Storm Total 6 to 9 inches……Upper jet to pull through this weekend with mainly dry weather expected…..MJO moving into Circle of Death….

Saturday 11/21/2020

Series of Northwest sliders will bring periods of breeze, cooling and maybe a few flurries or showers. 1st slider moves through Monday the 23rd, another Thanksgiving and the last in the series on the 30th. That one on the 30th may pinch off a closed low and give us some snow showers. Will update on that later next week to see if there is anything to it.  With Tropical forcing weak, (OLR) and moving east toward the western pacific, we are likely to ridge up and warm up during the first week of December. Next productive major change in the pattern will be in Mid December, as long range teleconnections show once again, the possibility of a (-PNA) teleconnection pattern setting up. Hope it makes it this time.  For whatever it is worth, the long range GFS Super Ensembles show the potential for some cold stormy weather the week before Christmas and the ECMWF Ext. Ensemble shows a stormy period from the middle of December all the way through months end and beyond a few days into the New Year….

 

Think Snow, Stay Healthy….

Dr Howard and the Dweebs……………………..:-)

 

 

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Stardate Nov 20, 2020:

Remnants for last weekends pattern are shifting east now with a weak branch of the westerlies bringing moderate winds over the Crest and light breezes in town. Temperatures began to invert again this morning with colder temps over the lowest elevations of town as compared to the upper elevations. Currently high clouds are streaming through with this weak upper jet branch. A short wave ridge moves in this weekend and will bring clearing skies and colder temperatures to the valleys along with stronger temperatures inversions.  Daytime highs will bump up a bit for Mammoth Saturday and Sunday with high temps pushing into the low 50s. Nights will be in the teens over the lowest elevations of town and high single digits over the colder valleys. However, up into the twenties in the upper elevations of town.  Nighttime snowmaking will be good as our airmass will be dry with NE flow.

The current pattern as it pertains to the East Asian Jet is very unimpressive. The upper jet resides over the Pacific Northwest keeping the windward Olympics wet with decent shadowing for Seattle and precipitation expected south through Oregon with lighter amounts south to Highway 80. Mother Natures definitely has her foot off the gas peddle over the central eastern pacific..

Looking at this mornings ensembles of both the ECMWF and GFS, there members favor the upper jet continuing to the north of us as it approach the Pacific NW coast then drops south as a NW slider into the Northern Great Basin. Over time, the long wave trof shifts east of the Mississippi. This is a dry pattern for the Central and Southern Sierra. However, on the optimistic side, there are a few members of the ECMWF that split off some short wave energy around Thanksgiving and again the very end of the month.  The CFS continues to hang on to the notion of a period of wetness between the 26 and Dec 2nd.  As mentioned yesterday, the vast number of ensembles do not favor any significant storminess through months end or for that matter,  the next two weeks.   However, if one wants to know what the outliner members show, the following was indicated in last nights 00z ECMWF;  It had two splitting systems that spin up closed lows, which one affected mainly Central and the Southern half of CA and the Desert SW.  The first brought colder weather to the Sierra along with light snowfall thanksgiving day then a stronger system that brought moderate snowfall mainly to the Sierra Crest westward. This was indicated in the Monday Night the 30th through Dec 1st. Again, there are just few of these ensemble members and is not reflected in any outlook.  The only glimmer of hope is that the Climate Forecast System (CFS) is still hanging on to the notion of a wet Northern and Central CA between the 26th and the 2nd this morning.  It will be interesting to see if they drop that notion over the next few days.

 

I’ll let you all know!

 

The Dweeber………………:-)

 

 

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Breezy weather continued this morning with windy conditions over the highest elevations w/gusts to 60mph. The Trof that brought us the snowfall Wednesday has sheared east and what’s left is a weaker trof that will gradually move through over the weekend. Looking down the road, there are several short waves that will be impacting regions to our north. The Pacific NW will benifit from these small to medium sized systems south at times to Northern California. Early next week (Monday) there is system that may bring some snow showers and gusty winds to Mammoth.  Temperatures will be fairly seasonal now with breezy periods going through next week. Expect highs in the 40s with lows in the teens this weekend. Travel weather does not look to be impacted at this time.  Great snowmaking weather will continue with cold nights.

