Colder Weather, Chance(s) of Rain/Snow Mix This Weekend

After a relatively uneventful week weather-wise, some colder weather with multiple chances of rain/snow mix or wet snow is ahead. Let’s take a look at the details.

Friday will be foggy in the morning, and sunny with highs in the mid-40s for the rest of the day.

Friday night/Saturday morning will be chilly with patchy fog. In some cases this will be freezing fog, which can be hazardous and produce dangerous black ice.

Below is the forecast low temperatures on Saturday morning (from the Euro model).

Expect lows of 26-28 degrees. Saturday will be foggy, then mostly sunny with highs of 40-45 degrees.

Saturday night into Sunday will bring a chance of rain/snow mix or brief wet snow, most likely above 500 feet and early Sunday morning.

There is a very small likelihood that any snow will accumulate. The most likely places for snow accumulations will be grassy surfaces above 500 feet. Snow will likely melt later in the day. 

As the UW forecast map for accumulated snow (above) shows, there is little or no accumulation in the lowlands through Monday morning. 

While snow may not accumulate, don’t be surprised to see some snowflakes falling this weekend!

Additional chances of rain/snow mix and snow are possible through the next week. I’ll have an update this weekend.

Calm Week Ahead, Colder Weather By Late Week

It will be a relatively calm week weather-wise, with relatively no rain and pleasant conditions for this time of year. 

Before we begin the forecast, I would like to highlight a photo of windstorm damage from this past Wednesday’s storm that was shared with me by a Puyallup area resident.

Notice the shallow root base of the fallen tree. This is a classic example of extremely saturated soils combining with strong winds and easily uprooting trees. Another reminder to be prepared for strong winds and the damage they cause.

Now...back to this week’s forecast. Below is the 10-day forecast for Puyallup from weather.com. 

While high temperatures aren’t much different than seasonal normals, notice low temperatures, particularly from the 22nd to 27th. Those are the colder temperatures that could contribute to possible snow. 

Before we get to snow...there’s a small chance of rain on Thursday, but besides that expect a mix of clouds and sun with overnight lows of 30-38 degrees. The coldest morning of the week will be Tuesday (30-34 degrees), then much colder weather moves in starting Friday.

Patchy fog is also possible in the mornings and late at night this week. Take caution in the fog!

Also, if you’re tired of rain and clouds, Tuesday, Friday, and Saturday will be partly-mostly sunny!!

The temperature outlook for January 24-28 from the NWS Climate Prediction Center is calling for a 60-70% probability of below average temperatures during that time.

It’s a safe bet that we will have cold morning temperatures in the 20s and 30s. However, even though snow icons show up on your weather apps, it’s a far cry from certain snow right now. 

Here’s what I can say regarding lowland snow...

It will be colder. That means we will have lower than normal snow levels. How low the snow levels are, the temperature, and the amount of moisture are all unknown. In short: snow is NOT certain, and the best thing to do is stay tuned and be prepared for rain, snow, or neither.

Regarding a reliable snow forecast, I recommend NWS Seattle and any of our local news stations (KOMO 4, KING 5, KIRO 7, Q13FOX).

I’ll have an update on Wednesday night unless something drastically changes in the forecast.

Analysis of the Strength & Impacts of the January 13th Windstorm

Many of you were impacted by the strong windstorm on Wednesday, January 13th. This blog will examine the following:

1. Why was this storm so strong?
2. What made this storm "unexpected" and why wasn't there a better forecast?
3. Why was there so much damage & power outages?
4. What can we learn from this storm?

Peak gusts from the January 13th, 2021 windstorm. 

1. Why was this storm so strong?

Late on the evening of January 12th, a small and rapidly developing low center made landfall on Southern Vancouver Island. As this weather system moved away, it created very steep rises in air pressure that caused strong winds across Western Washington.

Storms that are strengthening as they make landfall tend to be the strongest and most impactful types of storms.

Since the January 13th windstorm was strengthening as it made landfall (and continued to strengthen afterwards), it was a sign that it would be a strong storm.

The second reason this storm was so strong is due to the fact that this storm was strengthening as it made landfall, it produced very strong pressure rises in the wake of the low center.

