Unsettled weather returns to the high country with light snowfall Friday, Showers Saturday and some Upslope Snowfall potential Monday Night and Tuesday…..Temperatures will be colder than normal the next 5 to 7 days…..

10-18-2021

“Potential” for Event History for precipitation for October…….Central and Northern Sierra……

 

10-17-2021

Both GFS and  ECMWF global models show 1 to 3 feet of snow over Southern Mono County above 7000 feet by months end, most of which will fall next Sunday through Monday night.  It may be a cold All Hollow’s Eve.

Confidence is increasing by the day as more and more ensembles agree……

 

The Dweeber………:-)

 

10-16-2021. 9:45am

Brief update:

Sunday Night system is now deeper into California with stronger effects from system now expected.   Windy weather will develop for the high country late Sunday afternoon with light snow fall accumulations now expected in the high country Sunday night into Monday AM.   1 to 3 inches of snow. Possible for Southern Mono Country above 7000 feet Sunday night.

it will be much cooler for Monday with highs in the 40s.

The Dweeber will have a major update for the following weekend storm and accompanying potential Atmospheric Rivers this Wednesday the 20th.

 

10-15-21

Points of interest this AM;

  1. Surface development off Japan on the 19th is split, but consolidates over following 24 hours period in both GFS and EC. Down Stream amplification still very encouraging with western pacific propagation still looking very promising.
  2. No Significant PV over Hudson Bay area as AO fairly neutral, so pattern looks fairly progressive in the long run.
  3. As the long wave over the eastern pacific develops, several AR’s are forecasted to port into the Northern and Central Ca coastal areas beginning the weekend of the 24th, then on and off through about months end. Big question is, how far east will the ARs extend.  Better chance of pushing through Mono County about the middle of following week. (25th)  But lots can change.  It will be lots of fun seeing how this all plays out in time.  Still have over a week….  Pattern favors high snow levels with Snow level coming down into town late next week.  Wet Snow best now!!
  4. Take this following comment with a grain of salt….   GFS total QPF with today 12z deterministic shows 6 inches of water on the west side of the Mammoth Crest and up to 10 inches just west of Tahoe by months end.  Again, this is nothing to your hang hat on yet,  as this is mostly in the week 2 period which is fantasy land……but fun to watch!!  🙂

Will update Sunday or Monday.

The Dweeber………………:-)

 

 

10-13-21

SSTAs are different this fall with cool SSTAS and current warm pool between 170w and 150w.   Weak La Niña and -QBO will bring wetter winter to California than last!

10-12-2021

Snowfall totals 3 to 5 inches. Cold this AM with a low of 17 in the Snowcreek Meadow.
It will be warmer by some 10 Degrees Wednesday with another 10 degrees of warming by the Weekend.
A Stratowarm is in the early stages. It will probably not be as strong as the one last December that forced Meridional flow over Western Hemisphere. The point about Stratowarm is that it breaks up the polar vortex as it builds over the Arctic.  it can reverse some of the prevailing wind systems over the Arctic as well. Although there is no documented or direct correlation to a specific weather pattern in any specific area for the purposes of forecasting, it can break up the Polar Vortex and provide the mechanism for Meridional flow if it is strong enough. Meridional Flow develops because of high latitude blocking. The problem is, we do not always know where the meridional flow will occur, weeks out. The global models eventually pick up on the change. So it’s fun to watch to see just another of the wild events that can affect weather patterns over the higher latitudes. It is my understanding that there we be several Stratowarm events this winter. Possibly more than usual with the QBO being in its negative phase. Expect as a result, more blocking in the higher Latitudes and a better chance at times, to get more storms down over the west.
As mentioned earlier, the next chance of a storm will be around the 24th of October. You do not want to get too fixed on the date as there could be storminess within 3 days before or after as it appears that there will be more than one storm. I will say that the pattern really favors Northern CA. Tahoe resorts look to benefit the best. This 6 day period will be my focus over the next week. Stay Tuned….

