Mammoth Mountain Weather Forecast
Including Mammoth Lakes & Bishop, California
Sunday, October 6th, 2024 @ 9 AM Expect partly cloudy skies for Sunday and Monday, with a 20% chance of showers and thunderstorms in the high country.
The rest of the week will offer clear skies and warm and dry conditions, with temperatures a bit above average into Saturday. It looks like a great week and upcoming weekend for a Fall Adventure in the Eastern Sierra.
Mammoth Weather Forecast for Your Adventure
Basic Weather Details into Thursday: At the 8900-foot level, midday temperatures in the Main Lodge area will be in the mid to upper 60s. Overnight lows will be in the mid to upper 40s.
The wind forecast for the next few days calls for a south-west flow. The wind speed at the 8900-foot level will be 5-10 MPH, with gusts in the 15-20 MPH range during the afternoons. Over the higher elevations, expect afternoon gusts of 15-25 MPH.
In Mammoth Lakes, midday temperatures will be in the low to mid-70s, and overnight lows will be in the mid to upper 40s.
For Bishop to Mill Pond, midday highs will be in the mid- to upper 80s, with overnight lows in the low to mid-50s.
Mammoth Mountain Area Forecast Discussion
There is not much going on with the weather this week if you’re looking for rain and snow. Ridging to our east will be at odds with a short wave off the California coast. That allows some cooler temperatures this week, making the area feel more like Fall and not late Summer.
As the week goes on, a much deeper low will be off the coast, bringing additional cooling and breezy conditions late in the week into Saturday. The following week looks to start with; you guess what, more ridging and warmer temperatures.
The good news I have been seeing in the longer-range trend is cooler weather with a light dusting of snowfall for the last week of October. Temperatures could be cool enough for the snowmakers to test their systems for a few hours right at the end of the month.
Looking into the Ultra Fantasy Outlook period for the first two weeks of November, cooler weather with more snow showers shows up on the ECM, GEFS, and CFS long-range fantasy models.
Steve Taylor – The Mammoth Snowman
The next full weather page update will be on Tuesday, October 8th, by 5 PM.
Mammoth Weather Forecast Data from Weather Bell
ECM & GEFS Ensemble Models 500
10-Day ECM 500mb Anomaly GIF: Below is the entire 15-day run of the ECMWF ensemble model. I use this model to tell the Mammoth Weather Story you just read above. Compared to the other models, this solution has been effective more often than others over the years.
10-Day GEFS Ensemble 500mb Anomaly GIF: Below is the second most trusted ensemble model that we use that goes out to day 16. Model relaibily beyond day 7 can be very suspect expecialy during the transition seasons of Spring and Fall.
ECMWF Ensemble Jet Stream Gif
This is the Northern Pacific View of the ECMWF ENSEMBLE Run of the Jet Stream.
Temperature Forecast
Upper-Air Temperature Anomaly GIF: The reds are moving over California, which means above-average temperatures are here again. For now there are no signs of much cooling over the next 10 days.
*Temperature anomaly means a departure from a reference value or long-term average. A positive anomaly indicates that the observed temperature was warmer than the reference value, while a negative anomaly indicates that the observed temperature was cooler than the reference value.
The Wind Forecast
The wind forecast for the next few days calls for a west-to-south-west flow. Wind Speed at the 8900 foot level will be 5-10 MPH with gusts in the 15-20 MPH range during the afternoon hours. Winds gusts up top will be a bit stronger at 20-30 MPH at times. Expect an increase in the wind speed on Friday and lasting into next Saturday with upper mountain gusts in the 35-45 MPH range.
QPF Forecast
After a chance of some showers today the area is looking dry out to day 10.
Snowfall Forecast
Most models show the area getting little to snow snowfall over the next ten days, which is pretty typical for early October.
Precipitable Water Anomaly
45-Day Long Range Fantasy Outlook
This is the long-range ultra fantasy 45-day model run. These longer-range ensembles are suitable for examining long-range trends in the overall weather pattern. They should never be used or considered a forecast. We see below higher hights with drier weather in the region through most of October.
