Series of NW sliders to Keep the Chill on in the High country with colder weather, windy Show Showery weather ahead…..The Pacific finally opens up for a good Storm Late Wednesday into Friday…….

 THE PACIFIC FINALLY OPENS UP!!

 

Its been pretty scary for a longer range forecaster to go out into the week two period with a meaningful storm that may deliver well over a foot of snow during the 2nd half of next week.  As touted in past discussion, the MJO is strong now in phase 5 and staying strong into phase 6. That means that it is moving into the Western Pacific. When it does, typically, we ridge up along the west coast in the winter. (dry) (teleconnection)

However, the long range global models, the GFS and ECMWF have been very consistent in developing large scale cyclonic flow over the far Eastern Pacific,  Wednesday night through Thursday. The Cyclonically Curved upper jet usually means business here in the Eastern Sierra with lots of moisture being generated over the area with cyclonic flow like one Big Gyre of Lake Effect over the far Eastern Pacific Ocean.  According to the 120hr GFS, the pryor short wave coming town the pike has a bit more over water trajectory too. (Monday Night/Tuesday)  so there may be a bonus of snowfall with the Monday night/Tuesday system, with still light amounts possible, but more than the dustings we have been getting the past few days. (Remember, the light category is 1 to 6 inches)  We may get most of that, with the Monday night, into Tuesday NW slider.

There is going to be a big pattern change, the next weekend. With the MJO into phase 6 and then 7, a subtropical jet may develop and head for the coast of California around the 20th/21st.  It would be associated with an AR.   However, the big question is, will it penetrate the west coast and add to our snow pack? Will there be positive vorticity action and some cooler air following the STJ.

If the MJO stays strong into phase 7 then 8, a blocking high may set up over AK (-EPO) then its time to Pineapple Up…

Not certain yet….just something to look for…..

 

Dr Howard and the Dweebs…………………:-)

Series of NW sliders to bring cold to the high country Wednesday into next week….Storms will arrive about every other day…..Gusty winds over the upper elevations…….Only light accumulations expected with each system……Will the MJO put the Kabash on our off shore storm later next week….

4:00PM Tuesday

Read the new CPC discussion this morning….They are still bullish on the storm the 2nd half of next week.  The CPC new 6 to 10 and 8 to 14 day outlooks are wet for the Central and Northern Sierra in today’s update. Obviously they like the GFS and are going with it. Still the ECMWF is not that all convenience to me yet….Today is only Tuesday.  To be certain, the ECMWF will eventually have to come in line, or the GFS in line worth the ECMWF.

The GFS shows a heavy snow pattern for the Sierra the 16th and 17th with a deep closed low off the coast of the Columbia River…..That would be snowfall measures in feet….

Also worth mentioning but unrelated to west coast precipitation, the strong positive IOD has broken down over the Indian Ocean.

Convection Exploded over the Maritime Continent supporting the full demise of the IOD!!  The folk’s in Australia should gradually see their weather return to more normal with the possibility of future rains, climatically permitting before too long…

 

More later…..

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Beginning tonight , the first in a series of storms will begin their track over California. We can expect much colder temperatures, strong gusty winds and mainly light amounts of snowfall with each system. Best estimate is snowfalls with each system bringing anywhere from a dusting to a few inches.  Again, light amounts in the high country here is between 1 and 6 inches. At this time, 6 inches is quite unlikely from any individual system but over time, accumulations may add up tO that amount or even a bit more.  These systems are quite cold and the snow to water ratio may be high with snow to water ratios higher then 10:1 to as high as 12:1 to possibly as high as 15:1.

Next week:

Here lies the problem and concern,

Yesterday both Global Forecast System (GFS) and the ECMWF, EURO were in somewhat agreement with a strong short wave carving out a nice cold low off the cost of the pacific northwest with SW flow into CA. If we believe the GFS, it set sup a strong heavy snow pattern for the Sierra.