Dr Howard and the Dweebs………………………:-)

 

10-10-2021 2:00pm

An impressive 150 knot upper jet is currently developing west of Seattle and will dig SSE down the California coast tonight and Monday.  Before translating east over CA Monday night, this system is one of the classic inside slider types that drives main vort max south along the Eastern Slopes of the Sierra and in this case Monday afternoon. Strong 500mb/1000mb thickness packing with N/S gradient will favor high winds for the Owens Valley, behind the front Monday afternoon and night.  Winds in some areas in excess of 60mph is possible. A high wind warning is in effect beginning at 11 Am Monday for the Owens Valley. In this pattern, most of the Mono County snowfall will occur behind the front Monday afternoon into early Tuesday morning. Considering 700mb temps between -5 to -10C and thicknesses 500/1000mb down to 540 Monday night, I think Kuchera ratios are possible. So snowfall accumulations of 2 to 4 inches, between Town of Mammoth and higher elevations is possible. Another but weaker trof will translate through Wednesday.

Expect warming  temps Thursday through Saturday.   Low temps Tuesday and Wednesday Mornings in the mid teens in Mammoth. Highs in the upper 30s on Tuesday….then warming to low 60s for the weekend.

Next wetter system will be around the 24th of October.  It has support of Hovemoller surface bombing that spins up surface low pressure system off the coast of Japan on the 21st of October. As mentioned earlier, this storm could be a mountain opener…..

 

Dr Howard and the Dweebs……:-)

12:20PM 9-08-2021

Just a quick update.  Unoffical Storm Total so far on Mammoth Mt shows 6 inches at the Main Lodge with as much as 8 to 9 inches over the Summit, based upon .86 hundreds at the main lodge and considering the temperatures during the snowfall both at the main lodge and over the summit (24F)

A few snowshowers are possible today with little accumulation expected.   The next system will spin up a small Low over Northern CA tonight, then drop south during the day Saturday. This system is mainly over land. Some light snowshowers are possible.  There is an NE flow componant at 700MB Saturday afternoon and night, so some light upslope snowshowers are possible.  The system exits Sunday for a nice day. Then Cold Canadian system drops into the Great Basin Monday and Tuesday.  The latest GFS has this storm pretty progressive and so it may not do much for additional snowfall from Upslope.   Will update in this Sunday. There is a strong north wind signeture for the Owens Valley early Next Week so stay tuned for you travelers.   So the main word for early next week is cold and unsettled with possible snow showers Monday into early Tuesday. Some upslope as well.  High temps for Mammoth will be mostly in the 40s with 50s on Sunday and upper 30s to low 40s Monday and Tuesday. Lows in the upper teens and low 20s as well. Expect about 6 to 7 nights below freezing in town.

 

Brief Outlook;

Still looking like a couple of very interesting storms during the last 10 days of October.  They suggest the possibility of being Mountain Openers.  Will keep weary eye on those the next 7 days…..:-)

 

Dr Howard and the Dweebs……:-)

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It’s time to blow out the sprinklers this weekend as cold Canadian air invades the Eastern Sierra early next week.  In the meantime, a trof developing over the Eastern Pacific is splitting, with the more active southerly portion headed for the Central Sierra Friday morning. The most active period will be between 5:00AM and 11:00AM Friday morning for light snowfall.  During the wet portion of the storm, the snow level will be fairly high, generally above 8500 feet, elevations above 9000 feet may receive some 3 to 6 inches of snowfall mainly during the mid-morning period. The snow level does come down later in the day and overnight. However, by that time, most of the moisture will have fallen from the 1st system. The second system off the BC coast drops in behind the first one Saturday. It will have mainly an over land trajectory. There will be a period of NE flow at 700MB Saturday afternoon so possibly some light upslope precip. (Snow showers) The 3rd system is a Great Basin Storm with little moisture. However, it too will have a period of NE flow, (UPSLOPE) Monday night into Tuesday AM. It is possible to get an inch or two in town from that system.  The big message will be the coming chilly temps.   500-1000mb thickness Tuesday AM drop to 537DM. That’s good for teens in Mammoth Tuesday AM with highs in the 30s.   Takes some pics now of the aspens as many, but not all will turn black after the hard freeze…. Both Tuesday AM and Wednesday AM.

 

Outlook:

The remainder or 2nd half of next week looks dry.  A subtropical ridge is temporarily forecasted to build back into the west coast about Friday the 15th.  Looking at the ECMWF 5 day means, the long wave trof retrogrades westward to about 135 west by the 22. 500mb heights are reasonably high over Central CA.  The daily’s show another system that may affect Northern CA toward the 18th, so another trough is expected to affect the west coast with wind, cooling and possibly some light precipitation around the 17th or 18th.  Overall, the pattern suggests NW flow with the upper jet well to the north.

No major upper mountain snowfalls expected yet….