46-Day Fantasy Snowfall Outlook
These long-range snowfall outlooks are good for trends, and should never be considered a forecast. One thing I see in the long-range is a change to colder and snowier weather around 10/23 into the first / second week of November.
Second Look at Snowfall Season 2024-25
10-6-2024 – Time to take a look at the long-range data and see how the trends are developing for the upcoming snow season.
The newest seasonal long-range fantasy model runs are in as of 10/5. The ECMWF Seasonal has a weak La Nine in place for the November-January period; beyond that, conditions rapidly change to the natural range. With the (flip-flopping) CFS having a more moderate La Nina through January.
Besides the SST forecast, many other variables will affect the outcome of the upcoming winter. Many of those factors are impossible to gauge this far out.
So, if we assume the ECMWF is close to right on the SSTs, the snowfall season based on the past more then likely will be below the average mark (50% chance), with a 25% chance of being around average and a 25% chance of being above average.
Several very big winters have come from weak La Ninas over the last 25 years. (See the La Nina Winter Chart down the page.)
The ECMWF Seasonal has the snow season starting with average snowfall for November and December, with January into February being drier, with an average March and April. Confindence in this long range outlook is low as the last run had a well below normal winter. Going to be intresting to see what the outcome will be on the next update on 11/5 is.
Here is the CFS precipitation outlook for November through January as of 10/6/24. Take it with a grain of salt, as this model constantly changes its outcomes.
Temprature-wise, many La Nina years have also turned out to be colder than average. The troughs affecting the Eastern Sierra are, more often than not, inside sliders.
Those types of weather systems are drier and colder than you’re used to seeing on Mammoth Mountain.
However, the current ECM Seasonal model shows the area’s temperatures averaging above average each month this winter. Go figure; it seems like the model is still struggling with what might come our way over the next few months.
As we wait for the snow season, remember that La Ninas are much like El Nino winters. There is no one specific outcome; you can get massive snowfall or a total bust. It’s all fun to watch, especially when it ends with a deep base on Mammoth Mountain.
Let’s keep the positive vibes that Mammoth Mountain gets a perfect winter, with moderate amounts of powder snow mixed in with some dry periods and endless wind-buff days.
Steve Taylor – The Mammoth Snowman
PS: The next update for this snowfall section will be 11/6/24.
La Nina Years Snowfall Totals for Mammoth Mountain
Weak La Nina
1971-72 Snowfall Total = 268 with 139 in December
1984-85 Snowfall Total = 236
2000-01 Snowfall Total = 393 with 124 in February
2005-06 Snowfall Total = 578 with 4 100+ inch snowfall months
2008-09 Snowfall Total = 470 with 2 100+ inch snowfall months
2016-17 Snowfall Total = 617 with 245 January 163 February
2017-18 Snowfall Total = 262 with 142 in March
Moderate La Nina
1970-71 Snowfall Total = 255
1995-96 Snowfall Total = 321
2011-12 Snowfall Total = 263
2020-21 Snowfall Total = 244.5
2021-22 Snowfall Total = 260
Strong La Nina
1973-74 Snowfall Total = 306
1975-76 Snowfall Total = 197
1988-89 Snowfall Total = 251
1998-99 Snowfall Total = 323
1999-00 Snowfall Total = 382
2007-08 Snowfall Total = 333
2010-11 Snowfall Total = 668
2022-2023 Snowfall Total = 717 – Largest Winter Recorded over the last 100 years
ENSO Watch
Last Update from DWP Precipitation for Mammoth Pass & the Eastern Sierra
*Mammoth Mountain and Eastern Sierra Weather is updated on Sunday, Tuesday & Thursday by local Steve Taylor, the Mammoth Snowman. The goal is to provide detailed weather forecasts presented in an easy-to-read format. This isn’t a Hype, one-and-done model-run website. It’s just the basic facts from how I see it after 40 years of being involved in local weather and recreation. And yes, I use Weather Bell for my forecasting data. Snowman
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