However, there is a lot of caution here as the MJO, “The Madden Julian Oscillation” will be in strong phase 6 later next week This phase 6 location over the Pacific argues strongly against the solution of the GFS as the composites show somewhat below normal temperatures for Central and Northern CA. More importantly, the precipitation composite is quite dry for Central and Northern CA. In looking at the lagg composites at 200hpa height lagg composites, there is nothing definitive for the time frame during the second half of next week for any kind of a big ridge or any thing like that. However, again….The precip composites for central and northern CA are enough for the Dweebs to draw Caution to the week two forecast of the GFS.  Does the MJO always couple with the mid latitudes….NO!!

Updating more today…

 

The Dweeber…

 

Long Wave Trof to Deepen over the Great Basin this week and into the Weekend….Models are toying with the idea of retrogression week 2 to set up possible snow storm Friday the 18th….

Monday the 6th of Jan  3:45PM

Just looked at the ensembles of the GFS and EC.  Looking better for significant snow storm but pushed by to the 18th…

I still do not like that the MJO is not supporting this Pattern Change. Not sure why?

 

More Later.

 

SUNDAY PM 12-05-2020

 

Had a look at the new 12z runs of the GFS and ECM…  1st the operational models which can deviate quite a bit from the mean. However, if the change occurs close enough in time (72 Hours) You better take them seriously, especially if both are singing the same tune.  The GFS this morning is showing more retrogression the second half of week 2. Enough over water trajectory for a major storm. The ECMWF does show as much retrogression of the long wave, as its axis shifts from Utah to Eastern Nevada, not enough for an  AR or subtropical connection like the GFS does later week 2.  So what we have here is model agreement week 1 with a very cold Trof that deepens over the Great Basin with time this week. Some snow showers are possible anytime between Tuesday Night and Thursday AM. Colder weather yet next weekend as more modified Arctic Air pushes south, with light to possibly moderate snow fall Saturday into Sunday. Light (1 to 6 inches) Moderate (6 to 18 inches)

My sense today is upper end of the light, to possibly into low-moderate range. The main challenge is week 2. Looking at the MJO, it is strong and going into phases 4, which is wet for CA, then phases 5 and possibly 6.  The latter two are drier than normal for the state with phase 5 showing the best potential for eastern slopes up-slope snow with very cold temps.  Although there is not always coupling in the MJO teleconnection for the west coast, you have to use it and ERR this time to the drier ECMWF with its less retrogression. This is more like our past late fall and early winter WX pattern.  Note:  The Coldest Air arrives the end of this week into next week.

 

The Dweeber…….

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Latest GFS and ECMWF means are showing a pattern change….One of a deepening “cold” long wave Trof over the Great Basin, with its axis over Utah, according to the 7 day means. With this pattern comes much colder weather. There is definitely some modified arctic air that makes its way into our area over the next 6 to 10 days  However, with little over water trajectory, mainly light amounts of snowfall is expected through the middle of this week and most likely again next weekend, the 11th. For next weekend, there maybe slightly more over water influence, for a bit more snowfall next Saturday and Sunday 11-12th, but the fact remains that the long wave axis is still too far to the east next weekend for any big snows.  There appears to be a very strong short wave headed toward the west coast around the 15th or 16th the following week.. The Eastern Pacific high may retrograde enough to allow southwest flow to develop long enough for a good dump around that time. The Dweebs are still waiting for the Pacific to open up. It may take a bit longer though. With tonight’s modeling for the next 10 days, an AR is unlikely with this type of pattern. Only strong upper jet dynamics, squeezing what it can out of a fairly dry air mass..  Again, if one or more of these short waves is strong enough to carve back the long wave just a couple hundred miles, we could get quite a dump.   It would not be likely before the 15th….

On the positive side, if by chance, the Long Wave retrogrades westward, unlike the models are forecasting tonight, then that would change the Dweebs thinking for the Week 1-2 period.

 

 

This was your Saturday Night snap-shot

 

Dr Howard and the Dweebs………………………:-)