This Patterns Grand Finale is in sight with heavy snowfall predicted for lower slopes…..Mammoth Mts Night of Lights to be Fair and Cold with lots of Snow on the Ground….

As we head toward the Yule Season and looking back,  the weather events of the recent past seem to confirm the frustrations on how the state of the art WX modeling has a long way to go in handing complex patterns such as the one we are in at the moment. The flip-flopping of the global models in the medium range and the “at odds” of important parameters of the two most relayed upon models has never been more noticeable than over the past week.  All patterns come to an end and are replaced by new patterns. Then often times repeat them self’s later in the Winter. This pattern will too will come to pass, and before this upcoming weekend.

The change and what’s coming…..

The change in pattern that is being initiated is fundamentally a change from a stable 4 wave hemispheric pattern to a 5 wave, (progressive) pattern. It will break down the big high latitude block over the Bering Sea and weaken the (-WPO) and flip it positive. Over the next 10 days, the Polar Vortex will play a more dominant role over the Hemisphere setting up the key thermal anchor the Polar PV and cold over the Northern CONUS and East as we move into January.

For the time being there will be only two more AR events associated with the Kona Low this week.  One Tuesday into Wednesday and Thursday into Friday. The first event is focused most on Northern CA will only light precip for Mono County. The last in the series Thursday is key for snow pack over the lower slopes of Mammoth Mt.

The Grand Finale:

The Transition in the Hemi, from 4 to 5 wave will have the effect of sharpening the ridge over AK and driving and dislodging the Gulf of AK trough SE to the California west coast Thursday into Friday. As the block breaks down, the present Kona Low is being kicked out from North of Hawaii by another Kona Low that will redevelop later this week. As the old Kona Low ejects NE, it will open and combine with the digging “long wave” GOAK Trof southwest of California. The Long wave Trof approaching the west coast will build a short wave ridge ahead of it over the Desert SW slowing its progress. The Combination of the Front Left quad of the Sj jet, a wide PWAT fetch covering half of CA and the main Short Wave with Vort Max coming over the top of Mammoth Mt early Friday Morning will make for a Memorable Experience in Mammoth Lakes Thursday night with up to 30 inches of snow possible at the 8000 foot level. The Mountain may get 3 to 4 feet of powder.  Although this storm will not be cold enough for a Platinum Powder Alert, it will be plenty cold and the Powder will be very tasty Saturday AM!

 

The weekend outlook is cold with highs in the 20s. There may be some snow showers but any accumulation will be light!  Lows at night will be in the single digits so dress warmly for the Saturday Night of Lights fireworks show at Canyon Lodge.

 

Longer Range:

It looks quite cold between Christmas and New years with two inside slider type storms….

 

Stay tuned and dress warmly for the Holiday’s!

 

After Strongest AR Push into the Sierra Saturday with Rain Below 9K….Colder Storm Cycle setting up beginning this Tuesday and again next Friday into the following weekend…Several Feet of Snow top to bottom…

I have to say that this pattern and its evolution is certainly one of the most challenging in recent memory. The models have been gone a bit berserk with several solutions. I think that the up shot here is that we will have a moderate rain event Saturday with snow above 9000 to 9500 feet. Mammoth Mountain above 10K could pick up 2 to 3 feet by Early Sunday AM.  The next puzzle will be the Tuesday or Wednesday system  The EC is slower bringing it in Wednesday night with the GFS showing more of a Tuesday storm.  This should be all snow in the Towns of Mammoth and June with 12 to 18 inches in town and 18 to 30 inches on Mammoth Mtn.  Then we have the Thursday through Sunday curiosity….Oh My!  And it will be Snowfall!

I Will update the QPF in my weather letter Monday AM.

 

The Dweeber……………………….:-)

Active pattern returns to the Eastern Sierra with cold wave followed by Atmospheric River Event…

Just in at 11:L45 AM the new 12z ECMWF QPF has between 7 and 8 inches of precip for Mammoth Mtn and  west side over the next 10 days….

That could be 70 to 80 inches of snow!  Just in time for Christmas!

 

Dec 12th update:

Mammoth Mt reports 5 to 7 inches of new this morning with 4 to 5 inches in the Town of Mammoth.  Forecast model output suggests up to 3.00 inches of precipitation for Mammoth Mt by Sunday AM. So expect snowfall  amounts on the upper mountain to range from 2 to 3 feet.  The Snow level will rise through Friday night….  7500 today, 8500 tonight and to between 8500 to 9000 ft by Friday Afternoon.  The snow level may come down a bit by Saturday night.  Expect day time highs in town in the 40s and nights in the upper 20s and low to mid 30s.  Expect gusty winds in town increasing to between 15 and 35 MPH  with higher wind speeds on Mammoth Mt over the next few days.

