Chilly Today with strong Easterly Winds over the crest developing this afternoon…..It will be fair and milder later this week…..Dry weather is expected this week….

Tuesday AM:

It is another clear cold morning here in the Eastern Sierra. As the western ridge continues to build over the entire west coast and even up into Canada, a strengthening cold surface high over the Great Basin with a general off shore flow pattern is expected to prevail for several days.  Air Quality will diminish and those who live in the Eastern Sierra. We will note hazy conditions both day and night. This new pattern initiates with a strong east-west Gradient Aloft. Gusty easterly winds over the Sierra Crest will slowly diminish over time. Mammoth Mt was reporting easterly gusts in the 70mph range this AM. Again, winds will gradually diminish over the upper elevations as the gradient relaxes. At the Same time, warming aloft will begin today with the freezing Level expected to go up beyond 11,000 by tomorrow Wednesday. It stays there pretty much through the weekend.

This pattern over the far west is part of the infamous positive phase of the Pacific North American (+PNA). Its key teleconnection lies over BC, Canada were it is anchored. When teamed up with a strong negative phase of the Arctic Oscillation (-AO) (Anomalous high heights over the Arctic) This pattern along with a northern hemispheric four wave, (long wave pattern) is very stable and unlikely to change anytime soon. The Climate Anomalies from todays run (DEC 5th) of the CFSv2, Shows a 500mb positive height anomaly remaining anchored over the far west for both week’s 1 and 2, or through the 18th of December.  During week 1, the 500mb Height anomalies axis is located about 120west or over the Sierra. During week 2 it may shift east to about 110 west.  This eastward shift may bring further warming to the Owens Valley as there maybe periods southerly flow. By week 3 the interseasonal climate model shifts the northern part of the upper height anomaly over Canada further east to about 100West away from the PNA region, while the southern portion of the block remains strong over the Desert Southwest. This change will allow the westerlies to move back into the west coast from about Northern CA northward to Washington State. So the potential of an “AR” exists for the coastal regions of the PACIFIC Northwest. It would be primarily warm air advection precipitation over Northern CA, and most likely rain except for the highest elevations.

Based upon this mornings run, most of it remains to our north and that may be a good thing!  The week 4,  500MB height anomaly if we choose to believe it, definitely shows the Break Down of the +PNA pattern over the far west and SW Canada. So the pattern goes into transition, the last week of December.  Yesterdays European EPS PNA region showed the +PNA dropping to neutral by the 28th of December. What is even more encouraging is that the Western Pacific Oscillation goes negative about the Frist of January and the Eastern Pacific Oscillation goes negative beginning the first week of January as well. There two Teleconnections indicate that high pressure aloft blocking will develop between Alaska and the Bering Sea the first week of January and into the 2nd week. Just using these teleconnections along with a negative PNA, that tells the Dweebs that a stormy period will take place beginning sometime toward the end of the month of December and most likely into the first half of January. Of course, the Dweebs will have better visibility in about 1 to 2 weeks.

 

Stay Tuned……………………..>>>>

 

Dr Howard and the Dweebs………………..:-)

 

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Monday AM:

It is a beautiful morning in Mammoth with clear skies and cold temperatures…..10 degrees at the village!  Last little wave of the westerlies is currently moving through, resulting in a reinforcing shot of cold air. Mammoth Mt will be making snow today and tonight and  for the next 24 to 36 hours.  The aforementioned wave will increase easterly winds later today over the crest while the lower slopes will experience light winds. Winds over the crest will increase to 80MPH by tonight out of the East.  This little ripple is the last shot of cold air before the full latitude ridge sets up. This ridge has legs and will likely last for at least one to two weeks. The Upper Ridge will shift slightly east week 2 and that will allow the beginnings of some southerly flow to boost temps up in the Owens Valley next week. The Climate models (CFS) shifts the mean ridge position a bit more east weeks 3 and 4. However, 500MB heights remain pretty high over the Christmas holiday period.  I would suspect that we’ll see some AR precipitation beginning later during the 3rd week of December into the end of the year. The Dweebs note that in todays interseasonal Climate Models run, our air mass will be warmer than normal and that high elevation snow would be the more likely scenario, if we have precipitation during week 3 and possibly week 4. The CFS also suggests the absence of any blocking upper height anomalies over or near Alaska during weeks 3 and 4; IE -epo or -wpo. That is inconsistent with the EU EPS that came out a few days ago as it touted different teleconnections.

