Storm Part 2...Will your house have electricity in the morning plus a look beyond?

There's a good chance of seeing multiple power outages tonight with our upcoming wind storm.  And depending on how many outages there are, our much-appreciated hard working utility folks may not have all the power back on before you get up Saturday morning.  As such, you may want to make some contingency plans.  It would be a good idea to charge your battery powered devices this evening just to be safe. 

Round 1 of our storm series is over. The main result of it was heavy snow which fell over many parts of the Inland Northwest overnight and into this morning.  It is very unusual to have this much snow this early in the season, let alone for the first snow of the season. Here are the morning snow totals.  Since it snowed much of the morning, these totals will likely increase from what's posted here.

Now it's time to get ready for Round 2 and it could be a doozie: the wind storm.  The various computer models have their usual disagreements, but they're all saying it's going to be windy tonight.  One chart we often look at for wind events is the 850 mb wind forecast.  Think of this as the winds about 3000-5000 feet elevation.  Usually a wind of about 50 knots (58 mph) will get our attention.  In this instance, the GFS is forecasting 65 to 78 knots of wind tonight!  Other models so something of a similar magnitude.

850 mb winds for 11PM Friday

So the question is: can that wind that is 3000-5000 feet overhead mix down to the ground?  The answer is quite complicated and difficult to answer.  Meteorologists often struggle with this a lot.  In some instances, those strong winds above us stay above the ground and we never feel them.  But there are situations where those strong winds do make it to the surface.

One of those mechanisms is cold fronts.  And that's exactly what we'll have moving through our area tonight.  The front is moving west to east, and will go through Spokane around 1am tonight.  Before that, the rain in the Spokane area will taper off around 6pm, and then the winds will begin to crank up.  It will be windy with gusts up to 50 mph late this evening and then the front plows through. We still think there is a good chance that when the front goes through, we will see wind gusts in the 60-70 mph range for some locations.  The damaging winds should begin to taper off  before sunrise Saturday.

Here's the peak wind forecast.  Keep in mind that the valley locations like Colville and Republic may not see the highest wind speeds, but they have more trees to potentially knock down and thus produce more power outages. 

So what can we expect from an event like this?  At this point, there are some similarities between this event and the 13 Jan 2021 event.  That event had 850mb winds of 57 knots just before the cold front came through, which resulted in a gust to 71 mph at Spokane Airport.  But similar to tonight's event, the strong winds only lasted about 3 hours.  Still, the tree damage was significant, and power outages lasted for several days in some locations.

After the wind storm, we aren't done with the active weather, we still have Rounds 3 and 4 to contend with. 

Round 3 promises to deliver more snow, and in some cases it could be significantly more than what we just saw. The heaviest snow possibilities are honing in on north-central Washington.  The surface low will track south of us, which favors that part of the Inland NW due to easterly low-level winds pushing into the Cascades. This will cause rising air over much of that area, rather than the more typical downslope/rain shadow effect.  Snow should start there on Sunday morning.

Surface low position (off Vancouver Island at 11 am Sun) and precipitation

But since this low is tracking south of us, the front will move very slowly across the region.  It won't reach extreme eastern WA and the Panhandle until 24 hours later, Monday morning.

Surface low position and precipitation as of 11 am Monday

Here's the current forecast storm total snow for this event.  

And lastly, Round 4 will be the unusually cold temperatures that move into the region behind this storm.  There's a good chance that some locations will break daily records.  Here is a list of the record highs which could be broken (denoted in yellow):

As well as the record lows (denoted in yellow):

If there are widespread power outages from the wind or upcoming snow event, the cold temperatures next week could have a much bigger impact than they usually would. 

UPDATED....Is a significant snow event possible for Spokane,Coeur d'Alene or the Palouse late tonight and tomorrow morning?

