Record Hot July, Rain Anyone?

If you are hoping for some rain, we have good news for you!  But before we get there, another heat wave is about to hit the Inland Northwest which isn't good news for the ongoing drought.

Here is the latest U.S. Drought Monitor released today, July 29th.  Exceptional drought (D4) was covering a large portion of Eastern Washington and north Idaho.

U.S Drought Monitor released July 29th, 2021

Much of this drought locally is from very dry weather over the past 6 months which has had significant agriculture impacts to spring wheat, barley, and hay.

Percent of normal precipitation past 6 months

Combining the dry weather with lightning so far this July has led to multiple wildfires across the region.  The maps below show total lightning this month through the 24th.

And here is satellite image from July 23rd showing smoke from multiple wildfires over the region.

Evening satellite - July 23rd, 2021 courtesy of UW

Making matters worse has been the hot July, with temperatures over most areas running 4 to 8 degrees above normal so far this month.

And another heat wave is likely as we close out the month of July.  On Friday many locations will reach the triple digits, with the heat peaking on Saturday with near record high temperatures for the day.   Here the forecast high temperatures for Saturday as of this writing

NWS Forecast High Temperature for Saturday, July 31st, 2021 issued 230 PM July 29th

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These temperatures will equate to many areas nearing, or exceeding their all time warmest July on record.  Here are some locations that have a good chance of the hottest July, with observed average temperatures for July 2021 so far shown.

Spokane Airport (GEG)

Bonners Ferry, ID

Lewiston, ID

Wenatchee Airport, WA

Omak, WA

Changes Ahead!

After all this talk of heat, fires, and drought, let's shift gears and talk about changes this weekend.  Some surfaces may look like this by Monday.

Yes, we have rain to talk about!  Models are pretty consistent in showing an increase in moisture moving up into our region.  This animation below (courtesy of College of DuPage) shows available moisture (also called precipitable water) and is NOT a rainfall forecast.  It's more of an indicator of available moisture for rain.

12z July 29th GFS run of Precipitable Water Standardized Anomaly valid July 29-Aug 3, 2021

Note that as values reach the blue and purple shadings on Sunday and Monday that it corresponds to the highest end of the legend at the bottom of the graphic.  This means there will be close to the highest amount of available moisture over our area as we can get for this time of year.

But the big question is will this lead to an abundance of rain and will there be thunderstorms?  We think most areas will get some rain, but amounts are uncertain.  This is due to the convective hit and miss nature of showers and thunderstorms.  Here is one ensemble forecast for rain totals for Coeur d'Alene, ID.

12z July 29th GEFS forecast of precipitation for Coeur d'Alene, ID through August 3rd, 2021

Note the large spread in possible rain amounts with the solid black line indicating the average values of near 0.25".  One solution gives as much as 1.50", while several show 0.20" or less.  

There will also be a chance for thunderstorms which could lead to new fires.  But the good news is that downpours should reduce the threat of new fires becoming large, and could help current fires with some much needed rain.

And there may be more rain for the middle to end of next week.  Here is the 6-10 day precipitation outlook from the Climate Prediction Center favoring increased odds of wetter than normal conditions.

Climate Prediction Center 6-10 day Precipitation Outlook valid Aug 4-8th, 2021

To summarize, hot temperatures to close out July will give some locations the hottest July on record.  Exceptional drought covers much of the region.  August will start on a different note, with an increasing chance for showers and thunderstorms.   With exceptional drought, don't expect this rain to even come close to ending the drought, but will at least bring a change in the weather and should help out the fire situation over the region.

How hot did it really get in Spokane on 29 June 2021?

After our historic heat wave of 2021, it's time to take a look back and answer the question of just how hot did it really get in Spokane on June 29th.  Unfortunately, the answer does get a little sticky.  First we need to look back in history, as well as look at the topography of Spokane.

Temperature measurements in Spokane started in 1881, and these were taken in downtown Spokane.  The Weather Bureau office moved out to Felts Field in 1941, and with it, the official temperature of Spokane moved as well.  Observations were still taken in downtown Spokane, they just were no longer official.  Six years later, the Weather Bureau moved again, from Felts Field to Geiger Field (which would later become Spokane International Airport) on the West Plains of Spokane.  The official observation for Spokane has been at the airport since 1947.