I will update “on the EPS”,  later this week to see if there are changes to its teleconnections in the WPO and EPO regions.

 

Some thoughts this morning……

  1. At the moment, there is no doubt that there will be plenty of Great Lake, Lake effect snows over the coming two weeks. The Dweebs are just not sure that based upon the precip anomalies forecasted by the CFS for the Ohio Valley and east, that significant snows will be accumulating in areas that there would be enough for the feed back necessary to anchor this pattern in the long run. Although that is certainly possible, it just remains to be seen. On the same thought, without the feed back, we could see this pattern break down quicker or at least gets some decent storminess in here for a while.
  2. The pattern shift suggested by the CFS this morning would allow for a significant AR into California after Mid Month. However,  odds are it would be warm with high snow levels as there does not appear to be any cold air confluence with this interseasonal pattern shift, at least based upon this mornings look.  On a bright note, Mammoth Mt usually does much better for snowfall from AR events as compared to Tahoe, because of its elevation….:-)

Sensible weather:

Expect a couple of cold days, with warmer weather the second half of this week. Daytime highs will go from near 30s today and mid to upper 30s Tuesday,  to highs up into the 50s during the day by Thursday and into the weekend. The cold temps at night and early mornings as of late will moderate into the teens and 20s at the Village. By the weekend, expect lows in the 30s by Saturday.  It will be much colder over the lower elevations of town during the early AM hours the 2nd half of this week. IE Strong Temperature Inversions and diminishing air quality is likely!

 

More later after the new EPS is released this week….

 

Dr Howard and the Dweebs……………….:-)

Chilly Upper Trof Axis has pushed east of the Sierra Now and so Sunny skies are expected Sunday…..What appears to be the last shot of Cold Air will Follow Monday….Then its Ridge City for quite a while….

Today is a blustery day in Mammoth with light snow this morning and currently sunny skies. High temperatures today will be in the mid 30s and gusty west winds will make it feel even colder. Lows tonight are expected to be in the teens. There appears to be one more shot of cold air following this trough, between the upper ridge now crossing 140W and the Sierra Crest.  This short wave is dry, but will bring some high clouds, some breezes over the upper elevations and more importantly, a shot of cold air Monday for which Mammoth Mt will be able to make snow day and night. By mid-week,  the upper ridge now progressing toward the west coast will amplify, forcing the freezing level up to 10,000 feet by Wednesday night and over 11,000 by Friday. This west coast ridge is likely to become stationary for sometime. Possibly 2 weeks according to the Euro Model/(Mid Month). I suspect that the week 2 models or during the 2nd week of December, will have better visibility about a change in the pattern for the future.  For the Dweebs…..An important indicator that will give an even longer look down the road will be the RIMM Phase Space, showing where the locations of potential tropical forcing will be. The strength of the signal and speed will be important as well. The speed of the signal can give an indication of what it is.  IE, an MJO, Rossby Waves or Kelvin Waves. A “strong” MJO moving through the Indian Ocean in phase spaces 2 and 3 would  break down the +PNA and help bring retrogression to the pattern that is currently developing for the west coast and eastern US.   At the moment, the RMM chart this morning using the NCEP. (American Models) ,show more amplification within Phase 7 for week 2. This just intensifies the +PNA the following week, so this pattern setting up this week looks bullet proof for at least a week or two.

The good news is that Mammoth Mt received up to 6 feet of snow about a week ago and they are making snow nightly…….:-)  Skiing and boarding is reported to be very good!

 

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

Some light snow is possible this weekend….Then big blocking pattern developing with west coast ridge….There is light at the far end of the tunnel…I just hope it’s no Mirage

Friday AM Update:

Just has a peak at both the 00Z Friday EC and 06Z GFS:

Some interesting deterministic run possibilities….