Now getting to the point of the longer range and tropical forcing;

The Dweebs have been watching what has been going on over the Indian Ocean with the MJO.  More and More of the Ensembles Members of both the ECMWF and GFS has trended the MJO into the “Circle of Death”. The MJO peaked around 60E to 70E Monday and Tuesday and is now weakening rapidly. Thus the Climate Forecast System was wrong in its forecast of the MJO Remaining strong enough, long enough to flip the PNA to the extent that it would create both a deeper and stronger negative phase PNA pattern over the far west; “this cycle”. This means that it is very unlikely now but not impossible, that a good storm will occur this far south into California through early December. There are a couple of short waves the end of the month that may bring some light snowfall, however, a major storm capable of dumping several feet in Mammoth is not in the cards anytime in the next one to possibly two weeks. The La Nina Base State is very strong and maybe acting as a barrier with its quite cold water, destructively interfering to the MJOS convective envelope. LA NIna continues to strengthen as evidenced by the very strong trades blowing east to west.

So where to we go from here?

For the record, the Climate Forecast System this morning , (CFS) still hangs on to the idea of a stormy period for Central and Northern CA, northward in its forecast this morning for the 26th through the 2nd of December.  So it is still possible we may have a decient system the end of the month according to the CFS.  Its just that the MJO is decaying so rapidly that even most global ensembles models with the outliner of the GFS Super Ensemble, keeps everything to our north. So there maybe something else going on teleconnection wise, that it is seeing, However, with that said, the odds do not support a good storm from The Dweebs vantage point for the end of the month at this time……… If that were to change….we’ll let you know.

 

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

 

 

 

 

Breezy Today…Windy tonight! …..Light snowfall expected in town with low end moderate amounts over the crest Wednesday….

Lots of wind today but so far, not nearly as much as we had last Saturday…..  The main upper jet comes in tonight just to the north of us. So winds should get stronger tonight and really Howell by Midnight!.  Again the Main theme here is that the upper jet is still to our north with its axis to our north as well.  Snowfall amounts drop off quickly once south of Tioga Pass and even further by the time you get south of a latitude east of Huntington Lake. The latest QPF brings 1 to 4 inches of wet snow in town by the end of the day Wednesday and between 5 and 10 inches over the crest.  Let hope Mammoth Mt can squeeze a foot out of it…..That’s pushing it but Its possible……

The Trof over the Eastern Pacific will slowly progress eastward this week and be out of here altogether by this weekend.  However, there are a couple of waves in the flow. One Friday mid morning and the other on Sunday.  These will keep our airmass mixed out.  I am expecting partly cloudy weather and breezy at times this weekend into early next week.  As mentioned in my last discussion, I believe that the MJO, now over the Indian Ocean will modulate the westerlies leading to a good storm between Thanksgiving and months end. Both ECMWF and GFS show a fairly good storm for the Northern and Central Sierra the end of the month.  In the meantime, high temps will cool to the upper 30s by Saturday and lows will be in the single digits and teens…..Great snowmaking weather!!

 

COVID’s on the rise.

Be smart…..Be Safer, Wear a mask and cover that nose!!

 

Dr Howard and the Dweebs……………….:-)

Drier Medium Range…..Recap of weather past week…..New Indian Ocean MJO Event Possible in our future…..

Lucky Friday the 13th….  Mammoth Mt opens for the season….   See:   http://www.mammothmountain.com

I Just finished looking at this mornings guidence and the many weather sites around.  Lots of discuessions!   Lots of pretty maps!   What do thay all mean?  Then I remembered what an old friend of mine that used to work for the National Weather Service in Reno once said decades ago, when I enthusiastically called him on a midnight shift at 1:00AM in the morning.  It still rings home to me. Doug said,  Howard….   “Guidence is not a Forecast!” I never forgot those words!

DId have a peak at the new 12Z Euro Ensemble.  5 and 7 day means….No surprises. Mammoth flurts with 573 to 570 mean heights at 500MB.  That’s fairly high snowlevels and well south of the polar jet. So…mainly light amounts of precip here,  more orographic in nature than forced.  Tahoe will fair better to our north, but it will be pretty wet snow at 7K.   As in my discuessions below, the dynamic models are showing quite the blow up in the Convection with MJO over the Indian Ocean. The Hovemuller time series for the MJO, shows, the outgoing long wave radiation from convection forecasted to be very strong, as projected by the Climate Forecast System. The Dweebs are very encourged with this development. Timing after the 20th…..In the meantime, I am not expecting much.

