Do you trust weather long term forecasts ? How can they know ??

[TerryEspo]

I am looking at Accuweather for next month and don't like what I see.

How can weather people accurately forecast that far in advance ?

I am hoping people tell me they are "out to lunch" once guessing at 3 -4 weeks away.

Do I have good odds that what Accuweather says today about a day in March will be very different once that day arrives?

Fingers crossed the long term forecast comes from a Yatzee can of weather symbol dice !!

Terry

[odave]

I wouldn't trust anything longer than a 10 day forecast, and even that gets iffy beyond 3-5 days. I think I may start keeping track of the 10 day forecast temperatures and see how they do vs. actuals.

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[Cedar Eater]

Accuracy decreases the further into the future the prediction is for, but they've been looking at weather patterns with sophisticated modelling software and past and current data so they can calculate probabilities and then give the most probable as the forecast. I trust them to be not off by more than 20 degrees tomorrow, and then not more than 30 the next day, 40 for the next week after that.

[DoubleBrookMaple]

I have my own PWS (Personal Weather Station), a registered MADIS station on the CWOP, and can speak as a weather geek, that it is very dependent on your geographic location. I grew up in New England, and lived on the west coast for 35 years. The weather was VERY predictable, as everything came from over the ocean without any of the dynamics effecting air movements that you see over the mountains, across plains, or in your case lakes.
I live in the Green Mountains of Vermont, and it is unpredictable, and the forecasts in most of the sites are for 10-15 miles away, and at lower elevations.
I have 5 different weather sites bookmarked and sometimes review them all. For me the most reliable is the NWS site, as one can select a zone within a couple miles of your location, and it will compute temperatures and other conditions.
I personally use Weather Underground, and the NWS sites daily, but refer to the others including Accuweather on occasions, like impending runs.
Accuweather for me is not reliable,as it gives conditions and forecasts for some location that is unknown. Right now, Accuweather says the temperature in my town is -12. Weather Channel, WeatherForYou, and Weather Underground, all say -17, and that is what it is. In addition, Accuweather forecast is for a low on -16. The NWS forecast is -21, and it is before midnight and already -18 !!!
Anyway.... No, I do not trust anything to be within say 5 degrees beyond 6-7 days. You can see from my post on Forecast temps before the last run we had here that they were all quite close to the actual pemps until day 6, when it got much warmer than everyone forecast.. http://mapletrader.com/community/showthread.php?27072-Check-out-these-temps-for-5-days...-My-earliest-tapping&p=293717#post293717

[maple flats]

I only trust basic trends. This morning's forecast for example as of 10:00 last night, was to be -12, we are at -17. That's 5 off just 8 hrs out. They are the only profession I can think of that is wrong over 50% of the time and they still get well paid. There just seems to be too many variables and influences for the forecast to be very accurate.

[Russell Lampron]

I don't trust anything longer than 3 to 5 days out. I use The Weatherchannel, Weather Underground and Accuweather. I find the forecast's on The Weatherchannel and Weather under Underground to be the most accurate and that Accuweather is the most optimistic but least accurate. I don't know what your forecast is showing but if this turns out to be another year like 2012 I hope that I make more syrup than I did then.

[BreezyHill]

Long range is all about averages and the use of historical data to do a SWAG as to what could happen.

If you look at our accu weather long term and the actual temps they are pretty darn close. and majority of the precip has been fairly close to accurate.

Think back to 10 years ago when the farmers almanac predicted a large snow storm on Valentines day. We got 24" of white. It was the first storm we got as they predicted...how the heck you ask. Science and a we gee board. LOL


Don't for get SWAG is Scientific Wild A$$ Guess.

WAG is Wild A$$ Guess

I recall in 1981 we were all done and cleaning the evap on March 15.

This am was -18 and its only -14 at nearly 9 am with bright sunny skies. Not complaining just saying burr....but last year was far worse.

[log cabin luke]

if you want to see how inaccurate accuweather is you could do a little experiment like I did about 1 month ago. I printed out there 45 day forecast. I then compared it to the same forecast about 5 days later. It wasn't even close. It was like they had numbers that they just through darts at and put them up for a forecast.

[DaveB]

I'm a meteorologist and I don't trust any guidance over 7 days. The longest range models only go out 14 days with the best ones only going out 10 days. Anything beyond that is pattern based, heavily weighed towards climatological averages for the given pattern.

Having said that, the general pattern looks very favorable into March. The specifics depend on your specific location including elevation and other factors. Don't expect a forecast for a nearby city to be specific for your location.

[odave]

Question for the weather guys. When a Low temperature is predicted, is that the Low for the entire calendar day (i.e. from 12:00am to 11:59pm on 2/15/2016) or is it the Low for the "night" (i.e. sunset on 2/15 to sunrise on 2/16)?

[DaveB]

Question for the weather guys. When a Low temperature is predicted, is that the Low for the entire calendar day (i.e. from 12:00am to 11:59pm on 2/15/2016) or is it the Low for the "night" (i.e. sunset on 2/15 to sunrise on 2/16)?

It's usually for the day if you're looking at something like a calendar that says "high 45, low 15". Also, those are general numbers and not specific to any spot that takes local terrain and things like that in place. Usually a forecaster makes a call for a specific weather station, not a location. If you look at the NWS text forecast, it will give specific temperatures for different periods like night & day so that will have the low at night and high during the day.

[odave]

Got it - thanks!

[maplestudent]

there's a reason I call it Quaccuweather.

[DoubleBrookMaple]

Question for the weather guys. When a Low temperature is predicted, is that the Low for the entire calendar day (i.e. from 12:00am to 11:59pm on 2/15/2016) or is it the Low for the "night" (i.e. sunset on 2/15 to sunrise on 2/16)?
The forecast lows are for the overnight period ending somewhere near sunrise, and the low may be even shortly after sunrise. I watch 5 sources and that is what they all do. Weather Underground, National Weather Service, Weather Channel, Accuweather, and WeatherForYou.
You can see it on a graph on my personal weather station sight (just one of over 180,000)...
Today's forecast low of 9 degrees will occur at 6-7am tomorrow morning.
http://www.wunderground.com/weather-forecast/zmw:05350.1.99999

The NWS allows you to select your near exact location by clicking on a graphical map, and a computer makes adjustments for altitude, and maybe other factors. It also says a low tonight of 9 degrees, and that will occur near sunrise tomorrow.
http://forecast.weather.gov/MapClick.php?lat=42.80623247482152&lon=-73.01281929016113#.VsXcMfIrK_1

Most forecasts are for a region, and in my case are useless. I live on a west facing steep slope at 2000 ft, and it is 5-10 degrees cooler or warmer here at times than the regional forecasts depending on the conditions. Sometimes we get temperature inversions where the warm air rises from the valleys, but at other times it is colder down there, just 4-5 miles away.