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Mountain West Discussion

Chinook

By Chinook,
in Central/Western States

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Chinook

Chinook

Posted
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The time has come for a new summer thread. I was quite disappointed this winter. The models kept showing decent snowstorms over 6" for my city, but only one over 6" happened.

Looking forward to the future, some of the recent model runs have some rain and snow for the Front Range on about April 21st, with a very favorable 500mb low near the Four Corners. So we may look forward to seeing some needed rain out of this.

In the recent past, many mountain basins west of here have increased snowpack in the last week, with the Lake Tahoe area at 283% of normal snowpack. This is the part of the year where the snowpack (on average) peaks about April 1st, and rapidly declines due to warmer conditions, going towards zero on July 15th. (except for northern areas such as Washington.) So, after this point, the % of normal snowpack listed on the maps varies greatly day to day.

In response to Raindancewx, I find the thought of next year being a strong El Nino intriguing. I wonder if the heavier snows will make a comeback. Actually, if that happens, it would probably lead to wet conditions or even flooding in California again next winter. You would generally tend to think the global temperature may hit some high points like 2015-2016's winter.

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ValpoVike

ValpoVike

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1 hour ago, Chinook said:

Looking forward to the future, some of the recent model runs have some rain and snow for the Front Range on about April 21st, with a very favorable 500mb low near the Four Corners. So we may look forward to seeing some needed rain out of this.

 

Sadly, I am willing to bet this ends up verifying much further south.

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raindancewx

raindancewx

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I'm expecting the rest of Spring to be fairly warm for the West south of a line from Wyoming to Oregon, but I think May & June turn a lot wetter. Not expecting a hot summer, although I've never really found a way of usefully analoging summer. The best Monsoon indicator here is a blend of how many days you expect to have >=0.1" precip from June 15 to Sept 30 (I believe average is 11), and how high the mean high is from June 1 to Sept 30. Will be asking my twitter people for those numbers next month to come up with a Summer outlook.

Some faint signals exist for a near normal July-Aug here for temps/precip, with a cooler than normal June/Sept, but I don't put much stock in them. May after ~La Nina ish ONI in DJF is very dry in high solar years, and average or wet in low solar years here. May is also heavily favored to be wet after a wetter than normal Nov-Jan here. Other than March, which has now been drier than the 1981-2010 normal or the 1932-2016 normal for every year from 2008 to 2017 (a decade) in Albuquerque, June has the longest streak of below normal precipitation here, so it'd be nice to see that break, we did come very close to breaking it in 2015.

My general idea for NM & AZ is Warm/Wet Winter (16-17) to Warm/Dry Spring to Mild/Moist Summer to Mild/Wet Fall to Cold/Wet Winter (17-18). Spring 2018 probably Cold/Moist if the El Nino develops and the sun behaves as it has been.

BTW - I've had some success here predicting which month will be snowiest based on Summer temps / precip in my area. You guys may want to look into it up in your areas. Here a cool July favors Dec heavily, a cool June/Sept favors March, a wet monsoon favors Dec, and so on. When you aggregate the eight indicators together you get a pretty good guess at which month will be snowiest. It may not matter for Denver since March is head and shoulders above the other months, but it's useful in my area where the snow averages from Dec to Mar are all within 1.5 inches.

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raindancewx

raindancewx

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The PDO (JISAO) came in at 0.74 for March. Hard to get a big drought as long as it remains positive.

The Nov-Apr value is likely about 1.0, which is pretty high given a negative ONI for most of the recent months. Will be interesting to see if the PDO spikes again with the developing El Nino. Sometimes it seems like the PDO lags ONI trends, so I wouldn't be shocked if the PDO declines for a couple months as the El Nino comes on, and then goes back over 1.0 for a bit.

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raindancewx

raindancewx

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The GFS has snow down almost to Mexico on April 29th. Bastardi pointed out last week that a similar pattern ahead of the 1976-77 El Nino produced measurable snow in late April in El Paso, so I mean it's not impossible. The Euro has the MJO going from phase 7 to phase 8 which is traditionally a good pattern in Oct-May for powerful bowling ball lows bringing blizzards pretty far south - "Goliath" in Dec 2015 was at the transition from 7 to 8 with Roswell, most of southern/eastern NM, Chihuahua and large parts of TX getting their biggest blizzard since some of the legendary storms in the 1950s (the old Speedy Gonzales cartoons in the 1950s and 1960s aren't off when they show snow in Mexico).

