Marine Weather and Tide Forecast for Mammoth Lakes, CA

KEY MESSAGES

1. Slightly cooler temperatures for today and tomorrow, with a more substantial cooldown beginning in the middle of the week, and below normal temperatures continue into early next week.

2. A significant storm system is expected to impact the region beginning on Wednesday night, with the heaviest precipitation expected on Thursday into Friday.

3. Likely heavy snow has prompted the issuance of a Winter Storm Watch for the Sierra Nevada above 5000 feet from Wednesday night through Thursday night.

DISCUSSION
Weakening of the high pressure ridge over much of the Southwest will lead to a slight decrease in temperatures for today and tomorrow. These temperatures will remain above normal for this time of year until the middle of this week when a cut-off low pressure system moves through Central California. This will cause temperatures to become several degrees below normal starting Thursday and continuing through at least early next week.

Back to the low pressure cut-off, this is expected to move into Central and Southern California by Wednesday night, which would be a more direct impact for a low pressure system than previous systems that had a more northward trajectory. This will lead to a significant amount of precipitation for the region, especially in the foothills and Sierra Nevada mountains. The majority of the precipitation is expected to fall on Thursday and will continue into Friday. Current probabilities on Thursday for 2 inches of rainfall below 5000 feet in the Sierra Nevada is 60 to 70%, with similar chances in the Valley for at least 0.75 inches of rainfall. Moderate to heavy snowfall is also expected above 5000 feet, and especially for the higher elevations of the Sierra Nevada. A Winter Storm Watch has been issued for this reason, with 6 to 12 inches expected above 5000 feet and up to 2 feet in the higher elevations. It will go into effect Wednesday night and run through Thursday night. This cut-off may also have enough energy to produce some thunderstorms if the clouds clear enough for daytime heating.
Current chances for development are 10-15%, mainly in the eastern Valley next to the foothills.

This cut-off may stick around the region for a few days after all of this precipitation, according to the latest ensemble model runs. This would lead to continued below normal high temperatures across the region, as well as near normal low temperatures. Models are also indicating another system in the form of a low pressure trough out of Canada may move through Northern and Central California by Monday, which may bring more precipitation to the region by that timeframe.




AVIATION
A 10 to 15 percent chance of IFR conditions will exist this morning until 18Z. Otherwise, VFR conditions will prevail for the next 24 hours.

AIR QUALITY ISSUES
On Tuesday November 11, 2025, No Burning Unless Registered in Fresno, Kern, and Madera Counties. Burning Discouraged in Kings, Merced, and Tulare Counties, and Kern (Greater Frazier Park Area) and Sequoia National Park and Forest.



CERTAINTY

The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low
medium
and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback.

HNX WATCHES/WARNINGS/ADVISORIES
Winter Storm Watch from late Wednesday night through late Thursday night for CAZ323-326>331.