The longer range looks very interesting as the closed upper Anti-cyclone, over near Alaska remains the big driver in this pattern. Meanwhile, the seasonal development of the PV “Polar Vortex” will be developing over Central Canada the next two weeks. A good chunk of the cold from this PV may get pulled westward between the 15th and the 20th causing the deepening of the GOAK trof and the suppression of the Polar jet into South-Central Ca while the AR continues.   I hope all you Mammothites’ are ready for some serious shoveling after mid month!

The new 12z GFS model Run shows the “PV” really taking hold in the east as the “AMO”  Atlantic multidecadel  oscillation supported by anomalous warm SSTA off the east coast sets up a block. This would have the effect of bringing extreme cold to the east and by the wave length, ridge us up in the west.   However, this year, that may not last all that long by the way the pacific is setting up! Additionally, the MJO does not support this blocking pattern either.

On another subject, we are rapidly heading toward the solar minimum which is expected to be the strongest minimum in several hundred years depending upon which solar scientist you believe in.  There is some relationship to stormier winters in California during Solar Minimums. It just may be that we are in for a stretch of wet winters in the years to come…

 

The Dweeber………………………:-)

 

 

 

 

A Sierra Breeze came up Sunday afternoon in Mammoth, an indication that (heights) “pressures aloft” were lowering. A beautiful northwest-southeast sierra wave cloud prevailed much of Sunday afternoon, indicating that the upper jet was to our north.

Technical discussion related to current events…

Many thousand miles away a flood of moisture is being drawn northward by a strong Kona low (a quasi-stationary upper low NW of Kawaii.  The pattern effecting Hawaii at the moment, can be attributed in part to the strong blocking Upper High over the Bering Sea which is also related to the warmer than normal SSTs in the Bering Sea this Fall. The Teleconnection name of this Block over or near the Bering Sea is the “negative phase of the WPO”, AKA, the Western Pacific Oscillation. Although SSTA’s in the Bering Sea are cooling, the block continues to redevelop in the foreseeable future.

Over the next several days, the PWAT Plume “Precipitable Water plume” affecting Hawaii, will find its way to “couple” with the westerlies later this week…helping to create a moderate Atmospheric River Event “AR” for Central and Northern CA. As a side note, this plume is rich with moisture with the ECMWF model showing isolated areas of 3 inches in the column affecting the big island tonight and Monday. There will be flooding in several areas of the big island of Hawaii late Sunday night and Monday.

Short term forecast and discussion;

A northwest slider will quickly spill some very cold air into the Great Basin as it move east southeast. This system is different than the last cold system in that it is not a true inside slider, its bias is more east than SSE. Additionally, it is not as cold as last week’s system. It is unlikely to dump the 5 to 6 inches like the last system.  Estimates? A trace to 3 inches most.

Expect mostly sunny skies Monday with gusty winds out of the West Southwest. Expect winds 15 to 30 at times. Highs Monday will be in the 40s cooling to the low to mid 30s Tuesday with overnight lows down into the teens Tuesday night/early Wednesday AM. Expect a chance of light snow showers Tuesday and Tuesday night. Wednesday will be Sunny with increasing clouds later in the day. Highs near 30 degrees.

Longer term:

It is what happens after the dump of cold air that is so interesting weather-wise later this week. That rich moisture laden river of air will begin to merge with the polar jet and really spin it up! Jet-O’ geneses is what it is called which will deepen a surface low to some pretty low values. All this will advance upon the cold air in place over California by this Thursday. Precipitation will come from the warm air riding over the existing cold air dome in place for warm advection snowfall Wednesday night through Thursday and possibly into Thursday night. However, as the cold air mixes out at the surface, it is possible that snow will change to rain in many areas late Thursday and Friday. The AR event may continue into the following weekend or it may not. Details are forth coming. Snow levels are very difficult to know at this this point in time other then they will start out low and move upward later in the week and then back down.  Precipitation amounts could be moderate to heavy. Time wise, we are still 3 to 5 days out.  The Dweebs will update later this week. Check out mammothweather.com for an interim update Tuesday.

Dr. Howard and the Dweebs………….:-)