Rain chances this week in Colorado

Tomer’s Take:

  • Two Monsoon surges are on Colorado’s horizon.
  • The first is a medium intensity surge 8/15-8/17.
  • The second is a small surge 8/20-8/22.
  • The LT100 run takes place on 8/20.
  • In Colorado, the seasonal Monsoon normally runs July through August.

Current Setup

Water vapor satellite shows the Monsoon plume moving north through New Mexico, Arizona, Utah, and Colorado. Red/orange colors = drier air aloft.

Water vapor satellite, 8/15/2022 10:35am.

The San Miguel County Sheriff says the Bridal Veil area and Black Bear Pass remain closed due to recent flash flooding and rockfall.

Photo courtesy San Miguel County Sheriff.
Photo courtesy San Miguel County Sheriff.

Flash Flood Potential

Excessive Rainfall Outlook valid 8/15/2022. Yellow indicates at least a 15% chance.

Excessive Rainfall Outlook valid 8/15/2022.

Excessive Rainfall Outlook valid 8/16/2022. Yellow indicates at least a 15% chance.

Excessive Rainfall Outlook valid 8/16/2022.


Massive-Elbert ZoneAMPM

Breakout hourly forecast for 8/20 in Leadville:

LT 100Dry20%80%80%20%

Bonus Forecast: Crestone Peak

Crestone PeakAMPM

Here’s my 8/15 mountain weather forecast update video:

Monsoon surge this week

Tomer’s Take:

  • Two surges are lined-up.
  • Peak surge in Colorado occurs 8/14-8/17. This is a medium intensity surge.
  • A second smaller surge occurs 8/20-8/21. This coincides with the LT100 trail run in Leadville on 8/20.
  • Monsoon surges make rain/t-storms more likely. Sometimes the precipitation can start before Noon and last late into the night.

Current Setup

Water vapor satellite shows the southerly wind flow escorting this Monsoon surge north through AZ, UT, WY, and into CO. Red/orange colors = drier air aloft.

Water vapor satellite loop, 1:30pm 8/14/2022.


Massive-Elbert ZoneAMPM

Specific forecast for 8/20 LT100 run:

Elbert-Massive Zone5am10amNoon5pm9pm
Precip Chance 8/200%20%90%90%40%

Bonus: Longs Peak

Longs PeakAMPM

Total Precipitation

This is total rainfall by the night of 8/20. 1-3+ inches possible in the mountains south of I-70. The San Juan Mountains could see flash flooding.

Total precipitation by night of 8/20, GFS interpretation.

Here’s my 8/14 mountain weather forecast video:

Mountain weather update 8/12: Monsoon timing

Tomer’s Take:

  • LT 100 Mountain Bike Race: 8/13
  • LT 100 Run: 8/20
  • The events will straddle a Monsoon surge 8/14-8/19.
  • Bonus: Elk Range 14er forecast is also below.
  • Monsoon season in Colorado normally runs July and August.

Current Setup

Water vapor satellite shows the current Monsoon surge brushing Las Vegas, Arizona, Utah, Wyoming, Idaho, and Montana. This weekend, the high pressure moves east and opens the door for the surge to swing east through Colorado and New Mexico. Red/orange = drier air aloft.

Water vapor satellite, 8/12/2022 7:30am.

The Full Sturgeon Supermoon made an appearance over Colorado:

Thanks to John Williams for this photo.

LT 100 Forecast

Massive-Elbert ZoneAMPM

Bonus: Elk Range 14ers

Elk Range 14ersAMPM

Leadville events next two weekends: Weather

Tomer’s Take:

  • LT 100 Mountain Bike Race: 8/13
  • LT 100 Run: 8/20
  • A Monsoon surge occurs in-between plus a cold front. The LT 100 Run on 8/20 is looking cooler than normal with possible residual Monsoon moisture. Details below.

Current Setup

Water vapor satellite shows the plume of Monsoon moisture being directed south to north through Utah, Idaho, Wyoming, and Montana. By afternoon 8/14, this plume begins to pivot and swing across Colorado through 8/19. Red/orange colors = drier air aloft.

Water vapor satellite, 8/11/2022 7am.

Leadville Events Forecast


Additional note: Air temps by 8/20 may run cooler than normal behind this Monsoon surge. There is also a cold front involved.

Here’s a look relative humidity mid-atmosphere and it’s running abnormally high on 8/20.

