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Fall 2017 to Winter of 2018: Observing, Tracking, Probabilities, Predictions, and Progress to Winter of 2018 | High Sierra Backpacker

Fall 2017 to Winter of 2018: Observing, Tracking, Probabilities, Predictions, and Progress to Winter of 2018

Alex Wierbinski's picture

By Alex Wierbinski - Posted on 13 September 2017



Tahoe to Whitney

Tracking the Winter of 2018


Bottom of page below
Original September 13, 2017 Article & Data



FALL of 2017
to the
Winter of 2018

This page is concerned with observing the General Trends & Overall Character of this season's transition through the Fall of 2017 to the Winter of 2018's Character & Conditions, rather than the specific weather at any particular time. 

These are whole new sets of regional weather patterns we are watching and experiencing the emergence of, right now, around us.

Each weather incident or "event" we observe is just one "dot," one data point in this year's series of weather events that we will connect-up, to finally determine the outline and character, the trajectory of this year's seasonal transitions.


See the High Sierra Weather Page for Current Conditions. 

See the High Sierra Hazard Status Page, too!




Last Report

December 21


Calendar Report of December 23

Weather Prediction Resources 

Climate Prediction Center
Next Two Weeks to Three Months Temp & Precip Probabilities


National Weather Service
Climate Prediction Center
Expert Assesments


Synoptic Discussion




Recap of Fall of 2017
Winter of 2018



The High Sierra Backpacker's Calendar


Calendar Report of December 23


Last Update
December 21

Cold Temps, Big Ridge & a disputed La Nina Influence

La Nina Observations

A Quiet Return?



December 20

WEAK FRONT the 19th

Weak front crossing the Sierra brought light snows late on the 19th and early on the 20th, followed by a plunge in temperatures as the front passed, the skies cleared, and the cold Northern air behind the front arrived, and chilled-down significantly in clear conditions.

Backpacker's Calender


Tahoe Region Wind Advisory Overnight the 20th,
following the high winds of the 19th.


Nonetheless, it's likely to be the coldest night of the year so far. topping last night's cold plunge, so I declare a COLD WEATHER WARNING.

Check the Backpacker's Calender for last night's low temps, current temps, and snowfall accumulation along the Sierra Crest after last night's weak storm.






We last saw precip when light snows fell across the Sierra Crest on December the second, marking the ninth incident of fronts crossing the Sierra since the Fall rains began early this year, on September 14.
That last precip we saw  on the 2nd was followed on the 3rd by the beginning of this tremendously powerful High building-in, which has subsequently grown to massive porportions and strength, and still spins around us here today, showing no signs of relenting.

Prior to the weak storm that came across the Sierra on the 2nd, we had a moderate-strength cold front cross the Sierra on November 26th. The next eight days from now are looking as dry as the last ten have been.

The foreseeable future holds nothing at all, no Lows nor any precip at all is expected to come anywhere near having the power to break through the Vast High dominating the West Coast of the USA, at least through the 20th.

This is a Vast High, a ridge of Titanic porportions, and has proved itself to be as self-recharging, as persistant in sustaining its own position, as much, if not more than it is being sustained by a seemingly relentless daisy-chain of powerful High Pressure Cells moving East across the Southern edge of the North Pacific.

Earlier this Fall we were looking at a set of factors to track, who's specific alignment would dictate the character of our Fall to Winter to Spring trajectory.

The Progression of Factors

OK, the Arctic is super warm.

The La Nina has deepened and spead to titanic porportions.

October La Nina, the 20th

October La Nina Analysis, the 5th

September Situational Analysis

What this "boils down to," is that In the North, the Arctic is warm, incapable of "spinning-down" to its formerly super-cold character, which would draw tropical moisture North along the coast of Asia, super-charge it by contact with the frigid spinning Arctic Vortex as this formerly tropical moisture was "transformed" from tropical to cold as it was carried across the Bearing Straight, then cast Southeast across Gulf Alaska towards the NW Coast of the US as a cold North Pacific storm out of the Aleutians.

Those days are over.

In the South, cold waters from La Nina look like they are suppressing storm activity along the equatorial belt running West to the NE coast of Indonesia. This cold water dampens tropical storm activity in the very area from which supercharged tropical storm moisture is typically carried to the NW Coast of the US during "tropical" Winters, if not carried here by more indirect routes, getting sucked North up the coast of Asia before turning East. Both mechanisms are suppressed during La Ninas.

The bottom line is that the positioning of the "blocking ridge," the massive cell of high pressure who's increasing presence and positioning over the last thirty years has characterized, really ushered-in the rise of our new seasonal pattern of much shorter, much warmer, and much drier Winters we've watched establish itself over the last thirty years, has most powerfully and persistantly re-established itself again, this Fall.

