More February Snow - Storm Details

Yet another winter storm will impact the region through Wednesday delivering more moderate to heavy snowfall.  In this blog we will discuss this in more detail including start and end times and snow amounts so let's get to it.

Here is an Infrared Satellite image from 1 PM this afternoon (Monday).  The low center was off of Vancouver Island with a deep fetch of moisture noted by the cooler (green shade) cloud tops aimed at the region.

When will it start?  Well as of 3 PM is had already started in Wenatchee, Moses Lake, Pullman,  Lewiston, Spokane and heading northeast.  Here is the 12z GFS model depiction of how this storm will evolve.  Will look at individual time steps of precipitation going into Wednesday.  Blue is snow with darker blue shade indicating greater intensity.  Green is rain, and pink is a mix.

You can see the main snow event in terms of snow intensity will be tonight into Tuesday morning becoming more focused to the Cascade crest and Idaho Panhandle Tuesday afternoon.  Worth noting on Tuesday is milder temperatures and even above freezing over parts of Eastern Washington and north Idaho.  Here are Tuesday's forecast high temperatures

We could also see wind gusts of 20-30 mph around Ritzville, Spokane, and Pullman creating patchy drifting snow.  The snow transitioning to the wet variety combined with the milder temperatures should keep this patchy in nature but local impacts are still possible.

This essentially ends phase 1 of the storm.  We will get to Phase 2 in a minute.  First here are the snow totals for tonight.

And now Tuesday:

Phase 2 will feature a secondary surge of snow, with current models showing another round of snow moderate to heavy snow accumulations for SE Washington into the Central Panhandle Mountains.  Spokane and Coeur d'Alene may see additional accumulations as well.

Here is 4 AM Wednesday per the GFS model

And 4 PM Wednesday

And finally, the storm exits Wednesday evening

Here the projected snow amounts for Tuesday night

And Wednesday

Now, if we add all of this up, here is what we get

Now keep in mind this is a long duration accumulation forecast, and there will be a period of above freezing temperatures for some areas such as Pullman on Tuesday.  So the total snowfall forecast may not achieve these numbers from a snow depth change perspective.  This is an evolving situation so please check our website here for the latest forecasts, advisories, and warnings.

Stay safe out there as winter driving conditions continue.

Storm update, more snow next week?

There has been lots of talk lately about our big storm and the cold weather pattern.  But what about snow as we go into next week (Feb 10-16)?   We will look at this potential snowy pattern but first here is an update on the big winter storm.

The first part of this storm is the accumulating snow.  Here is our latest thinking (as of Friday evening) with additional snow amounts from Friday night into Sunday morning.  Note this does not include what fell Thursday night through Friday afternoon.

The big story Saturday will be continued moderate to heavy snow in Central WA especially around Wenatchee, along with blowing and drifting snow and localized blizzard conditions across the Columbia Basin, Okanogan Valley, Waterville Plateau, as well as around Sandpoint and Coeur d'Alene.   Some roads will likely close around these areas.  Here is a graphic of forecast peak wind gusts on Saturday.

These winds will usher in arctic air into the region.  Here are the forecast wind chills for early Sunday morning.

And high temperatures will be very cold on Sunday.  Yes, these are highs!

So what lies ahead going into next week?  Computer models have been trending towards more snow.  In addition to the storm for tonight and Saturday, there are three more that we are keeping a close eye on.

18z GFS depiction of 500mb heights and 700-500mb Relative Humidity during four snow events February 9th-15th, 2019

All this snow will add up with the cold temperatures (besides settling of the snow).  The Sunday night storm models show the best chances for significant snow accumulations south of I-90.  Here is the GFS Ensemble plumes of snowfall going into next week for Spokane.

18z GEFS Snowfall plume for Spokane (GEG)

You can see pretty good agreement with the first storm of around 3 inches of new snow tonight into Saturday for Spokane.  Not much snow with the Sunday night system, but again areas further south have a better chance.  Uncertainty increases as to how much snow we get beginning Monday night.  Anywhere from 6 to 17 inches through February 16th with an average of around 11 inches.  This however utilizes a lower snow ratio (10:1) meant for wet snow and given the drier nature of the snow amounts could be higher given higher snow ratios expected.

Stay tuned to current forecasts as we go into next week as we fine tune snow accumulations with each storm.  And the cold will stick around for a while.  Here is the latest 8-14 temperature outlook issued by the Climate Prediction Center valid Feb 16th-22nd.