Relative humidity and wind mid-atmosphere, ECMWF.

LT 100 MTB: Here’s the NWS digital point forecast for about 13,000ft valid afternoon 8/12 through 8/13.

Monsoon on vacation but returns late this weekend

Tomer’s Take:

  • Hot and drier across Colorado through 8/13 with normal afternoon thunderstorm chances.
  • Moisture starts to increase afternoon 8/14.
  • This equates to a large window for FKT’s, high altitude loops, and big outings.
  • Bulk of next Monsoon surge in Colorado occurs 8/16-8/18.
  • Colorado is currently isolated and protected by the position of the key high pressure. Monsoon moisture is being sent into UT and all the way north into ID and parts of the PNW.

Water vapor satellite shows the high protecting Colorado. Notice how far north the current Monsoon surge is traveling. Orange/red = drier air aloft.

Water vapor satellite, 8/10/2022 6am.


In Colorado, here’s my precipitation forecast for the Central Mountain Zone:

Central MountainsAMPM
8/16 SURGEDRY90%
8/17 SURGEDRY90%
8/18 SURGEDRY80%

Next Surge

Atmospheric moisture increases to 200% of normal over parts of Colorado 8/16-8/18.

Precipitable water anomalies valid 8/17/2022, GEFS.

Monsoon surge trending weaker this weekend

Tomer’s Take:

  • Overall intensity of this surge is trending a notch weaker in Colorado. Call it a low to medium intensity surge.
  • The location of most precipitation accumulation is also changing. Overall it’s shifting East/Southeast. It favors the Southern Mountains, Continental Divide and East. Lower precip chances across the Western Slope.
  • Saturday and Sunday mornings start mostly dry.
  • Watch for weather by 11am on Sunday and Monday in a few locations including the Sangres and Front Range high peaks.

Current Setup

The key area of high pressure is starting to move east and that opens the door to the next Monsoon surge.

Water vapor satellite, orange/red = drier air aloft, 8/5/2022 5:30am.

Precip Placement

The bulk of precip through the weekend falls in the Southern Mountains, Continental Divide and East. Less across the Western Slope.

The wettest mountain ranges through the weekend are the Sangres and Wet Mountains.

Total precipitation forecast through Monday, EPS model.


Crestone PeakAMPM
Longs PeakAMPM
Quandary PeakAMPM

Monsoon surge this weekend

Tomer’s Take:

  • The next Monsoon surge occurs over the Mountains between Friday afternoon and Monday morning.
  • The bulk of the precipitation occurs over the Southern Mountains with less impact as you go North.
  • Overall, this is a moderate surge. Not as big as last week. Primary impact is for higher chances of midday/afternoon/evening rain and thunderstorms.
  • It means smaller recreation windows but most mornings should be dry.

Current Setup

It’s beautiful morning Telluride. This illustrates how weather normalizes in between Monsoon surges.

Telluride, CO, 8/3/2022 6:30am.

The bulk of Monsoon moisture is currently to the Southwest of Colorado. The key high pressure is sitting just south of Colorado in New Mexico. By this weekend, the high pressure moves east and opens the door for the surge.

Water vapor satellite, middle atmosphere, 8/3/2022 6am.

By the weekend, the door is wide open and precipitable water values are above 100%.

Precipitable water valid Saturday 8/6/2022, GEFS model.


Mount EolusAMPM
Mount Eolus, San Juan Mountains, Colorado

NWS digital point forecast for 13,000ft Central Mountains near Twin Lakes/Mount Elbert valid 8/5-8/6.

Andrea Sansone climbs 12 14ers in under 24 hours setting new FKT

  • Andrea Sansone climbed 12 14ers in 22hrs16min (supported).
  • Eric Lee set the previous men’s and overall FKT with 11 14ers in 21hrs50min (supported) on 9/19/2020.
  • Becca Jay set the previous women’s FKT with 8 14ers in 18hrs33min (supported) on 7/8/2020.
  • FKT = Fastest Known Time

“This project has been a long time coming and there was so much effort from all ends. I didn’t want to let anyone on support down so when I doubted myself during the hardest moments I just had to do what I knew how to do – and that was hike,” said Andrea Sansone after setting the new overall 14er 24 hour FKT.