 The questions we've asked all season long have resolved themselves for the month of December. It has been cool and dry, with a pressure ridge formation reminisent of the drought years, if not a clear signal that the drought mechanism has not only, "not cleared out of the system," but that this Winter ridging may well be a permenant fixture in our new Winter weather pattern.



 December 6 


Although the wave of weak storms across the Sierra on November 17 put the 2017 High Sierra Fire Season to bed, Southern California has remained warm and dry. The vast blocking ridge along and off the West Coast of the US has fully reestablished itself, and has been knocking Arctic Storms around to our North, reducing Sierra snow pack, and starving SoCal of moisture, under warm conditions. 

Our drought never ended, but the increasing heat has been establishing a new Winter pattern bringing warm tropical moisture North, rather than cold Arctic storms South.

That's what happend last Winter, and what brought vast snows during a non El Nino year. The super-powerful El Ninos brought almost nothing to the Sierra, when they were in operation the previous two Winters...

This is a whole new set of regional seasonal and weather patterns that we are watching and experiencing the emergence of, around us, right now. 

Each weather incident or "event" we observe is just one "dot," one data point in this year's series of weather events that we will connect-up, to finally determine the outline and character of this year's seasonal transitions.

The same mechanism of changing heat distribution and transfer on our planet is what's established the blocking ridge typical of our drought years, the one that's sitting there off the West Coast of the USA right now, which is also the mechanism that generates the Santa Ana Winds, which are currently supercharging the fire potential of a very dry, warm SoCal.

Is this persistant ridging a permenant part of the "New Normal," or just another transitional step, one that we wil eventually pass through, as our outrageous irresponsible growth continues to change our weather? 

We will see.

Observe carefully. Take notes! We are watching each piece of whole new sets of regional weather patterns emerging, like new-born babies, as they are being first-forged by the completely new characters of our "new" seasons and seasonal transitions.

The heat distribution system has changed out from under our traditonal range of seasonal patterns, and they are gone. We are now watching the New World's Weather emerging.

Enjoy the show, it's going to be epic, and it's just getting started.



Fire & Smoke Resouces




November 27

Cliff Mass Reports

Direct to Report
Fall So Far

The last two days of light tropical moisture riding the edge of a descending Cold Front brought up to 20" of snow to the Northern Crest, with less the further South we go, typcially.

This was "light" for a Tropical Transport Mechanism.

 See November's Snow History on the Calendar




November 22 

Waves of Haze & Clearing

Special Weather Statement 
Eastern Sierra Counties


"A potent Pacific storm will move inland this weekend and bring
rain, mountain snow and gusty winds. The winds will begin Saturday
afternoon and continue through Sunday night. Precipitation will
begin as rain, even at the passes, as snow levels start high.
Snow levels will begin to fall Sunday with snow over the passes
possible by sunset Sunday. Expect holiday weekend travel impacts
due to winds and snow over the passes."


See the 2016 Hazard Alert, on the bottom-right of the Backpacker's Calendar. It applies now.


The vast majority of this activity spoken of in the Special Statement above will pass North of the Tahoe Basin.

Persistant-looking Highs/High setting up over the Four Corners Area are possibly going to bring Warmth North around its Southwestern Perimeter while deflecting Pac Storms North around the Sierra Nevada along its Northwestern edge, for the remainder of this month.

Drier and Warmer Yet, If this configuration of High & Low Pressure Zones persists.

Climate Prediction Center




November 21

The Big Low in Gulf Alaska is looking more like a stationary feature that's dragging tropical moisture NE from Hawaii, around its Southeastern perimeter. That's the driving element of the "Blob"-creating formation. If it persists. We've seen blobbing blinking in and out.

Weather Maps

Ocean Temps & Anonomolies

To the South a big Ridge off and straddling the Coast of California has been looking more stationary as well. That's the drought formation, that particular High-Low formation. It's also both parts of the "Blob"-creating formation. If it persists.

Latest Blob News 
"The Blob Returns?"

Ideally, compact Lows out of the Aleutians & Northernmost Gulf Alaska would ride the Northeast edge of a properly-situated NE Pac High to the Southeast, bringing Winter snows coming out of the Northwest across the Aleutians & Gulf Alaska, to the Cascades and Sierra Nevada. They drag nothern Cold Fronts to the South.

