Mountain West Discussion

[Dan the Weatherman]

Very hazy today. Couldn't even see the Flatirons driving in to Boulder, until I was actually within a couple miles. 

 

You must be getting the smoke from either the CA fires or the British Columbia fires, or a combination of both.

[Kayla]

First Winter Weather Advisories are up in the Beartooth Mountains for tomorrow with snow levels around 6,500'.

 

Highs should only be in the 40's in Bozeman tomorrow with a steady soaking rain around 0.5-1.0". Will likely be new record low high set tomorrow. Maybe even a rain/snow mix here tomorrow night which would be pretty remarkable for late August.

[Dan the Weatherman]

I am thinking the rain and snow season is going to start earlier throughout the western portion of the country this year because of how dry it was overall last year. So the rain / snow mix that may happen in Kayla's neck of the woods tomorrow night just may be a sign of things to come later this fall. I even believe Socal and the SW U.S. will get in on some of the action sometime around mid October or so.

[Black Hole]

First Winter Weather Advisories are up in the Beartooth Mountains for tomorrow with snow levels around 6,500'.

 

Highs should only be in the 40's in Bozeman tomorrow with a steady soaking rain around 0.5-1.0". Will likely be new record low high set tomorrow. Maybe even a rain/snow mix here tomorrow night which would be pretty remarkable for late August.

As much as I like snow and cold, no thanks. Just don't want that in August. My garden is going strong and I'd like to see production continue. The last 2 years I've had tomatoes into November. 

[Kayla]

As much as I like snow and cold, no thanks. Just don't want that in August. My garden is going strong and I'd like to see production continue. The last 2 years I've had tomatoes into November. 

 

That's pretty impressive! Can't grow tomatoes anytime of the year without a greenhouse here or starting them indoors.

[Kayla]

Currently 45F with moderate rainfall continuing. Approaching 0.75" over the past 24 hours so a real soaking.

 

Snow levels are up around 8,000' currently but will continue to drop through this afternoon as the front pushes by.

[Front Ranger]

As much as I like snow and cold, no thanks. Just don't want that in August. My garden is going strong and I'd like to see production continue. The last 2 years I've had tomatoes into November.

I'm guessing that's pretty unusual for that area.

[Kayla]

All sorts of precip and record low highs set in Montana today.  Helena, Livingston, Great Falls and Bozeman all set record low highs today and Bozeman MSU set a precip record for the day with 0.90" of rainfall.

 

Ended up with 0.86" of rainfall here and a high of 48F. Pretty impressive cold and wet system for late August! 

 

First frost is definitely on the table tonight in my yard if we can get enough clearing. Currently 43F.

[Front Ranger]

Fall is very short here, gotta enjoy the early signs of it. I get the sense that our first snow is only a couple of weeks away now!

 

It can be...but the reality of the Mountain West is that fall can include both raging snowstorms and warm, sunny days...often in the same week. Much like spring. 

 

Bozeman MSU has an average high of nearly 70 in September and 57 in October. Occasional highs in the 70s and 80s all the way into early October are not uncommon. But it can also get down into the teens in late September...just depends on the year.

 

Sustained cold doesn't usually arrive until sometime in November - last year being one of those years. But check out 2016, took a bit longer that year.

[Kayla]

It can be...but the reality of the Mountain West is that fall can include both raging snowstorms and warm, sunny days...often in the same week. Much like spring. 

 

Bozeman MSU has an average high of nearly 70 in September and 57 in October. Occasional highs in the 70s and 80s all the way into early October are not uncommon. But it can also get down into the teens in late September...just depends on the year.

 

Sustained cold doesn't usually arrive until sometime in November - last year being one of those years. But check out 2016, took a bit longer that year.

 

I feel like you're just explaining fall weather! Obviously transition seasons experience the most variety in temps and varies year to year. 

 

The definition of Fall/Spring type weather is up for debate and personal preferences along with relativity based on your location. In Bozeman, for me personally, I would consider last year "winter" hit on November 1st verses in 2016 it waited until November 28th. In 2015 winter hit on maybe November 3rd. Obviously I'm looking at a very small window of time here but that still shows a 3 year average start of "winter" being on November ~10th.

