Patrick Marsh
EF5
- Joined
- Apr 18, 2006
- Messages
- 783
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.
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Another questionable spotter report
- Thread starter rdale
- Start date
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
EF2
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
EF2
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
EF5
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
EF5
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
EF2
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.
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.
