Portland residents will be telling their grandchildren about this one.
The great Portland April snowstorm.
The latest NOAA/HRRR forecast shows bountiful snowfall over the lowlands of SW Washington and NW Oregon for the 24 h ending 5 PM Monday, with several inches around Portland. A drive down I-5 tomorrow morning may be exciting. A drive through the Gorge could be dangerous. And the southern Cascades will be hit hard.
Why this extraordinarily late cold/snow event?
We start with a very deep upper-level trough (see the forecast for 5 AM Monday below for 500 hPa...about 18,000 ft). Very impressive.
And this trough induces a deep low center (see the surface forecast for the same time), which draws in cold air from the north. In addition, heavy precipitation from this system will cause the atmosphere to cool by evaporation and through melting of snow falling in from above.
Anyway, a bit of Northwest weather history will be made tomorrow.
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2 inches of very dense snow at my house in S Richland this morning where trees and shrubs are in full bloom. The precip is very welcome but not the breaking branches.
ReplyDeleteI got a hailstorm last evening, but not thunder and lightning I was hoping for. But it was around 40 degrees all day.
ReplyDeleteEnough! Bring on the spring. Thursday was great though.
WHAT'S HAPPENING!!!!!!!!!
ReplyDeleteNWS forecast was 3-5" for our place (800', NW of Longview), we hit 3" but strong north wind never really kicked in as forecast so that put us at the low end. I see Ryderwood was 5½" so we were on the wrong side of the Willapa Hills.
ReplyDeleteI think it had more to do with somewhat random locations of the most intense precipitation. I am working at about 800 ft out of Rose Valley and there was probably close to a foot there. Even right near the Longview Wye, there was snow on the ground Tuesday morning whereas downtown had melted Monday early afternoon
DeleteWe are out in Toutle/Silverlake and got about 9 inches.. we’re at about 680ft.
DeleteOff topic, cliff is there any evidence that the four corners high pressure is moving further north? hence our hotter summers.
ReplyDeleteTim - read some of Cliff's older posts on this. The summers aren't getting hotter.
DeleteBut they are: https://www.ncdc.noaa.gov/temp-and-precip/us-trends/tavg/sum
DeleteWe are at 1400 feet in the foothills of the coast range west of Portland. I use the National Weather Service point forecast on their web page. Over the years I have noticed we generally get more snow than predicted and the temperatures are colder than predicted. For example, the forecast here was for 2 - 4 inches of accumulation, and we ended up with more than a foot. (Of course, it might be that I am more likely to remember the times we got much more snow than was predicted, and less likely to remember when it didn't snow.)
ReplyDeleteMy conclusion is the point forecasts are tricky, especially in cases like mine, where the topography varies a lot. Could this be improved with with a dense network of monitoring sites? With ubiquitous internet connectivity and available inexpensive small weather stations, I would think this is possible. I noticed a solar powered weather station installed on a power pole near my house, and I wondered if this is already happening.
There are also a large number of personal weather stations on the Weather Underground network. I realize the placement of these stations is not consistent, so that data from individual stations is not reliable, but I would think the ensemble average would be useful.
Finally, personal weather stations do not do a good job in snow. Not only does the precipitation not get recorded accurately, but the anemometer and wind direction indicator can get frozen in place. There is room for improvement here.
Cliff can probably speak to it better but my understanding is the point-forecast uses extrapolation from existing forecast models. I would be curious when you do the click, what kind of 'spot' does it give the forecast for?
DeleteFor instance when I sometimes click a peak I know to be 5200ft which is in the near proximity of Mt. Hood, it gives me a grid cover over it for the point forecast but it tells me the elevation is approximately 4400ft. I end up having to click closer to Mt. Hood and getting a point forecast for 6000ft to really better reflect the conditions I might expect there.
The anemometer can sometimes be heated so it doesn't freeze, I know that.
I grew up in Portland, and one year it snowed on my birthday, April 23. This was some year between 1962 and 1965. I did not go to school that day. We lived in the West Hills about 800 feet above sea level, compared to about 100 feet for downtown Portland. Apparently the event was not recorded, perhaps because the main weather station in Portland was then out by the airport, which gets different weather from other parts of the city. (it gets hit by blasts coming down the gorge, whereas the West Hills are an extension of the Coast Range.) I'm wondering if there is now more "recording" of the westher.
DeleteObviously, it's not possible for the weather service to create a forecast centered on every random location. I believe that most forecasts are actually centered on airports. This is because aviation demands the most accurate weather forecasting for safety reasons. As Matt indicates, all others forecasts (like the one at your location) are extrapolated from there, so they are just approximations.
DeleteNot good for farmers. Reports of flattened tulips and other early season field crops. Mountain snow is welcome, but low elevation snow this late is not
ReplyDeleteits freezing again dammit cliff fix this
ReplyDeleteWhat is happening down here weather wise? This is crazy weather, big thunder storm, hail and snow. But I haven’t heard anything going on up in Seattle? Why is it so crazy down here? Also hear reports of more snowing coming our way?
ReplyDeleteCliff can you please explain why they did such extensive chemtrailing the two days prior to this unique weather event?
ReplyDeleteI see he hasn’t replied but my guess based on his past discussion of contrails (not chemtrails) as well as the condensation plumes that sometimes follow ships at sea, is that Cliff would explain that airplane contrails become larger and longer (and more persistent) when atmospheric conditions (moisture, temp, etc) are right. If i’m not mistaken, he actually has a post specifically addressing whether chemtrails are a thing or it’s actually just misattributed contrails.
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