Moving the observation from downtown to Felts Field probably didn't have much of an effect on the temperature readings.  Both locations are at about the same elevation.  But in the 1940s, the area around Felts Field was more rural than downtown, so there may have been a little less "urban heat island" effect.  However, the move to the West Plains in 1947 was significant.  The elevation of downtown Spokane is about 1890' above sea level.  Felts Field is at the 1953 foot elevation.  But the Spokane International Airport is up at 2356 feet, an increase of nearly 500 feet.  Using the thumb rule of 5.5 degrees per 1000 feet, that results in a difference of about 2.5 to 3 degrees between the West Plains  and downtown. 

It's important to note that downtown Spokane is about the lowest elevation of the entire metro area.  57th Avenue on South Hill is at about 2360', which is the same elevation as the airport. Same goes for Five Mile.  Even I-90 at Stateline is at about 2100'.  So your location in the metro area has a big effect on your temperature, just from the standpoint of elevation.

Additionally, your surrounding environment also has an effect on your temperature.  If you're downtown with lots of concrete and asphalt, the temperature is probably a few degrees warmer than if you're near the river or at a golf course.

Late July of 1928 was extremely hot across the Inland Northwest.  Triple digits were common just about everywhere for several days.  For many locations, July 26th 1928 became the hottest day on record at the time.  Prior to this event, the hottest temperature on record at Spokane was 104F, set in 1898.  That mark was tied on July 24th and 25th of 1928, after a 102F on the 23rd.  On the 26th, temperatures peaked as Spokane hit the 108F mark.  Some other extreme readings on that day included:

• Omak  -  114F
• Ephrata  -  112F
• Lewiston  -  113F
• Orofino  -  114F
• Walla Walla  -  113F

The record of 108F for Spokane stood through for more than 3 decades of summers.  There were attempts, mind you.  The thermometer reached 106F in 1931 and 1934, and 105F in 1939.  Then in early August of 1961, extreme heat returned to the Inland Northwest.  This time the heat lasted only 3 days, but the extremes were more impressive.  Spokane once again touched 108F, tying its all-time record.  But recall that the weather observation moved up in elevation in 1947.  So which was the hottest day, 1928 or 1961?  Since downtown Spokane is typically a bit warmer than the airport, it's likely that 1961 was truly the hottest day.  And in fact, there was still a weather observation in downtown Spokane in 1961 and it reached 109F on 1961. This value was matched in Coeur d'Alene and St Maries.

Additionally, 1961 set the record for the hottest day in Washington state history, with a reading of 118F at Ice Harbor Dam (along the Snake River just east of Tri Cities).

So now we return to present day Spokane, and the 2021 historic heat wave.  We all know by now that Spokane Airport hit 109F, setting the all-time record for the city.  But was that truly the temperature that the citizens experienced?  After all, there's not many people who live at the Spokane Airport.  Thankfully, we now have a number of temperature measurements available to us to answer that question.

So while it was 109F on the West Plains, it was 113F at Felts Field.  So perhaps that should be the official temperature observation for Spokane during this heat wave?   Is that what most people experienced?  But then you notice that it there's quite a range of temperatures around the metro area.  It was 115F along I-90 in Spokane, but 108F near High Drive, and only 106F in Opportunity/Spokane Valley.  So perhaps the 109F at the Spokane Airport is a decent "middle of the road" temperature for the area.

For a bit broader view, several locations set their all-time high temperature record in the Inland Northwest on June 28th.

