We Got a Lot of Rain in May...Where Does This Leave Us?

After a brutally dry winter, May finally brought some welcome precipitation to the region. Now, where exactly does this leave us? Is the drought over? In a word, No. Does the recent rain and high elevation snow help? Most definitely! The rain did bring a bit of a recharge to area lakes, rivers, and reservoirs, but the relief is unfortunately short-lived. What we really need is a deep snowpack to slowly replenish water storage...of course with it being nearly June, we are out of time this season.

So, how did May 2015 stack up across California and Nevada...see for yourself below:



The greatest departures from average were through Mono County due to a snowfall event on May 8 which brought over a foot of snow (and liquid equivalents of 1-2 inches) to many locations. Here are some incredible photos and snow totals from the event:


June Lake - Photo Courtesy of Michael Cohen

McGee RV Park Across from Crowley Lake - Photo Courtesy of Anna Maier
After starting the month with a few of these winter-like systems, we transitioned to more showers and thunderstorms. This made the rainfall totals very hit or miss, with some places getting significant rainfall totals and others not nearly as much. Overall, totals for the month across the region ranged from a quarter inch upwards over 5 inches.

Now the big question...where does this leave us in terms of the drought? Well, we have had such a large deficit the past several winters that, to be honest, this is only a blip on the radar. Picture dropping a cup of water in a 5 gallon bucket - that leaves a lot of empty bucket still! Here is how many years worth of annual rainfall would be needed to even reach what is considered normal:


Of course, there remains one other big question...what about fire season? Well, this just delayed it, and in theory could actually make it worse. With the recent rains and now warmth, it will allow grasses and fine fuels to grow. These will then dry out in the summer heat, creating a new bed of fuels that can burn. The larger fuels - such as timber in the Sierra - are all quite dry already due to the past 4 years of drought. The rains have delayed their ability to burn, but these too will dry out again. A large number of wildfires are human caused, so make sure to do your part to help lower the risk of fire starts.

We'll have to see what winter of 2015-2016 brings us, but lets hope that it's a large Sierra snow pack!

The incredible winter of 2010-2011 (Look at the speed limit sign!)


Popular posts from this blog

NWS Wind Forecasts: AKA What's the Deal With Friction?

Image
We have had a number of comments on social media which mention much lower observed wind speeds locally than are in the forecast. Well, you are unlikely to know this (it is not exactly advertised!) but National Weather Service wind forecasts are for 10 meters, or almost 33 ft, above the ground. As we are about to explain, that makes all the difference in the wind between eye-level (~5-6 feet) and ~33 feet.  It is natural to wonder the purpose of a wind height forecast well above where you and I typically reside. The main reason for this is the complication in forecasting wind as one nears the ground due to frictional influence caused by the surface. Here is a diagram showing the concept of wind speeds change as one gets away from the ground.  As you can see above, there is a rapid speed reduction (gray dashed line) near the ground with a lesser change away from the surface. Note that the above diagram is generalized. How much reduction is realized depends on the nature of the surface wh
Read more

What is the Rain Shadow and What's Wind Gotta do With It?

Image
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
Read more

Forecasting "Dry Microburst" Potential From Soundings and Observations

Image
Summer afternoons in the valleys of eastern California and western Nevada usually feature dry low level relative humidity. In certain cases where low levels are very dry (single digit relative humidities) and enough instability for showers and/or thunderstorms exists, there is the heightened possibility for severe (over 60 mph) outflow winds. Now, severe winds are possible from strong thunderstorms in many cases, even without very dry surface relative humidity. However, what makes very dry surface or low level conditions special is that severe outflow winds are possible even with w eak  convection such as light showers...or even just cumulus clouds! When severe winds are produced by convection with little or no rainfall reaching the ground, it is referred to as a "dry microburst". Microbursts can be of significant danger to aviation and, if they are strong enough, life and property. Before we move onto what conditions we look for to determine the threat for dry microbursts,
Read more