A Very Icy Morning! Most Areas Melt This Afternoon

February 3, 2017

10am Friday…

A solid line of liquid rain moved over the metro area during the night, falling into the sub-freezing air.  That left a glazing of ice for most of us for the morning commute.  It wasn’t a lot, but as I’ve mentioned many times in the past, it only takes 10 minutes of that freezing rain to make a road very slick.

ibs_web_metrotemps

As of this hour temperatures are ever so slowly creeping upward.  More important, road surface temps are all at/above freezing except east of I-205.  That means the additional rain now moving into the metro area will actually help get the ice off the roads as we head into midday.  During daylight hours, anytime the air temperature goes above 30 degrees, the “extra heat” we get even through cloud cover allows pavement temps to go above freezing.  I remember first noticing this effect during an ice storm around 2006 when reporters were saying the road/sidewalk was melting even though it was 29 degrees.  Of course at night it’s a different story, but even during nighttime icing events main roads don’t tend to see icing until it’s down around 30.

To summarize:

  • We’ve seen the worst icing on roads already; all areas except the high parts of the West Hills and areas east of I-205 will see dramatic improvement in road conditions through the rest of the day.  The evening commute will be almost normal except close to the Gorge.
  • Any area still at 32 or below will continue to see ice glazing on trees/powerlines and other objects through the afternoon.  Of course once your temp goes above 32, it’s over for this event.
  • There will not be any re-freezing of roads tonight, temperatures will warm through the evening and overnight as a milder south wind takes over.
  • Near and in the western Gorge road conditions will go downhill with fresh glazing midday/afternoon.  Things won’t improve out there until tonight and Saturday AM when the east wind disappears and warmer southerly wind arrives.  That wind switch should arrive around 1-4am
  • Saturday we’re totally clear with regular rain…and quite a bit!

Chief Meteorologist Mark Nelsen