Author Topic: Erroneous Weather Forecasts  (Read 587 times)

nontpremlapi

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Re: Erroneous Weather Forecasts
« Reply #15 on: January 23, 2018, 03:46:21 PM »
To the OP.

Yes, it is.

Danny Rodriguez

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Re: Erroneous Weather Forecasts
« Reply #16 on: January 23, 2018, 05:52:17 PM »
Quote
I have been trusting the Clear Outside website lately.
But it can get it wrong too.
I am glad of the website's existence because I can key in my city (Dublin, Ireland).
But recently I set up my 158 mm apo before sunset.
Clear -Outside stated all day that the night in question was going to be clear.
However after my evening dinner I went out for an observing session, and found the sky almost completely overcast!
I then went back inside to discover that the website had been updated to 90% overcast skies!

I reckon some nerd woke up to realise he had made an error.
And accuweather are just as bad.

I reckon they all ought to be fined!

Aubrey.

Fined! How about fired?

Martin.

maogrinjorli

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Re: Erroneous Weather Forecasts
« Reply #17 on: January 25, 2018, 07:20:14 PM »
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Brownsville Tx would be good tonight. Florida maybe. Check water vapor found at bottom of this link.

http://www.goes.noaa.gov/browse.html

thanks for the reminder. It's been so cruddy here (at night of course, sunny during the day) that I stopped checking.

Marcus Kucrud

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Re: Erroneous Weather Forecasts
« Reply #18 on: January 25, 2018, 09:19:45 PM »
My weather is such I can't really care about "details" like seeing and transparency. So I just use normal weather forecasts to find out if there are any possible cracks in the cloudy periods. The predictions are very far better than nothing. So this is much about how much you expect the computer models, and the people working on them, to find out exactly how your local weather will be. The computers, measuring devices and models just need to get stronger for greater accuracy, a gradual process. Who says 2017 is the year? We are talking about global partly chaotic systems. The forecasts are just as good as they are, why would I be upset about that? Thinking there's some conspiracy?

I recommend using probability functions in the weather forecasts if possible. Gives perspective what to expect. Using more than one forecast plays partly the same role. OP, did you check out what for example Meteoblue predicted for the same time?

trimarnado

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Re: Erroneous Weather Forecasts
« Reply #19 on: January 31, 2018, 12:41:04 AM »
I don't have much luck with the forecasts. Theyget it about 75% wrong (and that is generous) this time of year, coin flip would beFAR more accurate. I will try to plan two or three nights out and they show night 2 as cloudy, night 3as clearandthe result isusually the reverse. Long range they show 1night of clear and 4 of cloud and instead I get two nights cloud (alwayson the onlyonethey predicted would be clear) andthen two nights of clear they didn't predict even 12 hours in advance each time, with the fifth night being a mix. Moving closer with the 1 day they change several times a day for the evening forecast and still miss by a mile on cloud cover/transparency. I ignore the specific forecasts,look at the trends and incoming cloud patterns via satellite,then at the sky and out to the mountains and into the valley at points I use as observing spots. Often I can tell if the mountains are likely to be clear either for the first 4 hours or the subsequent 4 hours. I can also tell if the valley spot north of me is going to be socked in with cloud/haze.

This time of year I make my call on whether or not to observe around sunset. That usually means losing several hours of dark sky time on a good night, but it avoids a lot of wasted trips where I get out look at the now fully overcast sky for a few minutes naked eye, then drive home. Or setting up observing one or two objectsthrough sucker holes before being completely clouded out.  My busted trip fraction isvery low as a result, no thanks at all to theprofessional"forecasting". Instead it comes from watching the skies, looking at the patterns, and being agile in my planning.

One of the more common aspects of agile planning and poor forecasting is that I get a string of consecutive nights that are usable even though none were forecast.Good news/bad news. They will be forecast as overcast several nights in a row, each night, and instead they end up clear even if the transparency is marginal some of them. I have become more flexible balancing other things with astronomy. My gear is half loaded and the mirror box is cooled/ready so I pack up late when the nightly pattern appears set and head to my spot.The first night is easy, the second night is tiring (since unplanned), and by night three I am tuckered out...but I alsoknow thatit might very well be the lastgood night of the moon phase soI better make use of it even if I decide to only do a half session.

