High mountain snow likely in Colorado this weekend

Tomer’s Take:

  • A series of cold fronts deliver colder air and snow accumulation above treeline Friday, Saturday, and Sunday in Colorado.
  • Below treeline precipitation stays rain.
  • Snow accumulation is possible in all mountain zones above treeline.
  • Some of the biggest totals might occur in the San Juan Mountains.
  • Air temps in the mountains will gradually drop each day.
  • Monday-Tuesday (10/3-10/4) look even colder with continuing snow chances.

Current Setup

Water vapor satellite shows a low pressure system and cold front sliding through Utah, Wyoming and into Colorado. Red/orange = drier air aloft.

Water vapor satellite 9/30/2022 11:15am.

Mountain Forecast

Atmospheric moisture this weekend will be running high. Rain is likely at lower elevations with snow above treeline. Here’s humidity mid-troposphere valid 10/1-10/2.

Humidity mid troposphere, Euro interpretation valid 10/1-10/2.

Monarch Pass and Above

Snow ChanceAMPM
Snow chances on Monarch Pass and Above.

How much accumulation? Possibly 1-2″ each afternoon/night above treeline.

Mount Sneffels and Above

Snow ChanceAMPM
Snow chances on Mount Sneffels and Above.

How much accumulation? Possibly 2-4 inches each day above treeline.

Total weekend snowfall is shown below according to the NAM model. It’s optimistic with accumulation and believes almost 18 inches is possible on the 13ers/14ers.

Total snowfall 9/30-10/2, NAM model interpretation.

Gates & Boudreau: Winter Outlook 2022-2023

Tomer’s Take:

  • Meteorologist Cory Gates and Ryan Boudreau released their official Winter Outlook 2022-2023 with heavy focus on Aspen/Snowmass.
  • I featured their outlook last winter and it was incredibly accurate for the Aspen Zone.
  • You can follow and subscribe to their weather updates on Aspenweather.net.
  • I released my Winter Outlook last week.

Here’s the full PDF file courtesy Gates and Boudreau.

October snow forecast; Fall color update

Tomer’s Take:

  • Two active periods for mountain snow are possible regulated by a ridge of high pressure.
  • Two active periods slightly favor Western Slope zones for higher totals.
  • Best accumulation will occur at higher elevations with melting in-between.
  • Peak Fall color in Colorado is running behind schedule in some mountain zones.
  • My full Winter Forecast can be found here.

October Pattern

The mid-atmosphere pressure pattern favors the Pacific Northwest/West Coast for above normal precipitation. In Colorado, we’ll get leftovers with high pressure regulating most days.

October middle atmosphere pressure pattern.

Snow Forecast

Forecast October grand totals are below. Best accumulation is at higher elevations in these locations. Normally, this snow falls then melts except on the higher peaks. Also, strong wind starts kicking-in with these stormy periods.

Wolf Creek12
Collegiate Peaks10
Winter Park12
Mount Elbert13
Monarch Pass6

Fall Color Update

Peak Fall Color is running behind schedule in Colorado. Parts of the mountains saw a robust Monsoon season.

Jennifer Broome snapped this photo on 9/22 in Vail:

Vail 9/22/2022, Jennifer Broome.

Some zones like Grand Lake, Berthoud Pass, RMNP, and the Northern Mountains are further along.

John Williams snapped these photos between 9/21-9/22:

Grand Lake 9/21/2022, John Williams.
Berthoud Pass 9/22/2022, John Williams.

Winter forecast 2022-2023

Tomer’s Take:

  • Rare triple-dip La Nina.
  • Multivariate ENSO Index strongest since 2010.
  • Warm blob is back but for how long?
  • Abnormally warm and dry Fall season across the West.
  • Late start to Winter.
  • Large Western ridge of high pressure September 2022 – March 2023.
  • Overall, target PNW, British Columbia, Banff Area, Wyoming, Idaho, and Montana for most consistent winter snowfall.
  • Two big unknowns: Warm SST’s North Pacific and underestimation of La Nina strength this Fall and early Winter. Both could complicate the Winter storm track and snowfall pattern(s).

Winter Forecast Video

Video contains my entire forecast.

