Let’s take a look at our recent winter storm, named Maya by The Weather Channel. As you may have read in my previous blog, this was quite possibly one of the most difficult snow forecasts, or really any forecast, that many of the meteorologists and those in the local weather community had ever seen. So many factors came into play with this particular set up, that even a one degree temperature difference would have meant cold rain instead of snow. In some cases we did see that at the beginning and end of the storm as temperatures cooled to below freezing before and during the storm, and then regulated back to above freezing at the end, a big testament to how important both temperatures and elevation are to whether or not we see snow here in the Puget Sound.

In many other areas across the United States, it is much easier to forecast for snow because the elevation differences are not anywhere near as large as the differences here in the Seattle area. For example, Klamath Falls, Oregon sits at roughly 4,000 feet above sea level and the elevation differences are not very big across the city area there. If it’s going to snow, it’s going to snow everywhere there if the temperatures are cold enough, which they often are much through the winter because of their higher elevation. A spotter in Klamath Falls has measured 48 inches of snow at his house this winter so far!  This is much different from Seattle with our range of elevations, where if the temperature is 33 degrees in Downtown, you’ll see rain….but when you drive up the hill 200-400 feet to the top of Capital Hill or Queen Anne and the temperature drops to 32 or below, you’ll see snow. Another example, Downtown Edmonds at sea level versus driving up the hill to Esperance where you are closer to 400ft above sea level. In a very marginal temperature situation like this storm, it is incredibly difficult to know what areas will see snow and what areas won’t when there is this much elevation difference across a forecast area. Not only that, Puget Sound acts as a temperature regulator. The closer to the water you are, the warmer the temperature is usually. The average water temperature of Puget Sound in January is 45 degrees, which actually will help warm the surrounding air ever so slightly when we are cooler than that. In fact, Puget Sound’s average water temperature today, February 7, 2016, is 46.8 according to the National Oceanographic Data Center (NODC) website, where temperature readings from bouys in the sound are averaged and placed online for reference. Between the elevation and temperatures being just borderline cold enough, it was incredibly hard to accurately forecast the storm ahead of time.

Why? Well, even though we have all these fancy forecast models, they don’t always take into account the elevation differences. We talked a bit about this in my previous blog before the storm, but the global forecast models tend to have a hard time accurately forecasting for the elevation changes across the region. We also see a lot of influence from the mountains being so close, sometimes the models overdo the snow totals because they in a sense “bleed” the mountain temperatures down into the lowlands and just assume that everything falling precipitation wise will be snow. The global models are also a lower resolution model, meaning they look higher into the atmosphere than a higher resolution model. In a really borderline situation like this, it’s best to look at the higher resolution models that look much closer to the surface for a better grasp on marginal temperatures. They’re still not perfect, but sometimes a better tool when faced with a high impact forecast such as this storm. The downside to that? Those high resolution models don’t become available until the storm is about 24 hours out. This presents a challenge for the local meteorologists in both the TV media broadcast business and our friends over at the local National Weather Service office. They want to be able to accurately break down a forecast and make the information available to the public as soon as they can, but sometimes that’s not possible until as many details are gathered as possible. There were a number of complaints on social media that the NWS office “waited too long” to issue a Winter Storm Warning when the models had been painting a significant snowstorm for a few days. This is where the problem with social media comes in. Forecast tools and models are available to the public, so many people will just grab a snowfall total model and assume that’s exactly what’s going to happen. We saw a lot of that this weekend. Meteorologists are trained to look past the forecast models at many other factors. Temperature, elevation, wind direction, front type, mountain influence, arctic intrustion influence….you name it. There is so much more to a forecast than just a snowfall total map. However, when all was said and done, some of the global models actually did pretty well with the 24 hour snowfall total models. That’s because the temperatures DID cool enough for it to snow. If they hadn’t, things would have looked much different around the sound come Monday morning. Without that Fraser Outflow pouring in much colder air, we would have just seen a routine wet Pacific Northwest storm. In fact, that’s exactly what happened down in Portland this time around.

