Why are we still in Drought?

The National Weather Service
Building a Weather-Ready Nation


Summary | Recent Storms and Snowpack|
What is Drought? | More Information

A very wet month of April shot precipitation averages at many climate sites east of the divide from well below to well above normal for the month. Nearly SEVEN FEET of snow fell on Casper Mountain, over two feet fell in the town of Casper during the first two snow storms, likewise in Lander; a foot and a half fell in the town of Riverton. In fact, this is Casper's second snowiest April on record with 37.8" of snow and 81.0" have fallen so far this season, with only 20.2 more inches needed to bring this season into the top 10 snowiest of all time. 

In Lander, the month of April looked like it was going to be as dry as it was last year with snowfall over a foot below normal for the water year. However, the first two storms brought Lander into a surplus; it now stands at 23.7" ABOVE normal for the entire month of April. The snowfall season (July 2012 - present) has now delivered 97.8" of snow so far, putting Lander 14.9" above normal for the year, and 34.5" above where we were at this time last year.

Labs "snorkeling" in the snow at Sinks Canyon in the Wind River Range.

Photo by Art Meunier
Hogadon ski lift on Casper Mountain had only the very top of the chair lift sticking out of the fresh 5 feet of snow!

Photo by Eric Aune
Travel was severely impacted during the storm. Portions of I25, I80, US 287, US 220, WY 251 were shut down for several hours.

Photo by Loresa Brinkerhoff

In Riverton, 24.7" of snow has fallen this month, which is 18.6" above normal for the month, and the 3rd snowiest April on record. Riverton has accumulated 54.5" of snow through the current snowfall season (July 2012 - April 2013), or 20.9" above normal for the season , and 34.1" above where we were at this time last year.

The April 16 - 17 snow storm in Casper moves into the number 16 spot for the biggest snowstorms on record:

Links to Biggest Snowstorms




With all of this new snow in the area, the snowpack should be fine - right? Well, it is finally beginning to respond as SNOTEL sites rocket toward normal. There was such a snow deficit when April began that these last few storms have only begun to restore the snowpack to a more normal level, and many sites are still well below normal and would need a couple more large storms to bring them up to normal. Usually, the snowpack peaks in April (and with several more inches of water held within) and then begins a slow descent into the early summer months (runoff season).

April 19 Snow Water Equivalent on Casper Mountain and the Wind Rivers

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The above graph shows the snow water equivalent contained within the snowpack this year (in blue) compared to last year (green), both compared to normal (purple) on Casper Mountain. So, even though over seven FEET of snow has fallen in the past few storms, there is still only as much water on the mountain as there was at this time last year, and there is much less (about 5" of water) than normal. However, the main difference between this year and last year is that we are still on an upward trend with our snowpack and we are expected to maintain it a bit longer into the season.

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The above graph shows the snow water equivalent contained within the snowpack this year (in blue) compared to last year (green), both compared to normal (purple) at Townsend Creek in the Wind River Range. So, the past few storms have handily put this station above where it was in 2012, it is still below normal. The deficit is not too difficult to overcome however, as only another inch or two of water is needed to reach normal levels.

 

 


Statewide Snowpack

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April snow storms have done wonders for our snow pack.

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The amount of water contained in this snow is rocketing toward normal, even exceeding normal for this time of year. The Wind River Basin and the Lower North Platte River Basin have finally moved into the 90th percentile (of median) after the storm last week!



There are two ways we can reach normal: 1) We have several more large snow storms in the next two weeks, or 2) We maintain below normal temperatures into May to hold onto the snowpack a little longer. Hopefully, we will warm up slowly so that this new wealth of water held up in the snowpack doesn't cause flooding!

Flood Potential Outlook
 
 

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Currently, the flood potential in most areas is considered to be low. Our Hydrologist will update the flood potential outlook on May 10th.




Conditions across the state range from "Abnormally Dry" in the northwest to "Extreme Drought" in the Southeast.

So, what is going on? Casper gets several feet of snow yet the snow pack is still well below normal? Yup. Hard to believe but the amount of water contained in the snow pack is still well below normal and even below where it was last year in some cases! However, the amount of water in the lower elevations has worked to move Natrona and Fremont counties out of "Extreme" drought into "Severe" drought. Casper's climate site is reporting over an inch above normal, Lander has exceeded their normal snow amount by over a foot now so the low elevations are doing well. We just need the mountains to store up some water for the summer...

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Earlier in April, much of central and eastern Wyoming was in "Extreme" to "Exceptional" drought.

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The map above shows that Fremont and Natrona counties have improved from "Extreme" drought to "Severe" drought due to the recent snow storms. We still have a way to go to get us out of drought completely.

 

It is important to remember that our drought is a long term condition: it took a long time to become this severe and it will take many months of above normal precipitation for the drought conditions to disappear.

There are three types of drought: Meteorological, Agricultural, and Hydrological.

Meteorological drought is usually the first to appear once a long period of below normal precipitation occurrs. We have certainly acieved meteorological drought.

Agricultural drought is usually a result of prolonged meteorological drought resulting in abnormally dry soils that affect crop production and effect local ecology. We were beginning to see some agricultural drought last summer.

Hydrological drought is normally the last to materialize as it involves stored water that cannot be replenished in time to bring reservoir, lake, or aquifer levels at or above statistical average. Streamflow around the state appears to be below normal with some portions of the state beginning to experience moderate hydrological drought.

 

Hydrologic Drought Monitor from the USGS

 
So, even though we have received a LOT of snow east of the Divide this month, we are not out of Drought yet. This just proves HOW dry we were coming out of this winter. Hopefully we will get a few more wet months so that we can recover from the extreme conditions brought about by the Spring, Summer, and Fall of 2012.

For more information on Drought in Wyoming Click Here
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