NWS Reno: Forecasting for the Sierra and Western Nevada Since 1905

The dreaded rain shadow - something that those of us who live east of the Sierra crest are more than familiar with and hate to hear. So what is this rain shadow and why does it even exist? Lets start with the topography just to our west... The Sierra Nevada mountain range runs 400 miles from north-to-south and is approximately 70 miles wide. It includes the highest peak in the lower 48, Mt Whitney at 14,505 feet, and rises above 10,000 feet in many locations. Left: The Sierra Nevada Mountains highlighted in blue. Right: A relief map showing elevation (in meters) of the Sierra. The Sierra are a significant barrier for Pacific storms which typically move from west to east. The movement of air masses and associated weather cannot go through the mountains and is forced up and over the mountain range. As Pacific moisture is driven eastward by the wind, the air mass is lifted up and over the Sierra. Rising air will cool and once it reaches the point of saturation, condense into...

Hope that everyone travels safely for the holiday! Let's check out what is in store for Thanksgiving and going into the weekend. We have an early season cold outbreak on tap for Thanksgiving weekend once the wind and snow move through the region. Post-frontal conditions will keep the maximum temperatures near and below freezing for the Thanksgiving Holiday weekend! Note that it would have been even colder in western Nevada if we had deeper snow cover and were expected clearer skies. From Wednesday through Saturday we are forecasting maximum temperatures near 30 or into the middle 30s with lows in the teens to low 20s for western Nevada valleys, while highs in the Sierra will be in the 20s with lows ranging from the single digits to low teens. These frigid temperatures may result in broken water lines if they are not well insulated, as well as very chilly temperatures for late night/early morning Black Friday shoppers. A few things to keep in mind...if you're heading ...

Winter Weather Returns Our first winter storm of the season with significant amounts of rainfall and Sierra snowfall is poised to affect Northeast California and Western Nevada Sunday into Monday.   A Winter Weather Advisory has been issued for Sunday Evening into Monday for portions of the Sierra from the Tahoe Basin down to Mono County. (areas in the purple shading) Link to view this map here Incoming Moisture This storm system will usher in a solid band of moisture off the Pacific Ocean and will provide healthy rainfall and high elevation snowfall totals to the region. The animation below shows a model depiction of this moisture band (orange and yellow shading).   This will also coincide with the expected precipitation timing. Rainfall enters northern Lassen County Sunday morning then drops across the Tahoe Basin Sunday Evening and finally Mono County Monday morning.  Rainfall & Snow Level : An important note to take away from this storm: S...

Welcome Tim Bardsley to the NWS Reno Team NWS Reno is happy to announce that Tim Bardsley recently arrived as the new Senior Service Hydrologist (SSH). As SSH, Tim is the primary NWS contact for hydrologic decision support, forecast and warning services in Nevada and the eastern Sierra.   SSH Tim Bardsley enjoying the great outdoors. Tim first became interested in hydrology as a college student while exploring the rivers, mountains and canyons of the West. His undergraduate degree in civil/environmental engineering (University of Colorado at Boulder) and Master’s in hydrology (University of Nevada at Reno) give him a solid framework for hydrologic research. As a researcher at Niwot Ridge, CO, and as a hydrologist at the NRCS Utah Snow Survey Office, he conducted numerous hydrologic investigations as well as repairs and maintenance at well over one hundred hydrometeorological sites in four states, including extensive field work throughout Nevada and the Sierra Ne...

Enjoy this post put together with information from Nevada Bureau of Mines and Geology about the 1915 Pleasant Valley, Nevada Earthquake on its 100th anniversary. All information was taken from The 1915 Pleasant Valley, Nevada Earthquake website . - - - - - - - When folks talk about earthquakes most people consider California to be earthquake country, but Nevada gets its fair share of seismic activity too! Northern Nevada was very active geologically during 1914 and 1915, as you can see on this short video which shows activity from 1850-2012. Magnitude 6 and 6.4 earthquakes occurred in Reno during February and April of 1914 and Mt. Lassen had several eruptions between May 1914 and October 1915, occasionally dusting Winnemucca with fine ash.    The Pleasant Valley earthquake of October 2, 1915 was the largest earthquake in Nevada's recorded history. The 1915 Pleasant Valley earthquake was preceded by a rare, highly energetic foreshock sequence that forecasted th...

Western Pacific typhoons are not always just a curious side note. In fact, they can affect the storm pattern over our region significantly, especially in the fall and winter. If a tropical system over the western Pacific gets absorbed into the storm flow at the right location, it can amplify/energize the pattern, potentially leading to stronger storms over North America. Check out the video** below, which shows  a typhoon (red symbol) just before absorption followed by the movement of the energy (shaded area) downstream after the typhoon is ingested into the flow. Notice how the flow (indicated by white lines) amplifies as the former typhoon energy moves across the Pacific and into Canada and the United States. Amplified flow can bring about a significant clash of air masses (cold Canadian and subtropical) and initiate the development of powerful winter storms. Computer models often have trouble predicting how exactly tropical systems will be absorbed into the flow, which unt...