Climate Prediction Center 8-14 day temperature outlook issued February 8th valid February 16-22nd, 2019

Update to weekend winter storm

Here's a quick summary of the main changes to the forecast:

• Less snow forecast for Moses Lake and all points to the east, including Spokane, Cd'A, the Idaho Panhandle and northeast Washington.
• Stronger winds

Here was the snowfall forecast that was from our previous blog, made Thursday morning.

And here's the current forecast:
 

Comparing the two images, you can see that we've markedly cut back on the forecast snow for locations east of Republic and Moses Lake.  The Spokane metro area is now only looking at 2-3" of snow.  The majority of this would fall Friday night.  The real heavy snow threat continues to be in central Washington.  The forecast hasn't changed much on this.

Let's take a look at a few model forecasts for snow fall.  First, here's the GFS model:

 The GFS has 2.4" for Spokane, 3.5" for Moses Lake, and 4.5" for Wenatchee.

Let's take a look at the new GFS, known as the FV3:

The FV3 is similar to the GFS for Spokane, but higher snowfall for Moses Lake and Wenatchee.

Here's the 12km NAM forecast:

 The NAM is a little snowier, with 3.7" for Spokane, and a whopping 15.2" for Wenatchee.

There's a 3km version of the NAM as well:

 2.7" for Spokane from the 3km NAM, 10.5" for Moses Lake, and only 3.8" for Wenatchee.

 Now for those in Spokane who are hoping for no snow, there is a model run by the University of Washington that should make you happy:

As you can see, the UW-WRF actually forecasts no snow for the Spokane metro area, while still hitting the western Columbia Basin hard with snow.

Hopefully this gives you a feel for all of the different computer forecasts out there.  The general screaming message for snowfall is central Washington will likely see the most snowfall from this event, and the farther east you go, the less snow you're likely to see.  So just to repeat, here's the current NWS snow forecast:

But what makes this event more impressive and unusual is the associated cold wind.  Here is the wind speed forecast for Saturday afternoon:

Those kinds of wind speeds and dry snow will result in a lot of blowing and drifting snow, most notably for Moses Lake, Omak, and the Waterville Plateau.  Drifting snow will make some roads in the western Columbia Basin impassable on Saturday.  Driving on Highway 2 between Davenport and Waterville could be tough going.  For Spokane and the Panhandle, there won't be nearly as much snow, so blowing and drifting won't be much of a problem.

The winds will also cause biting cold wind chills.   

The cold continues for the next 2 weeks.  In fact, the Climate Prediction Center put out a Hazardous Temperatures Outlook on Thursday:

You can see that while they show cold weather for much of the northwestern states, they've circled the Inland NW with a High Risk of Hazardous Temperatures for Feb 15-21.  In their discussion, CPC said:

Even at the very end of Week-2 (Feb 21), the calibrated GEFS depicts a 30% chance that minimum temperatures will fall into the lowest 1% of the observed distribution, suggesting record or near-record low temperatures in eastern Washington.

 Winter has made quite an appearance this month, after a mild December and January.

Not your average winter storm

We have the potential for a significant winter storm to affect the entire Inland Northwest this weekend.  But this isn't just your average winter storm.  Most of our storms go like this:  heavy, wet snow falling with temperatures around freezing and light winds.  Then as the snow ends, the southwest winds increase, and the temperatures warm.  For this weekend, things will be just the opposite; dry fluffy snow, cold winds, bitter wind chills and drifting snow.  Let's take a look.

First, here's the expected snow fall for Friday through Saturday.

Light snow will start early Friday morning across the northern border region.  It should be snowing in the Spokane metro area before sunrise Friday, with about 1-2" of accumulation during the day. 

But the real event will get going Friday night into Saturday, with the main focus for heavy snow in north-central Washington.  The above image is our best forecast at this time (early Thursday morning).  But computer guidance varies greatly.

We'll start off by looking at some forecasts from the traditional models, the NAM and GFS.  Here's their snowfall forecasts for Spokane:

 The blue lines are the GFS, the reddish lines are the NAM.  As you can see, the GFS is on the light side, with just a couple of inches for the metro area, while the NAM is more optimistic of a 5-7" event.

In central Washington, the forecasts are little more impressive.  Here's the forecasts for Wenatchee:

The GFS is again lighter than the NAM for snowfall amounts.  Some of the NAM forecasts are in excess of a foot of snow.  The Okanogan Valley also looks similar to the Wenatchee forecast:

And lastly, here's the forecast for Ephrata (near Moses  Lake):

That's a lot of snow for the Columbia Basin, if the NAM is right.  Even the GFS forecast of 6-8" is respectable.

