It is currently May 25th, 2019, 12:27 am

All times are UTC - 5 hours




Post new topic Reply to topic  [ 8 posts ] 
Author Message
PostPosted: August 29th, 2018, 10:13 pm 
Offline
User avatar

Joined: March 30th, 2010, 4:10 pm
Posts: 309
Location: Ringwood, NJ
I wonder if it's just me or anyone else has issues with InReach forecasts like this one: Tomorrow heavy rain, chance of precipitation 10%, rainfall total 0.1". Or: moderate rain, chance of precip 20%, rainfall total 0.01.
In reality it could translate to anything from clear skies to non-stop showers and thunderstorms for the next 24 hours. I have to admit that COP below 10% and above 30% usually could be relied upon, but my forecasts more often than not come with 10% COP, which renders them more or less useless.


Top
 Profile  
 
PostPosted: August 30th, 2018, 7:29 am 
Offline

Joined: February 12th, 2008, 6:01 pm
Posts: 424
Location: North Bay, Ontario
Don't know about InReach forecasts in particular, but my understanding is that the % figure can be interpreted as the proportion of the forecast area that will experience precipitation in the forecast time period. So, if you are in the forecast area (which you certainly are for an InReach forecast), and the POP is 10%, you have a 1 in 10 chance of experiencing precipitation. The "heavy" or "moderate" would refer to the amount of precipitation you would experience IF you were in the lucky 10%.

At least that is the way it has been explained to me...

Kinguq.


Top
 Profile  
 
PostPosted: August 30th, 2018, 7:58 am 
Offline
User avatar

Joined: March 30th, 2010, 4:10 pm
Posts: 309
Location: Ringwood, NJ
That explanation would make total sense except for one thing: I won't imagine that 90% of the neighborhood is dry for 16 hours in a row while it's raining cats and dogs where I am. Of course the "area" could always be defined wide enough to make it possible, but InReach is expected to provide local forecast, not an average for the whole province.


Top
 Profile  
 
PostPosted: August 30th, 2018, 10:44 am 
Offline
User avatar

Joined: August 5th, 2013, 6:48 am
Posts: 158
Just returned from a 16 day trip in Atikaki in eastern Manitoba and really liked the In reach forcast. I learned to ignore the rain part and relied on the% and amount. I found it amazing how accurate the 6 hour intervals were.

_________________
http://www.youtube.com/user/TheNorthwoodsman1


Top
 Profile  
 
PostPosted: August 30th, 2018, 2:29 pm 
Offline
User avatar

Joined: May 5th, 2015, 2:14 pm
Posts: 65
Location: London, ON
I believe the percent chance is interpreted as follows: given the current atmospheric conditions, precipitation has fallen XX% of the time in the past with similar atmospheric conditions.

Having said that, I agree the percentages as not very accurate. In my experience, it's rained 30% of the time when it forecast 10-20%, and pretty much 100% of the time with 30-50% forecast.

M


Top
 Profile  
 
PostPosted: August 30th, 2018, 3:28 pm 
Offline
User avatar

Joined: December 19th, 2006, 8:47 pm
Posts: 8890
Location: Rattlesnake Pond ME
Eddy Turn wrote:
That explanation would make total sense except for one thing: I won't imagine that 90% of the neighborhood is dry for 16 hours in a row while it's raining cats and dogs where I am. Of course the "area" could always be defined wide enough to make it possible, but InReach is expected to provide local forecast, not an average for the whole province.

It happened here yesterday . Poured for 30 minutes.. Confined to 1 square mile. Our local forecast was 10 percent POP but if it did would be heavy ( got about.5 inches)
Up north a tornado and horrific t storms in a swath about 30 miles long and 2 miles wide. No one else got storms or rain

It could be geography.. We get some interesting effects.


Top
 Profile  
 
PostPosted: August 30th, 2018, 5:46 pm 
Offline
User avatar

Joined: February 17th, 2014, 11:51 am
Posts: 274
Love the in-reach forecasts! In past, I used to download 14 d weather forecast day before going into the bush. Day 12 comes by and I'm working off a 12 d old forecast which is about as accurate as....[insert personal joke here]. Anyhow, being out there and downloading a new set of weather forecasts every couple of days is worth the price of the sat. subscription IMO. In Reach is an awesome tool, worlds ahead of spot, not quite a Sat. phone, but very affordable. What more could you possible want?


Top
 Profile  
 
PostPosted: September 6th, 2018, 4:24 pm 
Offline
User avatar

Joined: June 20th, 2001, 7:00 pm
Posts: 3422
Location: Toronto, Ontario Canada
Weather forecast via InReach have changed paddling (for me) in amazing ways! Now I am talking about long trips, for a week or less they are of less critical use.

It does take a little bit of time to learn how to interpret and generally speaking like any forecast it's only accurate for 24 hours, declining reliability after that. On my recent 51 day trip I did "splurge" on the 7 day premium forecast but it wasn't useful past 2 days. On the other hand the first 24 hours or so is hourly which for wind direction and speed is very useful to me. Besides telling me what to expect for tomorrow on the water I also found it very good info for selecting campsites, specifically ones that would give some protection from the wind not just that night but the next morning or day if being wind bound was a possibility.

You have to look at the details pages, the summary page is kind of useless and you also need to combine all the factors such as barometric pressure and wind direction and combine that with historic behaviour in that particular part of the world.

There were numerous times when the days forecast (in 2 hour blocks) proved to be extremely accurate, there would be many times when I find it accurate to +/- one hour.

As far as the percentages, rain less than 30% isn't meaningful, and cloud cover is similar, anything greater than 20 or 30% means it's likely you may see virtually no sun at all. On the other hand a 10% chance of 1mm or less means you might get a brief sprinkle if that.

Again much of my use is for wind speed and direction, as a solo paddler on big open bodies of water or long stretches of big water Class II/III rapids wind is the only thing that really concerns me and is the primary factor in deciding if I will be paddling or laying over tomorrow. I generally get my forecast late at night or when I wake up in the middle of the night.

The further out info is of some use in deciding just how far I might want to get today because there is a chance the day after will be a no travel day.

As far as the descriptors like heavy, moderate or light, not very useful.

I use the InReach for chit chat and tracking purposes, neither of these really impact my paddling at all but I do enjoy that aspect as well as the ability to SOS but it's the weather that really counts and I would have an InReach now even if that was the only thing it did.

I do wish they offered Gust speed as well as Sustained speed, a day where sustained are under 20kmph I will paddle but if I knew gusts would go to the high 30's or more that would change my thinking especially for rapid running (I am talking about rapids that take 20 minutes plus to run and where quick navigation is critical to a safe run) or an open crossing on a large lake of 5 - 10km.

If I ever get around to writing up a detailed report on my recent trip there will be lots of comment about how forecasts from InReach affected my paddling decisions. On that trip I had 15 (I think) layovers days, at least 12 of those were partly or entirely due to weather considerations especially in areas where it could be 10+km (2+ hours) at any point in a day to find a camp location that was at all feasible. For a small river or small lake/river trip with tons of acceptable camping it's not so important.

_________________
"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group