Quick update;

AR has moved on shore over the Bay Area. It should begin to snow later this afternoon.  The NWS Point Forecast for the Town of Mammoth at 8000 feet, forecasts between 2.5 to 4.5 feet by Sunday. Mammoth Mt above 9,000 feet “Point Forecast”  is 6.5 to 9.5 feet by the same time. Snow level comes down Friday night into Saturday. 80% chance of up to 10 inches of water over the crest from this storm.  There will be some kind of break later Sunday into Monday with another AR possible Monday Night into Tuesday.  More on that this weekend.


Dr Howard and the Dweebs………………:-)


DWP just came out with there updated water totals for the Sierra.

It looks like Mammoth Pass is very close to the Winter of 2017 as far as water content. about 79  inches of water

Remember the Grand Daddy is the winter of 1983 with about 90 inches of water on the pass.





12:00PM Update

Old Low off the coast of Oregon since last weekend is ejecting through California at the moment.  It will be out of here later today and we’ll have clearing sky’s for a while. Additional snowfall today is in the 1 to 5 inch range by this afternoon.

New runs of the GFS since 10:00PM last night backed off on the break that was hoped for on the Tuesday system. So potentially,  another large storm is expected with another AR possible Tuesday.

In the meantime the extension of the East Asian Jet is progged to reach the west coast Thursday. The moisture in the fetch reaches the Sierra later in the day/evening Thursday. The storm that moves in Thursday Night will be all snow in town up until about Midnight, as airmass modification will take into Friday more for the chance to rain or rain or rain/snow mix.


Of Note;

The Dweebs have to say that snow levels will be tricky Friday morning as NWS discussion’s are mentioning the possibility of an isothermal level, before the winds really kick up Friday. If that works out, the storm could be bring heavy snowfall to the town before the inversion breaks and it changes to rain/snow mix.  Well see how that all works out!   The first AR looks to be with us through Friday evening. Scripps earlier this morning lowered the AR Category to level 3 from the 10:00PM 3/7/23 GFS run, but bumped it back up to a Level 4. Most likely, the difference had to do with how fast the Atmos River is progged through. Then the 4:00AM run this morning may have slowed the River down again so were back to level 4 (Strong).  Here is a point I want to make for the Mammoth area. I do not see this storm as a flooding threat.  That will be mostly below 6500feet. The threat is the additional weight upon structures that have not been shoveled this winter with an already record snowpack.  This is especially true to lower pitched roofs that were built in the 1960s and 1970s. If your windows are difficult to open, and or your doors are difficult to close or just not catch in the slot in the Jam, that may be a problem. Most of the precipitation will be absorbed in the snow.  That is all extra weight on the framing of the home or cabin. With another wet storm moving in possibly next Monday night it just gets frightening!

Below is the latest QPF graphic from the WPC; It shows up to 15 inches of water over the Sierra by late Wednesday afternoon the 15th of March.












Cats out of the bag now with Cat 4 AR headed into Central CA.  Up to 10 inches of QPF the record, the freezing level goes up to 9000+ by late AM and with wind, that’s rain/rain snow mix in town.

rain is possible on the west side of the Sierra Thursday Night through Sunday AM. Flood Advisories are hoisted for many areas on the west side of Sierra now.

Our weather today is beautiful with some high clouds over head. There is little in the way of any wind in town. Skiers and Boarders are back scaling Sherwin Bowl. Mammoth Mt is in operation again!


The Forecast includes the fact that the low off the Oregon will get kicked inland Wednesday. As it does, an area of lift will come though our area and produce some light accumulations Wednesday. Some 2 to 4 inches of snow over the upper elevations is possible Wednesday.  By Thursday, a new pattern emerges. This is the beginning of the pattern forced by MJO. (Madden Julian Oscillation) (The extension of the East Asian Jet)

Initially it will bring West then SW flow, milder temperatures then increase clouds in the morning. Light Snowfall could begin as early as Thursday afternoon. In that there is a lot of cold air still in place, it is not likely for the snow level to rise enough for rain/snow mix before midnight, and there is the chance it may stay snow until later Friday morning at 8000 feet. The freezing level rises to 9,000+ by 4:00AM Friday. So the Snow will be very wet Friday and there is the chance for rain or rain snow mix during the day. By Friday night, if the snow had changed to rain during Friday afternoon, it will change back to snow during the evening.


Remember, the snow to water ratios will be quite variable. And if it is rain, the snow will absorb to the level of saturation. If by chance the snow on your roof becomes saturated;  Saturated snow weighs about 20 lbs./cubic foot. If you do not know how much your roof can handle, get it shoveled soon by a pro!

The following is an educated guess on the QPF in town for the storm;   QPF = Quantitated Precipitation Forecast

In Town, the Aprox QPF for Thursday afternoon until 10:00PM is about .60 inches of water.

Between 10:00PM Thursday and 4:00AM Friday QPF is about 1.30 inches of water.

4:00AM Friday and 10:00AM Friday 1.00

10:00AM Friday and 4:00PM Friday  1.00

4:00PM Friday and 10:00PM  Friday .75

10:00PM Friday  and 4:00AM Saturday AM  .50

4:00AM Saturday and Sunday morning   .75



For two deterministic GFS model runs, it has been backing off on the Tuesday Storm.  It shows lighter snowfall. Maybe we will get a break next week!   So far the European does not agree but there is plenty of time to adjust.

Keeping good thoughts!


Dr Howard and the Dweebs………………..:-)