The Dweebs viewed the new ECMWF season monthly height forecasts. Its encouraging with the 564dm mean heights lowering into Central CA for February and March. More importantly, It is the trend that is encouraging as well as  500mb heights seem to be trending lower this year as compared to last.   And last but not least, the -QBO now in its negative phase is strengthening. So the lower stratowinds along the equator blowing from east to west are getting stronger, increasing the possibly of more high latitude blocking this winter.

The Dweeber………………………:-)

Upper Trof to bring fall weather the next few days with breezy cooler weather and a refreshing of our smokey skies…..Some thoughts about the upcoming winter……

Expect cooler breezy weather through Tuesday with gusts in the 40 to 50 mph range at FROPA.  Expect high temps cooling to the upper 50s/low 60s in Mammoth the next few days. Nights will chill down into the upper 20s and 30s. Upper Trof will push a mostly dry cold front through our area tonight, Monday night.  Winds will be light again in Mammoth Wednesday with north breezes to 15 MPH.  By Thursday, upper ridging builds in with the thermal trough shifting to the coast and so offshore flow looks to keep good to moderate air quality over our region into the weekend. By the weekend, a small upper low develops off the coast of Southern CA. It builds heights further over the Eastern Sierra and Great Basin into early next week with even warmer temperatures Monday through Wednesday.  The low is expected to open and merge with a trough in the GOA for a return of cooler breezy weather as we move through the 2nd half of next week, in the week two outlook.

 

Thoughts about ENSO and the upcoming winter:

I have read several articles’ about the upcoming winter. Most give odds of a normal winters worth of precipitation for Central CA, pretty much the same as the forecast made for the winter of 2020/2021. We all know that was a bust for the Sierra. With one of the lowest snowpacks for the central and southern sierra ever recorded. Unfortunately, the accuracy of long range forecasting is not all that great as there is a big differences between a winter that is below normal and one that is historically low in precipitation.

Making the case for ENSO, odds are high again that La Nina will make another appearance this Fall and Winter. Odds are up to 70%  A point one should know is that there is a bias for drier than normal winters in CA. for the southern portions, like LA and San Diego, but the odds diminish as you go northward.  Northern CA odds for a wetter winter is quite a bit higher than Central CA. If you want to look at the odds, check out Jan Nulls Website of information regarding ENSO for California.  He has an excellent climate page and puts relevance of the past, to our current California Drought.  https://ggweather.com/links.html

Personal Thoughts’;

Some changes in the climate related teleconnections this fall to last.

  1. La Nina appears to be weaker than last year this time.
  2. GOA SSTAs are warmer, as well as the AMO. (two areas that will experience stronger high pressure aloft.
  3. QBO has moved into its negative phase as of last June.

QBO, MJO and higher probably of Sudden Strato Warm events are of interest according to some research papers.

 

A strong negative phase QBO suggests a weaker Polar Vortex with stronger blocking over the higher latitudes. Although the odds are highest for the channeling of the Arctic Express to be channeled down through the northern,  central planes and Great Lakes regions, especially with a strong Bermuda high and strong high over the GOA, the increased probabilities of more sudden strato warming events are also in the cards. (SSW) The research paper also suggests that the MJO is 40% stronger and last 10 days longer.  This all argues for several AR events for the west coast including Northern and Central CA,  January, Feb and March.  Wet Nina?

PS, The MJO progression and strength, was severely blocked last winter due to the cold water over the central pacific and strong upper convergence over the central eastern pacific.

SEE:  https://ncics.org/portfolio/monitor/mjo/

 

Abstract

The stratospheric quasi-biennial oscillation (QBO) and the tropospheric Madden–Julian oscillation (MJO) are strongly linked in boreal winter. In this Review, we synthesize observational and modelling evidence for this QBO–MJO connection and discuss its effects on MJO teleconnections and sub seasonal-to-seasonal predictions. After 1980, observations indicate that, during winters when lower-stratospheric QBO winds are easterly, the MJO is ~40% stronger and persists roughly 10 days longer compared with when QBO winds are westerly. Global sub seasonal forecast models, in turn, show a 1-week improvement (or 25% enhancement) in MJO prediction skill in QBO easterly versus QBO westerly phases. Despite the robustness of the observed QBO–MJO link and its global impacts via atmospheric teleconnections, the mechanisms that drive the connection are uncertain. Theories largely centre on QBO-related temperature stratification effects and subsequent impacts on deep convection, although other hypotheses propose that cloud radiative effects or QBO impacts on wave propagation might be important. Most numerical models, however, are unable to reproduce the observed QBO–MJO relationship, suggesting biases, deficiencies or omission of key physical processes in the models. While future work must strive to better understand all aspects of the QBO–MJO link, focus is needed on establishing a working mechanism and capturing the connection in models.

