Updated Weather Forks vs Utes

[PlainsUte]

Rain looking more likely, 70% chance during the game.   Wind, south 15-20 mph, becoming west 15-20 with gusts to 25 by the second half.  Cloudy and cool with kickoff temperature 61 F dropping to 52 by the end of the game.  Sunset 6:41 pm.

[salty-ute]

What does the percentage chance of rain actually mean? It seems like 50% means it will rain, and 90% means it will rain a s**t-ton. I’ve never gotten a satisfactory explanation for how to understand that metric.

[UtahFanSir]

50% chance of rain versus 90% chance of rain means the probability that rain will occur for the time period in question. The amount of rain is different. You could have 50% chance of a deluge, one that would require an Art to save the world, or not. Or 90% chance of just one drop or 10. That is how I take it. Ususally forecasts are done by the hour, once you get within a few days of the period in question. My take.

[PlainsUte]

Yes, what @UtahFanSir said.   More specifically given the same set of circumstances (in this case current weather conditions and current computer projections of the weather) 7-out-of-10 times it will result in measureable rain (0.01 inch or more) at a single point during the stated time period.  It says nothing about the intensity.   In this case thunderstorms are not expected so lighter amounts are expected.

I can also say, in this case, the chance of rain in the 2nd half is greater than in the 1st half.

Incidentally the probabilities should approach 0 or 100 as we get closer to the forecast period. That is not an inconsistency, just acknowlegement that as we get closer to the event time confidence in whether it will rain (100) or not rain (0) will increase. There are some days when confidence may never get higher than 70 or lower than, say, 30 — these situations can happen in summer, especially.

What does it all mean: take a good rain coat to the game. You’re more likely to use it than regret the small effort of carrying/wearing it into the stadium.

[Mr Chainsaw]

I remember reading once (“The Signal and the Noise” by Nate Silver I think?) that many weather forecasters will assign a minimum of 20% chance of rain even if the percentage comes out to be something less (like 5%).  There is a psychological factor in play.  People get upset if it rains when you there is a 5% chance but don’t get upset if it doesn’t rain when you say there is a 20% chance.  

[PlainsUte]

CYA can happen in human forecasts, though 20% seems like a high CYA value, but might be a common summer number in more humid areas or in mountainous areas. Some of this is a cost vs reward issue.  If you cause someone to grab a coat or umbrella and it doesn’t rain, that is a very small cost to them to be prepared, just in case, and they won’t be upset.  Whereas if they are pouring concrete or ripping off a roof to replace it and it rains, high cost, they ought to be sensitive to even low probabilities yet they might totally ignore a 4% chance forecast as “near zero”.   If they ignore a 4% chance 25 times they’re likely get rained on once at a potential high cost.

Of course if someone completed cancelled an event because rain was forecasted it could be a high cost, but people generally don’t completely cancel events unless particulaly severe weather is forecasted.

[AZUTE]

It’s called P O P.
Percentage of participation
A measurable amount of .01 inch or more in your forecast area

[Tony (admin)]

Not brutally cold, but the wind and rain could be a bugger. Nice weather for Scotland though.

[Tony (admin)]

What about weather before, as in tailgating?

[PlainsUte]

Tailgating may come off without rain, just the south wind. Rain is most likely around 6pm-9pm when that wind shift/front comes in and just behind it.

[Utahute72]

Watch channel 2 the night before the game, they do a really good job of translating those percentages to projected amounts by local areas.

[homer]

How much do we need to pay you to swap these weather patterns?

If it’s gonna rain, how about making it rain during my work week and have yesterday weather hit my days off?

You weather guys always messing my schedule. . .😉

[PlainsUte]

All my powers are focused on good weather for the game that I’m attending this weekend – happy wife, happy life and all that 😉

[Utahute72]

One reason you generally see more rain with higher percentages of rain is the calculation to determine that percentage. A number of inputs are uses like temperature and pressure, but a major factor is the amount of water vapor in the system, either as humidity or cloud cover. So obviously if there is more water vapor to precipitate out, there a a greater chance that you will get more rainfall. Not always true, because there are other factors, but it’s why most people equate higher percentage with more rain.

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