Mammoth Weather

10:00AM  11/7/2022 Update

Although Mammoth Mt reports 4 inches at the main lodge this AM, temperatures have been well below freezing on the top of Mammoth Mt, during the weak AR, Sunday. The weather plot at Sesame tallied over an inch of water in the data. Thus it is likely that the upper mountain above 10000 has picked up a foot of snowfall, so far this early morning. That is part of the 4 to 5 feet expected.

The Upper Low continues to dig south along the west coast.  The Central Sierra will be under Cyclonic SW flow with good orographic’s today and Tuesday. At the moment, the upper jet of 150 knots at 250MB is due west of the lows centered, near Southern Victoria Island, Canada, so digging continues.

Tonight, the nose of the upper jet will begin to round the base of the digging trough and move on shore about Santa Barbara about 4:00AM Tuesday. Shortly after, by about 7:00AM, very strong upper divergence will occur over Mammoth Lakes and the Southern Sierra.  With the upper jets front left quad taking over, snowfall rates rapidly increase to between 2 to 3 inches per hour in our area, with heavy snowfall expected much of the day into the night. Thereafter, the upper jet pulls the upper trough east then lifts it NE with its axis expected to come through about 10:00AM Wednesday. That is from this mornings 12Z GFS deterministic run. Thus improving weather is expected during the afternoon, with snow showers tapering off. It should clear over night with Blue Bird conditions very possible Thursday. However, for the first part of the day, gusty winds over the crest could be expected, diminishing during the day.

The Outlook for the weekend is less certain. Pattern goes into transition.  Although a strong -EPO is developing with an enhanced southern stream. The MJO is weakening rapidly now and thus the strength of the incipient southern stream is expected to die out leading to a large cut off low trapped below the closed upper high over AK.  There maybe something weak that gets in here early next week, that may bring some showers or light snowfall; but the trend now is for rising heights over the far Eastern Pacific. The new pattern will eventually deliver a series of chilly short waves from Central Canada to upper mid west,  and eventually the Great Lakes week 2. A Hudson Bay Low will try to establish itself toward Thanksgiving. Meanwhile, watching the MJO and Rimm Phase Space, there is some suggestion that the MJO or other air-sea coupled Kelvin or EQ Rossby wave will enhance tropical forcing in phase 6 (western pacific), possibly progressing to Phase 7. So we may be off to the races again…. As  always…Stay Tuned….:-)

The Dweeber………………..:-)

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Powerhouse Storm from the Gulf of AK is digging its way south tonight. Expect the snow level dropping below the Town of Mammoth after Midnight tonight. Storm is running slightly slower. Snowfall Rates will pick up Monday as the freezing level drops below 7000 during the day. The precip plot up at the main lodge shows a storm total of about an .75 of rain so far. So 6 or 7 inches of snow so far on top this evening? Its interesting to note that the Bullseye of the precip is in the Southern Sierra this time, but not that far south of Mammoth.

Snowfall rates will increase Monday with snow accumulating in town.  Most intense period will be Tuesday AM into the night. Still expect some 4 to 5 feet over the top by Wednesday Eve.

Outlook:

Interesting pattern taking shape with -EPO. This acts both as a high latitude block over AK while forcing subsequent short waves on on more southerly track. Wonder how long that will last? There are several mid latitude systems that may affect Mammoth later next week and beyond….. None exceptional, but potential for moderate storms.

Winter Storm Warning goes into effect at the Witching Hour….

Dr Howard and the Dweebs………………..:-)

11-5-2022 3:40pm

Quick Update;

1.  GFS came over to EC solution late Saturday AM.  That is digging a bit further west and about 12 hours slower solution with Trof Axis coming in Wednesday AM vs Tuesday night.  So QPF was bumped up about .75 inches for Yosemite and Huntington Lake area by RFC.    The Dweebs feel that on mammoth Mtn, snowfall totals will be 3.5 to 5 feet now. The TOML. 18 to 30 inches by Wednesday Eve.

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So as of this morning….The upper low is pushing into AZ while increasing northerly flow aloft is taking over the Eastern Sierra. For north wind prone areas, this means a rather blustery day is expected with gusty northerly winds of 30 MPH, while ambient temps will be in the upper 20s and 30s. Cloudiness will clear by evening and low temps will be colder than a snakes vest button by AM
Lows are expected near 10 degrees in Mammoth while Bridgeport valley goes below zero!

Friday will be a much milder day as short wave ridging builds in with highs up some 20 degrees from todays temps. So highs near 50 are expected in Mammoth with lows in the teens.

The next system is one that is as cold as this one, however, it is developing further west and it is slower moving. Integrated Water Vapor Transport (IVT) Shows 3 Weak AR pulses with the EURO; Sunday AM, Monday AM and Tuesday afternoon.

Being that this is another cold storm as well as our location being inland and high elevation, using the Kurchura method of Snow to Water Ratio seems prudent; snow fall amount up 36 inches are shown in the 12z Thursday GFS model while the Euro shows a whopping 58.4 inches storm total from last nights 00z deterministic run. Caveat; Snowfall amounts could be much less by the time the storm gets here. Will up date forecast amounts for this storm Saturday….

Dr Howard and the Dweebs………..:-)

2:20PM 11-1-22

Bullet Points..

1. Models have come in slightly wetter this afternoon.  Not that it will make a big difference.
2. Snowfall should start around 5:00PM in Mammoth
3. Longer range has the Euro with an IVT plume into our area,  IVT 300kg ((ms)) (small) but respectable AR Sunday, while the GFS it Monday AM.  Still a long way off.   But there is potential of a good base building storm!

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Happy All Hallows Eve! The Tricker Treaters should have no Ice to deal with this year. So pleasant strolling on the streets of the Trails……Although it will be a bit breezy.   Tomorrow, All Saints day, will be quite windy in town with advisory level winds especially later in the afternoon. Snowfall amounts are expected to be 6 to 9  inches over the upper elevations and some 4 to 6 inches in town by Wednesday Evening. The storm is a quick mover with modest over water TRJ for the Central Sierra, especially Southern Mono County.

Then next week will be quite fun to see what develops. The Models bring in a storm with the upper jet more to the north of us.  But at this juncture, this far out, no one should take a stab at this one yet!

Here are two interesting points about this upcoming pattern change for next week:

1. The MJO will be Phase 7/8 in the west central pacific. The teleconnections from the ECMWF in both Deterministic and Ensemble runs show an impressive -EPO. This is the Eastern Pacific Oscillation.  It tends to suppress the upper jet to the south. It is closed a high pressure aloft over AK.   The issue is, the teleconnection coincides with the RMM phase space 7/8 as suggested for this time frame around the 7th into the following week.
2. This also suggests the possibility of the development of an Atmospheric River(s) for the west coast.  Most likely in the Pacific NW but quite possibly for Northern CA and somewhat less for the Central Sierra.

This is just something to watch this week by keeping a weary eye on the Global Models mid-week into the following weekend. Will update later this week…..

Dr Howard the Dweebs…………………………..:-)