Let the Weather Patterns Begin!….Cold Storm 1st Mid Week then Wet and Wild over the weekend……General Quantitative Central Sierra precipitation forecasts of 25 to 30 inches of water EQ by January 13th……

Thursday AM Update:

Think we have had a big winter so far?  Think again…According to the DWP, as of January 4th yesterday, Mammoth Pass was only 101% of normal. However, that does not reflect much of the 7.85 inches that has fallen by 10:00AM Thursday….

 

  1. Mammoth Mt Reporting 3.5 feet to 7 feet of new snow storm total so far….Another 3 to 7 inches is possible today.
  2. At Mammoth WX .com 34 inches of snow has fallen.
  3. Mammoth Pass as of 8:45 AM Thursday, has a storm total of 7.84 inches
  4. Major flood event is forecasted for Yosemite Valley Sunday Afternoon
  5. AR event to begin as snow Saturday morning with snow changing to rain during the late afternoon or evening. Heavy rain is expected by Saturday night with the snow level at 9000 to 9500 feet into Sunday AM
  6. The Snow level will remain above 9000 feet until about mid afternoon Sunday. It begins to come down about 4:00PM Sunday then lower throughout the night and into Monday.

Here are the updated freezing levels for Yosemite from California Rivers Forecast Center (CNRFC)

  1. Sunday  4:00AM    10,000 feet
  2. Sunday 10:00AM     9700  feet
  3. Sunday   4:00PM      8900 feet
  4. Sunday 10:00PM      8600 feet  (Snow sticking at Canyon Lodge then Eastward to the Village at Mammoth over night)
  5. Monday  4:00AM     7900 feet   (Snow sticking in TOML)
  6. Monday 10:00AM    7300 feet   (Snow sticking on Highway 395

Note:   The snow level is 500 feet below the freezing level in a saturated air mass; These freezing level are provided by CRFC.

The Water EQ is still the same; about 10 to 12 inches over the Central Sierra through the weekend and between 6 and 7 inches in the Town of Mammoth. The good news this morning is that the very latest freezing level information from CRFC, for Yosemite, which I use as a guide for Mammoth Lakes is showing that colder air will be moving into our area sooner, like Sunday night into Monday AM.  For those that are interested, compare the freezing level info below in Tuesday afternoons update to what you see above. As you can see, by Monday 4:00AM, the freezing level is some 1200 feet lower!

Outlook:

AR = Atmospheric River  SEE:    https://www.esrl.noaa.gov/psd/atmrivers/

The latest “updated” QPF (Quantitative Precipitation Forecast) for the Central Sierra between 4:00AM today Thursday, through Friday night at 10:00PM the 13th of January is 30.00 inches of Water.

 

AR #2 arrives Saturday AM with a break Monday Night and Tuesday

AR #3 is a smaller AR and the Dweebs believe that Mono County will just get a lot of Snow above 6000 feet.

AR #4 arrives Thursday Afternoon the 12th. This too looks to be a colder storm with it winding down late Friday into Saturday the 14th.

I will have a special update on the longer range this weekend via my Weather Letter….

Dr Howard and the Dweebs………………….:-)

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Wednesday Jan 4th:

1st in a possible series of 3 AR events is unloading on the Mammoth Lakes 24 hour amounts 2.23 inches of water and 27 inches of new snowfall at Main Lodge. There is about 18 inches at the Village at Mammoth.

We are about 1/2 way through this storm…

2nd Atmospheric River will hit Saturday with the peak late Sunday AM. Snow level possibly going up as high as 9500 feet by 10:00AM Sunday. Snow level will come down late Sunday afternoon into Monday.

3rd Atmospheric River may occur next Wednesday through the following Thursday Night. This appears to be the last in the series…The wet pattern ends when the blocking over AK and the Bering Sea ends….which is about Friday the 13th of January…

Your lucky day….the Dweebs still see a total of 25 to 30 inches of Water over the Central Sierra from this storm cycle which began yesterday the 3rd and will likely end by Friday the 13th……

 

 

 

Tuesday 1:45 PM Update:

 

7 day QPF posted by WPC covering period through Tuesday night next week is 22.8 inches.  This does not cover the storm for Tuesday night through the following Friday,  which may be the last in the series….

There is chat about the rain on Sunday.  Here are the freezing levels just released by RFC

 

Here is the latest freezing levels for Yosemite for the subject time frame.