14ers climbed

  • Columbia, Harvard (2)
  • Belford, Oxford, Missouri (3)
  • Democrat, Lincoln, Bross (3)
  • Grays and Torreys (2)
  • Bierstadt, Evans (2)


Andrea Sansone and Andrew Hamilton are gracious hosts. We were sharing a wonderful enchilada dinner when the conversation quickly pivoted and Andrea said, “We’re going to start the FKT attempt on Thursday and finish Friday.” I said I need to look at those dates – I think that coincides with a Monsoon surge.

I’ve worked with Andrea and Andrew numerous times and they’re great friends. They’ll climb through almost anything. But, a 24-hour record really needs a cleaner forecast. So, we changed dates.

Andrea and Andrew.

Making it happen

Andrea shot this video on Mount Belford. You’ll notice the thunderstorms in the distance. At this point, Andrea is moving ahead and away from the thunderstorms.

Video by Andrea Sansone on Mount Belford.

Andrea shot this video on the Decalibron loop almost on the summit of Democrat. By this point the afternoon thunderstorms are dying quickly and she’s home free.

Video by Andrea Sansone on Decalibron loop.

Monsoon arrives and big event forecast update

Tomer’s Take:

  • Peak surge underway.
  • The first surge of Monsoon moisture combined with upper level jet support generated a major hailstorm in downtown Estes Park.
  • Golfball sized hail (or larger) fell just outside Fort Collins in Wellington, Severance, and around Timnath.
  • 1-3 inches of rainfall with a few different lines of thunderstorms accumulated around Fort Collins and across Northern Colorado.
  • Another surge of moisture Thursday afternoon/night delivers similar weather along with high chances for flash flooding.

Big Event Forecast Update

Never Summer Ultra, 7/29-7/31: Dry all mornings, periods of sun, 40-70% chances for afternoon t-storms (highest % SAT-SUN afternoons). Monsoon has less effect on the Northern Mountains.

Chicago Basin 14ers, 7/28-7/30: No-go 7/28-7/29, drier mornings 7/30 & 7/31 with 80% chances for midday/afternoon rain/t-storms.

Pikes Peak Ultra, 7/30: Dry morning, 80% t-storms by Noon through afternoon.

Estes Park Hailstorm

This occurred 10pm 7/27/2022 in downtown Estes Park, CO. Video courtesy Kirby Hazelton.

Downtown Estes Park 10pm 7/27/2022, Kirby Hazelton.

One additional photo courtesy the Estes Park Police Department.

Deep hail downtown Estes Park, EPPD.


Dewpoints are pegged at 60°F in Fort Collins = a clear signal of a Monsoon surge. This represents available moisture to fuel thunderstorms and flash flooding.

Robust Monsoon through 8/10

Medium/long-range data suggest above normal precipitation through at least 8/10. This strongly suggests a robust Monsoon.

Precip anomalies through 8/10, GEFS model.

Monsoon looks robust for next two weeks

Tomer’s Take:

  • The door remains wide open for an active Monsoon through 8/10.
  • Atmospheric moisture values run 150-300% of normal through 8/10 over parts of Colorado – especially the Mountains south of I-70. Drier north of I-70.
  • It’s important to time-out the surges. Life is more normal in-between surges.
  • Two surges in my CO forecast: 1) 7/28-7/30, 2) 8/3-8/4.

Big Events

Let’s get requests done first. I’ve had numerous forecasts requests. This info might be helpful to everyone.

San Juan Solstice Ultra, 7/30: Dry in the morning, high chance for midday/afternoon t-storms. Course will be wet from Thursday-Friday moisture surge.

Never Summer Ultra, 7/29-7/31: Dry all mornings, periods of sun, medium risk for afternoon t-storms. Monsoon has less effect on the Northern Mountains.

Chicago Basin 14ers, 7/28-7/30: No-go 7/28-7/29, drier morning 7/30 with midday/afternoon rain/t-storms likely.

Long Term Monsoon

Data suggest abnormally high amounts of precipitation through 8/10. This means the seasonal Monsoon remains robust.

From a forecasting perspective, this means afternoon rain/t-storms are likely throughout this period.

Percent of normal precip anomalies through 8/10/2022, GEFS data.

Here’s the NWS digital point forecast for 13,000ft around Twin Lakes/Leadville valid 7/28-7/29. Notice dewpoints in the 30s. That’s high for mountain environments in Colorado.

NWS digital point forecast 13,000ft around Twin Lakes/Leadville valid 7/28-7/29/2022.