• Omak: 117F, old record 114F (26 Jul 1928)
• Wenatchee: 113F, old record 110F (18 Jul 1941)
• Bonners Ferry: 108F, old record 105F (11 Aug 2018)
• Chelan: 111F, old record 110F (29 Jun 2015)
• Davenport: 107F, old record 105F (26 Jul 1928)
• Mazama: 112F, old record 103F (1 Aug 2020)
• Northport: 113F, old record 110F (28 Jul 1934)
• Odessa: 115F, old record 112F (4 Aug 1961)
• Plain: 109F, old record 104F (27 Jul 1939)
• Priest River: 108F, old record 105F (10 Aug 2018)
• Republic: 109F, old record 108F (2 Jul 1924)
• Rosalia: 111F, old record 108F (27 Jul 1934)
• Sandpoint: 106F, old record 104F (24 Jul 1994)
• Wilbur: 110F, old record 110F (3 Jul 1922)

But not every location set all-time records.  Coeur d'Alene hit 108F for 2 consecutive days in this heat wave, but both fell short of their all-time record of 109F in 1961).  A similar story for Grand Coulee Dam.  Moscow and Pullman fell 4 degrees short of their 1961 record.  

Daytime high temperatures weren't the only records broken.  The nighttime temperatures were rather uncomfortable as well.  Spokane airport also set an all-time record for warmest low temperature.  It tied the record on the morning of the 29th, cooling only to 77F.  This equaled the record set back on 27 July 1928.  After topping out at 109F during that afternoon, the temperature was only able to cool to 78F by the morning of the 30th, setting the all-time record.

The all-time high temperature record for Washington of 118F may have been tied or even broken at a few different locations during this recent heat wave.  A climate extremes committee will review this in the coming months.

 

We are forecasting the hottest day ever in Spokane history

 A heat wave like no other is becoming increasingly likely.  Prepare NOW!

The biggest heat wave to ever strike the Inland NW on record is becoming increasingly likely.  What makes this event unique?

• All time record high temperatures are in jeopardy for several locations
• And this is during June (our peak heat season is late July through early August)
• 100+ degree temps will last for several days
• Mild overnight lows in the mid 60s to upper 70s will provide little to no relief at night
• Occurring during a period of severe to extreme drought
• Fire danger increasing to record levels next week and as we near the 4th of July (for this early in the season)

The Climate Prediction Center's latest Risk of Hazardous Temperatures product shows our region in a high risk of Excessive Heat through next Friday, July 2nd.  Don't be surprised by future outlooks extending this out further.

What is going to cause the excessive heat?  A very strong ridge of high pressure (record setting for late June by some model solutions).  Here is one ensemble solution showing the strong ridge centered right on top of us on Sunday.

12z GFS model of 500mb heights, winds, and temperatures valid 2 AM PDT Sunday, June 27th 2021

Strong high pressure in late June spells trouble!  Why?  The lower atmosphere continues to warm as the ridge persists over the region as the late June sun angle brings an abundance of solar radiation towards the Earth's surface which continues to warm things up each day.  Here is one model prediction of near surface temperature anomalies from this Thursday through the following week (June 24-July 3rd).  

Note the large area of warmth that persists into early July over the northwest US and southwest Canada.

So it looks like this heat wave will be around for awhile, but how hot will it get?  Our current forecast is calling for all time records to be threatened beginning Monday.

NWS Forecast High Temperature for Monday, June 28th (issued June 23rd) as compared to current all time records.

And if we don't break the all time records on Monday, we will probably have another shot on Tuesday and Wednesday!  Here is our current forecast as of June 23rd for Tuesday.

NWS Forecast High Temperature for Tuesday, June 29th (issued June 23rd) 

It is worth noting that a few models (especially the GFS) want to take the heat up another notch, suggesting temps near or above 110F for Spokane and near 120F for Moses Lake.

Spokane

Meteogram of forecast raw model temperatures for GEG (Spokane International Airport) through Wednesday, June 30th, 2021

Moses Lake

Meteogram of forecast raw model temperatures for Moses Lake through Wednesday, June 30th, 2021

While these values are not currently forecast, it does have our attention.  The record for the state of Washington and Idaho is 118 degrees at Ice Harbor Dam, WA and Orofino, ID so we will be watching for this potential closely.

What other impacts are expected?  As mentioned in a previous blog post, here, our region is currently experiencing severe to extreme drought over much of Eastern Washington into the Idaho Panhandle.  The unprecedented heat is not good news for the region.  Wheat and hay crops are already starving for soil moisture, and this upcoming heat will only make the soils drier than they currently are.