 

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

 

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It was an amazing change we had in the weather last week.   We went from a Fall Scape to one of winter in a few days. The best part of the change was to put the kabash on the Creek fire so we could all breath a lot easier.

Snowfall:  The Dweebs Forecast of 10 to 15 inches worked out to the tee as Mammoth Mt reported 11 to 14 inches storm total. Its a good start, but of course we need a lot more snow!

To understand our Weather on a climate scale this year, we have to consider the base state of the Strong La Nina, now in process in tropics. The Latest CPC information put current sea surface anomalies over the NINO 3.4 region at -1.5C. This is regarded as a strong La Nina.  The ONI which is a lagging indicator was at -.9 for AUG, SEPT and OCT.   Projections show this La Nina possibly colder than -2C by Late Dec.   With a signal this strong, the stats favor a drier than normal winter for Central and Southern CA, vs the weak la Nina which can be wetter in many cases.   Nevertheless, we will have more storms this winter and the Dweebs will be reporting on their prospects, even on an interseasonal scale time frame

Getting back to the current La Nina Base state; it suggests that tropical convection will most likely remain far west of where it would normally be during a winter.  The colder waters just west of the date line eastward to the Central American coast will constructively interfere with the MJO this Winter, until it gets over the Indian Ocean!  Thus, it is very unlikely that Central or Southern CA will experience any MJO induced Pineapple Connections.

The Western pacific westward to the Maritime continent will have the most thunderstorms. Why is this important?  Because with persistent forcing in that region, that teleconnects to the positive phase of the Pacific North American circulation pattern, (-PNA; trof in the west) or (+PNA, Ridge in the west dictates either wetter or drier conditions out west. The -PNA teleconnection pattern is the one we want. And…. although it does not “Always” mean snow for Mammoth, more often than not it does in the winter.  Persistent tropical forcing in the Western Pacific and Maritime Continent usually is associated with the +PNA teleconnection. The PNA teleconnection is pretty neutral for now.

Current Forecasts:   The Short, (1 to 2 days; Medium 3 to 5 day and Long Range 6 to 10 day forecasts are not wet for Mammoth. There is some possibilities for light precipitation this Saturday with the chance of some 1 to 3 inches of snow over the crest.  Maybe just a skiff in town. This is a warm advection pattern whereby moist air is moving over the colder air currently in place, left over from last weekends storm. However of note, there is a strong NW jet punching into Northern CA tomorrow Friday. That is usually a windy pattern but a dry one at that.  The Medium Range guidance does show a rise in the freezing level this weekend so it will be warmer Sunday and Monday and with Ridging building in early next week, it will get warmer yet. Even through there are storms hitting the pacific northwest south to Northern California, they will not do much for the Mammoth area next week.  We need a change in pattern and change in the PNA teleconnection pattern that is negative in the PNA!! (PNA acronym for Pacific North American Circulation Pattern which is the most common teleconnection for the West.

 

Interseason Forecast:

Those that have been following the Dr Howard and the Dweebs page for years know that the Dweebs have stuck their necks out a long ways at times to forecast changes in patterns that can affect Mammoth Weather. There are times when the dynamic models show a signal that affects other signals that make it possible to perform outlooks some 3 to 4 weeks out in the future. This is one of those times when the Dweebs will do just that. However, it is just an outlook, and not a forecast yet and there is a difference.

MJO:   The Madden Julian Oscillation was pretty much wiped out as La Nina destructively interfered with it. Its convective envelope is still creating a favorable environment for tropical storms over the West Atlantic. The Prind point here is that the Dynamical model MJO index forecasts favors continued eastward propagation, with a potential of a “New Indian Ocean MJO event” materializing during Week-2. Should this occur, conditions would become increasingly favorable for Indian Ocean tropical cyclogenesis during the outlook period, and may promote renewed West Pacific activity beyond the two-week outlook period.  Indian Ocean MJO events also teleconnect well with a two-week lagged midlatitude pattern featuring troughing over Western North America and ridging over Eastern North America, which is consistent with model guidance for the Week 3-4 period with the Climate Forecast System. A flip in the PNA to negative is possible during the latter part of Week 2. This means that it is possible that a stormy pattern with enhanced snowfall potential will develop during the last 10 days of November into the first week of December…..

 

Stay Tuned to the Dweebs…..They will update on this next Wednesday!

 

Dr Howard and the Dweebs………………………:-)