Author Topic: NWS Western region now using USGS "Water Year" definition...  (Read 2024 times)

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Offline saratogaWX

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NWS Western region now using USGS "Water Year" definition...
« on: January 03, 2016, 09:20:57 PM »
I'd received a note from one of my website viewers saying
Quote
The National Weather Service has changed the way it tracks rain on an
annual basis, moving from a July-June calendar to an October through
September timetable.
so I fired off a question to the Western Region NWS asking
Quote
Hi,

I understood that the 'water year' for our area (SF/Monterey) was from July 1 to June 30 historically.
Has that now changed to the USGS  water year of October 1 to September 30th?
If so, was there an announcement to that effect?
and received the reply
Quote
Hi Ken,
Technically speaking, the water year has never been July 1 to June 30...up until last year, the our NWS office and a few others were misrepresenting the July 1 - June 30 time frame as the water year.  There is a bit of mystery as to where this date range (July 1 - June 30) came from, as the Oct 1 - Sept 30 Water Year is used by all hydrologists and most meteorologists in the Northern Hemisphere.  To reflect general usage of the term "water year" we adjusted/adapted our date range to Oct 1 - Sept 30 when referring to the Water Year, to be consistent with the USGS, CA DWR, and elsewhere.  We made the change, along with CA NWS offices, and numerous announcements were made (although I wasn't involved with those announcements, so can't point you to specifics).

For the "big picture" here, the date designation is somewhat arbitrary, as the intent with both date ranges is to capture our Mediterranean-like wet season.  You could just as easily start August 1 if you really wanted to.  We are just appropriately falling in line with the rest of the hydrology and meteorology community, especially when we utter the phrase "Water Year".  The statistics change a little, but not much.

Let me know if you have any additional questions.

Mark

I must have missed the announcement (and couldn't find it in a search on the NWS sites).

Anyway, the entire nation is now using the Northern Hemisphere convention of October 1st-September 30th for the Water Year and now matches the USGS hydrology measurement period. 

I've changed the rain detail page on my site to have an October start for the year's details.

Best regards,
Ken
Ken True/Saratoga, CA, USA main site: saratoga-weather.org
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Offline ValentineWeather

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Re: NWS Western region now using USGS "Water Year" definition...
« Reply #1 on: January 03, 2016, 09:40:37 PM »
Randy

Offline saratogaWX

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Re: NWS Western region now using USGS "Water Year" definition...
« Reply #2 on: January 03, 2016, 09:56:23 PM »
Yes, found that one.. but the Western Region had been using a July 1-June 30 period for reporting year and recently changed it to match the 'standard' Water Year.
Ken True/Saratoga, CA, USA main site: saratoga-weather.org
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Offline PaulMy

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Re: NWS Western region now using USGS "Water Year" definition...
« Reply #3 on: January 03, 2016, 11:24:16 PM »
And I guess that is why CoCoRaHS uses the end of September for their annual reports
Quote
November 20, 2015


Dear CoCoRaHS Canada
 Volunteers,

Important -- Water Year Summary Reports are
 Ready,

Your Changes are due no later than November 26,
 2015


This is an annual tradition of CoCoRaHS and is our way
 of thanking our rain gauge volunteers for excellent work this past year. 
"Water  Year Summary Reports and graphs" are generated for every CoCoRaHS rain
gauge  observer who submitted measurements during the 2015 water year (October
1, 2014  - September 30, 2015).

The summary information is compiled to
serve as  your "2015 Water Year Journal".

Paul

Offline Impala88

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Re: NWS Western region now using USGS "Water Year" definition...
« Reply #4 on: January 10, 2016, 01:05:07 PM »
I'm glad I saw this post as I wasn't aware that a change was made either.   #-o 

Offline n7xrd

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Re: NWS Western region now using USGS "Water Year" definition...
« Reply #5 on: March 15, 2016, 12:41:31 AM »
Ok So I changed my rain page to reflect October thru September for the Water Year  and when I add all the totals up they come out to 70.25" to today. My site only shows 34.67" since January how do I go about correcting this?