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

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 until t

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