Last AR storm (20st-23rd) numbers, snow 54" with liquid equiv of 7.60, patrol reported rain and snow mix at 9000k. Friend riding on ch 23 reported evidence of rain...but inconclusive to me how far the rain line went up. I'd warned this event could see snow level go as high as Mccoy...Evaporative cooling for snowfall at first then once the air becomes over saturated then it's pure wet cement...mammoth was fortunate most of the precip fell on Wednesday night not during the day time.

Next possible wet event around April 6th

Possible pineapple express action to bring rain and more rain with the EC having a little more south trajectory Models had this AR heading to the PNW but now has changed it up a little. Stay tuned as models are going through an inter-seasonal transition therefore don't hold your breath and turn purple...

The bad news snow levels look very high @ 10-11K if this event verifies.



EC operational





GFS operational





EC pwat showing the AR source

Quite a bit wetter than the previous run.





The GFS is showing it as an AR now too.

Although it would make sense with warmer spring temps, I can’t remember it raining significantly in April on the Mountain. And not so much in March either. To me, it seems they were mostly January and February events. A sign of climate change or just really weird weather this year? I hope those snow levels come down as we are going up next weekend. I’m old enough to see the overall pattern change of higher snow levels though. Except for December 2010 and last year, having snow stakes on 395 south of Mammoth seems a waste of effort the last 20years.

Days 6 & 7

Last night the Euro went drier and further north but its reversed today. It has everything falling between Friday afternoon to Sunday afternoon.

From SF

Models continue to forecast an atmospheric river (AR) event late
next week. Initially, on Thursday, the AR`s moisture plume is
expected to primarily impact far northern California and perhaps
extend as far south as our North Bay counties. But by late Friday
both the GFS and ECMWF forecast rain to spread south across most
of our forecast area. Rain rates through Friday are expected to
be mostly light to moderate in our area, except perhaps locally
heavy in the North Bay. Then, an upper trough arriving by next
Saturday could provide the necessary forcing to generate more
widespread heavy rainfall across our area. But this is still a
week out and so forecast confidence on the specifics remains
relatively low.

Reno

Friday and Saturday are starting to look like the best days for
precipitation...with Saturday the day with heavier precipitation.
The GFS is still a little faster overall and brings substantial
precipitation into the region by early Friday morning. The ECMWF
waits until the daytime hours. The overall slowing of the model
solutions also brings into play the possibility of much higher
snow levels initially; snow levels could reach above 9500 feet by
Friday with some areas as high as 10,500 feet. Luckily...this
first part of the main storm is fairly fast moving.

Snow levels do start to fall on Saturday...albeit slowly. This
happens as the main upper level trough approaches. This trough
also provides greater forcing so the heaviest precipitation is
likely Saturday morning and early in the afternoon. The approach
of this trough is also likely to result in stronger winds aloft
and near the surface.

The shifting nature of the model solutions means we are still a
little too far out to make definitive forecast of precipitation
amounts. Amounts were raised for Friday night and early Saturday
and we have an initial estimate of between 1.50 and 2.00 inches
along the Sierra Crest. This...of course...is likely to change
numerous times before next weekend. The lack of consistency in the
model solutions is keeping our confidence level on timing and
amounts in the low range.

Hot off the press

Same time frame as Cheaps mentioned..
Just to give an idea how warm this is. The QPF for MM area is 5.95" with snow total of 16" for higher reaches...
If any thing more of a Sierra slurry...

Not targeting anyone here just my own observation/opinion ....it cracks me up every time we get extreme weather the alarmists' conclusion is that it's human induced climate change. ARs occur globally and its intensity and variability is not fully understood based on limited data collection.
History: "A 43-day storm that began in December 1861 put central and southern California underwater for up to six months, and it could happen again... Sixty-six inches of rain fell in Los Angeles that year.."

Versus this,
"From December 2011 to March 2017, the state of California experienced one of the worst droughts to occur in the region on record. The period between late 2011 and 2014 was the driest in California history since record-keeping began"

This ski season has seen plenty of very cold storms. Last Monday Flaskman said it was -27 windchill on the hill.


Anyway, looking at this morning's EC runs 0Z EC ensemble (51 members) has around 4-5" of liquid for this event over mammoth. Expect models to wobble until 2 days out. This event is a looking different compared to the last AR cuz it'll hit harder under a shorter time frame and snow levels a little higher 10-11K. The upper level low steering this AR does not look to have the cold air support like the last one which is not saying much.

NWS has tapped into the hype so watch their forecast if anyone is planning a trip next weekend. Bring a poncho.

Thankyou for the heads up Will pack my board trunks...

Well, yes I feel a bulls-eye, although I appreciate your thoughts and knowledgeable weather comments. But I’m hardly an alarmist. I was making an observation that I don’t remember any significant rain events in April in past years, that they tended more towards January/February. I’m old and have been going to or lived in Mammoth for nearly 60 years so I’ve seen changes in the overall snow levels. Maybe I have Alzheimer’s, but I remember big snow events in April, not big rain events, and that the snow levels were more consistently 6500 feet or lower throughout the winter seasons. It seems to me that, although we still have a variety of cold and warm storms, there seem to be more storms with the snow level around 8500 feet.

I know all about some of the extreme past weather events in CA, including the great flood of 1861-62 and my personal favorite - 1916. In San Diego, rainmaker Charles Hatfield was hired to fill Lake Morena. After the extreme flood events that occurred, he had to lay low. Like many still hanging onto this forum, I’m fascinated by weather, particularly in the Sierras, because it can be extreme.

It would be interesting to see if there is any seasonal data related to the snowpack elevations over the years and whether or not there are any documented changes or trends. DWR would have snowpack data but I don’t know if they have gauges at varying elevations.

Not only is it much further south of the resort, but I assume there is all that snow cover in Spring since they are shirtless.

"since record-keeping began" is my bugaboo. Are they talking about 160 years or since the Chinese, Mayans and Egyptians kept written records? Are they talking about tree rings? Sediment layers?

I also remember skiing to Hot Creek on every Mammoth visit from the mid 80s to the 90s. Then it seemed to get really variable to non existent.

Comparing the run from yesterday



to today

The 00Z GFS has bumped up QPF for MM and So. Sierra to over 8" by the end of the 8th!
One thing for sure this will surely change and how many times? Bullseye - north, south, BC...?

It rained in April 2006 days before the post-control avalanche on Climax. I was soaked riding chair 3 the Saturday or Sunday before it slid.

Also don't forget the Jan 1997 rain with snow levels above 10K that caused flooding in Reno and the greatest flooding ever recorded in Yosemite.

There's a very long history of massive AR events all across the state.