Earlier this month we had a series of Lows try to ride the NE Pac High Southeast to N Cal & the Sierra, dragging Cold Fronts from the North, but they pretty much failed, diverted around to the North by the High. The weather we've seen so far this month has been split, with both Cold and Warm Fronts coming around the NE Pac High, from both the NW & SW, respectively, with those coming out of the SW, the direction that drags Warm Fronts Northeastward to the Sierra out of the tropics, being the stronger influence than those dragging cold fronts coming across, and Southbound out of the Aleutians, so far.

It's looking a lot like last year's November...

November 2016 Calendar

November 2017 Calendar




November 19

Waves of High Haze

The biggest parts of a series of Lows and Fronts are passing to the North of us over the next five days, with the forcasted exceptions of Monday and Friday, when the bottom ends of thes Fronts and Storms will bring light rains and some snow, mostly across the North Sierra Crest.

Thus this week may offer the first windows into our first snow backpacking oppertunities of the season.

The threats are first, that the storms centers and Frontal "Tails," come unexpectedly South, second, that they do not, and windows of clear skies bring colder than expected temps, and third, on the other hand, that it stays warm, and sloppy semi-frozen rainy snow falls across the Sierra Crest, which is always challenging in freezing conditions.

See the 2016 Hazard Alert, on the bottom-right of the Backpacker's Calendar. It applies now.



November 17

High Sierra Weather: Fall Storm Situation Report, November 17, 2017




November 10

La Nina Report
9 November 2017 El Nino & La Nina Report



Current Weather Analysis

Hazard Alert


Road Conditions & News





November 7

Crisp, & Cool

Stormy Weather Coming

A Huge Low is sitting up in Gulf Alaska, dragging a vast plume of tropical moisture Northeast. 

That's the persistant location of the High-Low formation that set up, "The Blob," from 2013-15.

More Blob

That Low's predicted trajectory to the Southeast should drag some snow across the Sierra by late Wednesday or early Thursday. 

Rain Probs

Snow Probs


All Snow Info

All Precip Info




November 5

Weather Notes
November 5, 2017

This first "cold" storm-front of the season that just passed through the Sierra over the last two days was a "dud," producing up to two inches of snow, rather than the forecast potential of two feet. There's a reason for that, and more was brought by this last front than snow alone. It's a harbinger of the season, our first looks at this Winter's pattern formation.

This first "cold" storm-front of the season that just passed through over the last two days was running from just NE of Hawaii, across the bottom, across the South end of a vast cold High coming Southeast out of the Bearing Straight & across Gulf Alaska. That High is now dropping South out of the Gulf Alaska, and it is currently bringing our next low down around its Eastern edge.

The next cold storm-front we are watching today is now bending Northwest from a Low sitting off the coast of Washington (to the East of the High), as this front is being pushed down and around the N Pac High, along with its attached Low, to the Southeast draging its seriously cold front along behind it.

"Behind" this next Low is another Low sitting above at the top of the N Pac High that's itself sliding South across Gulf Alaska.

That next Low, and the prospective Low behind it, are "loaded-up" to the North of the East Pac High, which is the configuration of the classic "West Coast Storm Gate." The "gate" depends on the location of the East Pacific High. At the proper location the East Pac High conducts Lows and their associated Fronts around its Northern perimeter, across the Aleutians around the top of its bulge, to "fire them up," then sweeps them down the Eastern edge of the High into the West Coast of the USA. That's the classic N Pac Storm Gate bringing Winter to the Sierra Nevada.

What we are seeing is the first formations of the classic Storm Gate as the chill of Fall deepens into Winter. Will this formation hold? Will the East Pac High slide North into the "void" created by a warmer Arctic, blocking the West Coast of the US, as was typical of our drought years? Was this drought position of the N Pac High "transitory," with the drought, or is this more Northern position of the East Pac High the new way Winter works in our "new," much warmer world's new weather pattern?

I'm thinking it's the latter, judging by the slow, decades-long Northern creep of the Winter-time positioning of the East Pac High. Nonetheless, the Forecasts show the beginnings of a classic "Storm Gate" formation over the next few days, bringing a couple of more Lows & their Associated Cold Fronts across the Sierra from the North. Classic.

The question is, "Will the Gate formation hold?" Will it predominate this Winter? That would be great news for the Sierra Forests, putting the dagger of final death into the heart of the drought.

This link below always shows the latest run of Animated, and the latest detailed N Pacific Weather Maps. If you view the animated map on Nov. 5 you will see the scenario I described above.

Animated Pacific Weather Maps

Pacific Weather Map


High Sierra Weather Page

All Maps




November 3



Moderate/Weak-strength storm bringing up to 2 feet to Sierra Crestline over this upcoming weekend. 
Winter Gear required.


Winter Storm Watch In Effect Above 7,000 Feet,
Sierra News Online, November 2, 2017.


