Mammoth Weather

3/31/2023

Turn on the lights….The Train of Winter Storms are over!!

Latest guidence shows a much weaker storm for Sunday night through mid-week with mostly wind and snow showers for the high country. Snowfall amounts 1 to 3 inches in Mammoth Monday through Tuesday.   It will be noted that this is a windy pattern for the high country beginning Saturday into next week. Snowfall totals will be mainly Sunday night through Monday…..Then showery thereafter into mid week.  It will be milder through Sunday then colder Monday into Wednesday.

Next unsettled period would be about mid month?

Dr Howard and the Dweebs………………..:-)

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As we wrap up the end of March, the week two models become increasingly unreliable. As a case in point, the Deterministic GFS model from 00Z Thursday last night showed a two week total of 10 more inches of water up on the pass. Now this mormning, it is down to about 2 inches.

Tuesdays Tropical discuession from the CPC hinted at another MJO rising its head over the Indian Ocean and progressing to the Western PAC.  Looking at the RIMM charts, I am not so convinced. The tropical wave looks more like an Equatorial Rossby wave than an MJO.   The MJO developing is suggestive of the continuation of LA Nina pattern this WInter and the long wave Trof in the West and Upper Ridge in the East, IE more storms would be on the way for CA.

This mornings new 12Z GFS showed this next system for Sunday night followed by another Tuesday being the last significant system within the pattern that has been ongoing since early March. The double barreled storm has the possibility to bring another 1 to 2 feet over the crest Sunday night through Wednesday PM.  2 Feet over the crest would be enough to reach that crazy 900 inches mark over the Summit. (75 Feet)   At the moment it is 880 inches with the snow that fell this AM. The Main Lodge has recieved officialy 702 inches with possibly another inch this AM.

Getting back to the 12Z GFS this morning, it should be of note that the pattern across the pacific is pretty unstable from a week 2 perspective. The lastest run suggests the Eastern Pac High redeveloping west of the Dateline then retrogrades again to over Kamchutka, Russia by the 15th. This last Retrogression is very significant as the down stream wavelength suggests a long wave ridge setting up just off the west coast.  Giving some credeance to this all, the Kona Low near Kawaii in both global models, dissapates the low, and is absorbed by the westerlies.  The new 12Z ECMWF is still running. If it is in agreement and its trend suggests yes, then the Dweebs are calling for game over…  Now this is not to say that we might not have another storm or two later in April and May as well as a chilly Trof over the Great Basin, But the long over due end, to the series storms of the Great Winter of 2023 is one for the record books…

Dr Howard and the Dweebs…………………..:-)

3/28/23

Update from the CPC this afternoon:

Following a robust Madden Julian Oscillation (MJO) across the Western Hemisphere earlier in March, the intraseasonal signal has since weakened as it moved over the Indian Ocean during the past week. The GEFS and ECMWF dynamical model ensembles are in good agreement regarding a weakened MJO signal for the next week followed by renewed strengthening across the Maritime Continent and Western Pacific in early April. This could lead to an extratropical response typical of La Nina, possibly leading to above normal temperatures over the eastern and below normal temperatures western contiguous U.S. during April.

This also means that periods of unsettled weather is a possibility during the month of April for the Sierra.

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March 27th

This mornings forecast maps showed a rapidly spinning up low pressure system off the Columbia River. There is a good subtropical tap and it appears that this storms Bullseye will be Mammoth south to the Northern portion of the Southern Sierra. Between 1 and 2 feet is possible at the Village at Mammoth and 2+ to 3 feet over the upper elevations. Most of this will occur Tuesday night into early Wednesday AM. The best break wil be Friday into Saturday with winds on the increase Sunday and more snowfall possible late Sunday night into Monday. This following storm is quicker moving and does not have any subtropical tap, so 3 to 6 inches in town and 6 to 10 inches over the crest seems reasonable.  PS, this is a cold pattern and snow to water ratios are at least 12:1 or better,

Longer Range: 

After the Monday system moves through, it looks cold, showery and breezy to windy Tuesday and Tuesday night with little in the way of any meaningful snowfall.  Wednesday looks cold with a slight chance of snowshowers.

Then we get into a bit of a change in the pattern over the pacific, where the Eastern Pacific High retrogrades somewhat. It will be April by then, and at this point in time, more speculative forecasts because of the month. I think the bias in the models that time of the year is to go weaker with storms. However, this is a very unusual year!  If it was just 2 or 3 weeks ago, I know we would be looking at a few large storms!  In fact there are at least 3 good sized systems.  The upper ridge in is the right place for good over water trajectory, but at the moment, the storms bottom out to the north and west of us. Clearly, more time will be needed to see which way this is all going to work out.

Just Updated:

As an updated side note, the Climatic Prediction Center has indicated today that Weak to Moderate Ridging is over the North Pacific with Trofing located over the Western US.

It was indicated that, “As the forecast period progresses during week 2, these anomalous features “Weaken as the 500MB Field trends toward climatological normals”.  This means that storms will be weaker during the week 2 period.  

Dr Howard and the Dweebs……………………….:-)

Although another Moderate storm is headed for the Town of Mammoth, There are encourging developments in the Week 2 Progs showing retrogression of the long wave Trof westward and upper ridging developing over the far west mainly April 6th on. This, if correct will give us a nice break from storms after the system on the 28th.  However, although La Nina has been over for a while, the state of the weather pattern over the Pacific has been one of La Nina State with a negitive PNA pattern or the long wave trof prevelent over the far west in the mean. Looking at the CFS, (Climate Forecast System) the model still keeps a long wave trof over the far west in the mean for sometime. Thus, even though a longer break in storms for CA is possible, it is too early to say winter is over.

Looking at todays teleconnections, There is plenty of negitive phase in the PNA to say that the La Nina like teleconnection is not over yet!   Weeks 3 and 4 maybe more encourging.

Lets give it another week or two to see how things develop!