So as we talked about yesterday, an unusually tricky weather scenario looks like it will unfold over the Inland Northwest. So what are we fairly certain about? We are fairly confident that a slow moving upper-level low-pressure system will take up residence over the Inland Northwest and produce a band of moderate to locally heavy precipitation. The big questions to answer are where is this band going to set up and will it cool the atmosphere enough that we could see some significant snow. The setup producing the unusual event looks quite similar to what we discussed in our previous blog. We still expect to see strong lifting associated with a slow moving upper level low parked somewhere over eastern Washington. Notice the green shaded area (representing upper-level moisture) remains parked over eastern Washington and the central Idaho Panhandle through much of Tuesday.

500 mb pattern 2am Tue-5pm Tue

The lifting from the low will be accompanied by plenty of moisture and instability which should be perfect for producing a band of precipitation. Just how much precipitation are we talking about? A lot to say the least. The areas in purple represent totals between 0.50-1.00 inches of liquid and the reds and yellows equate to amounts between 1.00-1.50 inches. This is for the 12 hours between 2am through 2 pm Tuesday. Notice the band of heavy precipitation has eeked farther north than what we were looking at in yesterday's forecast and blog.

Latest 12 hr precipitation forecast 2am Tue-2 pm Tue

Previous 12 hr precipitation forecast for 2am Tue-2pm Tue

We still highly suspect that whatever verifies from a precipitation standpoint will more closely resemble the top two panes showing a heavy east-west oriented band vs the more poorly defined precipitation blob in the lower two panes.

Since the forecast is nearing in time we can also use one of our favorite tools called the HRRR (a rapidly updating model that runs hourly and can ingest current weather conditions). Let's see what the latest run of it says. The loop below is a simulation of what the radar is expected to look like. Green and yellow shading indicates where the heaviest precipitation is expected.

Radar simulation for Tuesday morning

So this also boosts our confidence that this event is going to occur. Each subsequent run of this model continues to show a similar radar formation (with small variations in location).

Now the largest problem remains is will the temperatures cool down enough to support snow. The models vary in this regard and there is a fine line as to whether or not snow can fall and then whether it will get heavy enough so it can accumulate on roads. The odds of rain changing to snow over the Inland Northwest look fairly good especially over Idaho and southern Spokane County and northern Whitman County. However a tougher question to answer is will the snow be able to accumulate on the area roads? If the snow gets heavy enough the answer is yes, however if not, most of the accumulations will occur on grassy surfaces. So once again lets look at the plume diagrams to see how much snow 27 different model runs produce over Spokane, Coeur d'Alene and Pullman.

Spokane plume diagram shows snow totals ranging from 0.0 - 2.5" with an average around 0.3" 

Coeur d'Alene plume diagram shows snow totals ranging from 0.0 - 5.3" with an average around 0.8" 

Pullman plume diagram shows snow totals ranging from 0.0 - 3.5" with an average around 0.5" 

Generally speaking, these values are on par with what the models were showing last night, however with the band moving further to the north, the snow totals in Pullman are trending lower. Motorists are still urged to check the latest forecast before venturing out in the morning and be prepared for a potentially snowy commute. Here is our latest snow forecast.

Snow forecast for Tuesday (issued 9 pm Monday )

1145pm Monday Update....the band of precipitation was beginning to take form. Our confidence is growing the moderate to locally heavy precipitation band will develop. Still not sure if heavy snow will accumulate.

1147pm radar imagery. Note heavier precipitation developing between  Davenport and Ritzville. 

Severe Weather Monday?

You may have heard about the potential for severe thunderstorms on Monday, June 1st.  We've been talking about it in our forecasts for the past couple of days.  So how likely is this?  Let's take a look at a few things.

First, thunderstorms rely on instability.  There's several ways that meteorologists assess the instability of the atmosphere.  One of the more straightforward methods is called the Lifted Index, or LI.  There are more sophisticated methods, but we'll stick with the LI for simplicity sake.  Essentially, if the LI is less than 0, then the atmosphere could be unstable, leading to thunderstorms.  The more negative the LI value is, the stronger the thunderstorms could be.

