Last really mellow day today then winds on the increase as well as temps this weekend…..Storm/Timing still good for next week!

All large scale features still preforming well as forecasted, with upper pattern morphing toward a temporary REX block near the dateline Sunday afternoon. This is always good for the generation  of tropical and subtropical moisture for storms to feed upon at a later time.

 The eastern pacific upper ridge continues to progress into California as it becomes squashed over the area Saturday. On a smaller scale…..heights increase over Mammoth this weekend as  a short wave moves through the pacific northwest. This has the effect of increasing winds at 700mb and so it will be quite breezy over the upper elevation Saturday and at the same time, temperatures will actually be warmer.  By Sunday afternoon…the ridge axis shifts east into the Great Basin and the door opens to high level subtropical moisture along with stronger gusts over the Sierra Crest. The new 12z Friday GFS has a lot of upper level moisture advection at 700mb (rh) rushing in during the afternoon Sunday….so it is possible that although Sunday morning may be mostly sunny……then by the afternoon cloudy. 700mb winds will continue to increase Sunday PM.

Synoptic scale timing: 

Just using the new deterministic 12z Friday GFS for timing. 700MB (rh) has slug of mid level (50%) moisture into the Sierra after midnight Sunday night increasing to 70% by Monday mid morning then up to 90%  by late afternoon Monday. Initially, this is moisture advection without any dynamics from the subtropical 1st short wave.  Nevertheless, orographically induced light precipitation is possible as early as Monday morning with the chances increasing during the afternoon.  The actual energy and dynamic lift from this 1st subtropical short wave comes through during the early morning hours Tuesday. Thereafter….a larger scale Trof deepens with a vigorous cold front coming through Wednesday afternoon with heavy snowfall both frontal and pre-frontal. Snow levels may drop to 3500 feet by Wednesday night.  700mb winds natural to the Sierra may keep orographically induced snowshowers  going up to about 9 to 10z (UTC) Thursday am.  It is still too early to really predict how much snow we may get. However, the Dweebs have a 1st call of 2.5 feet over Mammoth Mt. by ooz Thursday…..just a guess at this time.

Longer Range: 

The longer range models still has the long wave ridge in the mean back between Hawaii and the dateline which is good. However, the GFS is beginning to display typical characteristics of Spring with an incipient trend of cut off lows during week 2. Once we get to March which typically begins cut off low season, week 2 reliability begins to diminish.  Additionally…looking at the fantasy charts of the GFS, the energy coming off Asia and Japan becomes split.  This often times creates a split flow pattern for the west coast. Of course, where the split occurs is what is important.

Although March is typically a very wet month on the average, this is an La Nina year. La Nina winters are usually more intense but shorter precip seasons. It may be that Cut-Off low season will begin earlier this year?

Future timing of “significant energy” through west coast “week 2”.

1. Night of Friday the 18th

2. Thursday morning the 24th


Dr Howard and the Dweebs…………………………….:-)

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Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

Cold inside slider brought some light upslope last night…..Light Mono Lake effect probably helped……Nice weekend shaping up with light winds followed by Storm Tuesday

Lee Vining and June Lake picked up a little lake effect over night. Infact some lake effect was still occuring at this time.  West coast upper ridge to begin reacting to pattern change as strong height rises are now occuring near the dateline and a deepening trof is digging south along 150w. The effect upon west coast upper ridge off shore are profound this weekend. The off shore ridge gets flattened with its high heights squashed into the west coast beginning Friday as it gives us a beautiful weekend! Winds will be light this  Friday, Saturday and Sunday with highs in the 50s Saturday and Sunday at resort levels. Heights peak out Saturday at 00z Sunday and temps will reach into the low 70s in Bishop Sunday. (Golf anyone?)

The next shoe to drop will be the rapidly approaching lead short wave with a fair amount of subtropical moisteure. The timing from the GFS seems pretty good now with the energy expected to come through Tuesday. Cylke’s Law says 12z Tuesday as the 1st iso bar reaches 150E at 12z Friday morning. 96 hours of propagation says energy to come through 12z Tuesday.  So snow fall could begin any time after Midnight Monday night. 500ht Heights are around 552dm at that time, so a snow level around 6000 to 7000 feet to begin with seems good depending upon the dew point and 700mb temps. The nature of the moisture is subtropical so it may end up a bit higher to start with. At the moment…..the isentropic surface along with the front slide through Southern Mono during the afternoon Wednesday. With some additional energy coming through Wednesday night.

A following shot of energy comes off Japan about the morning of the 14th. Although it really does not spin up for another day. Will watch that one the next couple of days….



The Dweeber…………………………………:-)

————————————————-
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

Ensemble members rapidly increasing trend toward wet pattern for California by Mid Month…Subtropical tap/connection very possible with set up….

Beautiful weekend shaping up…still gusty NNE winds over the sierra crest expected.  Expect highs in the upper 40s and low 50s this weekend with lows in the teens and 20s. Light breezes will be the rule for most areas excluding the sierra crest.

Outlook:

Next inside slider is headed for the Great basin Tuesday. Winds will pick up again with colder weather Tuesday into Wednesday. Highs will return back into the 30s.  The new 12z GFS has the system digging a bit further west now and so a dry back door cold front is expected with strong north wind for the Owens Valley Tuesday afternoon/night.  The weather looks milder Thursday into Friday.  Expect  increasing wind over the upper elevations that next weekend.  

LONG RANGE:

Over the past two days there has been a rapid increase of ensemble members showing a pattern change for the central west coast to a stormy one.  As usual…the timing is different between global model’s ECMWF and GFS. The ECMWF is faster with the change bringing snow to the Mammoth high country as early as the following weekend with the GFS holding it off until the following Monday the 14th.  Using the timing of Cylkes western pacific surface bomb 96 hour rule, the first surface system moves off Japan and spins up the night of the 10th…..so it energy should propagate through the west coast the night of the 14th (Monday). Then another stronger rapidly intensifying surface system moves off Japan the night of the 13th, and so its energy (propagate) would be expected to come through the west coast the night of the 17th based upon this mornings data snap shot. 

The good news is that the upper ridge at this time is forecasted to develop a REX Block signature and is expected to locate between 170w to 180 west. The tropical upper low that is part of the REX block is located about 28N and just east of the dateline. Strong convergence with the easterlies is hinted at, with a train of thunderstorms developing north of Hawaii the night of the 11th into the 12th. This tropical/subtropical moisture may get entrained into the first system headed for the Pacific northwest. As the polar jet slides south, the fetch may follow into California the week of the 14th.

Highlights:

Because of where the upper long wave ridge is setting up….This pattern is good for the development of tropical moisture which may entrain subtropical moisture and involve the confluence of both the polar and subtropical jets into California.

The upper ridge is still in a favorable position as late as 384 hours out and so an active pattern may continue once started, into the 3rd week of February.

Note:  We still have a long way to go time wise, and thus a lot can happen between today and next week. The Dweebs will keep good thoughts and hope that the models still show that a good dumping is in store for our area by mid month.


The Dweeber………………………:-)

————————————————-
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.