NOAA Reports Query

steve · **Posted:** Sat Dec 17, 2011 12:49 pm

RayProudfoot wrote:

I use inches so the conversion from mm seems unlikely to be the reason.

It's the other way around. The station's 'native' unit (being American) is inches. WL has to convert to mm for people who use mm.

Quote:

Are you using 5.9 or later? If so does that match what you're doing with Cumulus?

I don't currently have WL installed but I am now installing 5.9.3...

steve · **Posted:** Sat Dec 17, 2011 12:50 pm

steve wrote:

I don't currently have WL installed but I am now installing 5.9.3...

... or not. The download is only an upgrade, so I'm going to have to find my original software. Grrr.

steve · **Posted:** Sat Dec 17, 2011 1:08 pm

I installed WL 5.7, downloaded the logger data and produced a NOAA report for this month. It says it's doing ">.2mm" but it actually does ">=.2mm". I then upgraded to 5.9.3. It does the same.

RayProudfoot · **Posted:** Sat Dec 17, 2011 1:09 pm

Interesting... In the Help for generating NOAA reports in 5.8.3 it states...

Days of Rain
The number of days on which rainfall exceeded 0.01" (0.2 mm), 0.1" (2 mm), or 1" (20 mm) is displayed.

It will be interesting to see what the help for 5.9.3 says assuming you can find your original software.

steve · **Posted:** Sat Dec 17, 2011 1:14 pm

It looks to me like it's a bug in WL when handling mm and they really do intend it to be ">" not ">=". It's easy enough to change Cumulus, but it would still be nice to get an official definition. They are called 'NOAA-style' reports, but I have so far failed to find anything about them on the NOAA web site.

RayProudfoot · **Posted:** Sat Dec 17, 2011 1:17 pm

steve wrote:

I installed WL 5.7, downloaded the logger data and produced a NOAA report for this month. It says it's doing ">.2mm" but it actually does ">=.2mm". I then upgraded to 5.9.3. It does the same.

The thot plickens. :roll:

If Ken's site using 5.8.3 clearly shows ">" but 5.7 and 5.9.3 both show "=>" then it suggests Davis have changed the criteria twice which seems extremely odd.

You'd expect that going to the main NOAA website would have links to "Monthly Climatological Summary" but if they are there they're not easy to spot! I'm more confused now then when I started. :lol:

RayProudfoot · **Posted:** Sat Dec 17, 2011 1:22 pm

steve wrote:

It looks to me like it's a bug in WL when handling mm and they really do intend it to be ">" not ">=".

I suppose I'll only know if I update to 5.9.3. I'll try that later and come back to you.

RayProudfoot · **Posted:** Sat Dec 17, 2011 1:39 pm

Now running 5.9.3 and it's reporting 11 > 0.01; 6 > 0.10 - same as 5.8.3.

Looks to be a conversion to metric bug Steve. Not sure how you can handle that with Cumulus.

steve · **Posted:** Sat Dec 17, 2011 2:32 pm

I think we have to depart from copying WL exactly at this point, and choose to go with > or >= for both in and mm, and making the labelling match (my attempt to precisely match the format seems to have failed anyway). I have to say that personally I prefer the >= check. I found a sample of a NOAA annual report (they charge for the real ones) here - http://www.ncdc.noaa.gov/oa/samples/ancsumform.html. I'm guessing that's what these NOAA-style reports are emulating. Note that the real NOAA report does >= (the last three columns).

RayProudfoot · **Posted:** Sat Dec 17, 2011 3:06 pm

That report does appear to suggest the official guidlines are to use => so can understand why you would go with that.

Apart from Cumulus and WL does any other software output NOAA data? I'm guessing WeatherDisplay will. I've had a look at a few WD sites but I can't see any NOAA data. :roll:

I'm certainly not qualified to advise which is the option to use but could I just mention this. Cumulus allows us to set the trigger point for what qualifies as a rain day. Mine is set to 0.01". Others may well have theirs set to 0". The point of this was to ignore dew collection and for it to be treated as a dry day.

Is there any possibility you could use the trigger value when creating NOAA reports? That would at least produce consistent records should each user have separate rain records?

So where the trigger value is 0.01" (or metric equivalent) you use > 0.01" but where it is 0" you use =>0.01".

gemini06720 · **Posted:** Sat Dec 17, 2011 3:39 pm

Steve and Ray, this is what Weather Display reports:

The format for the display of the 'Days of Rain' is the same for Cumulus and Weather Display.

RayProudfoot · **Posted:** Sat Dec 17, 2011 4:00 pm

Thanks Ray. And do those totals agree with the actual data? Perhaps you could post the info for a month where you've had some rain.

Using WL with metric rain only gives the correct count if => is used whereas if inches are used > gives the correct count.

steve · **Posted:** Sat Dec 17, 2011 4:11 pm

RayProudfoot wrote:

So where the trigger value is 0.01" (or metric equivalent) you use > 0.01" but where it is 0" you use =>0.01".

I think that's just confusing the issue. And note that the check on the 'rain day threshold' value does a >= check. So if you set your rain day threshold to 0.01 and your first NOAA report figure to 0.01, they come up with the same answer.

gemini06720 · **Posted:** Sat Dec 17, 2011 4:37 pm

OK, Ray, here are two links:

[link removed] - not posted on my site

[link removed] - posted on my site on the [link removed] page

RayProudfoot · **Posted:** Sat Dec 17, 2011 4:39 pm

I've checked the threshold in Cumulus.ini and it's:-
RainDayThreshold=0.0199999995529652

So a rain day would require the rain total to equal that value or greater. Given that the Davis only records to 0.01 resolution 0.01 would equate to a dry day and 0.02 one with rain.

Ideally I would like what Cumulus (via the above setting) deems to be a day with rain to be the same as what is output to a NOAA report but I accept it's not a straight-forward process. This is, after all, an America-centric report so maybe our cousins can make some suggestions.

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NOAA Reports Query

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