Another questionable spotter report

[Chance Metz]

Here in amhonng county we got about 2 inches from a strom that went through about a hour ago. radar esiamted an inch a hour so I guess this proves that estiamtes are not worth a grain of salt. By the way they storm lasted less then a hour.

 

[Matt Gingery]

Is this about misreports again?? First its Scud Fingers from 20 miles away, now its destruction junkies going overboard on rain totals. Where will it end?? These spotters really need to check themselves before they wreck themselves.

 

[Chance Metz]

I am waiting for a report of 20 inch a hour rainfall rates. Wen that happen I know someone belongs in the nuthouse.

 

[Chris Carter]

Spotters should not report rainfall rates, as it is useless without other parameters (i.e. timeframe) and it is impossible to estimate.

As there is no way of knowing if the rainfaill fluctuated during the storm. So much harder to measure rainfall rates than snow. Anytime i see rainfall rates, i usually see it as a radar indicated rate.

 

[jdrenken]

You say tomato - I say tomato.

There is no 88D product that shows rainfall rates.
Spotters should not report rainfall rates, as it is useless without other parameters (i.e. timeframe) and it is impossible to estimate.

What's this and how does the NWS issues Flash Flood Warnings quoting 88D rainfall rates?

 

[Patrick Marsh]

What's this and how does the NWS issues Flash Flood Warnings quoting 88D rainfall rates?

Please read my post above. I've addressed your concern.

In any event, the NWS uses rainfall estimates, not rain rates, when issuing flash flood products. Rain rates and rainfall are not equivalent.

 

[Chance Metz]

Please read my post above. I've addressed your concern.

In any event, the NWS uses rainfall estimates, not rain rates, when issuing flash flood products. Rain rates and rainfall are not equivalent.

The problem with estimates is that they are often not right. tka what I had in my area yesterday. The rainfall estiamte was 1.5 inches but most places got over 2 inches in actually. It would be better to issue warnings off real storm totals form rain gauages.

 

[Jeff Duda]

The problem with estimates is that they are often not right. tka what I had in my area yesterday. The rainfall estiamte was 1.5 inches but most places got over 2 inches in actually. It would be better to issue warnings off real storm totals form rain gauages.

Unless you have a dense enough network with frequent reports coming in, that will not be a better solution than using 88D predicted rainfall amounts. The 88D data covers a much larger area with very much larger spatial and temporal density than a human network or one of rain gauges.

 

[Chance Metz]

Yeah but radar estiamtes are not as accurate. Who cares if it covers a larger area if it is off by alot it is worthless in my opinion.

 

[Jayson Prentice]

Yeah but radar estiamtes are not as accurate. Who cares if it covers a larger area if it is off by alot it is worthless in my opinion.

I would not say that in your case the radar was "off by a lot" in its' estimate of rainfall. It is true that the radar estimates will often be wrong in some way, as after all the reflectivity can be skewed by a number of things including hail. It is up to the NWS personal to look at the estimate rainfall totals and determine from there what the actual data might be, after all isn't that the point of an estimate?? Of course it would be better to use actual values, but how many areas have rain gauges that are dense enough to capture to true values of a storm? The answer to that is very few, mainly just metro areas in which overall account for a fairly small percentage of actual area that needs to be covered.

 

[rdale]

Who cares if it covers a larger area if it is off by alot it is worthless in my opinion.

But more times than not the estimates AREN'T off by a lot. That's why trained radar experts interpret the data and can figure out when the data is usable and when it is not. To throw it all out as "worthless" might speak more to how you use it, and not to how meteorologists use the data.

 

[Chance Metz]

True you do have to look at it and sometimes modify it a bit. Guess it is better then nothing.

 

[wsanders]

FWIW, when I was a Boy Scout we made our own rain gauges. If you use a large funnel and stick it down on top of a graduated beaker or bartender's measure, you can get a good reading in 5 or 10 min. Of course this was in Texas where 1 inch per hour is just an afternoon shower.

Attach the beaker to a board or piece of PVC pipe to hold it down and you've got yourself a rain gauge.

You could train your spotters by building a bunch in an evening class.

Also, we all know rain rates can vary 2 or 3 hundred percent in a small period of time. My weather station has recorded instantaneous rates of over 2 inches per hour (a stupendous rate for the SF Bay Area!) while the shower that produced it produced less than 1/2 an inch total rainfall.