Archive for October, 2021

Strong AR headed for California this weekend with Copious amounts of moisture to work with Dynamically…..Snow Level to remain high until the cold air arrives late Sunday night……

Sunday 8:10 AM

 

Everything on track for excessive wet event for October.  Accumulating snow probably Monday Morning in town. Freezing level down to Village about 800AM to 900am Monday morning.  This is a little earlier now than Fridays guidance. Amounts still look good for 3 to 5 feet above 9,000 feet now as snow level is down about 500 feet during moister portion of event.

Remember, in order to break snowfall record for October, we need close to 68 inches at Snow Plot as there was 18 inches already fallen. Water content is likely to be there either way so precipitation should be enough.

What a way to kick off the water year beginning with October!!!!

 

9:00AM Update

Latest IVT guidance (GFS) from Scripts IVT puts the October 25th Event in the strong category now as compared to the January 27th event which was moderate, west of Mammoth Pass. The January 27, 2021 event dumped aprox 10 feet of snow on Mammoth Mt. However, this storm is much much warmer. Freezing level above Yosemite is between 9000 to 11,000 feet during the day Sunday during the beginning of the event. However, by Sunday night and especially after midnight, the freezing level begins to come down as indicated;  11:00PM (10,200ft) down to (8900ft) by 5:00AM Monday AM.  Between 5:00AM Monday and 11:00AM Monday 8900 to 7100ft. Then 11:00AM Monday to 5:00PM Monday; the Freezing level goes from 7100 to 6700 feet. Then from 6700 to 6100 feet Monday night.   It is important to realize that in an saturated airmass,  the Freezing level is close to the snow level, within 500 feet. contrarily, micro physical processes can allow snow to fall much further down in elevation from the dendritic growth zone, if temperatures are cold enough in that zone and the vertical motion is favorable.  All in all, the main point is, precipitation for the Month of October may be historic for Mammoth Mt, whether we get the additional snowfall of 68 inches in addition to the 18 inches the mountain has already received.

 

Next update Sunday AM……………….

Dr Howard and the Dweebs…………………..:-)

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The stage is set for a good wholloping AR for California this weekend. The updated GEFS IVT plume forecast shows a magnitude for the coast, from the 06Z data at the mouth of the Bay Area, approaching 1200 (KG) (MS) which is in the extreme category for the (IVT) Integrated water vapor transport. For our part of the Sierra, it shows about 900 (KG) (MS) for the IVT, in the strong category.    This is on par with the January 26th-27th, 2021 AR. This AR will give relief to the many reservoirs throughout Central and Northern CA,  However, what about the mudslide threat for areas below the burn scars? Now I will say that the ECMWF model is not nearly as wet.  However, if you average them out it is still very impressive!

The Models are coming in line with some 5 to 7 inches of water for just west of the Mammoth Sierra Crest. The freezing level is high to begin with. So although the snow level may begin lower, it will rise to between 9,000 to 10,000 feet initially. However,  once the cold air induced vertical motion begins, the snow level will come down into the town Saturday Night or Sunday, then into Monday.   Expect excessive snowfall for October, with potential “Event History” in the making for record snowfall on Mammoth Mt.  The current record is 85.6 inches during October of 2004.  So far this October, Mammoth Mountain has received 18 inches.  Only need another 68 inches of snow by Halloween to break the October record.  This should be a 100+  year record for October based upon precipitation records for the Sierra dating back to 1895.

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………………………:-)