Archive for year 2020

High clouds continue to flood into Central California creating more grey days……Forecast Models have now backed off favorable tropical forcing for CA……next significant system the end of this week…..

January 21st Update:

No real changes today with the wave coming through tonight and again Sunday.  I had a look the 500mb Vort field for the 26th.  The consensus is that the short wave is going to split over Central CA, including the vorticity field Sunday. This makes for a challenging outlook precip wise, for Mammoth. The Dweebs will update in a few days.   Needless to say, Tahoe will do much better with this storm than Mammoth. The following week shows the upper jet pushing further north, and so it looks mild and dry.

Next Storm Possibility around the 4th of February….

 

The Dweeber……………………:-)

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The MJO has done an about face this morning in backing off on a significant -EPO and -WPO teleconnection for the end of the week. All models now rapidly weaken the MJO in phase 7.   This means the the upper jet will remain to our north this week. That Is not to say that there will not be some very light snowfall.

Outside of the high level tropical moisture covering Central California on and off this week, there will be two waves of low pressure that will come through. One Tuesday and the other the end of this week.  At the moment, the jet stream remains to our north on these systems. The Tuesday storm shows only .10 inches of moisture giving possibly up to an inch of snow over the crest for Mammoth Mt Tuesday night.  Next weekend could bring light to possibly moderate snow fall to Mammoth Mt, Saturday night through Sunday night.  The Dweebs will just have to keep an eye on the upper jet..

Temperatures this week look to be in the upper 30s to mid 40s in town, with lows in the 20s. Winds will be on the lighter side in town with moderate winds Tuesday over the crest to 55 mph. Winds will be light to moderate on Mammoth Mtn this week until next weekend when they will pickup substantially.

At this time no major storms are expected for Mammoth Lakes…this week…

However, in some of the models…the upper jet gets closer to our area briefly….Saturday night and Sunday this week….that would have the best chance of moderate snowfall…..maybe….

 

Dr Howard and the Dweebs………..

Moderate storm dumps 7 to 10 inches on Mammoth Mt….Next weather system warmer for Tuesday, with track mostly to the north….Still tracking the MJO

1-18-2020) 3:00PM

FLASH!!    

New 6 to 10 day CPC outlook shows -EPO!!

Westerlies undercutting the Western AK Block.

This is the First Model Alert of a Possible wet pattern developing for the central west coast in the 6 to 10 day outlook!!  (Possible AR)

 

More Later…..

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Our strong short wave Trof did not waste anytime moving through last night. Although snowfall amounts were still in the moderate range; low end…. 7 to 10 inches, I was expecting more based upon the guidance.  Today is a beautiful day.  Fresh powder on Mammoth Mt with decreasing winds…  Highs in the low 30s in town… Lots of high clouds…

 

WX Pattern;

Latest Satellite imagery shows quite the storm to the Northwest. The pacific has indeed opened up. This wave will hit the Pacific NW and BC coast Saturday with a lot of rain and wind. Central CA will be spared. However, there is a wave north of Hawaii this morning that is drawing in subtropical moisture. The flow down stream over CA will provide for considerable high cloudiness on and off through the weekend. The next wave related to the polar Jet will track further south next week and tap more of this moisture.  So far the guidance shows most of the precip going well to our north Tuesday. Light amounts expected over the upper elevations…. Thursday through the following Sunday looks dry for now….

 

MJO:

 

OK Here I go again with the MJO….

The CFS and JMAN are outliers of all the other models. The CPC thinks that there is a false signal because of the decaying +IOD, bias toward phase 3 and 4.  They feel that there is a chance of the MJO getting into Phase 8. See RMM  below.

Why is this important?   First of all, none of the other models show the MJO into phase 8. So none of the Models show the amplification that would result in a blocking high over AK that phase 7/8 often creates.

As indicated by the CPC….”It should be noted that this MJO event could lead to a regime change for North America, specifically the contiguous U.S.   Phase 7/8 events tend to favor below average temperatures over the eastern U.S” also Possible AR events on the west coast.

Here is the key….watch the EPO and WPO teleconnections.  If they go negative,  the Westerlies will be shunted to the south.

 

Dr Howard and the a Dweebs…….

 

 

 

 

Another Cold NW Slider on the way for late tonight with strong winds into Tuesday AM….A winter storm expected for Thursday then dry over the weekend……..

5:00PM Update 1-14-2020

The  CPC  report was very encouraging for the MJO moving into phase 7/8.  I keep blogging about this because this is the area associated with blocking over Alaska. This is critical for the shunting of the EAJ into the west coast. (AR) If this does not happen it may be dry for quite awhile after the upcoming Thursday winter storm. Speaking of that storm, it is now tapping subtropical moisture, so will most likely have to bump up the QPF (Snowfall) tomorrow on Mammoth Mt  for Thursday.