 

So, point still stands that fall is quite short here generally. But an argument could be made that it starts earlier some years allowing for fall like weather to last for the more standard 3'ish months. Possibly such as this year?

[Kayla]

Termination dust!

 

http://i68.tinypic.com/2n4p55.jpg

[Scott]

It can be...but the reality of the Mountain West is that fall can include both raging snowstorms and warm, sunny days...often in the same week.

 

 

Sometimes in less than 24 hours.  

 

Here is one of the most impressive events:

 

On 9/12/1993 Denver was 92 degrees.   The next morning 5.4 inches of snow fell.

[Front Ranger]

I feel like you're just explaining fall weather! Obviously transition seasons experience the most variety in temps and varies year to year. 

 

The definition of Fall/Spring type weather is up for debate and personal preferences along with relativity based on your location. In Bozeman, for me personally, I would consider last year "winter" hit on November 1st verses in 2016 it waited until November 28th. In 2015 winter hit on maybe November 3rd. Obviously I'm looking at a very small window of time here but that still shows a 3 year average start of "winter" being on November ~10th.

 

So, point still stands that fall is quite short here generally. But an argument could be made that it starts earlier some years allowing for fall like weather to last for the more standard 3'ish months. Possibly such as this year?

 

Sure. I guess to summarize, my point was just that because snowstorms and cold temps become possible doesn't make it winter in the Mountain West. 

 

By that definition, winter would really be a 9 month season! 

[Front Ranger]

Sometimes in less than 24 hours.  

 

Here is one of the most impressive events:

 

On 9/12/1993 Denver was 92 degrees.   The next morning 5.4 inches of snow fell.

 

Yeah, that's extreme. I don't remember ever seeing that example, crazy stuff.

[Black Hole]

49f in Bountiful this morning, coolest in quite a long time.

[Kayla]

Sure. I guess to summarize, my point was just that because snowstorms and cold temps become possible doesn't make it winter in the Mountain West. 

 

By that definition, winter would really be a 9 month season! 

 

As the common local saying goes; "There are two seasons in Bozeman, Winter (9 months) and construction (3 months) season!"

[Black Hole]

As the common local saying goes; "There are two seasons in Bozeman, Winter (9 months) and construction (3 months) season!"

People say something to that effect here too. 

 

By the way I clicked on your station and I see it recorded random temps of 0F a couple of times today. If you have a davis with weatherlink the following might be helpful. The same thing happened on my system because of having two windows of weatherlink opened at one time. Might as well see if that is true for you.

[Kayla]

People say something to that effect here too. 

 

By the way I clicked on your station and I see it recorded random temps of 0F a couple of times today. If you have a davis with weatherlink the following might be helpful. The same thing happened on my system because of having two windows of weatherlink opened at one time. Might as well see if that is true for you.

 

Yeah that has been an ongoing issue for a while now. I do have a Davis with a metobridge weatherlink so I'll give that a try, thanks! 

 

Seems to have worked so far!

[Scott]

Yeah, that's extreme. I don't remember ever seeing that example, crazy stuff.

 

Check out the weather data for 9/1993:

 

 

Daily 9/12/1993:

 

 

Daily 9/13/1993:

 

 

The 50 degree high on 9/13 was recorded at midnight.   It was a straight drop from 92 on the afternoon of 9/12 to 50 by midnight and 33 by morning on 9/13 with heavy snow.  5.4 inches fell by late morning.  

 

Here's an article about how it affected the baseball game:

 

https://www.washingtonpost.com/archive/sports/1993/09/14/astros-rockies-get-iced-by-denver-snowstorm/79379df5-c4df-4802-bedf-aa55f6722731/?noredirect=on&utm_term=.0a300ca05ae5

 

The next day it was 66 and the day after that 79, so the snow didn't last long.  

[Scott]

This morning (8/29) was the first frost at my house, though I wasn't home to see it.  Last frost was 7/1.

[Kayla]

August ended up being another below average month here even with the mini heatwave we had early to mid month. The airport ended up significantly cooler than average with a -3.6F departure. BZN ended up June-August with a temperature 2.4F below average so a pretty cool summer here overall.