  1. 4:00PM Saturday      8800
  2. 10:00PM Saturday    9300
  3. 4:am Sunday            9500
  4. 10:00AM Sunday   10000
  5. 4:00PM Sunday       9600
  6. 10:00PM Sunday     9200
  7. 4:00AM Monday     8500

Note;  in a storm like this the snow level is usually 500 feet below the freezing level.  (saturated air mass)

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The first in a series of wet storms will hit the sierra beginning today with 36 hours snowfall forecasts in the 4 to 5 foot range for Mammoth Mt and 2 feet plus at the 8000 foot level for Mammoth Lakes. There is a small Atmospheric River taking place tomorrow Wednesday. The Cold Air currently in place will gradually get flushed out over the next 24 to 36 hours. The set up is cold troughing in the pacific NW coupling with a WSW mid latitude upper jet undercutting the GOAK Ridge. This is associated with Gulf of AK Blocking pattern #1. (-EPO); Pattern #2 will be associated with the same ridge that will retrograde (back up) to the Bering Sea. The teleconnection is called the (-WPO) This pattern is warmer and wetter because with the new location of the upper ridge, and energy coming over the top of the ridge will dig a new long wave Trof, both further west and deeper into the Eastern Pacific. It just so happens that there is a mid latitude subtropical low NNE of Hawaii that will be picked up Saturday and Sunday. This coupling of this action picks up the AR and pulls it onto CA Sunday. This AR is a large one and broad. It is a two-day event. It will have precipitation rates of 1 to 2 inches of QPF  every 6 hour period for over 24 hours.  Last nights WPC 7Day QPF  showed 25 inches over the Central Sierra near Mammoth. That does not cover the end of this storm cycle.

 

If you want to know if the end is in sight, you have to know when the block will be gone from the Bering Sea. It looks like it will weaken by the end of next week.  So if that is true, about the 15th or so should  be the end of this pattern. If the blocking persists with any significance, the pattern will continue wet until which time the block either falls apart or it retrogrades west over Siberia, Rus.

Although this WX Patten will be an inconvenience to many, it will be fabulous for the forest and the reservoirs through out the state. It will put a huge dent in our drought!    Watch for Alaskan blocking to most likely return in February as well…..

 

Dr Howard and the Dweebs………………….:-)

Major Storm Cycle Ahead as -EPO Rex Block Forces Strong Southerly Stream into Central West Coast….Copious AR Precipatation Event Probable for the Northern and Central Sierra….

UPDATE 10:45 AM Monday:

The QPF updates keep coming and the resounding questions becomes… will there be a break as several waves of energy are expected to pound Central CA this week.

The series QPF 24 hour bull’s-eyes moves slightly north and south of a pivot point from about Mammoth Pass this week as follows..

  1. Day 1   24 hour amounts  4:00PM Monday to 4:00PM Tuesday      =              .35 to .50
  2. Day 2   24 hour amounts  4.00PM Tuesday to 4:00PM Wednesday =                 4.11
  3. Day 3   24 hour amounts  4:00PM Wednesday to 4:pm Thursday    =                 2.50
  4. Day 4   24 hour amounts  4:00PM Thursday     to  4PM Saturday     =                 2.50
  5. Total day 5 MAX   About 9.5  inches at Mammoth Pass Before Snow levels rise to 9000 ft  This means that the town may get 3 to 4+ feet before AR event.
  6. Total 7 day Max 18 inches over Mammoth Pass

Note:  This has the potential to be one of the historically significant precip events for Central CA.  Considering all the fires the past 5 years, leaving burn scars in the forest.  Rock slides, mud flows, and road damage on the west side of the sierra are being considered….

On the bright side, most if not all reservoirs will be topped out by the end of this storm cycle.  Some Dams may be forced to spill….

PS  I looked at both todays 12Z Monday GFS and ECMWF total 10 day QPF. added them together and averaged them out. They paint about 30 inches of water over a 10 day period at MAX over the Sierra.

 

 

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Monday the 2nd 8:40am update shows that the 1st storm moving in Tuesday afternoon will continue through Thursday morning with snow showers Thursday afternoon into Friday. The storm will drop between 18 and 24 inches of snow in town and about 3 feet on Mammoth Mt.

The big AR event for the upcoming weekend will begin Saturday in town. However, preliminary guidance indicates that the freezing level goes up to 9300 feet Saturday night the 7th.   At this time….Odds are higher that the weekend storm will begin as snow, turn to rain in town Saturday night and into Sunday….then turn back to snow late Sunday night…..  The snow level may rise as high as 9500 by Sunday 12:00PM. This of course is all subject to change…..but confidence is pretty high that a major Atmospheric River Event will hit next weekend……7 day QPF is between 16 and 17 inches over the Sierra Crest near Mammoth Lakes by next Monday AM. The Dweebs expect this forecast may even be under done….  Stay tuned for updates….here and in my weather letter….