So here's 4 LI forecasts for Monday afternoon.

Lifted Index forecasts from four models valid Monday afternoon, 1 June 2015

The yellow, orange, red, and pink colors show areas of LI less than 0, with pink showing the areas with LI less than -4.  So as you can see, these 4 models all show instability on Monday afternoon, with some areas of rather strong instability (pink shading).  The exact location varies a bit, but in general they agree on the southern Idaho panhandle.  So from an instability standpoint, Monday certainly looks favorable for strong thunderstorms.

Another parameter we look at is wind shear.  We look at this over a layer of the atmosphere, typically from the surface up to about 4 miles.  Shear measures the change in wind speed as you go up.  For strong storms, we want lots of shear.  This helps the thunderstorm develop.  Weak shear means the storms will be more vertical, which isn't as good for strong storms.

Here's the shear forecast from the GFS model (the others are similar to it)

Forecast 0-6km Wind Shear for Monday afternoon, 1 June 2015

The colors of purple indicate shear of less than 30 knots.  This isn't very strong.  The cyan color shows shear of 30-40 knots, which is moderate, but still not strong.  So the shear forecast doesn't look very promising for strong thunderstorms.  

We also need a "kicker", something to get the ball rolling so to speak.  Often times this can just be the sun warming the ground.  So let's see what the forecast looks like for clouds.

Relative Humidity Forecast for Monday morning, 1 June 2015

This is the Relative Humidity forecast from the GFS model for Monday morning.  The green shading shows the atmosphere nearly saturated, which usually means clouds.  As you can see, there's the potential for a lot of clouds Monday, which would limit surface heating from the sun, and thus diminish the thunderstorm chances.

But there are other ways to make thunderstorms without sunshine.  A strong low pressure system can do the trick.  And that's what is causing the spiral of green off the Oregon coast in the above image.  This low could bring enough "dynamic" lift to kick off thunderstorms.  In fact, for  strong/severe storms, we usually want both (sunshine and strong low).

Here's the model precipitation forecast from 4 models.  Again, there's fairly good agreement.  These would seem to indicate that the best activity could fire off in the Panhandle and quickly move into western Montana.

Forecast precipitation from four computer models, valid Monday evening 1 June 2015

This is still a few days away, so there's still time for the models to refine their forecast.  Timing will be critical.  If the low comes in too fast, there will be too much clouds; too slow, and the sun will be setting before things can get going.  So as always, stay tuned to the forecast.

Is it still looking wet for this Memorial Day Weekend?

So a couple days have passed since our last blog post about the weather outlook for the Inland Northwest for the upcoming Memorial Day weekend. Consequently, our confidence in what sort of weather to expect should be increasing. Recall that in the last post, there were suggestions that this could be a very wet weekend. In fact, perhaps the wettest Memorial Day weekend since 1997 and the second wettest on record (since 1970). So is that still the case?

Saturday 500 mb height

Above is the 500 mb map for Saturday from the GFS. This is a similar setup to the maps we explored earlier this week with a deep low centered over the Pacific Northwest. So is this GFS run an outlier or do other model agree with the solution?

4 different models showing 500 mb heights for Saturday (upper left model did not come in fully)

Here's is a look at 4 models compared to each other and they all show a low focused somewhere over the Pacific Northwest on Saturday. So where is this low on Sunday?

500 mb maps for Sunday

Again there is great agreement that there will be a low focused somewhere over the Pacific Northwest. The top 2 models take the low into southern Oregon, whereas the bottom two models drop the low into southern Oregon. Now, what the positioning of the low on Memorial Day?

500 mb maps for Monday

Again all the models keep the low over the region, however, the consensus is to drop the low south of the Washington/Oregon border.

So our confidence in this event is quite high. We are certain this low will form and move over portions of the Inland Northwest however how long it will remain over the area and where its precipitation  band will set up is the big question. Looking at the GFS for the Saturday and Sunday yields a significant northwest to southeast orientated band of precipitation.