On the evening of Sunday September 27th (mainly between 7 and 8:30 pm), we will be able to view an astronomical treat that hasn't happened in over 30 years! There will be a combination of a supermoon (perigree full moon) along with a total lunar eclipse! So what exactly is a supermoon? It's a new or full moon closely occurring with perigree - the moon's closest point to Earth in its orbit. This particular supermoon will be the closest supermoon of the year (other full moon supermoons this year: August 29th and October 27th) being only 221,754 miles away from Earth. About three or four times a year (in the spring and the fall), the new or full moon coincides closely in time with the perigree of the moon - the point when the moon is closest to the Earth. Image Courtesy NOAA Like I mentioned earlier, this September supermoon will be a treat because it will coincide with a total lunar eclipse! Check out this great animated video by NASA's Goddard Space Flight Center ...

Let's take a look back at Summer 2015. Although astronomical fall hasn't begun, meteorological summer has ended. What? There is a bit of a difference between the two. Astronomical summer ends (or fall begins) when the Autumnal Equinox occurs, around September 22-23 ( specifically September 23, 2015 at 8:20 UTC in the northern hemisphere ) So why would meteorological summer end (or fall begin) at a different time? It's basically because the astronomical seasons are based on the Earth's position related to the Sun while the meteorological seasons are based on the temperature cycles through the year. For a more in depth discussion on what the difference is between the two, check out this great write-up by NOAA's NCEI (National Centers for Environmental Information).  Anyways, back to the Summer summary for Reno. Looking back at the summer, we had a VERY active monsoon pattern which resulted in multiple days of thunderstorms and flooding for the Sierra and weste...

Well the smoke has returned... it seems like an appropriate time to have Washoe County Air Quality guest blog about the smoke again. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -      Wildfire smoke contains many different pollutants with fine particulates (PM2.5) being the most concerning (see blog post "Wildfire Smoke in Northern Nevada ). The Washoe County Air Quality Managament Division's PM2.5 monitoring network has been monitoring since 1999. In addition to the two permanent PM2.5 monitors at our Reno3 and Sparks monitoring sites, we recently deployed portable beta attenuation monitor (E-BAM) for PM2.5 monitoring at Pleasant Valley Elementary to expand our network during wildfire season (see map). An E-BAM's purpose is to get accurate PM2.5 data so that the public can make health based decisions as soon as possible. Decisions like keeping windows closed at night, having recess or practice indoors, and cancelling events like a triathlon ar...

El Niño and La Niña are weather catch phrases that are thrown around pretty frequently, but how many of us truly know what these features are? They are complex atmospheric-oceanic circulations, and to be honest, it's more than we could even explain in a short blog post, but we will cover some of the basics here. Let's start with El Niño since we currently have these conditions in place. El Niño is the warm phase of the El Niño Southern Oscillation (ENSO) and refers to warming in the equatorial Pacific sea surface temperatures (SSTs) compared to normal. Here is a quick video explaining this phenomenon: La Niña is the cool phase of ENSO and refers to cooling in the equatorial Pacific SSTs compared to normal. One more quick video to explain: The strength of El Niño and La Niña episodes is determined by the difference in SSTs compared to normal and are measured in a region of the east-central Pacific Ocean known as the Niño 3.4 Region: The Oceanic Niño Index (...

Everyone is familiar with weather radar and how it can detect areas of precipitation, but radar is also an indispensable tool when it comes to helping identify storms which have the potential to become severe. Normally when we refer to severe storms in the West, we are referring to storms that are capable of producing damaging winds/hail and also flash flooding. Here in the Sierra and western Nevada, tornadoes are fairly uncommon but still can happen as was the case this past June in Hawthorne, NV where an EF-1 tornado formed.  Smoke on Satellite   The satellite image below (fig 1) shows a true color view from the afternoon of the 8/18/13. What is notable is the smoke plume from the American Fire hovering over the Sierra west of Lake Tahoe. The next image later that afternoon (fig 2) show thunderstorms had formed across the Sierra south of Tahoe while smoke had begun to travel up slope of the Sierra.  Figure 1: MODIS-Terra satellite image from the afternoon...

Enjoy this guest post from our friends at Washoe County Air Quality !  - - - - - - - - Forecast calls for sunny skies and hot temperatures for Northern Nevada. The air quality should be good as long as there isn't any wildfire smoke, right? Well, not necessarily. Let me explain.  Summer is the season of ozone (O 3 ). There is both stratospheric and ground level O 3 . The stratospheric ozone protects us from the Sun's harmful ultraviolet radiation. Ground level ozone is an air pollutant that harms humans and the environment especially during hot and sunny summer afternoons.  Ground level O 3  is created by the chemical reactions between volatile organic compounds (VOCs) and oxides of Nitrogen (NO x ) in the presence of sunlight. NOx and VOCs, also ozone precursors, come from motor vehicles, industrial processes, power generation, and consumer products among many other things including wildfire smoke. Urban and suburban areas will have higher leve...