Refreezing Unlikely For Morning Commute

December 1, 2015

11:30pm…

Whew…way too close this evening.  But over the last two hours just about all readings in the metro area have held steady or even risen a degree or two.  Good news, the evaporational cooling from rain falling into dry air has ended.

MarkFreezingRain_Metro

So unless we get some sudden clearing towards daybreak after the precip ends we should be all clear for the AM commute.

Models are pretty insistent on keeping the atmosphere saturated the next 12 hours so that’s why I’m pretty confident that we’ll avoid clearing sky.

Lots of thick ice in the West Hills, Mt. Scott, and East Portland/Gresham/Troutdale areas.  Again, luckily not on the roads.

On to rainy and windy weather at times over the next 8-10 days…should be more weather fun ahead!

Chief Meteorologist Mark Nelsen


Ice Storm In Progress

December 1, 2015

9pm…

Whew…it has been WAY too close for comfort here in the metro area.  Some of the hills and areas east of I-205 north of about Foster are seeing plenty of ice on objects, but so far very few reports of ice forming on roadways.  Latest temps:

PLOT_Temps_Metro

Generally you need temperatures down to about 30 for roads to turn icy while it’s pouring down liquid rain.  We’ve seen that a few times in the past.  Ice will accumulate on other surfaces but it’s tough to get solid ice on pavement in this situation.  I highlighted the areas in which we are VERY close to roads freezing up.   I noticed West Hills temps have bottomed out and a few other spots have finished with evaporational cooling as well.  ODOT road temperature sensors show temps 34 or higher across the metro area except 32 at Troutdale on I-84. As a result…

I don’t expect any significant icing of roads anywhere west of Troutdale/Gresham areas.  We are just about as cool as we are going to get right now.

I put this graphic on Facebook and Twitter just before 7pm when it became obvious ice was coming closer into the metro area…make sure you are following us on FOX12WEATHER for both of those.  I frequently get information out much more quickly on those two sites.

MarkFreezingRain_Metro

Chief Meteorologist Mark Nelsen


Here Comes The Ice Storm!

December 1, 2015

4:30pm…

Temperatures are at/below freezing through the entire Columbia River Gorge at this hour:

And now a wall of rain is moving into the Portland metro area as a very juicy Pacific system moves inland:

KPTV_Default

This is going to be a fast-moving storm with moderate to heavy precipitation from now until around 3am, then we pretty much go dry until tomorrow afternoon.

Let’s hit the highlights first:

  • All rain metro area EXCEPT temps at freezing upper parts of Troutdale/Camas/Washougal/Gresham so there will be freezing on objects…likely SLIGHTLY too warm for freezing on roads out there.  But it’s going to be close!
  • Western Gorge west of Bonneville Dam could see 1/2″ ice glazing by 4am when the freezing rain stops.
  • East of Bonneville Dam likely a snow/ice pellet mix, maybe 1-3″ snow accumulation, then a glazing of ice on top of that possible once precip stops before daybreak
  • Slow thawing during the day tomorrow, but I-84 will be a mess tonight and tomorrow morning

You notice we’ve inserted snow into the forecast.  Observations from Red Hill and Ausperger Mtn. at 3-4,500′ show the cold pool is up to at least 4,000′ thick still!  The Wasco profiler east of The Dalles also shows the top of the cold air up around 4,000′ too.  Yet by the time the cold airmass reaches the Troutdale profiler it’s only around 1,500′ thick.  Cool stuff eh?

So it’ll start as snow east of Bonneville most likely.

By the way, the east wind continues tomorrow, although a bit reduced, then a switch to southwest wind Thursday afternoon should make it into the Gorge for the big warmup.

Chief Meteorologist Mark Nelsen

 


Cold Eastside…Much Warmer West

December 1, 2015

1pm…

I’m at work a bit early this afternoon because I wanted to take a run and didn’t need to slip and then freeze to death all alone near home out in the Corbett  area.  Good choice, what a difference here at work in Beaverton!  45, calm, and mostly sunny feels positively tropical compared to windchills in the teens and 20s far east metro area.

screenID005

Speaking of freezing to death, in the past hour the east wind has ramped up and we’re now seeing the strongest wind so far this season.  It’s a 100 mph day on the Keely Chalmers Memorial Steps at Vista House,  but I’m confident no one would want to be out there.  Peak gust 85 mph around noon on that sensor is only 8 below the all-time high the past few winters.  Corbett gusted to 71 mph an hour ago as well and is sitting at or just slightly above freezing…brrr!  Obviously there is going to be a significant ice storm this evening and tonight in the Columbia River Gorge with just a couple degrees evaporational cooling coming up.  Check out the beautiful inversion over Troutdale.  Profiler (in place for this winter and next) shows much warmer above 1,500′ at the exit region of the Gorge:

tde1533420a_ras

More later…

Chief Meteorologist Mark Nelsen