NWS Watch, Warning, Advisory Display,
with links to local NWS Office Hazard Warnings.


Weather Resources

All Rain-Snow-Precip Tools

All Radar

All High Sierra Forecast Zones

Graphical Interface Forecast Display



Crestline reporting stations

Right now: surface low tracks

All reporting stations


The High Sierra Outdoors-folks Weather Page


 Let's Gear-Up for Winter

 On September 15 the temps and conditions shifted enough to require shifting our gear setup from Summer to Fall gear kits.

Sept 15, 2017.

Now we've hit the Winter Line, and we've got to deploy the necessary elements of our Winter Gear Kit. Not the whole thing, but some serious Winter gear needs to come out now.


Four-Season High Sierra Gear List


This storm should finally end the Fire Season, too...




November 1


First Major Storm of Fall 2017 Coming? 



Latest Observations



October 31


When is the First Real Storm going to hit the Sierra Nevada?

When will two feet fall?

First Significant N Sierra Rains-Snows-Precip Predicted 
6pm Thursday running through 6pm Monday

Run the Animation

All Rain & Snow Tools



All Forecasts




October 24

Is the Great Sierra Tree Mortality, the Vast Die-Off, Over?




October 20

What's Next?

Winter Weather Forecast Factor: La Nina REPORT




October 17 

First "Sizable" Snow Storm?

No, but biggest so far. Rain & Snow Forecast Thurs Night through Daylight Hours of Friday




October 5, 2017

Fall Update

Typical early autumn conditions prevail; some thoughts on La Niña,
California Weather Blog, October 5, 2017.

We've been tracking the bubbling, then strengthening, La Nina for months now.


Two Forces Drive our Seasonal Prognosis

General Factors

Specific Events & Trends 


My View, September 15
"Warming Arctic, Cooling La Nina"


"Two Outcomes"
9-13: "To Ridge or not to Ridge"
That is the Question.


August 12 Observation-Analysis
State of the Weather





Sept 19

We've recieved reports of how very warm the Arctic Circle is this Fall, and recently observed a streghtening of the La Nina. Taken together these are early signals of a dry, cold Winter for the Sierra Nevada.

Arctic Conditions, 2017

La Nina Strengthening: Click Graphic to run report


also see





Temp Drop in 2017: Sept 15

Temp Drop in 2016: Oct 31

Temp Drop in 2015: Oct 14

Temp Drop in 2014: Oct 2

"Temp Drop" day is point Fall gear elements must be included in pack, after which point significant chances of Fall-Winter weather "incidents" exist which must be accounted for with the proper levels of gear, skills, & fitness.


 Latest Observations




September 13

What Brings This Winter of 2017-2018?

Nothing? Everything?

Lake Tahoe 2017-18 winter forecast: ‘Be ready for everything.’
Tahoe Daily Tribune, September 13, 2017.

The article above offers no significant insights. The links below are much more instructive, and my short essay below is more descriptive of our current situation. 


Future Probabilities

Climate Prediction Center
Next Two Weeks to Three Months Temp & Precip Probabilities


Synoptic Discussion


Two days later, the 15th,


The Experts

Right now (9-13) NOAA is calling for it to be hotter than average for the next three months, with average precipation. During the past three years we've seen the driest Winter in recorded history (2014-15) and nearly the wettest (2016-17), if not the wettest, with an average year in-between (2015-16).


My View

Right now I'd say there are two basic likely outcomes. Either the big "Blocking Ridge" that's been setting up off the NW Coast of the US through the drought years, sets up and establishes itself, or it doesn't. We are likely to see this increased heat we are experiencing turn into a deep drought if this Blocking Ridge reforms and reestablishes itself again this Winter.

IF this ridge fails to reform we have a chance of experiencing another "normal" Winter bringing storms out of the Northwest, across the Aleutians and Gulf Alaska to us. Yet I've seen the expanded "power" of the equatorial band come to increasingly dominate US West Coast Winter weather over the last two decades, so a Winter dominated by storms out of the Southwest and West would not surprize me one bit.

Da Key

The key to the situation is going to be where the Northeast Pac High moves to as Winter Comes. Or does not move to, as the case may be. Oh, and a La Nina has been forming up strongly in the Southeast Pac. That does not mean it will persist, but the line of cold water was strong during August, but faded into September.

La Nina Information


 How do you think it's going? Post up your predictions, or how your bones, "feel," below. 


Latest Observations




A Specific Set of "Events," or the Development of a New Trend?

Blob Mom
Scientists link California droughts and floods to distinctive atmospheric waves,

The Blob

More Blob 




October 2017 High Sierra Trail News 

All September Trail News






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