SEATTLE -- I think we've qualified for a 6-'R' Brrrrrr.
Many low temperature records were broken Tuesday morning as temperatures plunged into the teens and, in some cases, single digits -- even colder than the cold snap of 1972 that hold (held) the records for this time of year.
Among those rewriting record books: Olympia with a low of 6 (old record of 10), and Seattle at 18 (old record: 21). Even on the coast next to the relatively toasty Pacific Ocean, it was a frozen night, with Forks dropping to 17 and Hoquiam down to 15.
Here is a list of low temperatures from around the region:
- Olympia : 6* (Old Record: 10, 1972)
- Shelton: 6
- Tacoma: 7
- Kelso: 7
- Arlington: 9
- Bremerton: 10
- Vancouver (WA): 11
- North Bend: 12
- Hoquiam: 15* (Old Record: 19, 1972)
- Mount Vernon: 15
- Bellingham: 16
- Seattle (Boeing Field): 16
- Renton: 16
- Forks: 17
- Seattle (Sand Point): 17
- Seattle (Sea-Tac): 18* (Old record: 21, 1972)
- Gig Harbor: 18
- Oak Harbor: 18
- Port Angeles: 19
- Everett: 20
- Seattle (UW): 21
- Friday Harbor: 26
The weather made for some pretty pictures, but didn't seem to cause any problems on the surface, however, the cold, dense air has become quite stagnant. A Stage 2 Burn Ban is now in effect for King, Pierce, Snohomish and Kitsap Counties. More information at the Puget Sound Clean Air Agency.
Why is it warmer in the city?
Seattle's proximity to Puget Sound, which is near 50 degrees most of the year, helps keep us a little warmer, but even more of a factor is what's called the "urban heating effect." In essence, just by being a big city, we generate a lot of heat on our own. All the asphalt and concrete from roads and buildings to a better job of absorbing the day's warmth and then radiating it back out into the city at night, where as vegetation and forests in rural areas don't keep the heat in as well.
That's why Seattle typically is among the warmer cities when we do a list of overnight lows -- note how the UW, in the heart of Seattle, was fairly warm, as was Everett.
There are other factors in play as well, especially on nights where it is clear. Any kind of decent wind will mix things up a bit, keeping some of the warm air radiating back to space at night still mixed in, where if it is calm, that warm air escapes. On cold nights where there is a gusty east wind blowing through the Cascades, sometimes North Bend hardly cools off at night at all.
(Note, It can actually be too calm. If it is completely dead air, cold air will really stick to right near the surface to where it might be, say 2-3 degrees colder at your toes than your head. Prime conditions for maximum cooling are a wind of about 3-5 mph.)
How long does it stay cold? And where's the snow?
Snow fans are probably starting to feel cheated. How can it be this cold and yet we can probably count the number of snowflakes we've seen around the region this week on two hands?
Bad luck -- there just hasn't been any moisture around. Even frost has been hard to find since humidities behave been in the 30-45% range.
Snow fans might remain somewhat disappointed because we'll start to gradually warm here and it might not be quite so prime conditions for snow by the time our next storm arrives as had it arrived, say, today.
The main source of the arctic air is slowly moving off to the east, and that will allow a slow warmup here for the rest of the week. Temperatures Wednesday night are expected to be cold again, but range from the mid teens to low 20s as opposed to 7-15. Highs Thursday should climb back above freezing to the mid 30s and then lows Thursday night/Friday morning are "only" supposed to be in the low-mid 20s.
Clouds will increase Friday as a weak system brushes by to the north. This could put out a few flurries north of Everett, but we're working with limited moisture here. It should be a cloudier though.
Friday night into Saturday is our first chance of precipitation, which we should still be cold enough that whatever falls would be snow. However, right now, forecasting models keep almost all the moisture in Oregon to perhaps as far north as Longview. Up to the north, it paints a few flurries here and there with the Puget Sound area stuck in the dry center.
Beyond Saturday, forecasting models are in serious flux over what to do about Sunday and Monday, with scenarios all over the place from light snow-to-rain on Sunday, to just rain showers Sunday, to perhaps dryish Sunday but perhaps a snow-to-rain event Monday evening into Tuesday. It all depends on how well we can scour out the cold air that's in place now, and whether a reenforcning shot of cold air that some models hint could happen Sunday would really materialize or just miss us to the east. Either way, probably not as cold as now -- perhaps just 3 or 4 'R's for the "Brrr".