 

Bozeman ended up with a 63.3F average for the June-August summer period. While I averaged 60.8F for the same period so the extra 500' of elevation (and more rural) made quite the difference. Same thing for maximum temps, Bozeman saw nine, 90+ days while I only saw two 90+ days this summer.

 

Summer precip ended up right about average after a very dry July. 6.29" fell in Bozeman verses 5.53" in my back yard.

[Black Hole]

Back from my trip to Texas. It seems more like early fall now with lows falling into the 50s with regularity now. No storms in sight though. 

[Kayla]

High of 66F after a low of 36F here this morning. Outside shot that I drop at or below freezing tonight. Really noticing the leaves changing colors now with all the dry cool nights we've been having lately. Warming up the rest of this week though, looking like low 80's even on Thursday and Friday.

 

Currently 54F.

[TT-SEA]

High of 66F after a low of 36F here this morning. Outside shot that I drop at or below freezing tonight. Really noticing the leaves changing colors now with all the dry cool nights we've been having lately. Warming up the rest of this week though, looking like low 80's even on Thursday and Friday.

 

Currently 54F.

 

 

I think we probably have close to double the amount of time during the year with leafed out trees.

 

Normally along the I-90 corridor the trees are generally leafing out by late March or early April and keep their leaves through early November... about 7 months.    

 

It sounds like you might have around 4 months there... late May through the end of September?

 

Here is November 18, 2017...

 

 

 

And this was March 13, 2018 in North Bend... less than 4 months after the above picture.  

 

[Jesse]

Kayla lived here before moving to Montana.

[Kayla]

I think we probably have close to double the amount of time during the year with leafed out trees.

 

Normally along the I-90 corridor the trees are generally leafing out by late March or early April and keep their leaves through early November... about 7 months.    

 

It sounds like you might have around 4 months there... late May through the end of September?

 

Here is November 18, 2017...

 

And this was March 13, 2018 in North Bend... less than 4 months after the above picture.  

 

 

 

I'd say through early to mid October normally. Then come back around late May so maybe 4.5 months of leafed out trees!

 

This was October 15th 2017 at the creek near my house - 

http://i66.tinypic.com/qoakpg.jpg

 

November 1st and completely bare in Bozeman near I90 -

http://i63.tinypic.com/1h8bra.jpg

 

Still looked like this on April 23rd...

http://i64.tinypic.com/256s5k2.jpg

[Black Hole]

Getting some bigger temperature swings these days. Highs are a bit lower than summer, but bigger difference in the lows. Mid 50s climbing to upper 80s most days. 

[Scott]

Getting some bigger temperature swings these days. Highs are a bit lower than summer, but bigger difference in the lows. Mid 50s climbing to upper 80s most days. 

 

That would be a small temperature change for us.  Thus far, at teh airport at least (our house is usually colder at night than the airport, but days are about the same) the average high this month has been 84.6 and the average low has been 39.6, but lows in the 20's with highs in the 80's aren't that uncommon when the skies are clear.   Today's range was 89/30.  

 

Perhaps more interesting though is that those changes you point out above didn't used to be uncommon along the Wasatch Front/SLC/Bountiful.  

 

When I was younger and started paying attention to weather statistics (I grew up in Granger/West Valley), it was the 1941-1970 30 year average that was used.   At the SLC Airport the average high in September was 80 and the average low was 49.  For July the average was 93/61.

 

Up until the early 1990's, 40 degree diurnal changes in SLC weren't that uncommon.  I remember it going from the 50's to 100's and the 40's to 90's.  6/3/1990, for example had a low of 48 and a high of 90.   It wasn't as uncommon back then.

 

If you are interested, here is the comparison between the 1941 to 1970 average temperatures vs the 1991 through 2018 ones, which will be the next average calculation in when 2020 ends.  

 

 

Day temperatures have risen a little, but it's really the night temperatures that have changed a lot.

 

Also interesting, November and December have stayed about the same temperature wise, while months like March have risen dramatically in temperature.   March used to be similar to November, temperature wise, but now March is much warmer than November.  Summer nights have also seen a dramatic increase in temperature.   