48 hr precipitation amounts for Saturday-Sunday (latest model run )

This is quite similar to the previous model run we looked at a couple days ago(see below). Both model runs show a similarly oriented band of precipitation, however,  the latest version has the band a little farther to the west leaving places such as Sandpoint and Colville much drier than the previous forecast.

Rainfall forecast for Saturday and Sunday (Monday's model run)

Obviously wherever this band sets up will determine who gets a lot of rain and who doesn't. If we decide to consult another model solution it also shows a similar NW-SE band setting up, but this time it's displaced even further west. If this solution were to pan out even Spokane would miss out on the bulk of the rain as would the Silver Valley. 

Another Saturday-Sunday 48 hr precipitation forecast

So given these uncertainties it will be hard to pinpoint exactly where the band will take up residence. This is where ensemble model forecast can sometimes help to pinpoint the band (s) of heavy precipitation. So once again referring to the GEFS/NAEFS ensemble forecasts we see that it maintains a NW-SE oriented band of heavy precipitation as well. However the model has backed off from previous runs which suggested this would be a 99-99.9 percentile event for this time of year. Nonetheless the model still suggests this is potentially a 90-97 percentile event which is still significant. 

NAEFS/GEFS Ensemble 48 hr rainfall Sat-Sun

So what about the temperature forecast? We are holding onto our thoughts of hitting near 70° each day in Spokane this weekend, however if the band hits our area what will our temperature be? To say there is some uncertainty in this forecast would be an understatement. The 12z run of the GFS (dark blue line) has our high hitting the mid-70s that day. How about the 18z run of the GFS? A chilly mid-50s! That is about as uncertain as things can get. Its pretty much the same story for other parts of the Inland Northwest including Moses Lake (bottom meteogram)

Meteogram for Spokane

Meteogram for Moses Lake

This forecast remains a problematic one. Suffice it to say a good portion of the Inland Northwest is going to see a soggy beginning to the holiday weekend. Specifically where that will be, we still can't say with good confidence.  We expect the wettest day of the three-day weekend will be Saturday with a gradual improvement expected after that.

This winter compared to last...and will we see a normal recovery?

A couple weeks ago we posted a story on our Facebook page that said, climatologically speaking the harshest part of winter is now in our rear view mirror. Here's was the post.

We stated that since the days are getting longer, sunnier (very slowly) and temperatures are on the rise that in fact, climatologically speaking the worst is over with. However, we did put a caveat in the story which said we can still get some very good winter storms during the remainder of January into February. One astute reader mentioned that we stated something similar last year in a blog entry. Last winter we had a very dry and relatively snowless beginning to the winter and wondered what the chances were of it continuing. Needless to say we recovered quite nicely in the second half of winter. This winter, things might be just a bit tougher. Just for comparison sake, here was the mountain snowpack last year on this date.

And here's how it looked this year

Not a lot of differences. All locations were seeing below normal snow water equivalent values for both years. The Okanogan Highlands and the northern Cascades are doing a little better this year, and things are a little worse elsewhere.  Also, notice how poor the snow water numbers are for the southern Washington Cascades and the Oregon Cascades.  However, these maps aren't really telling the entire story. Why is that? If we choose to just look at the amount of precipitation which has fallen since October 1st (beginning of the water year) rather than the amount of water in the snowpack the winters are completely different. Here was 2014 through January 19th. Just like the drier than normal snowpack, the precipitation was similarly dry.

Oct 1 2013-Jan 13 2014 percent of normal precipitation

Now look at the data for this water year. What a difference a year makes! All basins are seeing normal to slightly wetter than normal conditions.

So what gives, why the big difference? In one-word temperatures. Temperatures this winter and late fall have been significantly warmer temperatures than what we saw last year. Much of what's been falling has been dropping as rain as opposed to snow. Take a look at the temperature departures from normal below. They exhibit a huge difference. In the first half of winter 2013-14 temperatures were well below normal.

