Rain Arithmetic Problem

60 acre hillside · Sep 8, 2013

How many 20% chance fro rain will equal one good 2" rain ? It takes 100% to make a rain so it Skyhook engineer discovered 5 days at 20% should get us one rain. Three days at 50% will get a flood. Does it work this way?

donjr · Sep 8, 2013

Figure it this way. If there is a 205 chance of rain, by NWS standards, you have a 20% chance of 1/100 of an inch. Or a 50% chance of 1/100 of an inch. In other words, they're hedging their bet. They don't want to rule out a sprinkle. Even if it will ruin your day because you think it might rain for the next few days. I never knew how much hay I could lose until I got the weather channel They called for 20 or 30%, and I wouldn't cut hay when the next few days had a spit coming, and hay would have never been hurt. I solved the problem by turning the Weather channel off and looking at a National map......

casecollectorsc · Sep 8, 2013

Grandpa always said "more time wasted waiting for rain than actual rain". Neighbors are that way, can't cut cause it spose to rain. Pretty soon a week of dry weather has gone by and they could have been done.

Gene Stevens Tx-Oh · Sep 8, 2013

10% chance of rain = 90% chance you won't get any!

old · Sep 8, 2013

Well figure this one out. You get 15 inches of rain the first week of Aug but in the next 4 weeks less then an inch of rain and the heat index is 100 plus so we are now in a drought again. 3 inches the first day was good and the dry ground soaked it up. But then you get another 3 inches the next day so that runs off due to the ground being soaked full and that cycle goes on till you only have run off so 90% of that 15 inches goes down the creeks and rivers to the ocean so it does little good and now it is as dry as a popcorn fart

ldj · Sep 8, 2013

Lick your finger and hold it up. If it stays wet it is raining

Anonymous-0 · Sep 9, 2013

I just saw a story on this subject a few days ago. It said that when they give a 20% chance of rain, that meant that 20% of that particular area would recieve measurable rain. No amounts were promised, just "measureable", which in their terms means 0.01" or more. With that being said, we were told last Sunday that we had a 60% chance of rain for Tuesday night. Now in our area, 60% chance will usually get your hopes up pretty good, so we didn't start swathing proso millet until Wednesday morning (it DIDN'T rain on Tuesday night) because we were going to be in a dry pattern for the next 10 days. 0.18" on Thursday morning and close to an inch last night. So much for being right this time.

Dan T in MO · Sep 9, 2013

% chance doesn't add up. So 5 days of 20% chance ain't equal to 100% chance. Figure it this way. 20% chance it will rain today is 80% chance it won't. Each day, multiply the % chance that it won't and after 5 days, you have roughly a 33% chance of no rain. So you have a 67% chance of getting at least 1/100th of an inch in the next 5 days.

Rain Arithmetic Problem

60 acre hillside

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donjr

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casecollectorsc

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Gene Stevens Tx-Oh

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old

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ldj

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Anonymous-0

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Dan T in MO

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