WEATHER BLOG MORNING 2/9

9:00am Saturday…

Portland officially received 4.2″ snowfall at the NWS office in Parkrose overnight.  3″ fell in north Portland at the airport.

I see a 6″ in Gresham, 5″ in Evergreen area of East Vancouver, and 2.5″ in central Vancouver.  Somehow I ended up with 8.5″ at 1,000′ SE of Crown Point and just got a report of over a foot new snow in Dodson near Bonneville.

IMG_0325

But many of you are feeling left out with a trace or even NOTHING on the ground west and south metro.  I think ODOT’s traffic speed map shows the story pretty well with slow speeds in about 2/3rd of metro area (central, north, & east) and normal freeway/highway speeds in the western/southern 1/3.

Traffic_Sat9thAM

A few thoughts

Models absolutely nailed the warming south wind (which many forecasters somewhat ignored leading into it, including me) yesterday evening.  They also nailed the overnight switch to cold/dry easterly wind changing us over to snow.  I was pleasantly surprised when I rolled out of bed and saw all temps below freezing throughout the metro area.

By the time it was cold enough near sunrise, the moisture had mostly run out.  There were also very strong hints that would happen.  Even the ECMWF from yesterday morning showed spots in the metro might get almost nothing.

ecm_snowthru10am

The GFS was predicting little/no snow for this event for Portland, it was terrible except south/west metro and into the valley.  It kept temps too warm.  That 2″ you see it plotting for PDX is more of a low-resolution contouring issue, it was keeping temps above freezing most of the time in the city.

gfs_6hr_snow_acc_portland_6

Far more snow fell than expected in some areas, like Camas, Gresham, western Gorge.  The 5-8″ totals are a surprise.

We knew there was a decent chance the west/south side of the metro area would get hosed, but I figured all of you would get at least a dusting.  I suppose that’s still possible in the next few hours before we dry out and temps rise above freezing.

REST OF TODAY AND TONIGHT

Temperatures gradually rise a few degrees above freezing, that cold east wind continues to blow, and road conditions improve.  Travel should be just fine where little snow fell, and travel should be much better this afternoon in the areas that saw under 4″ of snow.  Snow showers continue, but I expect less than 2″ additional accumulation.  Best chance will be in the west metro

ALL AREAS freeze tonight, and a dusting to 1″ is possible in the east metro as a wrap-around band nails the Gorge and north-central Oregon with a bit more snow.  Most likely dry west metro

SUNDAY

Mainly dry, most roads, even east metro, in good shape by afternoon.

SUNDAY NIGHT THROUGH TUESDAY

Two waves of moderate-heavy precipitation roll through the region during this time.  Models this morning all say much of the metro area will be on the warm side of the arctic boundary.  By that I mean most likely we’ll get southerly wind with both of these as surface low pressure goes by to the north.  There’s a decent chance the entire Willamette Valley gets little or no snow while the metro area starts as snow and goes to rain quickly during the night.  Looks like some areas north of Portland will get a bit snow event (don’t yet have a good handle on exactly where), and the Gorge is going to get buried in a LOT of snow.  I think the WRF-GFS sums up snow Sunday PM-Monday PM pretty well.

or_snow48.60.0000

I’ll take a much closer look at this later today, but for now (if you have the snow), get outside and enjoy the sledding!

Chief Meteorologist Mark Nelsen

Chief meteorologist

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