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Mountain West- Winter


Chinook

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It now appears fairly certain that the arctic air will be back in a few days, in the general sense, expanding greatly across the country in mid-week next week. Some of the GFS runs show that some snow >3" will develop in our area Monday Jan. 2, 18z to Tuesday Jan. 3, 18z. (see 12z GFS below.) Note: the liquid-equivalent of snow is not really going to be very high.  The trough develops in the West moves through Colorado on Tuesday and out to the Midwest. ECMWF runs show that snow will happen for a long time here. Some of the trough moves to the Midwest, and a piece of the 500mb trough sits back in the West, continues to provide lift, while we have weak upslope. The 12z ECMWF says that Denver will get accumulating snow over 5 straight days. That's probably too many days in a row. In my experience, if a piece of a deep trough sits in the West like that, we can get light snow with temps around 15 for 1-2 days. So that might happen. The GFS says it will be -11F in Denver on next Wednesday, but that's probably too cold. We'll have to watch the forecasts to see if it gets around 0 next week. That seems reasonable.

BU9Q9QU.png

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On 12/13/2016 at 7:44 PM, raindancewx said:

Increasingly looking like the analogs had it right for Montana/Wyoming this winter - stupid levels of cold so far.

US Temp Departures Dec 16.png

Been impressive watching the cold get washed out by the warmth since the middle of the month. It's been pushing in the from SW and in from the SE. Been warm down here, but not really that close to records.

12-1 to 12-27.png

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Looks like a cold and snowy first week of 2017 for parts of Colorado. 

Euro output for Northglenn next week:

12/25 12z: 0.0"

12/26 00z: 0.0"

12/26 12z: 9.9"

12/27 00z: 7.3"+ (snow still falling through 240hr)

12/27 12z: 6.3"+ (same reason)

12/28 00z: 5.4"

12/28 12z: 6.8"

12/29 00z: 7.9"

12/29 12z: 6.2"

 

Long duration event, so headlines would likely be WWA if this comes to pass. 

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Things are looking sort of interesting for the Reno area and Western Nevada in general for next week. It's possible they are setting up for the type of pattern that results in heavy snows in that area even in lower elevations, with lake effect snows also a possibility in the Reno/Carson area. Still uncertain this far out, but fascinating. It's too bad I'm in Iowa ATTM and not there.

 

I grew up in Reno.

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Right now, Boulder and Broomfield (BJC) are over 60 degrees, Greeley is 33 degrees. Downsloping winds started at nighttime. Denver area was above 40 degrees after midnight. Fort Collins and Greeley were still down around 20 or colder after midnight.

Huronicane: Now I can say this (since I signed up for Eurowx.com.) Yes, the Euro 240hr snow totals are about 5-8" for my area depending on the run.

Mercurial: the NWS has -40 degrees in the forecast for Butte! (note: I didn't put in Celsius of Fahrenheit. -40F is -40C)

The 12z GFS today has 8"-10" for the cities in the 24hr time period of Wednesday-Thursday. I guess the GFS decided on a different day for the snowfall. On yesterday's runs, the max snowfall was Tuesday-Wednesday. Note, that still includes Kuchera ratios that over 20:1.

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9 hours ago, Chinook said:

Right now, Boulder and Broomfield (BJC) are over 60 degrees, Greeley is 33 degrees. Downsloping winds started at nighttime. Denver area was above 40 degrees after midnight. Fort Collins and Greeley were still down around 20 or colder after midnight.

Huronicane: Now I can say this (since I signed up for Eurowx.com.) Yes, the Euro 240hr snow totals are about 5-8" for my area depending on the run.

Mercurial: the NWS has -40 degrees in the forecast for Butte! (note: I didn't put in Celsius of Fahrenheit. -40F is -40C)

The 12z GFS today has 8"-10" for the cities in the 24hr time period of Wednesday-Thursday. I guess the GFS decided on a different day for the snowfall. On yesterday's runs, the max snowfall was Tuesday-Wednesday. Note, that still includes Kuchera ratios that over 20:1.

12z Euro this morning spit out 14" for Northglenn. GFS has been drier for the Urban Corridor for the first week of the new year, but maybe starting to catch on to a heavier snowfall solution. 

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9 hours ago, Chinook said:

Mercurial: the NWS has -40 degrees in the forecast for Butte! (note: I didn't put in Celsius of Fahrenheit. -40F is -40C)

Looks like the Missoula NWS lowered them down to -45.  Lol.  They're super bullish on this arctic event.  Typically forecasters are more conservative in these situations here, since a light wind or some high cloud cover could be the difference between -10 and -40.  But at the same time the NWS often busts because they underestimate overnight radiation in the usual cold spots (Butte, West Yellowstone, Cut Bank, etc).

 

http://forecast.weather.gov/MapClick.php?lon=-112.55151955566403&lat=46.00929241715181#.WGcvrPkrKM8

Monday Night
A 20 percent chance of snow. Mostly cloudy, with a low around -26.
Tuesday
A slight chance of snow showers. Mostly sunny and cold, with a high near -7.
Tuesday Night
A slight chance of snow. Partly cloudy, with a low around -45.
Wednesday
A slight chance of snow. Mostly sunny and cold, with a high near -5.
Wednesday Night
A slight chance of snow. Mostly cloudy, with a low around -35.
Thursday
A slight chance of snow showers. Partly sunny and cold, with a high near 4.
Thursday Night
A slight chance of snow. Mostly cloudy, with a low around -15.
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Here's hoping for a wetter 2017. Precip at DEN for the second half of 2016 was 3.13 inches (yeah, that's half a year), with over a third coming in July... so only 2.06" past 5 months. Was trying to see if I could look up records that would allow assessment of record dry 5-month or 6-month periods, but I struck out.