Triple-dip La Nina

What is La Nina? Colder than normal (-0.5C or colder) sea surface temperatures in the Equatorial South Pacific (see graphic below). El Nino is the opposite (+0.5C or warmer). Both anomalies have global implications on weather and climate.

Currently, sea surface temperatures near the equator are running colder than normal for the third straight year. Triple-dip La Nina’s are rare only occurring three times in the last 73 years.

Sea surface temperature 28-day anomalies.

Here’s the global sea surface temperature anomalies valid 8/29/2022. Red/orange = above normal. Blue = below normal.

Notice the sea surface heat wave in the North Pacific and North Atlantic.

Global sea surface temperature anomalies valid 8/29/2022.

The Multivariate ENSO Index (MEI) factors in five different variables and assigns a value. It’s currently the strongest (coldest, negative) value since 2010. It says this dip is the strongest of the three dips so far.

The five variables MEI incorporates: (sea level pressure (SLP), sea surface temperature (SST), zonal and meridional components of the surface wind, and outgoing longwave radiation (OLR)) over the tropical Pacific basin (30°S-30°N and 100°E-70°W)

Strongest triple-dip La Nina since 2010:

Strongest triple-dip La Nina since 2010 (MEI value).

Warm Blob

Sea surface temperatures are abnormally warm in the North Pacific (off the PNW/B.C. coast and California coast). This directly affects the storm track and precipitation patterns. Will this continue all winter?

28-day sea surface temperature anomalies.
  • This is where important uncertainty remains in the forecast.
  • I believe the water off the PNW coast stays abnormally warm through November then cools-off in December. Some forecast data suggest this water does not cool-off and the PNW stays abnormally dry.
  • The result: warm and dry across most of the Intermountain West through November then snowier/colder weather settles in December-March.
  • I believe the water off the California coast stays abnormally warm the entire winter. The result: warmer and drier than normal winter.

Warm and Dry Fall Season

Most of the Intermountain West is in for an abnormally warm and dry September, October, and November. It will mirror the last few years with a large Western ridge of high pressure.

Said another way, it’ll be a late start to winter.

The most consistent snow and cold temps arrive in December as the jet stream finally dips south.


I agree with the official NOAA ENSO forecast, which maintains high chances for La Nina through Fall (blue bars) then it fades in January 2023 to Neutral phase (gray bars).

Important note: It’s possible some forecast data is underestimating the strength of La Nina this Fall and early Winter.

NOAA ENSO probabilities.

The latest ensemble forecast spread from the Climate Forecast System shows a strong Fall La Nina that fades early 2023.

CFS v2 ENSO Ensemble spread (PDF corrected), 9/20/2022.

My big picture pattern forecast. Notice the large Western ridge of high pressure.

Winter 2022-2023 big picture pattern mid-atmosphere.

All other forecast specifics are in the Winter Forecast Video at the top of this page.

Merbok takes aim at Alaska; Weekend events in Colorado

Tomer’s Take:

  • Remnants from Typhoon Merbok to bring 50ft seas and 70mph wind gusts to Alaska.
  • In Colorado, remnants from Kay and a jet streak keep rain/snow and gusty wind going in the Central and Northern Mountain zones 9/15-9/17.
  • Pikes Peak Ascent/Marathon and Run Rabbit Run events occur this weekend.

Current Setup

Water vapor satellite shows the remnant tropical moisture continuing to influence Colorado as winds turn counterclockwise around the low. Orange/red = drier air aloft.

Water vapor satellite 9/15 6:20am.


The track Typhoon Merbok’s remnants is noteworthy. Talk about a recurvature.

Impacts: 50ft swells and 70mph wind gusts. Impressive forecast graphics from the GFS valid 9/16-9/17.

On Denali, it’s more of a glancing blow with outer bands from Merbok. I’m forecasting 90mph gusts and snow.

Wave height forecast valid 9/16-9/17, GFS interpretation.
10m wind and SLP GFS forecast valid 9/16-9/17.

Colorado Weekend Events

Pikes Peak

  • 9/16: AM dry, PM 50% rain/snow/thunder, 15-35mph summit gusts, 20s/40s (low/high) summit air temps.
  • 9/17: Dry, 20-35mph summit gusts from SW.
  • 9/18: Dry, 30-40mph summit gusts from SW.

