Close to Freezing Rain in Some Valley Spots; But No Icy Roads

December 7, 2018

9:30pm Friday…

A band of rain is moving through the Willamette Valley at this hour, and temperatures are in the 30s for most of us.

web_temperature_ORWA

I see about 3 locations where temperatures are right at freezing; Monroe, Sweet Home, and Eugene areas.  The good news is that dewpoints (measure of moisture in the air) are rising everywhere outside of the Portland “east wind zone”.  The atmosphere is moistening up over the valley and there won’t be any additional cooling (evaporative cooling) tonight.

All the previous points on this morning’s blog post are valid plus:

  1. In the next 2-3 hours trees, decks, tops of cars could get a little ice on them in these coldest spots.
  2. Same thing may happen in the West Hills and other areas above 500′ in the Portland metro area.
  3. NO ROADWAY ICING IS LIKELY ANYWHERE WEST OF THE CASCADES.  IT’S TOO “WARM” IN THE METRO AREA FOR FREEZING RAIN

Temps hold steady or rise a few degrees by morning as we see a bit more rain.

Chief Meteorologist Mark Nelsen

 


Light Freezing Rain/Snow Tonight in Gorge

December 7, 2018

11:00am Friday…

What a chilly night again with temperatures way down in the 20s for most of us.  A strong east wind continues to push cold air westward from east of the Cascades and out into the metro area.  We’ve finally lost the “downslope” wind coming off the Cascades;  that’s why it is much calmer for most of us compared to yesterday morning.  The wind is confined closer to the Gorge.  In the Gorge itself wind will turn quite a bit stronger through late tonight then back off a bit Saturday & Sunday.  That cold east wind will not totally stop blowing until Sunday night.

It’s always nice when our forecast remains consistent; not much has changed in our forecast during the past 36 hours.  Most of the points in the previous post are still valid.   A very weak weather system moves inland this evening, spreading rain into the I-5 corridor (metro area) sometime after 10pm.  It won’t reach the western Gorge until midnight or so.  At that point temperatures will be above freezing in the metro area.  But the airmass in the Gorge has cooled the past two days and freezing rain is likely anywhere from around the Corbett/Cape Horn areas east.

Gorge Wintry Weather Text 1

A big point here is that we don’t have a lot of precipitation coming.  At most 2″ snow could fall in the central Gorge (Cascade Locks & Stevenson) to only a trace out towards Mosier and The Dalles.  Since temperatures are marginally cold, I don’t think it’ll take much for roads to thaw Saturday…a mainly dry day too.

The wetter cold front moving inland Sunday is going to be a bit slow to get here.  Most models are holding off steady rain until at least 10am in the metro area and beyond noon in the Gorge.  That minimizes the areas that should see freezing rain with the heavier precipitation that day.  I feel it’s unlikely I-84 or any other location at river level will see below-freezing temps through the daytime Sunday.  Also, areas west of Bonneville Dam even in the hills will be just above freezing Sunday (Corbett & Cape Horn areas).

Gorge Wintry Weather Text 2

I’ll keep a close eye on conditions through the weekend in case something changes.  Here in the metro area it’ll be a cool one since the easterly flow doesn’t go away until Monday.

Chief Meteorologist Mark Nelsen