The graphic above shows pressure observations at Sea-Tac Airport from 11 PM Tuesday (12th) to 4 AM Wednesday (13th). Pressure rose from 1002.4 millibars to 1007.5 millibars in ONE HOUR!! A 5.1 millibar pressure rise in one hour is quite large, and will produce strong winds. That steep of a pressure rise is rare for Western Washington.

The largest pressure rises around the Puget Sound area happened between 12 and 1 AM on the 13th, directly causing the peak winds and hundreds of thousands of power outages.

2. What made this storm "unexpected" and why wasn't there a better forecast?

This storm was unexpected because it was relatively weak and wasn't picked up by most of the forecast models. Additionally, its fast development caused a strong pressure gradient which resulted in strong winds.

One forecast model (the European model) had a forecast for a rapidly developing storm with winds of 50-60 mph two days before it happened. However, because no other forecast predicted this, the European model was considered an "outlier."

Above is the blend of 4 forecast models for Puyallup that I posted on this blog just hours before the storm. The red outlined area is the European Model's forecast. While not perfect, it outlined the possibility of strong winds (50-65 mph) and predicted the storm's development perfectly, unlike the other models.

Seeing the European Model's prediction verifying as the storm developed on the evening of the 12th, forecasters at NWS Seattle issued a Wind Advisory at 8 PM, just 4-5 hours before the storm began. These forecasters did a great job seeing the developing storm and warning the public accordingly.

However, the relatively late warning of this storm led to most of the public being relatively unaware that a strong storm was coming until the strong winds hit. Thankfully, I was able to publish a blog about the storm (though I underestimated the winds) by 9:30 PM on the 12th.

3. Why was there so much damage and power outages?

A big impact of this windstorm was the large amount of power outages and tree damage especially due to saturated ground, something that had been predicted beforehand and was a big concern.

Our heavy rains in the previous weeks set the stage.

This graph from the Western Regional Climate Center shows that since January 1st, we have received 200-300% of our average rain (2-3 times the average) in Western Washington (totals of 5-9 inches for January so far).

Additionally, the graph below shows recent soil moisture levels.

When was the peak saturation in soils? You guessed it...midnight on the 13th, the same time as the peak winds.

These factors above, combined with the 40-65 mph wind gusts in the Puget Sound area, were the main reasons for the large amount of power outages and storm damage from this windstorm, as seen below.

A downed tree (background) completely snapped a power pole in Sumner, WA. The pole was left leaning over the road, with power lines stuck in a downed tree.
Taken 1/13 by Don Neptun.

Fallen trees and downed power lines closed this road in front of the Sumner, WA YMCA.
Taken 1/13 by Don Neptun.

A tall power pole leans precariously over a closed street in Sumner, WA. 
Taken 1/13 by Don Neptun.

I would like to give a special thank you to Don Neptun for sending me these amazing photos of storm damage in Sumner, WA.

Those kind of scenes were common around Western Washington following the storm.

At the storm's peak, nearly 569,000 people were without power in Western Washington. 

This storm would go on to produce wind gusts of 60-120 mph across large areas of the Western & Central United States.

A map of damaging wind reports from January 13th-15th, made by the National Weather Service and featured by The Washington Post.

Wow! The storm's extent is revealed in that map, with hundreds of wind reports over many states.

4. What can we learn from this storm?

We can definitely take some lessons away from this windstorm. I've listed some below.

1. It is always good to be prepared. Sometimes weather events happen with short notice. Have a way to receive weather alerts and be prepared for the impacts of strong winds and other hazardous weather.
2. Large amounts of rain followed by strong winds will result in lots of damage. We already knew that this occurs, but it is a good reminder that shows what happens when heavy rain and strong winds combine.
3. Don't count out a forecast model because its prediction is different than the others. While this mainly applies to meteorologists/weather enthusiasts, it is important to remember that a forecast isn't incorrect until the predicted event happens (or doesn't).
4. Storms that strengthen as they make landfall are the strongest kinds and produce the biggest impacts. Also, a storm doesn't have to have a deep low pressure to pack strong winds, as we saw.