Run Rabbit Run

  • 9/16: AM 10%, PM 80% rain/thunder, 15-35mph gusts from SW.
  • 9/17: AM 10%, PM 60% rain/thunder, 15-30mph gusts from S.
  • 9/18: Dry, 15-30mph gusts from SSW.

Weekend events; Loveland tests snow guns

Tomer’s Take:

  • Remnant tropical moisture slides across Colorado 9/14-9/15. Flash flooding possible.
  • Light snow on the 14ers on 9/14, 1-3 inches.
  • Lingering moisture with a jet streak on 9/16 and 9/17 north of I-70.
  • Jet streak appears weaker today with only a glancing blow to Colorado.
  • Drier, sunny, and gusty on 9/18.
  • Pikes Peak Ascent and Marathon, and Run Rabbit Run take place this weekend.

Current Setup

Water vapor satellite shows the tropical remnants (of Kay) crossing Utah and rolling into Colorado. Orange/red colors = drier air aloft.

Water vapor satellite 9/14/2022 6am.

It’s a wet morning in Western/Southwest Colorado including Telluride. Light snow possible on the Wilson Group.

Telluride live cam 9/14/2022 6:30am.

Telluride Regional Airport:

Telluride Regional Airport.

Snow forecast next 24 hours (9/14-9/15). Light accumulations in blue.

Snow forecast 9/14-9/15.

Flash Flood Potential

Flash flooding is possible on 9/14 with this remnant tropical moisture.

Excessive rain potential valid 9/14/2022.


Friday 9/16 holds the highest percentage chance for morning and afternoon rain showers. A notch drier on Saturday 9/17. Significantly drier on Sunday 9/18 but gusty.

Forecast mid atmosphere relative humidity valid 9/16, Euro intepretation.

Pikes Peak


Run Rabbit Run


Loveland Testing Snow Guns

Loveland Ski Area says snowmaking could start in 16 days. Last year, Loveland officially opened on October 30.

Mayor Parker the Snow Dog, Photo Dustin Schaefer.
Testing the Snow Guns, Photo Dustin Schaefer.

Andrea Sansone finishes Nolan’s sub 46 hours setting new FKT

  • Andrea Sansone set new supported woman’s Fastest Known Time (FKT) on the Nolan’s14 course going south to north in 45:52 between 9/10-9/11.
  • Prior supported woman’s FKT (10/3/2020): Sabrina Stanley 48:49.
  • The overall FKT is held by Joey Campanelli at 41:00 on 7/2/2020.
  • Nolan’s requires athletes complete fourteen 14ers in less than 60 hours. This equates to about 100 miles of distance and 44,000ft of climbing in the Sawatch mountain range between Salida and Leadville.
  • Sansone also holds the overall FKT for most 14ers in 24 hours.

“This was the hardest yet most rewarding accomplishment I’ve experienced so far, and an impossible feat without my crew. I’ve never been pushed so hard by an incredible group of athletes – they wanted this for me as much as I wanted it. It was their dedication and incredible effort that made this attempt successful.” – Andrea Sansone

FKT crew.
Andrea finds clear skies above with fog below.

The Setup

A few weeks ago I received a text from Andrea. I love getting these because they normally include some ambitious future project!

Fast forward to last week and it was game-on for Nolans14 FKT. I was hooked. Then the wildfire smoke and two cold fronts started showing up in my morning weather analysis. Normally, September is dead quiet after the Monsoon. But, in recent years wildfire smoke has become commonplace.



Andrea Sansones’ Garmin InReach Nolans14 FKT final track.

According to Andrea, this was a crux moment (possibly the crux moment):

“It was pretty incredible how miserable I was, that we seem to almost immediately forget the pain. Andrew told me I could quite (I was so close to making that call…) but I would regret it about 3 hours later when I was feeling better.”

Andrea and Andrew on course.
Andrea above the clouds.

Smoke, tropical remnants, weekend events

Tomer’s Take:

  • The tropical remnants from Kay arrive in Colorado Tuesday afternoon (9/13) and continue through 9/15.
  • This precipitation might end as light snow on the 14ers late on 9/14.
  • Smoke goes away on 9/14 as the storm systems sweep the atmosphere.
  • Then a jet streak arrives with wind and lingering rain shower chances north of I-70 between 9/16-9/18.
  • Two big events this week: Pikes Peak Ascent and Marathon, and Run Rabbit Run in Steamboat.

