Why Didn't Rain Count against the Record Dry Days This Year?

I read that Las Vegas is breaking records for consecutive dry days. Currently, it's at around 170 in a row. But when I was there in June, it actually rained a little late one night. Why didn't that count?

Yes, there have been a few sprinkles and isolated showers around the valley on occasion since last April 20, when two-tenths of an inch was measured at McCarran Airport. But there are two reasons why the rain didn't count in the record book.

First, it might not have added up to more than one-tenth of an inch, which is required to be considered "measurable" rain.

Second, it might have rained somewhere in southern Nevada more than a tenth of a inch, but not at the airport. McCarran is Las Vegas' official measuring site for precipitation and even though the airport received a trace of rain here and there over the past six months, it still didn't qualify as enough to end the consecutive dry streak.

It's extremely unusual that no measurable precipitation falls during the monsoon season here, which starts in June and goes through the end of September. The year that the previous record was set, 150 days in a row in 1959, the dry days started on February 22 and ended on July 21 -- with a monsoon storm.

Nevada and most of the Southwest are experiencing drought conditions, but Clark County is now officially in an "Extreme" drought, according to the U.S. Drought Monitor. Extreme drought is the second worst designation, as gauged by the U.S. Department of Agriculture. The worst category is "Exceptional" drought. Sections of seven states are experiencing Exceptional drought: Arizona, Utah, New Mexico, Colorado, Kansas, Oklahoma, and Texas.

As of today, the number of consecutive dry days is 188.

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Comments

rokgpsman Oct-25-2020

Drought vs Hoover Dam

Does the extreme drought in all those states greatly affect the lake at Hoover Dam, or does most of its water come from up in the mountains?

Jerry Patey Oct-25-2020

Rain.

Ask HAARP about weather if !!! You know what HASRP is

Dave Oct-25-2020

You’ve contradicted yourself

From your first paragraph:

when two-tenths of an inch was measured at McCarran Airport. But there are two reasons why the rain didn't count in the record book. 

From your second paragraph:

it might not have added up to more than one-tenth of an inch



So which is it???

Ray Oct-25-2020

Dave, it was just unclearly stated

April 20th was the last day of measurable rain, but the question was about the sprinkles in June and the answers were about why THAT rain or any others after April  were not considered measurable rain.

David Oct-25-2020

Rain amount to be considered "measurable"

The actual amount is .01", not .1" as stated in the answer

Kevin Lewis Oct-25-2020

Bellagio isn't doing its job

No, .01 would be a hundredth of an inch.

Bellagio should turn up its fountains to full blast and leave them on 24/7. Then at least, we'd have rainfall on the Strip.

JerryD Oct-25-2020

Measurable rain

David is correct, and Kevin is correct except for the word "no."  The QOD answer should have said that one hundredth of an inch is deemed measurable precipitation.  Anything less is called a "trace."  Seems odd that the answer got it wrong.  That should have been the first piece of research.

Kenneth Mytinger Oct-25-2020

Water Level

To the first commenter:  All the water comes from "the mountains" -- the snowpack in the mountains around the Upper Colorado Basin.  The water level is managed by the Bureau of Reclamation, and is dependent upon how much they release from Lake Powell.

Here's more stuff for the techies:

http://snowpack.water-data.com/uppercolorado/index.php

Lake Mead Storage Capacity:
https://www.nps.gov/lake/learn/nature/storage-capacity-of-lake-mead.htm

Water Level History (opens a pdf file)
https://www.usbr.gov/lc/region/g4000/lakemead_line.pdf

Map:  https://www.usbr.gov/UC_SnowMap/

Question of the Day - 25 October 2020

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