To be fair, when I lived in the Midwest and East Texas the forecasts were much more accurate over a 48 hour stretch...and some of that was decades ago. Out here...well, they don't get much severe weather and their short/intermediate/long range forecasting doesn't need to be as good...and it isn't.

vuicapathvie

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Re: Erroneous Weather Forecasts
« Reply #20 on: January 31, 2018, 02:14:45 AM »
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... Using more than one forecast plays partly the same role. OP, did you check out what for example Meteoblue predicted for the same time?

Viewer, no; I didn't know about 'Meteoblue' but, thanks to you, I do now.
I booked marked that and will include that in my daily checks - thanks!

pesorramidd

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Re: Erroneous Weather Forecasts
« Reply #21 on: January 31, 2018, 08:23:16 AM »
I forecast that it will be clear whenever the moon is near full. Seems to be correct 90% of the time. Also, I forecast that it will be cloudy when there's a special event happening in the skies that I want to observe.

Abdullahi Archer

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Re: Erroneous Weather Forecasts
« Reply #22 on: January 31, 2018, 12:19:09 PM »
Wait till you live where its 75*f today with 6 inches of snow by morning....happens almost every Winter.

bardersgarli

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Re: Erroneous Weather Forecasts
« Reply #23 on: February 02, 2018, 07:12:07 PM »
...Or -20*C (that's warm) with a foot of snow, like where I live.

Martin.

pensranbafarc

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Re: Erroneous Weather Forecasts
« Reply #24 on: February 02, 2018, 08:53:01 PM »
I recall the 2017 solar eclipse like it was yesterday ... well, it almost was. I began paying attention to our local forecasters in Lexington as they began devoting time to the forecast in West Kentucky (Hopkinsville), about a four hour drive to the SW. August is a dicey time to predict clear skies, or at least 80 % + chance of clear skies. And there was a lot riding on getting it correct. Anyway their forecast held, and everyone of the 10s of 1000s that made their way here were treated to one of the most dramatic natural (or otherwise for me) phenomenon seen by we mortals. They kept tweeting the forecast, but the general conditions of clear and hottish, with thunderstorms rolling in the night of the solar eclipse day, and extending to the next day held. Had the eclipse been one day later, most of the country would have not seen it, or at best only through peep holes in the clouds.

I realize the meteorologists were really studying the patterns, current, near-current and historic data for this, but overall they do a great job, imo. Planetary science is chaotic and dynamic, they do well. It was great when I lived in FL and went through three direct/very close hits by hurricanes none caught us off-guard/surprised with time to prepare. I also find CSC do well enough for me to plan both here at home and for my acreage located about 85 miles to the SSE.

Randy

rarisata

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Re: Erroneous Weather Forecasts
« Reply #25 on: February 04, 2018, 01:36:20 PM »
A number of years ago a meteorologist from Penn State gave a talk at an ASH meeting. He said that the factor that was the most accurate in weather forecasts was temperature.

Dave Mitsky

Ben Marquez

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Re: Erroneous Weather Forecasts
« Reply #26 on: February 09, 2018, 01:15:06 AM »
Been using Meteoblue for the last couple of months and am happy with it. I don't pay much attention to their special Astronomical Seeing section, though.

It's usually dead on with winds...to the hour. We get crazy winds and it mentioned today that the wind would get near 50 around 2pm. It was dead on, as usual. Some of the gusts sound like a freight train! This is the third day in the last week that it nailed the highest wind gusts down to the hour.

The best part of the site is the Satellite cloud cover map that will animate the prior 4 hours. I watch it all the time.

isanruptysp

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Re: Erroneous Weather Forecasts
« Reply #27 on: February 09, 2018, 10:09:33 AM »
I've thought about this as well. You'd think they'd be better at forecasting within 24 hours. Generally they're pretty good about predicting precipitation and catching major weather events (high winds, severe weather, etc), but cloud cover seems to be particularly unreliable.