Current Setup

Water vapor satellite shows both low pressure systems approaching Colorado. Orange/red = drier air aloft.

Water vapor satellite 9/13/2022 5:30am.

Wildfire Smoke

Light to moderate smoke concentration remains in Colorado on 9/13. Smoke gets swept away on 9/14 by both low pressure systems.

Forecast below valid 9/17:

Yellow = light to moderate.

Pink = moderate to extreme.

Forecast wildfire smoke valid 9/17.

Event Forecast

A jet streak moves into Colorado 9/17-9/18 and wind above treeline increases.

This is normal in September and especially October-November with cold fronts every few days.

Jet stream level forecast valid 9/17-9/18, Euro interpretation.

Pikes Peak Ascent and Marathon:


Run Rabbit Run:


Tropical remnants, Pikes Peak, Run Rabbit Run

Tomer’s Take:

  • Double trouble with a Pacific low and Tropical remnants this week.
  • Weekend pattern dominated by a jet streak and fast-moving cold fronts over Colorado.
  • The bulk of rain/snow move through Colorado on 9/14-9/15.
  • Smoke forecast looks good for the weekend (see below).
  • Pikes Peak Ascent and Marathon 9/17-9/18.
  • Run Rabbit Run 9/16-9/17.

Current Setup

Double trouble. Two low pressure systems lined-up for Colorado. Water vapor satellite. Red/orange = drier air aloft.

Double trouble. Two low pressure systems lined-up for Colorado. Water vapor satellite 9/12/2022 5am.

Pikes Peak and Run Rabbit Run

By the time we get to the weekend, a very Fall-like pattern establishes itself. A jet streak arrives and delivers a few different cold fronts that brush the Northern Mountains. Wind and scattered rain/snow showers possible.

Notice the dip in the jet stream below:

Jet stream forecast valid early 9/18/2022, Euro interpretation.
PikesAMPMGusts (mph)
Pikes Peak Ascent and Marathon forecast.
RRRAMPMGusts (mph)
Run Rabbit Run forecast.

Precipitation forecast early 9/17/2022:

Precipitation forecast early 9/17/2022, Euro interpretation.

Smoke Forecast: 5am Saturday 9/17

Yellow, orange, and pink = light, moderate, extreme smoke concentrations (respectively).

Smoke forecast valid 5am 9/17/2022.

Tropical remnants 9/13-9/17

Tomer’s Take:

  • Mega High breaks down 9/9.
  • Wildfire smoke circulating.
  • Tropical remnants fill the void 9/13-9/17.
  • Light mountain snow possible.
  • Run Rabbit Run forecast below.

Current Setup

You can see where the tropical remnants will come from in on this water vapor satellite image.

Water vapor satellite, 9/7/2022 6:15am.

Wildfire Smoke

Smoke is circulating from wildfires in ID, OR, and CA.

Look at the thick smoke over the Tetons on 9/6. Photo taken by Pilot Chad Andrews (@crjcaptchad):

Teton wildfire smoke, 9/6/2022 Chad Andrews.

Forecast image below valid Noon 9/7.

Vertically Integrated Smoke valid Noon 9/7.

6pm 9/7:

Vertically Integrated Smoke valid 6pm 9/7.

Will the wildfire smoke stay in Colorado this weekend? Yes.

Tropical Remnants

After the Mega High breaks down what fills the void? Remnants from a tropical system. Forecast image below valid 9/15.

Precipitation forecast valid 9/15/2022, Euro interpretation.

Impacts in UT, WY, CO:

  • Valley rain showers 9/13-9/17.
  • Light snow on the highest peaks.
  • Air temps drop.
  • Gusty wind above treeline 20-50mph.

Run Rabbit Run 9/16-9/17

The trail run takes place in/around Steamboat Springs, CO.

DayPrecip %
9/15PM 60%
9/16PM 50%
9/17PM 40%
9/18PM 30%

Mid-atmosphere relative humidity shows the moisture across the northern half of Colorado on 9/16-9/17.

Mid-atmosphere (~15K) relative humidity, Euro interpretation.