winter Storm Warning out until after dark this evening, because even with a surge of showers moving inland this afternoon, I doubt it’ll be cold enough to get widespread accumulation until that time.  So most likely the afternoon/early evening commute will be fine.

Models are doing well (except NAM, see below) and continue to be relatively dry over us…no sign of the heavier snow amounts I’ve seen forecast elsewhere (4-6″).  Still the best chance for that 1-3″ snow is overnight tonight and tomorrow anywhere west of the Cascades.  Tomorrow won’t be significantly colder than today…it WILL be above freezing most or all of the day, but highs only peak in the upper 30’s inbetween snow showers.  The cold and dry arctic air moves in after sunset Thursday, freezing everything solid.

About that NAM.   Remember on Sunday evening I mentioned the NAM was significantly colder down here in the boundary layer compared to the GFS.   For you wishcasters, it turns out the GFS was correct.  This morning the 500-1000mb thickness is 527dm and 850mb temp over Salem is a -5.7.   I think the NAM does pretty well on surface low placement (November), but often tends to run a bit cold in snow/ice situations.

Chief Meteorologist Mark Nelsen