Both Models continue the trend of the Blocking pattern with ridge in the west. And continuing their trend of the possibility of a bit more moisture for the weekend (Sunday) system for Mono County. I think that I covered it well in the late Thursday afternoon update below.

A new twist though showing up from last night 06z GFS run with some hang back energy underneath the building ridge early next week from the Sunday system. The GFS has this weak low left over or near Southern CA that may just provide an off shore flow and a warm up for LA. However, the ECMWF has a bit more energy that follows the Sunday system early next week that spins up a small closed low on its drack south then off the coast of Paso Robles, CA. That would dampens LA’s warm up and actually put Mammoth in the upper Divergent NE quad of that system, providing some light snow or snow showers anytime between late Monday afternoon and Tuesday night. The system does track south off the SO-Cal coast and so the off shore flow is probably just delayed in this case.  An important point to make is that this all happens as the upstream building ridge that will eventually take over the west coast, later Wednesday into Thursday.

Some New Twists to the longer range:

Earlier in the week I mentioned that the ridge that will be building next week will be top-heavy. This means that a lot more high pressure aloft (Anomalous higher heights) will develop over the higher Latts, and eventually over AK.  +(PNA) & (-EPO). That in its-self reinforces the pattern that has the potential to deliver very cold weather to the Ohio Valley and south to the Gulf States in the 6 to 10 day period. The EPS, AO has that teleconnection dropping to -3.5 standard deviations of normal, meaning that this Block has legs and will likely hold through the 10 or 12th of Dec. However, both EC and GFS are showing some changes there after as the AO goes to 0 (neutral) by the 18th. The WPO area (Bering Sea) has increasing heights at 500MB between the 14th and 18th of Dec. This is signaling a change with the possibility of retrogression of the upper west coast block allowing CPK air (continental polar) air mass to back up over the far west. (Cold)  More later…….

 

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I Just looked at the last few runs of the GFS and EC (American models) and Euro for the weekend. The Trof that is forecasted to come through this weekend is holding on to a WSW flow better in the GFS as compared to the ECMWF.  This is being reflected in the Models QPF.  The EC just brings us a dusting while the GFS suggests possibly 4 to 5 inches of snow over the crest, out of .3 to .4 inches of water.  The 18z GFS is showing higher QPF amounts as compared to its previous runs.  What ever we do get, the ratios of snow to water is going to be pretty high. Possibly 13 to 1.  So some light powder to begin the new week. This will be a windy system for the upper elevations and breezy for the resort levels. It will also be a cold system with temps at 700MB (10K) lowering to -8c to -10C on Sunday. Not all that unusual for early December.

Long Range:

I have beaten this dead horse enough so I will leave it alone for a while and concentrate on the Inter-seasonal outlook.

Today the ECMWF EPS 46 day weekly’s has updated. All I will say for now is that its long-range teleconnections are encouraging!

Here is a brief summery of what I have found out.

  1. The Current negative phase of the Arctic Oscillation turns Positive after the 18th of December and trends more than 4 standard deviation’s above normal by January 7th. So Lower pressure develops over the Arctic which can lead to a more progressive flow across the CONUS. (US) At the moment we are headed toward a very blocky pattern across the CONUS next week with a -AO. This is usually dry for California in a La Nina.
  2. In the same time frame, “Early January to mid Jan, the EP turns very negative, meaning a strong block over Alaska. A strong block over AK with a -AO is dry for California. However, a +AO with a -EPO could be wet for the West coast. The PNA which is positive now will trend negative between Christmas and New years,  while the WPO become negative IE (Blocking over the Bering Sea), toward the end of the year. This suggests Trofing along the west coast toward year end, and a block over the Bering Sea could be a wet west coast pattern. These teleconnection patterns work together and offer various solutions.  My sense is that we will begin to turn stormy around Christmas with several  period’s of snowfall up to about mid of January.  I am just using teleconnections, but that is all I have to work with at this time.

Dr Howard and the Dweebs………………….:-)