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14 hours ago, Mercurial said:

Looks like the Missoula NWS lowered them down to -45.  Lol.  They're super bullish on this arctic event.  Typically forecasters are more conservative in these situations here, since a light wind or some high cloud cover could be the difference between -10 and -40.  But at the same time the NWS often busts because they underestimate overnight radiation in the usual cold spots (Butte, West Yellowstone, Cut Bank, etc).

 

The -37 that Butte already had this month is remarkable, but not an all time record. If Butte gets to -45 on January 3rd, that would break the daily record by several degrees.

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Anyone wanting a break in Montana isn't going to like the trend in the Canadian model for January when you compare the November to December forecast. I was pleased with it though, wetter in the SW than before from January to April (dry to near avg, near avg to wet depending on the month), and cooler February - April.

 

Canadian January Forecast 2 (Nov v Dec).png

Canadian January Forecast (Nov v Dec).png

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The 12z GFS is pretty low on snow (plenty for the mountains). The GEFS means have something like 0.25" QPF for Denver (2.5" to 5" of snow).  The Canadian has 10.8" for Fort Collins, 3-5" for Denver. The Euro has 14" snow for Fort Collins, 6-10" for Denver. I am not sure what to believe, but I know it will be cold with higher snow ratios. This series of storms should be helpful for snowpack in many western areas, maybe some drought relief in California. Yesterday's models had something like 15"-20" of QPF in 240 hrs for the Sierra Nevada.

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Whats it looking like for the Snowy Range west of Laramie this coming week? 

 

I have a snowmobile trip arriving Thursday.  We will be over 10K ft pretty much the whole trip. 

 

 

BTW Im not educated in the weather much, I just come on here to watch for potential snow storms in the midwest usually.

 

Thanks much!

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38 minutes ago, mayjawintastawm said:

Just keep an eye out in avalanche terrain. The snowpack isn't yet very stable, and a new avy cycle is likely if the snow gets heavy enough. Lots of wind last week on top of new snow created some pretty big slabs.

Yep, thanks. 

 

If it snows as much as I hope, we won't be on anything real steep anyway. lol.  We aren't big risk takers in higher risk avy terrain.  Sounds like there should be plenty of snow in the trees. 

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19 hours ago, Chinook said:

The 12z GFS is pretty low on snow (plenty for the mountains). The GEFS means have something like 0.25" QPF for Denver (2.5" to 5" of snow).  The Canadian has 10.8" for Fort Collins, 3-5" for Denver. The Euro has 14" snow for Fort Collins, 6-10" for Denver. I am not sure what to believe, but I know it will be cold with higher snow ratios. This series of storms should be helpful for snowpack in many western areas, maybe some drought relief in California. Yesterday's models had something like 15"-20" of QPF in 240 hrs for the Sierra Nevada.

BOU continues with the "a few inches of snow" for the Plains story. As consistent as the Euro has been with a hefty dumping (not mentioned in any discos), the GFS ensembles and op now coming in wetter, and the cold that will be in place, at some point I have to think they'll start talking about heavier totals. This continues to look like a longer duration event, so headlines will be interesting. 

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The Euro/Canadian have one pulse of snow hitting Fort Collins/Cheyenne tonight-Tuesday, with about 1" in Fort Collins and much heavier snow for Cheyenne, Laramie, and Snowy Range Ski Area (West of Laramie). Then more substantial several inches for the Colorado region on Wed/Thu. The Euro/Canadian and GFS completely disagree about Friday. The GFS says all of that stuff, plus there will be an entirely new storm on Friday, which tracks into Joplin and Fayetteville AR (see OK/MO/AR discussion). So the GFS says a lot of snow for NE Colorado over this week (today-Saturday). The Euro has some substantial snow. The Canadian has a lot of snow with a whopping 0.90" liquid equivalent at Fort Collins.  12z Euro still in agreement with 00z Euro. The NWS-Boulder will need at least a winter weather advisory or possibly a winter storm watch, Wednesday.

side note: I just read a tornado warning in -lower case- letters for the first time in my life.

 

Snowy Range ski area (32 mi west of Laramie):

Today
Snow. Temperature falling to around 10 by 5pm. Wind chill values between -5 and 5. West wind around 15 mph. Chance of precipitation is 90%. Total daytime snow accumulation of 3 to 5 inches possible.
Tonight
Snow. Low around 3. Wind chill values between -10 and -15. West wind 10 to 15 mph. Chance of precipitation is 100%. New snow accumulation of 4 to 8 inches possible.
Tuesday
Snow. High near 13. Wind chill values between -5 and -15. Breezy, with a west wind 15 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 80%. New snow accumulation of 3 to 5 inches possible.
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6 hours ago, Chinook said:

00z NAM, GFS, and Canadian also have significant snow totals for this week. It is snowing in Cheyenne now. Fort Collins is cloudy and it has dropped to 16 degrees (which really isn't too weird for a nighttime low temp.)

Perfect! 

We are leaving around midnight tonight. Should be there around 6-7pm your time Wednesday.

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