For over 33 years I have been a weather watcher from my home in Galena Forest and now Montreux located in the Carson Range of the Sierra Nevada mountains near Reno, Nevada. Our current location is about 700 ft. lower in elevation but in the same general area. My interest in the weather dates back to my childhood when I am told I would pretend to be the TV weatherman. My years of flying as an instrument rated pilot increased my interest since many times correct weather interpretation kept my family and me alive. As an avid skier I am always interested in the storms that produce the heaven like powder snow we love to play in.

Over the years I found there are lots of folks interested in the same thing. Long range forecasting is my main interest, and it seems that local weather people are very hesitant to forecast very long range ( more than five days). Hence, I decided to begin sending an e-mail to my friends who shared the common interest or just wanted to plan sick days off around big snow dumps. Updates are posted every few days as weather predictions change during the active weather months. From June through September updates are seldom. Daily updates are found on our weather station site noted below. - Randy York

October 3, 2020, 6PM (Graphics on three month look ahead updated 10/15/20)

The 2020-21 Winter Forecast

Although we are a couple of weeks into Fall, if you look at the thermometer today you would think it is still August. It has been a very dry Summer with the precipitation less than half of average. Since April the Reno Airport has recorded just .51" of rain. Early in the Summer we were also running quite cool, but the second half of the Summer was hot, and continues to be so into October. Fires in California have reeked havoc as well, although we haven't had any major fires in our area so far, plenty of dense smoke has filled our Valleys for much of the last month. We aren't the only area to experience drought. We were in Phoenix earlier this week and they are extremely dry. It seems that the Monsoon season never showed up this year.

So what kind of Winter can we expect? The Climate Prediction Center says that we have a 75% chance for a weak La Nina ENSO this Winter. The El Nino Southern Oscillation (ENSO) is a significant feature in the Pacific Ocean that impacts temperature and precipitation all over the world, but especially on the West Coast of North and South America. Although they are saying a 75% chance, it is pretty certain we will see a weak La Nina this Winter.

As you can see by the graphic above, the general trend for La Nina is above normal precipitation in Northern California and below normal temperatures in the Pacific Northwest and points east. It also generally means dryer than average in Texas, the Gulf States and Florida. With a weak La Nina we have to modify this a bit by moving the wet and cold further to the North. Below is what one forecaster is predicting for the coming Winter.

In this graphic you can see that the wet weather has moved north, the dividing line is about the I80 corridor. Over the years this path has proved to be very reliable in weak La Nina forecasting. My prediction will come later, I am just trying to give some context and background. What we are talking about is the BIG picture for the Winter. We can conclude that a weak La Nina will be wetter and colder north, dryer and warmer in the south.

In preparing for this Winter forecast I looked for similar Winters which had a weak La Nina and a dry Summer prior to the weak La Nina. Since last year was a "Tweener" year, I was able to identify a few similar Winters. This helps me with more context and, to a certain extent, timing. Being a weather observer, I try to take in as much information as possible in my deliberations. I also check out what the Farmers' Almanac and the Old Farmer's Almanac have to say. They seem to be diametrically opposed this year, so they won't be much help. I also consult with other forecasters, organizations and universities to get their take. Most don't publish this early, but any information I can glean helps. NOAA also puts out general trends for up to six months, I use their three month look ahead in this blog, the graphics can always be found at the bottom of the blog and they update every month. Just for fun here is their four and a half month look ahead for February, March and April.

You can see they are forecasting a La Nina pattern, showing our region dryer and warmer than the other graphic of the typical La Nina pattern. I have a couple of other graphics to share before I get into my predictions. These are from Accuweather, they are one of the large scale companies that put out an early Winter forecast. Here is what they expect for snow and temperature.

 

Enough for all the pretty pictures and context, let's jump into our prediction. As we experience near record temperatures for early October it is likely we will see a slow transition to Winter weather. In a way this is a blessing since any significant precipitation will be delayed until later in the season, meaning we will have a better chance in seeing snow rather than rain above 7500 ft. The years that have been wet in late September and October usually are dry in November and December. This year I am predicting that any storms that arrive later this month and November into December will produce snow at the Ski Areas.

That is the good news, the bad is that I think we are going to be limited in the number and intensity of the storms that do arrive until December. Late next week, around the 10th we may see some precipitation, which given how dry it is will be well received. Temperatures will cool down, more seasonal in the low 70's. Beyond next weekend, the earliest we see another system would be the last few days of October. Halloween has a reputation of being cold, we might see a light rainfall along with the cold this year as a Trough moves through the area. November will see mild temperatures that will slowly cool to seasonal temperatures around Thanksgiving. The first significant storms will likely arrive right after Thanksgiving. Late November and into December we will see seasonal temperatures or just below. It will feel cold since the Northern Jet Stream will work its way south over the first couple of weeks of December increasing our winds. Another Winter storm will arrive between December 15 and Christmas Dayand should be a good snow producer for the Sierra and maybe a White Christmas for Reno. The latter is not a sure thing as it may produce a mix of snow and rain in Reno.

Early January will likely be dry and not as cold as late December. The dry pattern will shift to a more Winter like pattern in the second half of the month with the arrival of one or two good storms. They will carry into February which is likely to be a cold and wet month. Beyond February is anyone's guess, we will have to wait and see how January and February pan out. If we are wrong about February and it ends up dry, March will likely see a couple of good storms. All in all we should have an average to just above average Winter with a snowpack ranging from 85% in the southern part of the forecast area to 125% in the northern part. By the way our forecast area is from Mt. Lassen to the north and Mammoth Mtn. to the south.

Now the disclaimer, If I take you back the the graphics at the top of this blog, you will be reminded that the I80 corridor is often the dividing line between wet and dry, cold and warm in La Nina years. The trajectory of a storm is very important since 50 or 100 miles can make a huge difference in precipitation amounts, and this will be one of those years where trajectory is very important. Going back to 1950 there have been 23 weak La Nina events, and half were above average (the biggest year was 175%) precipitation and half below (the lowest year was 56%) of precipitation in the Northern Sierra. You would think this alone would keep us from predicting a near normal year since we would only have a 50/50 chance of being right, but we factor in way more than just 70 years of historical statistics. So that is my story for the upcoming Winter, we will be watching and reporting on all significant weather events and hopefully be able to give our readers a heads up on powder days and other winter activities.

Below you will find a three month look ahead published by the Climate Prediction Center for November, December and January. Every month it is updated around the middle of the month. You can also visit our weather station site where we forecast daily, usually by 8 AM. The site is www.goybs.com/weather.html . In 2021 we are going to make a big change in our presentation and a new web site, renowx.net. WX is the international symbol for weather, and since were in Reno I thought this was an easy name to remember a web site. It should be up and running by the end of next Summer. We are always happy to see any questions, comments or suggestions, you can email us at info@goybs.com.

 

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