Archive for year 2014

An unsettled period is expected today through the weekend with light snowfall accumulations expected…..Snow levels will average above the Town of Mammoth……It looks quite Breezy to Windy Saturday/Night into Sunday AM…..

The Ridge Trof Pattern over the CONUS will continue through the Weekend with eastern pacific short waves (Areas of Rising Air) moving through the Mean ridge Position (Large N/S elongated area of sinking air) along the West Coast. In the meantime, the current Frigid Trof and cold air will flush east out over the northwest Atlantic and slightly open the wavelength of a slight weakening of the upper west coast ridge Thursday/Night. This will give us our best chance of precipitation which I think will be light at best. Possibly 3 to 6 inches over the crest. There are other systems that will be effected by this weakening upper ridge. So unsettled weather is expected through Sunday beginning as early as today. With that said, no major amounts of Snowfall are expected…best guess “About” 3 to 6 inches over the next 5 days.

Based upon the 21 day cycle…..Our hemispheric pattern goes into transition later next week. The big question is where is it going and if it will be a stable hemispheric pattern. ———–

For an understanding of the extended outlook, one has to look at the tropical Indian Ocean for organized areas of convection that are progressive.

During Warm ENSO years, the MJO becomes less coherent as it moves toward the Western and Central pacific as the Base State SSTA is generally Warm and so the MJO signal becomes more incoherent. With that said, there is usually plenty of definition over the Indian Ocean to the Maritime Continent.

The point here is that the Dweebs look toward the MJO for hints of a pattern change and what the pattern may be like.

Currently, The MJO is in the coherent base state wave I,  which favors the current ridge in the west and a trof in the east. If a strong progressive signal is identified and is forecasted to progress through the Indian Ocean IE Phase III, that would have major implications for the CONUS.  It would essentially flip the pattern to a warmer upper ridge over the SE and a West Coast Trof. and allow for an extension of the EAJ to the Central West Coast.

 

Here lies the Concern this Morning:

In reading the latest CPC discussion……It acknowledges that “A coherent Wave-1 upper level zonal wind anomaly structure exists” over the Western Hemisphere.  Furthermore, Some of the Models…IE the ECMWF, UKME and JMAN all show a signal that is fairly strong into Phase III which is what we want for lots of snow out west by the end of the month or 1st part of Dec during later week 2.  However, the American models namely the GFS (NCEP) shows it stalling on the border of Phases 2/3 and weakening. The key to all this is using and watching the Satellite pics over the Indian Ocean and looking for large concentrated amounts of Convection, (Lots of Thunderstorms)  and organized areas of Sinking air (Areas of clear) that develop or do not develop over the Indian Ocean. That as well as the lower level flow pattern coming across Africa. In reading the paragraph below, one can certainly put doubt to the validity of the strength and forecasted locations of the MJO currently forecasted by the 3 models aforementioned above.

 

Below is a transcript of the latest tropical discussion from NCEP on the developments over the Indian Ocean.

A more coherent MJO signal was evident during the previous week, with the RMM Index indicating that the enhanced phase propagated across the Western Hemisphere to the far western Indian Ocean. A coherent Wave-1 upper level zonal wind anomaly structure exists, with equatorial easterly (westerly) anomalies present across the central and eastern Pacific (South America through the Maritime Continent). The low-level wind field is less coherent over the Indian Ocean, and while the upper-level velocity potential pattern continues to exhibit a Wave-1 structure, the anomaly field has weakened during the past several days. Despite the fairly robust MJO signal indicated by the indices, “equatorial convection has been weak across the Indian Ocean”, with localized areas of enhanced convection displaced from the equator. Anomalous low-level equatorial easterly anomalies across Africa may be helping to inhibit widespread convection, in addition to destructive interference from the base state that favors suppressed (enhanced) convection across the Maritime Continent (western and central Pacific).

The Upshot of this paragraph states that there is little confidence yesterday of the Idea fostered by the 3 models mentioned earlier, trending the MJO strongly into Phase III.  For that matter, the long-range guidance The ECMWF EPS is connected to the MJO INDEX Forecasts as well. Meaning that if the MJO index forecasts do not validate, the long-range guidance is currently wrong as well.

The Forecasts for all that QPF will not likely materialize in November, partially because the data was garbage…..

The Eastern Half of the CONUS is in Trouble……

 

Stay Tuned>>>>>>>>>>>>>>>>>>>>

 

Dr Howard and the Dweebs………………….:-)

 

 

 

 

 

Series of weak systems to move through mean ridge position this week…..Cold Temps great news for snow making on Mammoth Mountain….Mammoth Mountain opening up new trails……

Record cold continues to grip the nations central and east with the highest snow cover for so early in November according to news agencies…  Dr Ryan Maue of Weather Bell says it’s the coldest across the country since 1976…some 38 years ago….

Looking at the analysis at 500MB, The Polar Vortex is located over the Great Lakes states with trajectories of Arctic chill moving south from Canada through the Northern Plains States early this morning.  On the back side of the PV the latest Jet max was over the Dakota’s while the next max will be more west through Montana later today. As long at Arctic air is in trenched over the central states, our upper ridge will remain strong along the west coast.

 

This mornings 06Z GFS run showed a few short waves, (WX Systems) coming though the upper west coast ridge.  Thursday a WNW short wave will bring the best chance a some light snowfall with 3 to 6 inches possible by Friday AM. Then Saturday, a NW slider will move through Northern CA with strong winds and showers. This NW slider is a particularly windy system with a 130 knot upper jet. However NW Sliders are usually dry bringing mostly snow showers if that. The best opportunity is from the Thursday/Thursday night system as the split is further north and the trajectory is more from the WNW. Again this is  not a major storm but it could bring 1 to 3 inches in town and 3 to 6 over the crest.

