Forecast Bust; Rain Was Late = No Ice

January 23, 2013

2:30pm…

No way of getting around that one today…the rain showed up late, thus no freezing rain for most of us.  If you go back through the previous two posts I mentioned that it had to be in the morning hours or else it would be too warm.  Still, now that the rain is going, it’s surprising that the evaporative cooling has cooled us to just 1-3 degrees above freezing.  If the steady rain that arrived around Noon-1pm would have shown up at 6-7am the morning commute would have been a mess.

The only freezing rain areas at 2pm are the highest hills around town (top of the West Hills) and Troutdale east into the Gorge.  I see Washougal schools closed early as did Corbett.  Hopefully all those kids get home safely (mine stayed home based on their Dad’s advice).  The cold east wind is dying down quickly out there, but no warming south wind in the Valley this evening means no warmup in the Gorge either. 

Freezing rain should stay in those locations until the precipitation stops this evening.  It’s interesting to note that as cooler air is moving in higher up in the atmosphere, the combination of that plus the leftover cold air near the surface is allowing some spots to change to snow.  I just saw someone mention that in comments; I think in Clark County.

PLOT_Temps_Metro

With some clearing overnight, temps will quickly drop to around freezing in spots.  So another round of black ice or icy spots and/or freezing fog for tomorrow morning’s commute.

So again, we’re done with the freezing rain threat across the vast majority of the lowest elevations. 

Chief Meteorologist Mark Nelsen


Morning Freezing Rain Update; Looking Better

January 23, 2013

7:45am Wednesday…

Looks like our RPM model has done a little better job showing a slower arrival of precipitation this morning.  So far no reports of rain/freezing rain and radar looks very dry east of the Coast Range, where most of us live.  This is a good sign if you want to avoid ice on roads.

It’s pretty clear now that the “worst case scenario” mentioned in last night’s posting isn’t going to happen.  We’re going to see spotty freezing rain at best the next couple of hours in most of the metro area and north/south along I-5 to Salem and Clark County. 

Forecast:

  • Spotty freezing rain still possible between now and 10am anywhere west of the Cascades in the lowest elevations.  Key word here is “spotty”.  Some areas are warm enough it’ll be just rain
  • Much better chance of icing on roads in the West Hills, or east of I-205 as you get closer to the Gorge (colder air) between now and noon.
  • After 10am it’s over.  If for some reason precipitation hasn’t arrived by then, it won’t matter, roads will be too warm just about everywhere except close to and in the Gorge.
  • Rainy and mild with temps close to 40 this afternoon; no issues for evening commute except IN the Gorge east of Troutdale.

Gorge Forecast:
My kids are sitting here at home, waiting for the 2nd “school call” around 8am (after a 2 hour delay) to see if it gets called off or not.  Probably quite a few administrators waiting to see what happens the next few hours.  I can’t offer any good advice other than sending kids to school when roads could be very icy this afternoon seems like too high a risk to me.  Take a snow day, it’s been a mild winter with no closure yet anyway here and no sign of impending snowy/icy weather as we head into early February.  Okay, that was my advice.  Freezing rain quite slow to get started in the Gorge the next few hours, but when it does start, it’s below freezing on all surfaces through at least noon. 

The ice pellets/snow in the central/eastern Gorge may not arrive until almost noon out there.  Then a few inches of snow before temperatures creep up around freezing this evening.  There will be no quick warmup in the Gorge through tonight.  No mild west wind.

For the hardcore weather folks:
Temperatures at the lowest elevations WEST of I-205 (away from the Columbia River Gorge) are very marginal for freezing rain, meaning that unless precipitation doesn’t begin by 9am it’s probably over.  Solid cloud cover during the night didn’t allow the east wind to decouple either, so we’re pretty much back to a “gorge influenced” event instead of having lots of sub-freezing air stuck in the Valley.  BUT, no south wind either, in fact it was interesting that the 4am sounding over Salem showed no warm southerlies in the lowest few thousand feet of the atmosphere.  When precipitation finally does arrive, most of the metro area temps will drop 1-2 degrees (assuming it’s more than sprinkles) due to evaporative cooling.  But looking at pavement temps at Rocky Pt and I-205/Division, even then it’ll be tough to get rainfall to freeze in those areas.  Remember, to get freezing rain to freeze to pavement during the day (after 9-10am), it’s got to be at least down to 30 degrees; very unlikely that’s going to happen except well east of I-205.

There IS plenty of cold air still pouring out of the Gorge, that gradient is still around 8 millibars TTD-DLS.  12z NAM-MM5 just out shows no south wind today in the Valley and the Gorge wind just gradually dies down.  If we had started with the low level cold air pouring out of the Gorge about 5 degrees colder, today would be a perfect ice storm here in the entire metro area.  I think it still will be east of Troutdale in the Gorge.

Chief Meteorologist Mark Nelsen


Follow

Get every new post delivered to your Inbox.

Join 288 other followers