We are going into a very complex, difficult weather situation, with substantial uncertainty.
But some things are clear:
- There will be heavy snow in the mountains.
- There will be a return of serious precipitation on Friday, starting as rain
- Some areas near sea level will have snow starting on Saturday.
- Very much colder air.....cold enough to snow at low levels...will move in on Saturday and stick around for days.
- The surface and road surfaces have cooled to freezing and will not be warm enough to melt incoming snow.
Step 1: Friday "Warm" Storm
On Friday, a moderate low-pressure center will sweep off the Pacific and move into British Columbia. As shown by the sea level pressure forecast for 1 PM Friday, warmer southwesterly winds will move into the Northwest. Yellows and light green colors (at around 800 meters ASL) are relatively toasty.
Stage 2: The Cold Air Moves in
Behind the cold front, very cold air will move in.....cold enough to snow at relatively low elevations. Near sea level, the warming by the Pacific will create a shallow layer above freezing.
Consider the temperatures above the surface...in this case about 5000 ft above sea level (850 hPa pressure). When such temperatures drop below approximately -6°C (21 F) meteorologists worry about snow reaching sea level.
Here is the temperature forecast above Seattle at this level from an ensemble of many forecasts. Wow. Cold enough to snow on Saturday!
The European Center forecasts for surface air temperatures at Seattle for the next week show highs only in the mid-30s from Monday onward.
For the lowland parts ofSeattle to Tacoma area, it never snows when predicted. It has to sneak up on us. Probably due to the rain shadow of the Olympics and such....
ReplyDeleteThanks for the info Cliff, always love reading your blog, I check it several times a week. Never thought I’d be interested in meteorology but you’ve changed that these last several years!
ReplyDeleteDoes this appear to be a Hood Canal snow event with residual cold air trapped leading to higher than surrounding areas snow totals ?
ReplyDeleteInquiring minds and all that...
Yeah i live between Sequim and Port Angeles and I will bet we see between 2 and 6 inches of snow between Saturday night and Monday. Some.models are calling for it to round out through Wednesday and more to come in next weekend as well. The last time anyone called for "and inches or two", we saw 3 1/2 feet; that was around this time back in 2019. I remember bc my daughter was pregnant with my grandson.
ReplyDeleteForcast calls for just a few inches, but we can get buried when the convergence zone sets up along highway 2. Should be interesting to see how this plays out.
ReplyDeleteI see 2 days of snow and then another dry cold 14 day forecast of no snow for the BC interior as the storm track shifts south after a bone dry January. We used to get consistent snow and westerly flows from the Pacific in Revelstoke most of the winter, hasn't happened in the past 3 years; this trend is concerning. Drove through Nakusp yesterday and could have gone mountain biking.
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ReplyDeleteHi, I live in Shoreline and the map of the “accumulated snowfall through Monday morning at 4 AM” has an unfortunate arrow right over my city. Is there somewhere that I can view a map without the arrow, so I can get an idea of how much snow my kids might have to play in?
ReplyDeleteZooming in it looks like about 2 inches... Sorry, a bit scant. But you never know until the fact.
DeleteThanks for the heads-up! Your predictions are excellent. Whatever blows our way, we'll be prepared. It IS still winter, b'gosh!
ReplyDeleteOye! Just stepped out - it's snowing here, 7:52 pm Thursday. 'Might want to update that prediction. We're just a "hair short" of 1000 ft elevation. Temp is 32 on the nose. (Prof: Not necessary to publish this - just thought you'd find it interesting.)
DeleteCliff, can you comment on the very recent development (last few weeks) intensification of la Nina as it has built eastward towards Peru (ENSO region 1+2)...Isn't this HIGHLY unusual since la Nina events by late January have already reached their peak intensity and rarely build east towards Peru/ENSO 1+2? Is this going to have effects for the rest of winter, spring and/or summer in the PNW? Thanks for keeping us up-to-date on the latest as our pattern changes.
ReplyDeleteKBLI had its coldest January since 2017. There were 20 freezing minimum temperatures during January 2025 which is the 9th most freezing daily minimum temperatures among Januaries at this location.
ReplyDeleteThe remarkable aspect of this crisp, dry, but not particularly cold month is that all but one of the freezing minimum temperatures were consecutive - from 1/12 through 1/30. 19 consecutive freezing lows is quite impressive for this location and ranks 3rd among Januaries. In fact, 19 consecutive freezing lows ranks January 2025 5th overall behind only January 1949 (25), January 1957 (23), January 1993 (23), January 1969 (21), and tied with February 2019 (19) and December 1964 (19).