Mammoth Weather Outlook

The Prospects for another AR are once again diminished…..However, Pattern to remain active over the next one to two weeks……

The weather maps are once again back peddling on the early next week AR.  As I mentioned earlier this week, the EAJ has retreated and will have little influence on west coast weather very soon….This next AR stream does not appear to be strong on shore and is further south. todays hype in the news is not justified I believe. The snow level is below 7000 feet with it and lowers to 4500. So this is not a warm wet system as compared to ones in the past.  I will post an example below. You can see that the rich moisture really does not push far into Central CA.   It does help the QPF but not to the extent many of the others had.  After this one, we are done as far as I can see.  BTW, Scripps has not updated an AR 3 or better since the 06 UTC 03/16/2023 GFS run.  That was two nights ago…


The Southern Sierra looks to benefit best with the Owens Valley getting some good precip next Tuesday. There are other weather systems to follow. As a point of interest, I have read that MJO induced wet west coast patterns with Atmospheric Rivers, effect the west coast for about 10 days. Today is day 10 so its probably over.

Today Saint Patty’s day, will be a beautiful one with light winds and lots of sunshine. Another dry day is expected Saturday, however, more clouds are expected earlier in the day. Highs today in Mammoth will be in the 30s with lows in the teens. The leading edge of the remains of the EAJ will move into the west coast Sunday with snow showers possible. There are two systems in this pattern. One for Monday that will bring winds and at least moderate snowfall and another that is deepening off shore that may focus most precip to our south.  Nevertheless, between Sunday and Wednesday night, 2.5 to 4 feet is possible over the Southern and South Central Sierra, over 4 days.

A break looks to be in the cards Thursday.  Then a weak cold splitting system with light snow is expected Friday the 24th. Again, this is late March now and models do a poor job in handling systems from a week 2 perspective this time of the year.

For what it is worth, another weather system following, looks stronger than the Friday system that may affect our area just after that following weekend. It’s a Monday the 27th through the 30th system. That may be a good snow producer based upon pattern recognition, as it is cold and showery and a has good over water trajectory, but don’t bank on it.

Looking way ahead, without any blocking over Hudson Bay Canada, I am afraid this years weather system’s will continue into CA, just weaking over time, possibly well into April or May. I guess big record winters don’t end abruptly.  “Like die hard skiers and boarder, with age, they just fade away” 😉


Bi-Generational Mammoth Pass Record close to be broken….1983 record has stood for 40 years……AR winding down as coast to coast upper East Asian Jet no more….Still….Several storms will bring more snowfall to the high county through months end……

10:30AM 3-16-2023  PS  Double click on the title to get formatted discussion


Its Mid March, the Sun is higher in the sky. The days are longer, but Winter is still hanging on! After a couple of Atmospheric Rivers, it appears that we are going to get one more Monday night and Tuesday. The storm that is coming in next week is digging a bit more west and slowing. The AR train still intact will lift a bit more to the north and get Central CA. Some 6 to 7 inches of water is forecasted to the west side of Mammoth. So, another 5 inches of water is possible for Mammoth Mt from this storm by Wednesday. It is colder as we are getting more of the forcing into CA instead of it being parked to the north of us while the AR’s hang into the state.

So this will be a major snowstorm, much like we had in February. 3 to 5 feet of snow is very possible. The odds of another AR is very much much lower with the next short wave over the following weekend as the wave train of the southern jet really contracts and the system is much faster moving. As said in an earlier discussion. You cannot trust March forecast models like February and January!

PS the following system that weekend looks to bring a foot or two at this time.


PS  It can not be over stated to shovel your roof if it has not been shoveled recently!!   

Roofs are cracking and collapsing in Mammoth.


Dr Howard and the Dweebs………………:-)



8:00AM 3-16-23


Scripps just came out with a level 3 AR for next weeks storm. Obviously they Feel that the AR over Southern CA will lift North a bit.  More after 9:00AM



3/16/23 7:30AM


East Asian Jet Retreat is well under way preventing any further ARs’s from hitting CA. A good cold storm with a good subtropical tap will hit the High Country Monday Night and bring heavy snowfall Tuesday into Tuesday night. Snow to water ratios will be at least 10:1 again. Upper mountain in for another 5 feet by Wednesday AM. The MJO has moved into Phase 1 and will shortly be into phase 2.  This will transit pattern to move of an inside slider pattern by months end which is a colder dryer pattern with light snowfall as we move into April.

There is at least one more storm after the Tuesday system.  So a storm that following weekend may dump another foot or two.  Winter is winding down…….Springs arrives next week!


Get plenty of photos of Mammoth Mts upper mountain next week with a greater snowpack on it than ever before!!!



Some one has to get the “I survived the Mammoth Winter of 2023” going!


Dr Howard and the Dweebs………………….:-)




I. Note:

Scripps has NOT issued an advisory for an Atmospheric River for the Monday/Wednesday Storm.

The Storm has a good subtropical tap but not qualified for a moderate or strong AR. However, the storm is colder and that will be good for a high quality snowfall producer.  3 to 5 feet is possible during for the Monday Night though Wednesday storm. Another storm over that following weekend may dump another 1 to 2 feet.

A quick update is to post a few new charts.

  1. The new 12Z GFS 500MB Means for the next 10 days is attached below.  The big message here is that these storms are highly susceptible to changes now, due to the fact that they are closed lows and because of the change in the season.  Closed lows often have a mind of their own and can change direction with quick notice. This means that the models can bust much easier, just a day or two ahead.  We are moving into the second half of March and models are not as accurate as they were, like in February or January.