 

UHI can explain some of it, but it seems to be a pattern for Northern Utah in general, minus the Uinta Basin, and including rural areas.

 

Snowfall has also decreased dramatically in the Salt Lake Valley and Bountiful in recent decades, especially in areas that are prone to lake effect enhanced storms.   My own guess is that much of it can be attributed to the shrinking of the Great Salt Lake.  30 years ago, the Great Salt Lake covered about 3300 square miles.  Now it is about 900 square miles.    That's a lot less surface area to produce the lake effect snows.

[Black Hole]

That would be a small temperature change for us.  Thus far, at teh airport at least (our house is usually colder at night than the airport, but days are about the same) the average high this month has been 84.6 and the average low has been 39.6, but lows in the 20's with highs in the 80's aren't that uncommon when the skies are clear.   Today's range was 89/30.  

 

Perhaps more interesting though is that those changes you point out above didn't used to be uncommon along the Wasatch Front/SLC/Bountiful.  

 

When I was younger and started paying attention to weather statistics (I grew up in Granger/West Valley), it was the 1941-1970 30 year average that was used.   At the SLC Airport the average high in September was 80 and the average low was 49.  For July the average was 93/61.

 

Up until the early 1990's, 40 degree diurnal changes in SLC weren't that uncommon.  I remember it going from the 50's to 100's and the 40's to 90's.  6/3/1990, for example had a low of 48 and a high of 90.   It wasn't as uncommon back then.

 

If you are interested, here is the comparison between the 1941 to 1970 average temperatures vs the 1991 through 2018 ones, which will be the next average calculation in when 2020 ends.  

 

slc.JPG

 

Day temperatures have risen a little, but it's really the night temperatures that have changed a lot.

 

Also interesting, November and December have stayed about the same temperature wise, while months like March have risen dramatically in temperature.   March used to be similar to November, temperature wise, but now March is much warmer than November.  Summer nights have also seen a dramatic increase in temperature.   

 

UHI can explain some of it, but it seems to be a pattern for Northern Utah in general, minus the Uinta Basin, and including rural areas.

 

Snowfall has also decreased dramatically in the Salt Lake Valley and Bountiful in recent decades, especially in areas that are prone to lake effect enhanced storms.   My own guess is that much of it can be attributed to the shrinking of the Great Salt Lake.  30 years ago, the Great Salt Lake covered about 3300 square miles.  Now it is about 900 square miles.    That's a lot less surface area to produce the lake effect snows.

 

I'm aware of the temperature trends you mentioned, but its nice to see a more complete write up on it. Why do you think March has warmed so much compared to other months? And what about the nighttime lows warming so much?

 

I think the transition months have generally seen less deep cold troughs than in the past. Some of that seems to be the pattern, but some may be that the airmasses that come just have a little less punch. UHI is a factor too. 

 

I've also strongly suspected a lot of our decline in snow is from a smaller lake. 2016/17 was a fantastic winter pattern and mountain areas did very well, but it still yielded slightly below normal snow in SLC. My guess is the smaller lake was a big part of that.  

[Scott]

Why do you think March has warmed so much compared to other months?

 

 

 

I'm not sure.   Mid winter to early spring have seen a bigger increase in some areas as compared to the past.

 

For a lot of places out West (including as far east as at least Denver), during the last 30 year calculation, the coldest month has shifted from January to December.    Denver, for example, before the last 30 year calculation has always had January as the coldest time period, but that shifted.  Whether it's just a temporary trend or a long term one is unknown (at least to me).

 

In SLC and the surrounding areas, spring snowfall has dropped significantly.  Late fall and winter snowfall, haven't dropped as much.   The method of measuring snowfall was standardized in 1949, so I'll use the 1951-1980 time period.  See that it's really Spring that has changed significantly (it's less than 1/2):

 

 

Historically, March is a much snowier month than November in the SLC area, but that has definitely changed in recent decades.  

 

 

And what about the nighttime lows warming so much?

 

 

UHI might be part of it, but it has been a trend all over northern Utah, including the rural areas, so there is more going on than that.   