And what about fire danger?  Fuel moisture is expected to dry out considerably, reaching record low values for late June.  Fuel moisture comes in different sizes, but all are measures of how dry the grass, twigs, branches, and timber are.  

Forecast 100 hour (branch size) dead fuel moistures based off model data from the NWCC (Northwest Interagency Coordination Center) are shown below.  Red is observed, while blue is the forecast.   The bottom gray line is the minimum value on record.  The plot below is for NE Washington but the same idea applies to other areas of Central and Eastern Washington into the ID Panhandle.  As you can see the red line has dipped near the minimum value several times since mid-May (likely due to the drought).  The blue forecast line is expected to drop fuel moisture to record lows for this time of year.

100 hour fuel moisture (%) for NE Washington.  Red is observed, Blue is forecast from model data

Safety tips

So what can you do to stay safe during this heat wave?  Here are some suggestions

• Drink plenty of fluids and wear light colored clothes
• Check on and take care of those vulnerable to heat (children, those with chronic medical conditions, elderly, pets)
• Stay inside during the hottest times of the day (afternoon and early evening)

Heat is On The Way!

 This week it will be hot and dry for most of the Inland Northwest and the Pacific Northwest. Seeing some of the model guidance and predicted temperatures for this week and next weekend reminded us of the June 27-28 heatwave of 2015 (you can read our blog post here). Let's dive into the comparisons of this heatwave vs 2015 and lay out the expected forecast for this week.

We talked earlier this month about our record dry spring, and in the last 30 days the story of very dry conditions continues. Many locations did receive some good rain from the thunderstorms of June 15th. But the total amount of precipitation in the Inland Northwest has been very low. For many places, around 25% of average or lower.

Here’s a look at our normal precipitation for May and June (since June isn’t complete yet, we went back into May) shown by the brown line, what we have accumulated on the green line, and compared this to 2015 since we know that year saw a hot spell in June. We can see that compared to 2015, this year (2021) is drier for the May - June period.

Taking into consideration the very dry spring and now start to summer, along comes a strong ridge of high pressure that will continue to strengthen and settle over the northwest. Below is a loop of the 500mb heights and anomaly from the GFS model, Thursday through next Monday.  For this weekend and early next week, extremely strong high pressure will dominate southwest Canada and the northwest US.

For June in eastern Washington (we’ll use Spokane International Airport as a point of reference), the normal high temperature is 74F. This week, we’re looking at temperatures 10 to 25F degrees above normal, or higher. Yes, higher. By next weekend, daytime temperatures in the 100-105F range are possible. This kind of heat hasn’t been seen since 2015, and thus why we look back to 2015 to see what kind of conditions were going on and what the models were saying then, giving us an idea of what might be to come this week and weekend.

Putting this into perspective, the record hottest temperature ever for Spokane is 108F set on Aug 4, 1961.

Going back to the comparison of 2015, June 27-28 saw temperatures of 102F (27th) and 105 (28th), with upper 90s on days leading up to and after that heat wave. The afternoon of June 28th, the 850mb temperature was 29.6C giving us that max temperature of 105F. What do the models say for our 850mb temps this week and next weekend? Below is the sounding climatology from SPC for Spokane (OTX) for 850mb temperatures. The all-time max 850mb temperature is 31.5C from early August.

Current deterministic model guidance for 850mb temperatures are quite jaw-dropping:

ECMWF:

Saturday - 28.85C

Sunday - 30.85C

Monday - 33.85C

Tuesday - 35.3C

Wednesday - 32.0C

GFS:

Saturday - 28.3C

Sunday - 29.7C

Monday - 33.2C

Tuesday - 34.5C

Wednesday - 33.3C

So all around very hot temperatures for this weekend and into early next week. Leading up to Sunday, the ridge strengthens Friday through Sunday with Sunday looking like the hottest in the next 7 days, which is as far as our forecast goes out at this time.