Oct 1-December 2013 temperature departures. Note widespread below normal temperatures

 While this year...they have been generally well above normal. The swing from last winter to this winter is around 3-6°F warmer. That may not seem like a lot, but in terms of snow it makes a big difference.

Oct 1-Jan 18 temperature departures. Note widespread warmer than normal temperatures. 

Anyway we digress. We simply wanted to demonstrate that although we have seen similar snow totals to last winter in the mountains, how we got to those totals is completely different. Last year was an ENSO neutral year which often does not foretell what sort of winter to expect. This year is an El Nino winter (albeit a weak one). Typical El Nino winters deliver warmer than normal conditions (sure enough it has been warmer), and a variable precipitation signature. So let's examine some snowfall numbers across a few valley locations including Spokane, Wenatchee and the always snowy Holden Village (on Lake Chelan). Just like the mountains, most valley locations are seeing sharp snow deficits. In fact, most locations are seeing a top-10 least snow winter since 1949. We are utilizing 1949 since that year is when the NWS began keeping track of  El Nino/La Nina data.

Least 10 snowy Spokane winters through 1/19 since 1949

Least 10 snowy Wenatchee winters through 1/19 since 1949

Least 10 snowy Holden Village winters through 1/19 since 1949

So of those three sites, this year ranks as either the 5th or 6th least snowy winter through 1/19. But more importantly how did the rest of the winter fare and could the snowfall deficit be made up. The answer is an overwhelming no. In Spokane, none of the 10 least snowy years through 1/19 was able to recover to normal. The winter of 1989-90 was close. Last year was also somewhat close as much of the region saw a record or near record snows in February. However, those were not El Nino years. Of the El Nino years, three of them, the remainder of the winter failed to deliver more than 6 inches of snow.

For Wenatchee, two of the winters were able to recover to above normal levels after such a slow start to the snow season.  Both of those years were ENSO neutral years. During the El Nino years, the numbers were quite meager. The two El Nino winters on the list experienced snowfall of less than an inch through the remainder of the season. On average, less than 5" of snow typically falls during the remainder of the season. 

Now onto the ever snowy Holden Village area. The numbers for here spell bad news for heavy snow lovers. Of the 10 least snowy winters through 1/19, none were able to get back to normal. Last year was close (after an astounding and record breaking 142" of snow in February) as was 1989-90. Both of those years were ENSO neutral ones. The trends during an El Nino year are much less promising. Of the 4 El Nino years on the list, none were able to recover to normal levels. Additionally, 3 of the 4 El Nino years saw significantly less snow than normal through the remainder of the winter.

So climotology tells us the odds of recovering from such a slow start to the winter are slim and given our weak El Nino conditions the chances are even slimmer. However, keep in mind that long-term weather forecasting can prove a futile endeavor and ultimately anything can happen. 

Through the remainder of the month the weather pattern will not be conducive to adding significant amounts to our  snow totals. Although wet weather will likely return by the end of the week, this moisture will be accompanied by unusually warm temperatures at least over the mountains. The 6-10 and 8-14 day outlooks are calling for a good chance of warmer than normal temperatures and average or slightly wetter than normal conditions. 

8-14 day precipitation outlook

8-14 day temperature outlook

Are the chances of a White Christmas improving?---UPDATED 12/18/14

...Here's an update to yesterday's blog. We replaced the images with the latest weather forecasts...  

 Since our last post, we have gotten a little more resolution on the prospects of seeing a White Christmas across the Inland Northwest. But before we answer that question we need to deal with a weak weather system tonight and Friday and then a much stronger system for the weekend. As of our latest forecast (issued 3pm Thursday). Tonight and Fridays weather system is calling for light snow, mainly confined to the mountains. Valley snow chances will be reserved for the Cascade valleys, Okanogan Valley, and a small part of the Waterville Plateau. These locations will generally see amounts ranging from 1-3 inches with locally heavier amounts near the Cascade Crest. There will likely be some travel concerns going over the Cascade passes.