 

Getting back with the Saturday/Night system, it will be interesting to see how the new BETA GFS T1534 does with the system. This is the new updated higher Res GFS out in its Beta run for the time being. Looking at the comparison between the old GFS which is widely distributed and the new  High Res Model, it shows the upper NW Jet stronger over Northern California Saturday PM into Sunday AM. If by chance the NWS puts out a High Wind Warning for Saturday PM you’ll know that the new T1534 is a better model for our area…or at the least in this pattern at this distance in time. The official forecast is for breezy, not windy Saturday and Saturday night at the moment.

 

Pattern Goes into transition:

As touted two weeks ago by the Dweebs….The pattern will go into transition next week. That would mark the end of the 21 day cycle that started about the 5th of November. It is kind of like driving in your car with GPS and you take the wrong turn. Once you do, the GPA recalculates and gets you to your destination. Only this time it is a different destination…..So the question is….. where are we going and how to we get there?

1st, We have to get rid of the cold Arctic air in this country. It is part of the ridge-trough-ridge syndrome that keeps us drier then normal.

2nd, we need the eastern pacific ridge to retrograde or at the least, the high latitude block over AK/NWT to retrograde to Eastern Siberia….That change would shift the long wave trof eastward closer to the west coast.

3. We need an extension of the East Asian Upper Jet.  The MJO would help if it would become more robust and transit into Phase 2 then 3. I think that this is where we have to look for the future of our longer range outlook 30 days. On a bright note, the ECMF, UKM and JMAN are all in favor of a robust signal, into at least Phase 2 and some into Phase three.   If the Signal goes the gambit, expect a much milder CONUS with a wet west coast.  With that said, we are a long way from that happening….

Optimistically, if the MJO goes into Phase space 3, it is likely that we will have a flip in the ridge Trof pattern that is currently occurring. So that timing of that is about 10 days or so away.  IE We may have a couple of significant storms the end of the month into December.  The CFS is in agreement as well.

 

On a bright note, the AU Gov just updated there NINO Basin SSTAs. I am happy to say that the SSTA’s are now at the threshold of Moderate as follows:  Nino 4 (+1.05C), Nino 3.4 (+0.93C), Nino 3 (+0.96C), Nino 2 (+1.12C).  Remember, +1C or greater is what we want so we are close and if the Nino Basin can hold on to the heat, through January and February, Odds are good that we could have a nice wet winter. We also need that for at least 3 months.  I think that +.5C for 3 months seems like a good bet since we have had a good deal of time on that now.

 

 

The Dweeber…………………..:-)

 

 

 

Weak System Currently progressing through the West Coast Upper Ridge….Some light rainfall occuring this morning in the Town of Mammoth with about an inch of Snow over the upper elevations as expected…….A fair but Partly Cloudy Weekend is expected…..

Monday PM

 

Will update late this afternoon…..Time permitting..

 

Thursday Am Update:

 

New 12Z GFS has just finished running. The west coast ridge is a bit weaker on this mornings run.  The Short Waves (Storms)  for Tuesday/Wednesday and again early the following weekend are more progressive. This once again enhances the odds for snowfall in the high country next week.  Will have a look at the 12Z ECMWF as soon as it finishes about 12:00 PM today. The 12z GEM as well.

Stay Tuned……

———————————–>>>>

This Mornings extended guidance continued the trend showing an amplified upper flow pattern at 18000ft from the central pacific to the east coast of the CONUS. The models are predicting trofs to remain over the Bering Sea/Aleutians and East/Central North America.

The pattern continues to be very amplified including the more dominant west coast ridge in between. This morning Global Forecast Model’s (GFS) deterministic run continued the trend of “Some” short wave energy undercutting the west coast upper ridge next week. However, the trend is certainly weaker with the mid week short wave. IE the Tuesday/Wednesday storm)

Looking at the 2 week ECMWF 5 day means hemispheric guidance, the planetary wave pattern transits to a three wave from the current four wave pattern. The Blocking high over NWT/AK is expected to retrograde to Siberia, while the trof over the Bering Sea is expected to progress eastward into the Eastern Central Pacific. The upper flow pattern over the eastern pacific should become more active during week 2 with the upper jet aimed more toward Northern CA and Oregon. The Pacific NW is thus likely to get another bout of heavy precipitation week 2.  At the moment, 500MB 5 day means between the 22nd and the 27th of NOV for heights on the ECMWF 500mb Ensemble control are still about 570DM over Mammoth, which is border line for precipitation here in the central sierra, unless it taps a lot of subtropical moistures along the way. The Dweebs will follow the trend to see what changes there may be in the location of the upper jet the next couple of weeks.

In conclusion, fighting the west coast upper ridge….The models have been back peddling on the Tuesday/Wednesday system the past 2 days…. As it is not clear at this time on how it will hold together as it comes through the west coast ridge Tuesday night and Wednesday.  If I had to take a wild guess at this point I would say any ware from a couple of inches to as much as 8 inches depending on again….how it holds together, or if it splits and goes south into Southern CA.   With that said, the upper ridge will begin to weaken next week as the upper pattern goes into transition later in the week. If by chance the upper trof over the Bering sea decides to progress further east to say 130W to 140 west…..that would make a big difference in heights over the central west coast.

As a side note; even though a lot of the teleconnection’s and indices effecting what we might expect weather-wise across the US are different this year, the eastern pacific ridge is still the dominant feature effecting California’s weather and for that matter its ongoing drought.   So far, the expected enhanced upper jet has yet to show up related to the developing El Nino.  However, that is not unexpected, as it is still only mid November as the East Asian Upper Jet out over the Pacific is still quite incipient.

 

Dr Howard and the Dweebs……………………:-)