I will post part of the discussion below and highlight where it is significant to phase 8. This is still as wishful thinking but keeping good thoughts….

 

From CPC;

The MJO signal has seen a significant uptick in activity on the RMM index, close to 3 standard deviations above normal, over the past week. It moved out of the unit circle into Phase 4, quickly strengthening and traversing into Phase 5. With the decay of the +IOD, the convective signal of the MJO is clear in the OLR field over the Maritime Continent. This strong MJO is likely to be the dominant forcing in the tropics over the next few weeks, with impacts emanating outward to the mid-latitudes. Dynamical models forecast a maintained high amplitude event propagating eastward a fairly fast phase speed through all of week-1 (phases 5/6/7) and part of week-2 (phases 7/8). Models do indicate a drop in the strength of the signal as it moves toward the Western Hemisphere toward the middle of week-2. With the impact of the anomalously strong +IOD over the past few months dissipating, the RMM index may be biasing toward Phase 3/4, thus impacting the eastward propagation in RMM space.

 

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Tuesday 9 AM

Conditions are windy as forecasted this morning with gusts over 40 mph in Town and 60 + across highway 395. Gusts over 80mph over the crest. A few hundreds has fallen of precip.

 

Winds should begin to weaken a bit this afternoon but still remain moderate. Higs today in the low 30s.

 

This update is primarily to discuss the Winter Storm for Thursday. As mentioned in my post last week, I have had concerns about this storm for the eastern sierra since last week because the MJO was going to be in phase 6, (The Western Pacific ). This is not the best place for a west coast storm and lots of snow. The pattern is in retrogression and the best thing going for it is the cold upper long wave trof over the great basin that is moving west wards, so that the next short wave will have over water trajectory. This is the wave that will come through Thursday night with snowfall preceding the wave Thursday afternoon.  I look at this as a storm with moderate intensity and snowfall with some 6 to 18 inches possible over all. The long wave trof will be too far off shore to fire another meaning full short wave into California. That wave is headed for the pacific NW and BC.

The long wave is still headed NW toward the Bearing Sea next week.  To get a general idea of the weather next week, the MJO in phase 6/7, usually means higher heights for our area. (Polar Jet to our north). However, The models are are hinting at some blocking in the EPO region and a more positive PNA teleconnection.  around the 25th and 26th. Looking at the the pattern next week, (500mb) GFS 12z today, there are a few AR channels backing to the tropical central pacific. Some approach the west coast. There is some weak blocking in the GOA later in the month according to the ECMWF.  So there is something going on worth watching for a possible AR for CA .  There will be a discussion today from the CPC today.

The key here I think will be how far and strong the MJO is/gets. the CFS still shows it into phase space 8 which is supportive of a CA AR later in the month.

CA needs an AR as it is becoming deficit in rainfall now.

More tomorrow……

 

Dr Howard and the Dweebs…..

 

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High Wind Warnings are hoisted beginning at 10 PM tonight into early Tuesday afternoon. A few snow showers are possible between 4:00am and 10:00am Tuesday.  It will be milder today and cooler Tuesday. Winds will be moderate on Mammoth Mt this afternoon.

Expect a high of 40 today in the Town of the Mammoth. Tomorrow back down to the mid 30s with lows in the teens. Moderate winds will continue Wednesday with the next weather system,  As per discussion below, the long wave retrogrades and gives Mammoth a 20 hour period of WSW from ahead of the Trof axis passage, Thursday evening at (03Z Friday)  The storm looks to be gone by Friday mid morning. Snowfall expected  18+ inches on Mammoth Mt. and about 12+ inches in town.

The weekend looks partly cloudy, breezy over the upper elevations but dry.

As per the last discussion, I was concerned about the MJO in phase 6 (DRY) and what it would do to our winter storm for this Thursday. Make no mistake about it, it is having an effect on our pattern. Retrogression is very evident in the 5 and 7 day means of both GFS and EC models. However, this time, it is simply retrograding the upper long wave Trof westward off shore so we will have one decent storm Thursday before it heads up into the Bering Sea to its demise next week. There is another storm approaching next Tuesday, but it will be fighting higher heights so that it may split. Well see…..

The tropical forcing is definitely causing a change to our pattern to one eventually of ridging over the far west.

Looking down the road, the MJO is forecasted by most models to move through phase 7 then into the circle of death. Dry for us…..

However, the CFS (climate forecast system and GEFS show it strong into Phase 8. Phase 7/8 is where typically we get strong amplification and an extended East Asian Jet to the west coast sorta like a pseudo El Nino for a week… That would mean the possibility of an AR type storm during week 2/3.   Most models to not agree with that scenario. The Dweebs will keep a eye on that and report here on the Dweeb Report later this week….

 

In the mean time, get ready for a more than welcome snow storm Thursday….!!!   :-)C