 

 

More later as La Nina develops…..

Cool Breezy Weekend on tap as a strong late Summer weather maker dives into the pacific NW and Northern CA. Showers possible for the Northern Sierra with mainly wind and cooling for Mono County….More breezy weather possible late next week as Summer comes to an end…….

Quick update for the Weekend:  9/15

Several runs of the Euro has a confluence of both the Polar and at least a weak branch of the subtropical jets on Sunday. This is a departure from the GFS runs that omits this merge as well as the polar jet being a bit further north in the GFS as compared to the Euro. If the Euro is correct, it may bring us some light rain or rain showers over Mono County Sunday afternoon or night. Additionally, gradients are tighter with the EC and so it is a windier scenario for late Sunday/Night.

As much as 15 degrees of cooling is possible now with a freeze early next week for many of the colder valleys. Mammoth and June may get down to close to freezing as well Monday AM with highs in the upper 50 to low 60s Monday.

 

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For the inland areas of California, it’s been the warmest Summer on record, a departure from Coastal California, mainly influenced by the chilly waters of La Nina creating more temperate weather.  This weekend is expected to be breezy to windy in the Central and Northern Sierra, as a strong late Summer Trough dives into Northern CA.   Although some models bring the chance of showers as far south as Mono County Sunday night, at this point, it’s unlikely this far south by the majority of the model runs.   What is likely, is a cool down of at least 10 to 15 degrees by Sunday along with breezy to windy weather Sunday Afternoon and night.  This weather system is remarkable in that it has a “Very Strong” AR accompanied with it for areas like the Columbia River inlet along the OR/Washington coastal border. The IVT Plume is over a whopping 1200! in the Integrated vapor transport scale. As an example, the AR that affected Mammoth late last January which dumped 8 to 10 feet of snow was around an 700 to 800 IVT.  So the forecast is for an AR some 35% to 50% stronger!   Pretty impressive for a late Summer upper Jet, up in the pacific NW.

At resort levels, the days will cool down into the low 60s by Monday, while nights will cool down to the lower 30s by Monday AM…..20s are likely in the colder valleys.  This is the first of the early fall systems that are common during the end of Summer and the first weeks of Fall.  The further outlook shown by the EURO model, has a nice period of weather the middle of next week before another migrating wave, one that may get “cut-off from the westerlies, that may affect the west coast later next week.

 

ENSO:  The latest updated  “IRI Compilation of SST Forecasts for the Nino 3.4 Region” show a weak La Nina expected for this Winter.   Last Winter we had a moderate La Nina. 

The bias of dryness goes with a La Nina here in the southern Mono County area. However, not all La Ninas are dry here. Other teleconnections are more interesting! Such as the The quasi-biennial oscillation (QBO), which is a quasi-periodic oscillation of the equatorial, lower strato zonal winds which oscillate west to east, then east to west.  All of last winter they were in west to east mode or in the positive phase which is highlighted by a deep Hudson Bay Low. There was a flip in the index last June to east to west or the “negative phase”.  This is most significant I believe, as the Polar Vortex will tend to be weaker with the opportunity for more Meridional Flow, which tracks the upper jet along Longitudinal Lines, VS latitudinal lines.  This can make for a colder than normal winter across the US, and with blocking in the right places, such as the EP region, (-EP) an upper jet that can bring more storminess to California and Nevada. Additionally, it is known that there are more Sudden Strato Warm events which again, creates more Meridional Flow and the potential for “ARs”. Read abouth the QBO here:  https://en.wikipedia.org/wiki/Quasi-biennial_oscillation
Also: The effects of the negative phase QBO upon the *MJO  https://www.nature.com/articles/s43017-021-00173-9

Last Year, the MJO weakened rapidly over the western pacific, and there was a barrier of cold water over the central pacific. The article in the above link from Nature Mag is encouraging I believe. One that may argue against many of the current drier than normal winter forecasts for the Central Sierra.

*Madden Julien Oscillation    (air sea coupled region of rising and falling air near the Equator that can modulate the westerlies.

Dr Howard and the Dweebs………………….:-)