Snow forecast for tonight-Friday

The storm system for Saturday and Sunday stands a much better chance of producing significant snowfall as it will contain much more atmospheric moisture. This will be care of a very well-defined atmospheric river that has its sights set on the Pacific Northwest. Here's what the atmospheric river is expected to look like by Saturday morning. This river will draw its moisture from well south and west of Hawaii.

Atmospheric river forecast for Saturday morning. The darker the colors, the more moisture content. 

While the river will assuredly produce widespread precipitation, it will also deliver steadily warming temperatures. Our confidence is high that snow levels will be low enough to produce moderate to heavy snows near the Canadian border and in the Cascades. It would not be surprising to see snow amounts approach a couple feet in the Cascades.  Meanwhile, the forecast for the nearby valleys is a much tougher call as temperatures will be critical. If they warm much above 32°F the snow accumulations could be less than forecast, in fact much less. Right now, we are forecasting temperature very close to freezing over most of these lower elevation locations and putting moderate snow accumulations in the Cascade Valleys. Most of this valley snow threat would occur between Saturday morning and early Saturday evening.

Weekend Snow forecast

By Sunday afternoon, temperatures will warm significantly as the warmth associated with the sub-tropical moisture continues its northeastward surge. Snow levels will rise to 4000' or higher over the entire Inland Northwest. This will translate to melting snow over most of these valley locations. The big question is can we melt what falls? That depends on how much accumulates over these locations. The warming will be accompanied by breezy conditions which will help melt the snow especially as the dewpoint temperatures and nighttime lows rise above freezing. And that's what we are expecting as of our latest forecasts. Here's a look at the high-temperature forecast for Sunday.

Sunday Forecast Highs

 So based on the current forecast the only valley locations which stand a chance of snow before Christmas Eve would be near the Canadian Border, or the Cascades. How about the remainder of the region? Well, as we talked about in our last blog entry we are expecting a big pattern change, right around Christmas Eve. That's still true. Our mild west-southwest flow of late will take a decided cooler turn to the northwest. Here's what the upper-level pattern is going to look like (at least something like it anyway). The wind flow will be parallel to the yellow height lines and it will deliver cooler air into the area (blue and purple shading is cold air, other colors are relatively warm) via the Gulf of Alaska. Meanwhile, the remnants of the weekend moisture stream will get hung up somewhere over the Pacific Northwest. The big question is where is that going to happen? Most likely it will occur immediately downstream or east of the curve in the yellow lines. In the picture below that suggests that will be somewhere over extreme southern Washington and northern Oregon.

500 mb Heights and temperatures

So is there good model agreement in where that curve is going to form? That is the key to this forecast. As of the latest model runs, consensus is growing. Here's a look at four various model runs all looking at the afternoon hours of Christmas Eve. We placed the precipitation forecast on top of the 500 mb yellow height lines. Notice, they all show a similar curve in the height lines or flow, however they vary on how far north to place it.  Model trends continue to support the band forming well south of I-90. Notice some don't place any precipitation over eastern Washington, while others only give us light precipitation amounts. Based on the trends, our confidence in seeing precipitation remains highest for locations near the Oregon/Washington border, such as Lewiston and Pullman. However, even in these locations temperatures may remain just a little too warm for snow.

Various weather models for Christmas Eve. Shading represents the precipitation. 

So to answer our original question. Are the chances for a White Christmas improving? For locations such as Mazama, Republic, or Plain the answer is a decided yes. For Lewiston or Pullman the answer is a maybe. Folks in Spokane, Couer d'Alene, Moses Lake, or Wenatchee the odds are not great. Of course, Christmas Eve is just under a week away and much can change between now and then. So stay tuned and maybe just maybe the yellow curve will decide to set up over the entire Inland Northwest resulting in a White Christmas for all.