Based upon today’s 5:00AM run for QPF, another 15 inches is possible to the west of Mammoth Mt.   This most likely will be much less.  Will look at it again in a few days…..

The next storm timing is, Monday afternoon the 20th into Wednesday AM the 22nd. Then other system Friday night the 24th through Sunday 26th.

The storms will trend colder, as most have a more NW/SE trajectory like the ones we had in February.







1983 was the year Mammoth Pass tallied 90 inches of water. 1983 was a very wet year but did not have nearly the snowfall that 2023.  2023 was a much colder year.

DWP updated their Snow Survey today the 14th of March. It indicated 87.1 inches of water on the pass and 204% of normal for April 1st. Bishop has 13.16 inches and is 211% of normal now for September 30th, the end of the water year.

Mammoth still has 17+ days to tie or break the all time record.

Weather Outlook:

Weather pattern out over the pacific is looking a lot weaker over the next few weeks as compared to a couple of weeks ago. Days are getting longer quickly now, and with the longer days and more sunlight reaching the higher latitudes, the amount of cold for storms is certainly diminishing. Although there are still storms that will affect the high country over the next several weeks….The scale and size of these systems pale compared to what was observed just a few weeks ago.


Check out the Hemi Upper Jet Map from Asia extending to our West Coast over the next two weeks. What a change in strength! Note how much it weakens! There are storms but they are almost more localized as compared to just a few weeks ago!





There is still plenty of weather systems to break the Bi Generational water year of 1983.

The following weather systems have the potential to drop anywhere between 1 to 3 feet of snowfall to Mammoth Lakes. Of course these are progs, and as such, are subject to change, especially in Spring, in the week two period.


I’ll post a few weather proggs of storms, with that potential….






MJO Tropical Forcing is ending as Classic Anti Cyclone is dissipating over the North Pacific….Like a two mile long freight Train…..It will take time to slow down…..Mother nature takes her foot off the gas peddle and the extension of the EAJ pulls back later this week……

3/14/2023  9:00AM   

(Click on Title to get formatted discussion)


Bishop picked up 2.31 inches storm total; Looking forward to the DWP update!!  🙂

Mammoth Mt at the base lodge reported 60 inches, upper mountain possibly picked up 7+ feet as it was colder.

The Town got a few feet of Sierra Slop.

The next storm is not as warm as Thursday’s storm, so the snow level will be below 8000.

Expect 2 to 3 feet in town, with 3 to 4+ feet on Mammoth Mt by Wednesday Night.

There will be a break Thursday.

The MJO (tropical forcing) weakens rapidly later this week as the complete collapse of the East Asian Jet is expected.

Storms will trend weaker and cooler this weekend then colder next week as the MJO dives into the Circle of Death!


By April, the MJO Re-Emerges in phase 7.  However, by then it is April, and may no longer have any affect on the Pacific Jet Stream….









3/12/23 at 2:25PM

24 hour snowfall forecast for the Town of Mammoth from 4:00AM Sunday Morning to 4:00AM Monday  (4 to 12 inches)

4 day snowfall forecasts (Sunday through Wednesday) for Mammoth Mt.  (4 to 7 feet)

Note, this next storm will be cooler with the snow level about 1000 feet lower.


Pattern is winding down, so after the mid week AR, forecasts will be come more challenging; Any Subtropical Taps into WX fronts over Central and Northern CA will be much weaker.

LADWP will be out with their update for Mammoth Pass, hopefully this new week. We have got to be getting close to 90 inches. That is the high mark (1983). Bet were there by next weekend?



Current RMM  MJO chart

Notes from the Dweebs….

During March 5th, 6th and 7th, amplification was occurring leading up the Classic Closed Upper Anti-Cyclone SE Alaska. The extension of the the East Asian Jet resulted, further energized by the coupled series of upper lows dropping out of the Gulf of AK over the Anti-Cyclone.  On the 8th, a powerful level 3 AR hit the California Coast bringing copious amounts of rainfall on the lower elevation snow pack. The Dweebs had forecasted the possibility of a major AR well back in February, (Read past discussions)  as the RMM was bullish in this scenario during the 3rd week of February. The Global models only gave it a 10% to 15% chance of occurring as late as early March 3th/4th.  A strong MJO in phases 7/8 is like putting your foot on the gas of a 1000 HP engine in a Deuce Coupe. Looking below, this MJO was off the chart.



The Closed Anti Cyclone was still intact this morning, but is weakening:

The EAJ extension is still intact allowing one more Atmospheric River to hit CA Tuesday




Mother Nature takes her foot off the GAS………………..



One more weaker but colder system try’s to make it was in Sunday the 18th through 21st




Then quiet time for the high county?  Well see……

Afterall, only a fool makes a prediction on the 1st of April…especially during a year like 2023  🙂




This is what the snow level has done the past several hours directly to the west of us along the Sierra foothills



Here is the QPF from WPC through next Sunday the 12th




Hang in there…..The 2023 ski season with full operations will begin shortly 😉


PS; the Hype is already going on about El Nino. Yes it looks like El Nino will make a return in the Fall.   However, it does not mean a thing for a wet winter unless it is Full Basin El Nino.  The Modoki or Partial Basin El Nino is a sucker bet!