 

Last Stand of Snow 4.29.17.png

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raindancewx

raindancewx

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I don't know that I've ever seen the GFS show this much snow, this close to an event, this late in the season in New Mexico. 95% of this snow would fall by hour 144 - including 2-6 inches of snow in Albuquerque. The latest the city has had 3.0" snow is April 26 1984 - would be impressive to beat that by 3-4 days with 3-6". I'm sure it will change, but the snow trend is up at the moment, kind of fun to see.

Also, this type of event is consistent with El Nino + Solar Minimum in the SW - you get ridiculously powerful late season storms in the Spring when those two combine forces. I'm starting to lean toward a blend of 1963, 1997, 2009 as an early idea for next winter, but the nine El Ninos near the minimum are pretty epic in their own right (1953, 1963, 1965, 1976, 1986, 1997, 2006, 2009). You could add 1930, 1918, 1905 as "interesting" too.

Last Stand of Snow 4.png

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Chinook

Chinook

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I think I can reasonably say that I think it will rain and snow at my house this week. QPF may be around 2". If that happened, that would put my area over 3" of total precipitation for the month. Fort Collins has not had a lot of precip in one month since May 2015.

Here is the precip graph for Fort Collins from June 1 2016 to Nov 10 2016. We were at 27% of normal.

 

a9lF5ZB.png

 

Here is the precip graph from Nov 10 2016 till recent days. Near 100% of average. Our drought is mainly due to last year's lack of rain and the warm November, February, and March, evaporating soil moisture when it shouldn't have been evaporating so much.

P2p8LJl.png

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mayjawintastawm

mayjawintastawm

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Nice analysis! I wonder if 1939 had the kind of heat we've been seeing since November. The 30s seem famous for warm, dry weather in these parts, with the Dust Bowl being famous but the subsequent years pretty tough too that I don't hear much about.  I'm really intrigued by the relationship between climatology and the settlement and subsequent history of the West.... in some ways we haven't learned all that much.

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raindancewx

raindancewx

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14 hours ago, mayjawintastawm said:

Nice analysis! I wonder if 1939 had the kind of heat we've been seeing since November. The 30s seem famous for warm, dry weather in these parts, with the Dust Bowl being famous but the subsequent years pretty tough too that I don't hear much about.  I'm really intrigued by the relationship between climatology and the settlement and subsequent history of the West.... in some ways we haven't learned all that much.

The West seems to have relatively fast changes in mean low temperatures due to urbanization (harder to release heat from a darker ground?) but at least in my area the highs show much slower changes overall on an annual basis. I've always assumed it was a sunlight hours thing - you just don't have as many clouds or cloudy days as in the East. The solar cycles in the mid 1930s to late 1950s were also high enough to prevent certain types of "cold" events that seem to only happen regularly in low-solar El Ninos. On a relative basis I also think the warming that happened from 1938 (strong La Nina) to 1940 (probably a super El Nino) caused all sorts of craziness, maybe even more than 1995 to 1997 since since solar activity was so high back then.

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raindancewx

raindancewx

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This is one of the highest snow forecasts I've ever seen for this late in the season for ABQ NWS - and WPC has 0-4" for ABQ (25th - 75th percentile). My high for Saturday is forecast at 45F, which has to be among the greatest late season cold shots on record here. My average high is 75F on April 29th.

 

april 29 forecast.gif

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mayjawintastawm

mayjawintastawm

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Wow the next 36 hours are going to be weird. Models are still pretty darn variable. The ones I've seen have come up some on their QPF, and snow ranges from small/believable to massive/much less believable (WPC 25th-50th-75th %iles for here are 3-11-20 inches!!) Even GFS is more at 12z, up to 1" QPF with 8" snow. HRRR is coming into range and is not real generous with snow through 11 PM MT though QPF is consistent with the others. The source I was using for quick and easy NAM output went away. Would like to see what that's saying...

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