Looking Back at What Happened

Late Saturday night and Sunday morning, the cold front that brought us our widespread snowfall was beginning to develop out in the Pacific Ocean. It began it’s move inland late morning, landfalling on the coast of Oregon. From there, it moved Northeast up into Washington.

Satellite Image Courtesy GOES EAST – Time 12:15 UTC February 5th

Throughout the day on Sunday, southwest Washington saw widespread snowfall, as the cold front brought the temperatures down just enough to support snow through evaporative cooling. When it snows, the atmosphere cools. The heavier it snows, the faster it cools.  The front dropped some pretty heavy snowfall in southwestern WA, which allowed many areas down there to rack up a foot of snow or more through this event. Many areas in southwestern WA are also much higher in elevation than many areas in central Puget Sound.

As the front advanced northward into the (somewhat) more mild Puget Sound region, many areas closer to sea level saw cold rain, while higher hills began to see snowflakes. As the sun went down, the Fraser Outflow air began it’s intrusion into the metro areas. This was the key factor in this storm. Had that air not come down from Canada, we would have remained a cold rain, as temperatures would not have cooled off any further without it. It pushed into the region through the evening and eventually changed almost all areas to snow, even down to sea level in Downtown Seattle.

Satellite Image Courtesy GOES EAST – Time 19:45 UTC February 5th

Since there was nothing to moderate the temperatures above freezing, and the outflow was keeping things nice and cold (LBCWeather hit a cold 26 degrees overnight), it continued to snow as the front made it’s way through the area. The bulk of the precipitation moved through by mid morning on Monday the 6th. A few stray showers followed behind the front and a relatively larger band dropped a little bit more snowfall around the region during midday, including some VERY large and wet snowflakes. This round didn’t really account for too much more accumulation because we were borderline too warm to support accumulation, let alone snow. The heavier snowshower was what likely kept it as snow and not rain, through evaporative cooling, which I explained above. A degree warmer and it would have been, since it was very close. The larger the snowflake, the closer it was to changing to rain. As soon as the last showers moved out, we quickly began to warm up as the evaporative cooling process came to an end. Many areas with very little accumulation melted out completely by sundown. So, as quickly as it began, it was over.

Another effect from the snow during this storm was power outages and downed trees. The snow from this particular storm was much heavier, wet snow due to the marginal temperatures, and it weighed down power lines, and caused tree branches and trees to fall or break. There were close to 70,000 people without power at one point during the storm. LBCWeather in fact lost power twice during the storm, but it was quickly restored thanks to our excellent lineworkers!

Top 30 Statewide Snowfall Totals – Courtesy of Seattle NWS and the CoCoRahs Network of Observers

(the columns are liquid water, new snow, and total snow–and the data is sorted by the new snow amount) – SEA NWS Facebook account.

This shows that most of the higher accumulation totals were much further south than Seattle, and in Eastern Washington where the elevation is much higher. Some areas such as Redmond or Woodinville where the elevation was above 500ft also saw close to 6 inches of snow. Here at 260 feet at LBCWeather in North Woodinville, we measured almost 4 by the end of the storm.

So…when we look back, did the global models come close to accurately predicting totals? They actually did pretty decent. Despite the challenges of a marginal temperature, they came reasonably close. The models assumed that we would be cold enough, and given the precipitation forecasted, the totals were reasonably correct. The snow ratio of snow to water in the models is 10:1, but because this snow was much more wet, the ratio was probably closer to 7:1 or so, perhaps even larger, so that did affect the totals on the models, but even so, they did decently well. When the higher resolution models began to show that we would see a significant snowfall as well, confidence in the forecast increased significantly, which is what warranted the issuance of a rare Winter Storm Warning for the Puget Sound region. In the end, the warning verified.

Some Snow Photos from the Storm – Courtesy LBCWeather/JB Hawkins Photography

For more photos, visit:

JB Hawkins Photography