Wetand News

 Today is sunny, but cool, with temperatures in the teens across eastern Washington and in the lower to mid-30s in the west.  Viewed from the space, the state is mostly covered in snow (see below). My podcast this week (which you can listen to with the link below or through your favorite podcast server) describes a warming trend over the weekend and a generally dry Saturday. A strong Pacific front approaches on Sunday, with the certainty for lots of snow in the mountains and the potential for more lowland snow on Monday morning into Tuesday.   But lots of uncertainty remains regarding the lowland snow...thus I will need a blog on Sunday to provide a more confident update. I hope all of you have a good new year.  Has to be better than what we have been through this year..... You can listen to the podcast below or through your favorite podcast server. Some major podcast servers:     Like the podcast? Support on Patreon 

 The event last night played out similar to predicted.    For most locations in western Washington, a few inches of wet snow fell and temperatures rose just above freezing. We have had a remarkably cold period in many ways.   It was the first time since 1998 that Seattle remained below freezing for three days in a row.  Many locations fell below daily low-temperature records.  And Vancouver, Canada at 4.5F had their coldest temperature in 50 years. The winds and temperatures coming out of the Fraser River valley during this event were historic. But something interesting (and threatening) could happen tonight and Friday night....a slush freeze ...as cold temperatures temporarily return to the region. Washington DOT and Seattle DOT need to be aware of it. Good in a cup.  Not so good on our streets. Courtesy of Frankielion A Tale of Two Types of Streets Seattle and most other towns have two types of streets:  major roadways in which plowing, sanding, and salting have taken place and the r

 Forecasting snow in western Washington is very difficult, even with modern prediction tools. Before high-resolution models and satellite observations over the Pacific, it was nearly impossible to accurately predict local snow events and major local snowstorms occurred with little warning (for example, December 18, 1990).    Picture courtesy of Oran Viriyincy Consider: 1.  There is roughly a one to ten ratio between precipitation totals (amount of water falling from the sky) and snow totals, so a small error in precipitation amounts results in huge snowfall errors.  Making a 0.10 error in precipitation provides a 1-inch error in snowfall. 2. Temperatures over the western lowlands are often marginal for snow.  Right on the edge.  So small temperature errors can produce huge changes in snowfall.   Same with small changes in elevation or distance from the warm water.   3.   There are huge local differences in precipitation because of our local terrain, such as rainshadows, convergence

 You have all heard of a rainshadow.    Air approaching a barrier rises on the windward side, producing lots of precipitation, while air sinks on the lee side, causing drying and a lack of rain (see graphic). On Thursday, we are going to have a profound snow-shadow situation for large portions of the western Washington lowlands, particularly around Puget Sound, and snow lovers like myself are going to be disappointed. Below is the latest super-high resolution UW snowfall forecasts for the 24-h ending 4 AM Friday morning.  Light green is less than an inch, while purples and darker colors indicate more than 6 inches. Plenty of snow on the windward (western) sides of the Olympics and Cascades.  Bellingham is going to be snowed in!  But little around Puget Sound and virtually nothing from north Seattle to north Kitsap.  No snow near Yakima on the eastern side of the Cascades. Looking at snowfall for the entire region for the same period (below), you can see little snow on the lower

 Western Washington can brag about world-class coffee and leading corporations, but did you know we also have some of the worst road icing conditions in the nation when we get some snow? Icing so bad that mayors can lose their jobs when they forget this meteorological fact? Icing that can cripple parts of Seattle, killing and injuring both drivers and pedestrians? Roosevelt and NE 75th Around 1 PM. ICE! It happened again last night and today.  Let me tell you why. Western Washington has a mild winter climate and our soils and roads cool down in autumn, of course, but remain well above freezing during the winter. Then we get a snow event, with several inches falling on the roadways.  This snow starts to melt into a slush layer. Next, much colder air comes in, as the low center and upper trough that produced the snow moves out.  The air temperatures become cold enough that the slush layer begins to freeze...and if cold enough (like yesterday today), it freezes solid to the roadway surfa

 Update:  Here are the latest storm totals from the National Weather Service.  Heavy snow near Port Angeles (10-15 inches) and 1.5 to 5 inches around Puget Sound. Here is an expanded version around Seattle.  Perhaps an average around 3-3.5 inches. _____________________ As predicted, the cold air pushed into western Washington, with the arctic front on the leading edge, with highly variable snow depths reported at 7 AM this morning (see Cocorahs snow map below).  Cold air entered Bellingham yesterday leading to lots of snow (4-15 inches reported), and as the cold  air pushed southwestward later yesterday, the northern Olympic Peninsula area areas (e.g., Sequim to Port Angeles) got hit hard, with up to around a foot of snow. Over Puget Sound, most of the snow action was with the arctic front this morning, with 3-5 inches being reported.  The radar image at 7:37 AM this morning clearly showed the intense arctic front snowband (yellow colors) pushing southward.  The high-resolution models

Some light snow has fallen around Bellingham and environs in the Fraser River outflow (see below), and modest snow has also fallen to the southeast of the Olympics over portions of the Kitsap Peninsula.  Snow has whitened the region above roughly 1000ft, and heavy snow continues to fall in the mountains. I5 north of Bellingham But the real action is ahead, both in cold and snow, and it appears that we have a shot of more extensive lowland snow on Thursday. The Cold A modified Arctic front will move through Puget Sound around midnight.  Temperatures will plummet with its passage, which will also be accompanied by a dramatic shift in wind direction to the north.   Cold air has already started to pour through the Fraser River gap into Northwest Washington, with temperatures dropping into the mid to low 30s, borne by strong northeasterly winds (see map for 11 AM, red numbers are gusts in mph). The forecasts are now consistent and reliable.... western Washington will experience temperatures

I will have a Snow Update at Noon (Dec. 25th) _____________________________________ As we get closer to an event, very powerful tools become available to meteorologists:  high-resolution model predictions, high-resolution ensembles of many forecasts, the NOAA/NWS HRRR model, to name only a few. And forecast skill obviously improves as we get closer to the event.   So based on all this technology, and decades of experience in predicting Northwest snow, let me provide you with the latest update. NOAA HRRR Model Snow Depth Predictined for 6 AM Saturday First, temperature.   The temperatures are too warm for snow over the lowlands today, with the current freezing level approximately 2300 ft.  The snow level (the level at which all snow is melted) is about 1000 ft lower (1300 ft). Near-surface temperatures will remain above freezing throughout the night and Saturday morning/early afternoon.   Temperatures will be a bit colder around Bellingham as cold Fraser River air starts to move in.  Bu

Detailed update this afternoon....I will have the forecasts from the more powerful high-resolution forecast models by then.... ___________________________ I have some disappointing news for many living over the western Washington lowlands. Saturday, December will not bring extensive lowland snow on the ground. On the other hand, many of you will enjoy seeing snowflakes falling out of the sky, which coupled with a rendition of Irving Berlin's classic music and some hot chocolate, might be enough. Not this year.  Picture by Steve Voghut Large amounts of snow are expected in the mountains, so snow recreation will be excellent and close. Snow 101 The temperatures during the next few days will be marginal for snow near sea level, which is often the case in our region. In addition, the ground temperatures are relatively warm, as illustrated by the current soil temperatures from the WSU AgWeather network, which are in the low 40s in the west and mid to upper 30s over the Columbia Basin