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………………………:-)

Positive Phase Indian Ocean Dipole weakening now…..Positive Phase AO keeping Arctic Air Bottled up but not for much longer!!!! Retrogression of the Eastern Pacific High to begin Mid Month……

It’s a great time to be an Amateur Weatherman. All sorts of fun tools available. I have some great friends, now retired that have taught me much over the years……

Today I thought I would include a bit more in my discussion as there is a lot going on over the Hemisphere. Earlier in the Fall I discussed in several posts in regards to the IOD. “Indian Ocean Dipole”. The Indian Ocean is a long way from California. It begins near the Maritime Continent, North of Australia and stretches west to Africa. As climate is what you expect and weather is what you get; the climate can change greatly when great wind systems blow in the opposite direction. In this case, the IOD in its positive phase (Winds blowing east to west} has blown a tremendous amount of warm water from the Maritime Continent to the Arabian Sea.  So with the warmer water being displaced westward, from an area like the Maritime Continent, which is possibly the warmest Ocean Water on a large scale anywhere in the world, that resulted in much cooler water in that area.   The combination of the cooler waters, less convection along with a lot more upper convergence, (Air forced to converge to itself above 18,000 feet, over areas like Australia as well the Maritime has caused a short period climatic variation that forces sinking air over areas like Australia.  Hence the record setting fires that are currently raging in areas of Australia. Even though the IOD is quickly weakening now, there is a new tropical storm over the Arabian sea, that will possibly reinforce that system, keeping the weather hot windy and dry in those same areas of AU for a while longer.   Th good news is that the system of the +IOD appears to be breaking down and so I hope it will not be too long before some beneficial rains return to that area.

 

What does the IOD mean for California? I have done a little research on this, and have found a weak correlation of a colder and somewhat drier far west. This is from the readings of CPC researchers and their discussions. With the IOD weakening, Australia will get relief and the weather over the CONUS with begin to change.  For one, the MJO will have more of an influence in the weeks to come I believe. (Sorry to be so esoteric)  The MJO has been masked quit a bit due to the strong low frequency state of the +IOD, Easterly moving Rossby waves and Kelvin waves. Look for the MJO to have an increasingly affect on our weather and WX over the Hemisphere, by Mid Winter.

 

Speaking of the MJO, it is punching into Phase 4 and 5 strongly over the next 1 to 2 weeks. I do not see much influence over our part of the CONUS with Phase 4, however, phase 5 has a very cold signal for the Far West.  That is week 2 beginning the following weekend and that following week. If by chance that Arctic Air gets off shore, than we are off to the races for lots of snow. We’ll see….

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What happened to our warmer than normal winter?

All the forecasts called for warmer than normal from a climatic point of view. That has not panned out.  Obliviously, the forecasters did not plug in the +IOD!!!!  Well its weakening now so there is still time for that later this winter I guess.  😉

 

Short and Medium Range forecast.

The current pattern of upper ridging into California will continue today with high temps in the Mid 40s in Mammoth through Saturday. There is a wave in the westerlies that will come through Saturday AM. It will bring gusty winds, that will be stronger over the crest tonight and Saturday. The upper Jet Axis is well north of Mammoth just south of the OR/CA border…..So it will be dry. Another short wave will come through Sunday AM, winds will continue into Sunday. The Sunday Wave has a bit more WNW angle and thus in the rear of that wave, there are slightly lower thickness values. (This means it will get cooler Sunday.) The main point is that it will begin to cool down Sunday. Monday, seems to be a pretty nice day as a short wave ridge translates through California. Highs will be near 40 in town. There after, another weather system will dig a bit more in from the NW Tuesday night, (NW Slider) and bring cooler temps with some clouds and possibly some showers. It does not look like a major storm but it will be followed by some pretty chilly air Wednesday. The tempo begins to pick up the next weekend as far as a much colder and stormy weather pattern. This occurs as the long wave deepens over the Great Basin and just begins to retrograde, according to the ECMWF days 7 means. In fact the inference is a significant arctic outbreak over the Pacific Northwest coast during the weekend of the 11th. PS the EURO is a bit slower) Looks like Seattle my get some snow the weekend of the 11th.  The westerlies in this storm is cyclonicly curved; they will dig south down the coast all the way to Mexico. This storm will being some nice Platinum Powder to the high country. With ratios 15:1 possible. I will sound the platinum powder alert later next week. Otherwise it will be a cold storm with a good soaking for the entire state.

I am seeing continued retrogression in the long wave for that following week  13th -18th. If that verifies, as it is a long ways out, expect the storm gates of the pacific to open for the first time this season…..

 

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

 

Happy New Year from the Dweebs!!!….End of Year Forecast and Long Range Ahead!!……………………………

Short Term,

Most the of the short term is about wind and milder temperatures….

The Dweebs believe that the Arctic Oscillation in its positive phase will tend to keep most Arctic Air bottled up well to our north. As a result, our wet storms of late November and cold storms of mid to late December will take a back seat until high latitude blocking in the right places sets up.

The short term forecast for the next few days, shows diminishing winds today following by a NW jet diving into the Great Basin New Years Day Wednesday. So today is a good break between the winds and the up-slope cloudiness of Monday with a Sunny Warmer day  and diminishing winds.  Highs today will be in the 40s in town and 30s on the mountain.   Get up there today and carve it up!

A Great Basin Slider will crank the winds up on Mammoth Mt for a few days, beginning on New Years Day into Thursday.  NW winds over the upper elevation will crank up into the 70-80 MPH range over the crest by the afternoon Wednesday with lower elevations in the 40 mph range. Temps will be in the 30s and 40s.  Friday AM looks to be a windless morning…

For the Weekend Outlook, Expect Light Winds Friday AM with Winds strong enough Friday night for some silky wind pack Saturday AM. Winds Saturday and Sunday will be moderate over the upper elevations.  Sunday’s breezes could be lighter than Saturday.   At the moment, the weather system for the weekend does not look to bring any significant chances of precipitation to the high country. It will be cooler over the weekend.   As we begin the new week,  expect lighter winds Monday into Tuesday with Blue Bird Conditions.

Some increase in wind is expected toward the 9th……

Long Range:

As we approach the middle of the month, the GFS Ensemble Mean shows the long wave Trof over the Western Mid-West trending to retrograde westward again. So between the 10th and the 15th the weather will be turning colder again and more unsettled with colder storms.

Its been a long time since the Pacific has opened up with long fetch storms that are wet in nature. The Euro, both in its weeklies and ensembles are showing a period between the 20th and 30th of January with a strong -EPO teleconnection early in that period that ends up with a strong  -WPO toward the end of the month of January. This suggests strong high pressure blocking over the AK to the Bering Sea region by the end of that period with significant under-cutting of the westerlies into the west coast during that time period. That highly suggests the potential for a few AR episodes during that time period.

 

The Dweebs will keep a weary eye on the developments this January…..

 

Happy New Year to all…

I wish you all the very best for the beginning of the new roaring 20s!! 

This new year will mark 40 years of providing weather to the Eastern Sierra

Dr Howard and the Dweebs………………….