Mammoth Mountain Extended Fantasy Weather Discussion…

8-29-2024 @ 8 AM  After the cut-off low moves out on Monday, you can expect more ridging to rebuild over the Eastern Sierra, bringing dry conditions with warming temperatures to the area out into the 7-10 day period. Yesterday’s model runs did have the high in a position to bring in a moisture surge around the 10th of September, but that surge is not showing up on last night’s, and the early morning model runs today.

As we move into September, you can expect just above-average temperatures for at least the first half of the month. Beyond that, drier and warmer conditions are more likely to prevail. 

Please note that we are moving into meteorological fall with the start of the new month. Models can get a bit weird over the next 6-8 weeks as we enter the transition season from Summer to the next Snowfall season, which will hopefully start in late October or early November. 

For many years of September past, the first small Fall system moves through around the 21st of September, give or take a few days. Signs are showing off and on the longer-range ECM Weekly model, with that scenario returning in 2024.

Predicting what might happen is difficult when looking ahead to the next snowfall season. If a weak La Nina does form, as is the forecast now, there is a good chance we will have a drier season. However, several very big, weak La Nina winters have occurred over the last 25 years. (See the La Nina Winter chart on the page.)

So don’t bank on a drier season just yet. It could be the perfect winter, with moderate amounts of powder snow mixed in with longer dry periods and endless wind-buff days. 

Snowman

15-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 not over the years.

Temperature Anomaly GIF: Warmer Days are on tap through the next 144 hours.

*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 GIF: Winds will remain in the lighter range over the next 24 hours and then slowly start to increase, with moderate winds expected on Sunday into Labor Day. 

The QPF Forecast – That cut-off low shows some low QPF output for Saturday and Sunday. 

Jet Stream – This is the ECMWF ENS Run of the Jet Stream

Precipitable Water Anomaly Forecast

45 ECMWF ENS Run – Over the next 45 days, the weather is looking about what I would expect for September in the Eastern Sierra. Dry with a bit above average temperatures for the month. Let’s hope for a dusting of snow again at some point in time. 

This is the long-range ultra fantasy model run. These runs are good for looking at upcoming trends in the overall weather pattern.

45-Day Fantasy Snowfall Outlook: The ECM has a very light dusting in the third week of September and another in early October. These are the ultra fantasy model runs, so keep this in mind.