[Black Hole]

I'm not sure.   Mid winter to early spring have seen a bigger increase in some areas as compared to the past.

 

For a lot of places out West (including as far east as at least Denver), during the last 30 year calculation, the coldest month has shifted from January to December.    Denver, for example, before the last 30 year calculation has always had January as the coldest time period, but that shifted.  Whether it's just a temporary trend or a long term one is unknown (at least to me).

 

In SLC and the surrounding areas, spring snowfall has dropped significantly.  Late fall and winter snowfall, haven't dropped as much.   The method of measuring snowfall was standardized in 1949, so I'll use the 1951-1980 time period.  See that it's really Spring that has changed significantly (it's less than 1/2):

 

slcsn.JPG

 

Historically, March is a much snowier month than November in the SLC area, but that has definitely changed in recent decades.  

 

 

 

UHI might be part of it, but it has been a trend all over northern Utah, including the rural areas, so there is more going on than that.   

It's especially interesting that March has seen so much of a drop off as its not a time you would expect a lot of LE precipitation given the relatively colder temperatures of the lake. March 2018 was a good snowy month, but otherwise most of the last few March's have seen abundant ridges and a lack of good storm patterns...or at least that is the way it has felt. 

[Dan the Weatherman]

It's especially interesting that March has seen so much of a drop off as its not a time you would expect a lot of LE precipitation given the relatively colder temperatures of the lake. March 2018 was a good snowy month, but otherwise most of the last few March's have seen abundant ridges and a lack of good storm patterns...or at least that is the way it has felt. 

 

March in recent years has been consistently drier and much warmer in southern California than in years past, although March 2018 was cooler and somewhat wetter. It seems to be a trend that is affecting most of the western and southwestern states except for possibly the far north such as Montana and Washington.

[Black Hole]

Made it down to 51F this morning with a high near 80F expected. A brief return to the 90s this weekend but then nicer weather returns. 

[Kayla]

62/41 day here yesterday and showers here this morning. Things have turned decidedly Fall here now with the chilly nights and leaf changing in full swing. Still waiting on my first freeze though which seems possible tonight depending on cloud cover.

 

Looking like a brief warm up into the low 70's this weekend with some showers before highs drop back into the 60's with lows dropping back into the 30's next week. 

[Scott]

It has been one hot year here and the trend continues.    So far here are the departure temperatures (in degrees) from average:

January = + 6.3

February = +4.4

March = +3.9

April = +1.8

May = +3.8

June = +3.7

July = +4.8

August = +1.8

September = +3.9 

 

This may end up being the hottest year on record, beating 2012.  There is no UHI here either.

Although we have had several frost at the house, the airport still hasn't had a frost yet.   The coldest it has gotten so far this season at the airport is 36 degrees on 8/29, 9/4, 9/7, 9/8, 9/10, and 9/13.

At the airport, I think the latest first frost we have had was 9/21 so if there isn't a cool down, we could be flirting with that record.

 

Also, every day so far this month has been in the 80's which is something very unusual for an elevation of 6250 feet in September.   Thus far the average high is 85.6 and the average low 40.0, which is remarkably warm.

[Front Ranger]

Looks like I'm missing a blowtorch month back home. After a seasonable start to September, the last few days have been in the low to mid 90s, and that will continue for the next few days.

 

Hopefully it will actually feel like fall when I return next week.

[Black Hole]

47F at my place this morning, north of a shallow cold front. South of the front there is a huge fire that may burn homes today.

[Scott]

It could go from the 20's to 90's today; we'll see.  The temperature has already dropped 49 degrees since sunset a few hours ago.  Today's high was 88 and the current temperature is 39.  The morning of the 14th was the first official frost at the official weather station (a bit later than average).  

 

 

If it really does drop to 31 in town, it will be in the 20's at my house almost for sure.  Since the afternoon high is supposed to be 89, it only needs one degree above that to reach 90.

[Black Hole]

Low of 74F at my place with gusty south wind keeping temperatures up. Should be headed for the low 90s today. 

[Scott]

28 this morning and sitting at 86 at 12:25. Four more degrees to hit 90. If it does hit 90, this will tie for the record latest 90 in the season (tie with 9/15/1990).