A Historic Cold & Snowy March Day

March 6, 2019

7:30pm Wednesday…

What a crazy day.  As expected the light morning showers turned to steady snowfall.  Most of the day it didn’t accumulate much because we were a few degrees too warm.  But a good burst of snow between 4-6pm across the east metro area dropped a coating of white just about everywhere east of I-205.

First the snow.  Officially 0.5″ fell at the Portland NWS office.  That makes it the 5th measurable snow event in Portland, all in the past 4.5 weeks of course.

Winter Snow_Ice Totals So Far

  1. It’s the first March snowfall (measurable in the city) in 7 years
  2. This is only the 5th March with measurable snow in my lifetime.  All of them except 1989 have been in the past 14 years.  Interesting don’ t you think?
  3. Looks like plenty of 1/2″ to 1″ totals eastside, with up to 2″ or so up around 1,000′ far eastern edge of metro area
  4. This is the first time since the late 1970s we’ve seen 3 consecutive snowy winters.  Around 7″ these past two winters and then 11.2″ in 2016-2017

Portland Snow Last Few Times In March2

Now as of 7pm, Portland’s high temp has only made it to 35 degrees.  That could change in the next 4 hours now that the wind has gone westerly through the Gorge (we’ve lost the cold source of air coming at us from Eastern Oregon).  And we’ve now got 3 millibars southerly gradient west of the Cascades from Eugene to Olympia.  We’ve completed the transition to weak onshore and mild air flow.  It’s possible we rise to 36-38 before midnight.

Assuming we don’t…this is the latest we’ve seen a sub-37 degree day in Portland.  We easily broke a record for coldest high for the date (41 was the record).  IF we don’t go above 35, it’ll also be the coldest day of winter!  That’s crazy and I’ve never seen it happen in March.

Coldest temp in Months

The forecast is much easier now, brief clearing this evening in spots could lead to some icy roads.  OR, we just remain mostly cloudy with snow showers returning after midnight.  The chance for widespread sticking snow in the lowest elevations has gone downhill.  More likely the next two nights/mornings we’ll see at least a dusting up on the higher hills around town.  Then each afternoon we’ll change to rain showers with daytime “heating”.  Friday morning should be our last brush with low-elevation snow.

Snow Headlines Metro Tonight

Chief Meteorologist Mark Nelsen


A Snowy Day but Warming Temps = Clear Roads Most of Portland Metro

March 6, 2019

10:30am Wednesday…

Our forecast worked out well last night and this morning.  Just VERY light precipitation, in the form of flurries, sleet, and even a spot or two of freezing rain.  And for most of us the commute was pretty typical.  I remember saying in each of the 5 newscasts yesterday evening  “good chance you look out the window and see nothing on the ground”  Of course with the sleet and freezing rain there were a few spots of icing early.  Here’s a shot from Gresham.  Pic by Jesse Kerr

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Radar has now “filled-in” with light-moderate precipitation, mainly snow, as models had advertised.  By the way, when you see one of these radar images (whether on TV, app, or web), the “snow/rain/freezing rain” is not what the radar actually sees, but a “mask” put over the radar based on observations and modeling. Just because it’s green doesn’t mean it’s actually raining over you.  An algorithm is just taking a guess based on those observations/modeling

web_metroradar

From now through late afternoon expect gray skies and snow falling most of the time.  That said, we’re talking “conversational snow” again, it may even be “dumping” at times. But air temperatures stay above freezing through this evening, gradually rising close to 40.  That limits accumulation on ground, lawn, trees, etc…  Yes, your neighborhood could turn white under heavy snow showers, but roads shouldn’t.  In fact at 10am road surface temps on US26, OR-217, I-5, & I-205 are already well above freezing, up around 40 degrees.  It would be different in December or January.  But the sun is as strong as early October now!

web_metrotemps

web_temperature_ORWA

The best chance for getting accumulating snow the rest of the day and this evening will be in two locations:

  1. Near/above 1,000′.  That’s in West Hills, Mt. Scott, Powell Butte, etc…  Could see up to an inch, even turning roads white up there.
  2. This evening possibly in far eastern suburbs up around 500′ or so.  Hills of Camas/Washougal, Battle Ground, Boring, Sandy, Estacada.  Maybe, but snow will need to come down at a moderate/heavy pace for that to happen.

Otherwise your evening commute should be just plain wet with temps in the mid-upper 30s.  Snow will come to an end sometime after 6pm.


TONIGHT & THURSDAY (All areas west of Cascades)

I see a typical showers/sunbreaks pattern, but a cold one.  That means mainly snow showers late night and early morning hours, but rain showers 10am-10pm.  We have a southwest breeze blowing much of the time so that makes it extra tough to get significant snowfall.  More “conversational snow” like we see in March some years.

LOWEST ELEVATIONS:  Nothing to a slushy dusting for the Thursday AM commute.  Snow showers early transition to rain showers midday/afternoon.  Lows 33-35, highs 42-46.  MOST OR ALL ROADS STAY CLEAR

UP AROUND 1,000′:  Dusting to 2″ for the Thursday AM commute, best snow up north in Clark/Columbia county foothills.  Snow showers all day, snowy roads possible early in the morning, then wet.  Lows near 32, highs in upper 30s

FRIDAY & BEYOND

Good news!  It’s appears that Friday morning will likely be our last close-call with snow in the lowlands for the season.  Spring weather will finally arrive.  No, not 70 and sunny, but 50s and showers.  That means highs moving back to normal as we head into the weekend and next week.  Check out the ECMWF 15 day outlook; a nice upward trend.  First time in 5 weeks we’ve seen that!

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And the ECMWF ensemble snow forecast for Salem shows the next two days are likely it for snow to lower elevations

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Chief Meteorologist Mark Nelsen