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October, at the moment peering forward, a wild stormy affair?


Typhoon Tip

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lol, no that was last winter.  09-10 was so far south it didn't even hurt that much.

Ha, maybe it was okay in Vt, but I lived in southern Ct at the time and could watch the precip shield from all those MA storms hit a wall just south of Long Island and jet east. Confluence has been a dirty word for me ever since.

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Ha, maybe it was okay in Vt, but I lived in southern Ct at the time and could watch the precip shield from all those MA storms hit a wall just south of Long Island and jet east. Confluence has been a dirty word for me ever since.

 

Meanwhile central and northern Maine were obliterating warmth records for the first 1/3 of the year.

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I'm not sure why he gets so hung up on it, but probabilistic forecasting can be useful.

 

We've established that equal chances really means there is no signal. So you default to the curve on the right (assuming snowfall is a normal distribution). Now CPC considers equal chances to be 33% of the time always (except in extremely strong signals). If CPC then says 20% chance of below normal, all you are doing is shifting the distribution left. Below normal values grow at the expense of above normal, leaving equal chances untouched (until above normal values no longer exist).

 

If you think of a normal distribution then 33% of your data would be +/- 0.5 standard deviations from your normal value. BOS as an example normal is 43", then normal snowfall is anywhere between 33 and 53". Problem is that is a fairly narrow range (we're talking maybe less than 2" QPF over the course of 4-5 months). So if there is no signal, it's hard to definitively say which bin snowfall will fall into (above, below, or normal).

 

It is even more complicated if you see it even more black and white, as in 44" is above normal and 42" is below normal. That truly could be a coin flip, and a rogue snow squall difference. Equal chances.

 

post-44-0-23755500-1445003929_thumb.png

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Ran across the ASOS call in and web links page for ASOS if anyone is interested

http://www.faa.gov/air_traffic/weather/asos/?state=CT

 

On a related note, RKD got upgraded to an AWOS-C recently. And nobody knows what that is, but it's acting like an ASOS now (i.e. updates on the hour, can spit out a SPECI, reports present wx).

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No one wants to look at a map and see equal chances, or 33%.

 

In all seriousness, the public really doesn't understand what above or below normal means, but the majority of the complaints here are because no one wants to look at a map and see anything other than above normal (snowfall that is).

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In all seriousness, the public really doesn't understand what above or below normal means, but the majority of the complaints here are because no one wants to look at a map and see anything other than above normal (snowfall that is).

lol.

The forum collective wants 90% chance of above normal precip and 90% chance of below normal temps. That means there's still a 10% chance winter sucks though.

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