 

The Dweeber……………………:-)

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The Dweebs have been watching the global models and their handling of a weather pattern that has already happened before in early December and has been destined to repeat itself again now for January. It appears that the current Arctic front will stall itself out, mostly north of 40N and give way to a strong under cutting, subtropical jet which will eventually couple with the polar jet later this week.  The trend of ensembles are nothing less exciting than the event itself which may deliver some 5 to 8 feet of snow to the Town of Mammoth, (If it is all snow) and some 12 to 16 feet over the upper elevations of Mammoth MT over the next 7 days. We will have two Atmospheric River events, one light to moderate one mid week and the other AR event will hit Saturday into the following Monday. Folks…that one will really get your attention! So pineapple up and ever,

This is a developing pattern with the forecast ability of the details likely only within a 24 to 48 hour period before each surge….The Crescendo is likely over the upcoming weekend into the following week….

Get the shovels ready and the snow blowers fired up and working….We should have a wild 7 days ahead,  beginning soon….

 

More later……………..

 

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

Forecast Models Throwing inside slider…..Strike 3 for the Weatherman….Big changes ahead…

Its been interesting to watch the big mass of cold Arctic Air being handled by the forecast models.  It is important to realize that it takes a reservoir of cold air to tap from over Canada for the pool to from. Keeping in mind that for the far west coast, which normally does not get this kind of cold air mass, even every 5 to 10 years of this magnitude, the pattern has to be especially out of kilter.

This year up to today, New Years Eve, has experienced a lot of the pattern of the -EPO and -WPO. The negative phase of the Eastern Pacific Oscillation (-EPO) is one where you have a big blocking high pressure system in the Gulf of AK.  To get Arctic Air In January to plunge down the west coast, you need the Block to have strong legs as well!  This means that it needs to be pretty much a full latitude ridge, just west of 140W and positive tilt as well.  However, climo wise,  full latitude ridges in January are not that common in this area.  They are more common in December. The forecast has been one of tapping the polar vortex and pooling up some amazingly Cold Arctic air and plunging it south through at least Central CA.  Temperatures at 10,000 feet (700MB have been forecasted to flirt with -20C for the middle of the new week for Eastern CA and Western Nevada.. That would be highs in the Town of Mammoth in the low teens and nights below zero for a stretch of at least 4 to 5 days!  IE A real Pipe Buster!  However, this is no longer as likely to happen!

Changes Ahead!

There has been some real back peddling with the southward push of this frigid air mass of late, stalling it out over Northern CA and NW Nevada.  To add insult to the weatherman and injury to his ego, the air mass will shift east pre maturely. According to both last nights 00z GFS and ECMWF runs, and now this mornings 12z GFS and European, this happens by Tuesday.  An important point to make is that the 12Z deterministic run of the European is similar to the GFS, but is not as dynamically aggressive with the lead undercutting (Storm), that the GFS says will hit the sierra early Wednesday AM, the 4th of Jan.  Both models handle short wave energy and the height field differently between Wednesdays storm and the Sunday Storm. This is of concern to any fair weather forecasted between systems.  The Sunday (Jan 8th) storm into the following week is associated with a deepening (-WPO). This means that the block over the -EPO region will retrograde to the -WPO region or from the Aleutian chain,  into the Bering Sea.  The wave length suggests retrogression of the long wave Trof from 120 west to about 130 West, then positive tilt deep into the Subtropics. Thus a major “AR” event is possible about next Sunday into the following week.  All Global models show it including the GFS, ECMWF and the Canadian.

So what this all means, is that the odds are, that it will not get as cold, but expect more snow,  beginning as early as Tuesday night into at least Wednesday Night…..

Another model run or two with a consistent  GFS and or European model run will give the National Weather Service the confidence to either go to a winter storm watch for either Tuesday night or Wednesday or a snow advisory.  The Wetter GFS models is suggesting a few feet from the Wednesday Storm.   The Sunday through Wednesday storm for the following week is currently showing up as a monster!   ……  The powder for the Wednesday system looks cold and dry but the platinum powder criteria is becoming less likely….

 

Dr Howard and the Dweebs…

 

I’ll have an update written tonight for your New Years Day Weather Letter…..

 

The Dweeber…………………..:-)