What about beyond Sunday? Forecast model guidance gets tricky the farther out in time, however strong high pressure patterns are ones that have a tendency to be more persistent, so confidence isn’t completely out the window with the idea that this heat could last into the middle part of next week. Ensemble guidance has also been very consistent in highlighting this strong ridge through early next week. The suite of models are showing 850mb forecast temperatures next Tuesday of 33C - 35C. We have many days between now and then, so these numbers may fluctuate a bit but this is something to keep in mind.

In 2015, we observed 4 days of maximum temperatures 100+F, and in 2020 we observed 3 days (the most is 6 days set in 1928).

The Climate Prediction Center is highlighting a high percentage of excessive heat for June 29-30, next Tuesday and Wednesday. This would suggest our ridge has lower chances of breaking down and better chances of this heat to persist into the middle part of next week.

Other factors we have to take into consideration are the overnight low temperatures. With such strong heat during the day, the overnight relief may become less of a relief. Together, this will increase our heat risk for various populations in our region. Currently, here is a snapshot of our heat risk forecast.

Our confidence is fairly high that we will see this prolonged heat last into early next week with this upcoming weekend seeing the hottest temperatures of the year, the hottest since 2015, and the hottest in the next 7 days. After that, it’s possible we will see continued hot temperatures and perhaps slightly hotter?

 We've never seen a drought like this

It's well known that weather in the western US is drier than in the eastern US.  As such, droughts are more common in the West.  Most of the West is designed to accommodate this drier climate.  The mountains get heavy snow in the winter, which slowly melts off in the spring and summer.  There are numerous dams throughout the West which catch much of the snow melt, using it to irrigate our farmland (as well as generate electricity).  This enables western farmers to grow crops in some rather arid locations.  

Still, there are some areas in the West that, similar to their eastern counterparts, rely solely on the rain and snow to irrigate their croplands.  In the West we call this "dryland farming".  The biggest example of this is typically wheat and barley, but also includes a lot of hay.  The Inland Northwest is known as one of the largest producers of wheat in the US.  

These dryland crops require moisture through the spring and into the early summer.  Grains such as wheat and barley will ripen during the hot summer months and so they don't really require much if any rain at that point until they are harvested in late summer.  This matches the usual rainfall patterns we see here in the Inland Northwest.  But not this year.

Rainfall this spring hasn't just been light, it's been nearly non-existent.  We haven't seen anything like this before.  Spokane just finished it's driest February through May ever.  EVER.  Records for Spokane go back to 1881.  That means this was the driest spring in 140 years!  And it wasn't just Spokane.  The dark red area in the image below shows all of the areas that have had their driest February-May on record.

As you can see, it's been dry over much of the Northwest this spring, but the Inland Northwest has been the epicenter of this dryness.  The three month period of March through May was the driest for many other locations in the Northwest.

So the natural question is "what caused this drought?".  The answer isn't straightforward and probably incomplete given our current understanding of weather and climate.  One contributor that we are aware of is La Nina.  To which you may be saying "I thought La Nina meant wetter than normal conditions for our area", and you would be correct.  Here's a diagram showing the basic jet stream pattern for a typical La Nina that you may have seen before:

The purple and orange lines are meant to represent the variable jet stream patterns we normally see during a La Nina winter/spring.  The purple line shows a colder phase of the jet stream, diverting up into Alaska and then bringing colder but drier air into the Northwest US.  But then the jet stream will also at times follow the orange line, bringing Pacific moisture into the Northwest.  The problem is that for the spring of 2021, we've seen a LOT more of the purple jet stream, and not so much of the orange jet stream. 

Note in the image above the big H and the blocking High Pressure in the Gulf of Alaska.  Here's the air pressure anomaly at about 18,000 feet in the atmosphere from the Feb-May period this spring.

What this shows is that the air pressure in the Gulf of Alaska has been higher than normal this spring.  This compares very well with the idealized La Nina image previously shown with the Blocking High in the Gulf of Alaska.  So this looks like what we would expect for a La Nina winter/spring.

