Mammoth Mountain Weather Forecast
Including Mammoth Lakes & Bishop, California
September 22nd, 2024 at 1 PM – Welcome to the first day of Autumn
Currently, Mammoth Mountain and the Southern Eastern Sierra are under mostly clear skies. There has been no rain or snow in the area since last Thursday; look for the dry weather to continue for the next week.
I checked the area weather stations this morning. Up top, the temperature is 47 degrees with a S wind at 17 MPH, gusting to 30 MPH. Down at the Main Lodge / 8900 elevation level, the temperature is 59 degrees with a SW wind at 4 MPH, gusting to 15 MPH at times.
The temperature is 67 degrees in Mammoth Lakes, 67 degrees at the Mammoth Airport, 68 degrees in Crowley Lake, and 77 degrees in Bishop.
Weather Forecast for Your Adventure
Basic Weather Details Sunday into Wednesday: Look for clear skies, turning PT cloudy this afternoon with a few very isolated showers south of Mammoth over the high country.
For the Main Lodge / 8900 Feet, midday temperatures at the 8900-foot level will be in the mid to upper 60s. Overnight lows will be in the mid to upper 40s.
The wind forecast for today calls for SW winds at 5-10 MPH with gusts to 15 MPH at the 9000-foot level and wind gusts up top at 11,053 feet at 25-35 MPH at times.
On Monday, expect a NE wind at 5-10 MPH with gusts to 15 at the 9000-foot level and gusts up top to 20-30 MPH. The wind will be NW on Tuesday, with a wind speed near what we expect on Monday.
Midday temperatures in Mammoth Lakes will be in the low to mid-70s. Overnight lows will be in the mid to upper 40s with light winds. For Bishop to Mill Pond, mid-day highs will be in the mid-80s to 90s, with overnight lows in the low 50s.
Mammoth Mountain & Eastern Sierra Weather Discussion & Outlook
Now that Autumn is here, it’s time to enjoy the cooler, drier days before the colder winter weather moves in. When that happens this year is anybody’s guess at this point.
The week starts with a strong progressive ridge of high pressure moving into the Pacific Northwest and quickly moving east by Wednesday.
In its place, a cutoff low will form off the central and then the southern California coasts Wednesday into Friday. That low weakens to almost nothing by Friday as a zonal flow with higher heights takes over once again.
Expect warming into Tuesday, a cool-down starting Wednesday, and more warming for the following weekend. This pattern looks to be in place for the next 10-14 days.
This is a perfect time for hiking, fishing, and mountain biking in the Mammoth Lakes and Bishop areas.
Longer Range Fantasy Outlook
Now that we have had a taste of Fall and a second dusting of snow, the next few weeks should be warm and dry, with little hope for rain or snow yet.
Models continue to show October as overall above-normal in temperature and below-normal in precipitation. Ensembles do try to bring weak dusting in around the 6th/7th.
The 45 Fantasy Outlook’s longest-range trend calls for wetter and cooler weather around October 23rd, lasting into early November. I will keep you updated on that trend. For now, enjoy the Fall and pray for a big snowfall in about a month.
Steve Taylor – the Snowman
Steve Taylor – the Mammoth Snowman
The next full Mammoth Weather Forecast Update will be Tuesday 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. 0
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.
*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
QPF Forecast
The showers showing in the QPF image below are for 9/22, and I highly doubt they materialize.
Snowfall Forecast
Most models show the area getting no snowfall over the next ten days, which is pretty typical for late September or 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 week of November.
First Look at Snowfall Season 2024-25
9-5-2024 – When looking ahead to the next snowfall season, predicting what might happen is difficult at this time of year. If a weak La Nina does form (66%), there is a good chance we will have a drier-than-average snowfall season.
However, several very big winters have come from weak La Ninas over the last 25 years. (See the La Nina Winter chart down the page.) Everyone must also remember that many other factors are at play than just warm or cooler water along the Pacific equator.
For now, Ted (Powder Forecast) and I are not forecasting what the winter might be like. We will better understand how this may play out in late October / early November. As we have all seen in the past, patterns can quickly flip and change in late December and January.
La Nina seasons are like El Nino and can bring drought, moderate winters, or large ones. Many factors are at play, and the situation can change as the winter season starts to ramp up in mid-to-late December.
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 new runs of the ECMWF Seasonal come out for forecasters on the 5th of each month.
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
Most Recent Posts
*Mammoth Mountain and Eastern Sierra Weather is updated 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.
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Author – Steve Taylor – The Mammoth Snowman – Over the last 30+ years, Snowman has spent countless hours studying and learning about Mammoth Mountain Weather and Snow Conditions first hand. He has been skiing around the hill with marked ski poles since March of 1991 so he can measure the fresh snowfall amounts out on the hill.
Snowman started blogging this information back in 1990 on the old Mammoth BBS system, then the RSN Forums, and then on to MammothSnowman.com in 2004 with Video and photo Blog reports. (There was No YouTube back then.) Facebook was added to the fold in 2008, and the Facebook Group was added in 2016.
Reports, videos, and photos from the website have been featured on local TV Stations here in Mammoth and Bishop, as well as KTLA, AP, Fox, ABC, CBS, and NBC News.
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