But that's just 2 models.  There are also multi-model ensembles that we can look at.  We'll start with the GFS ensemble for Spokane:

 
The blue line is the GFS forecast.  The thin grey lines are all of the ensemble members, and the thick black line is an average of all the grey lines.  So 4" looks like a good forecast, but the range could be anywhere between 2" and 6".  

Here's the same forecast graph for Ephrata:

 
You can see that the GFS (blue line) has about 9" of snow, while the ensemble average (black line) is closer to 6".

Lastly, let's take a look at the SREF model, which is actually an ensemble of 26 different NAM models.  Again, we'll start with Spokane:

 The SREF would suggest a forecast of 6", with a possible range of 2" to 11".  

How about Ephrata?

 The average of the SREF members has a forecast of about 8" for Ephrata, but a few members want to go as high as 17".

Wenatchee is even more impressive.

 Yes, you're seeing things correct.  The average of the ensemble is 19" of snow at Wenatchee, and a few members have over 3 feet of snow, while others have less than 10".  The Okanogan valley is similar to Wenatchee.  These extreme forecasts have very little chance of being correct.  It's worth keeping in mind that the 48-hour snowfall record for Wenatchee is 24.7" set back in 1971.

So, as you can see, lots of different computer forecasts, with lots of different snow fall amounts.  But the screaming message is that there could be a LOT of snow for north central Washington.

But so far, we've focused on snowfall.  But during the day on Saturday, cold winds will blow from the northeast.  Here's the forecast wind gusts for Saturday afternoon:

Winds this strong, coupled with dry, fluffy snow, will result in the potential for a lot of blowing and drifting snow.  Drifting snow has the potential to make some roads impassable, especially in the Columbia Basin, the Waterville Plateau and Okanogan Valley.  If you have travel plans on Saturday, you might encounter roads like this:

Lastly, if you're hoping for warmer weather, you're going to have to wait awhile.  Here's the outlook for next week:

Temperatures in the Inland Northwest will remain below freezing for the next week.  And even for the week after that, there's a really good chance that temperatures won't warm much.  A few locations might see a daytime temperature slightly above freezing, but in general, we're looking at staying sub-freezing for the next two weeks.
 

Amazing WA State temperature contrast - Sunday Jan 27

Sunday was a day where Meteorologists were amazed by the temperature contrasts across the state.  Some locations didn't rise above freezing.  Others were near all time January record warmth!  What caused this?  Where was this record warmth?  Let's take a look beginning with the new GOES-17 Satellite imagery.

GOES-17 Day Snow-Fog Satellite 2 PM PST January 27th, 2019

This image is from 2 PM Sunday.  Purple is where the low clouds are, encompassing much of the Columbia Basin, Colville area, and Spokane/Coeur d'Alene area.  Red is snow cover, while the green shade is bare ground with no snow cover.  Note Ellensburg is in the green shade (more on this later). 

Now, here are yesterday's high temperatures (Sunday Jan 27th)

Observed high temperatures for January 27th, 2019

Now typically the presence of low clouds does not have a big impact on day time temperatures in Eastern Washington in late January.   The sun angle is still low in the sky and not very effective in warming up the surface.  The number that stands out on this map is Ellensburg, reaching a balmy 62F.  It was a nice day as this WADOT web cam shows.

Meanwhile you'll notice from the temperature map above Ritzville and Spokane didn't even make it to freezing!  Here is a web cam from Davenport, WA (located about 25 miles west of Spokane)

Dense fog, can't see very far!

So why did Ellensburg get so warm?  We will get to this in a minute.  The 62F was very impressive for late January.  It was the warmest January day on record at the airport.  The 2nd warmest January day taking into account a 64F reading recorded by a COOP observer on January 31st, 1971.

 

The northwest flow pattern can bring better mixing of the atmosphere to the Kittitas Valley.  While there wasn't much wind, just the solar heating was enough to spike up the temperatures.  There was also no snow on the ground which is a good reflector of solar radiation.  Here are the observations from Ellensburg Bowers Field.

Ellensburg observations 8 am - 4 pm PST January 27th, 2019

And the 62F was after temps near 30F at 9 am with freezing fog.  An impressive deal to get this warm after a cold and foggy morning.  Wenatchee, which had a similar amount of sun as Ellensburg, did NOT manage to get as warm with afternoon temperatures only in the upper 30s.  A temperature inversion lingered here despite the sunshine which is typical for late January.