But now here's the jet stream anomaly for this past spring:

Do you see that ribbon of bright colors along the Canadian west coast?  That shows that the jet stream this year has been coming from the northwest a lot more and a lot stronger than usual.  Note that those bright colors extend all the way back to Alaska, across the north Pacifc and Kamchatka Peninsula.  In other words, the "purple" jet stream has been doing its thing during a La Nina winter like it should.

But then look at the other area of bright colors in the image above, out in the eastern Pacific.  Those show that the jet stream across the Pacific has been much weaker  and infrequent than normal.  So the "orange" jet stream that is supposed to bring the moisture, hasn't been doing its job this spring.  

The result is that we've been getting a lot more of the "purple" jet stream from the northwest (which is a dry weather pattern), and not nearly enough of the "orange" jet stream from the Pacific (which is a wet weather pattern).

Is there any hope of this pattern changing?  Officially, the Climate Prediction Center declared the 2020/21 La Nina over.  That's not to say that our weather pattern will necessarily change, especially since we are heading into the typical hot dry summer season.

Here's the computer forecast for the June-July-August season for temperature and precipitation.  They call for a warmer and drier than normal summer overall all of the western US.  

But this of course is a computer forecast.  And you may be wondering if the computer forecasts correctly predicted our record dry spring.  That's a good question, and the answer is no, the computers never saw it coming.  Here's the forecast made back in February 2021 for the Feb-Mar-Apr timeframe.  That area of light blue in the Inland Northwest shows that the computer actually expected that we would see normal or possibly wetter than normal conditions for our area, which agreed with the usual La Nina pattern.

Will changes this week bring any drought relief?

As was mentioned in the previous blog post, found here, a record dry Spring has been experienced in many locations so far.  But will the changes this week bring some rain?  We will get to that later but first let's take a look at a few updated drought maps and an imminent cool down.

Drought update

Here is a look at the latest % of normal precipitation map over the past 90 days

Some of the driest areas relative to normal since February 1st have been from the Columbia Basin into the Spokane area. The driest Feb 1st-May 15th period on record has occurred at some locations including Spokane and Davenport.  Here are a few graphs showing what has fallen so far versus the normal.  

Spokane Airport has received 1.31" of precipitation since February 1st; normal precipitation is 5.20".

Spokane observed precipitation since Feb 1st.  Green line (observed) vs brown line (normal)

Davenport: Observed: 0.60" Normal 4.21" 

Davenport observed precipitation since Feb 1st.  Green line (observed) vs brown line (normal)

Let's look at one more site - Ephrata.  The 2nd driest period has been recorded with only two days of light precipitation since February 15th.

Ephrata: Observed 0.36" Normal 2.24"

Ephrata observed precipitation since Feb 1st.  Green line (observed) vs brown line (normal)

The dry conditions this spring have not been good for the spring wheat crop.  The map below shows planting areas of spring wheat (by county) with drought areas overlayed

And this is a big increase over the past 3 months because of the dry weather.

Changes ahead

So our region needs some rain!  The weather pattern this week will change as low pressure sets up near the region.  We are confident that temperatures will cool significantly Tuesday and Wednesday with highs Wednesday dropping into the upper 50s and 60s.  Here is one model projection showing the cooler than normal temperatures over the area.

12z/May 16th GEFS 2 meter temperature anomaly (deg C) valid 5 PM PDT Wednesday, May 19th

But will we get some rain?  It looks like there will be an increasing chance mid to late week as bands of showers rotate counterclockwise around a low over Oregon.  Below is one model showing the low position on Wednesday with the green areas showing elevated moisture content and thus the greatest chances of showers over the Idaho Panhandle and Cascades.

12z/May 16th GFS 500mb heights and 700-500mb Relative Humidity valid 2 PM PDT Wednesday, May 19th

On Thursday into Friday the low drops south, but bands of showers rotating around the low may give parts of our region additional opportunities for some rain.

12z/May 16th GFS 500mb heights and 700-500mb Relative Humidity valid 11 PM PDT Friday, May 19th

There is high uncertainty as to which areas get rain, and how much.  But at least it's a change and an opportunity for rain.  Stay tuned for forecast updates this week as we monitor the track of the low and the showers associated with it.