Boundary Waters Quetico Forum :: Gear Forum :: inReach weather forecast issues
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walllee |
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timatkn |
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mpeebles |
Off topic a little, it's a great communication device and I love the Earthmate app. Safe travels........ |
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gravelroad |
WhiteWolf: "Interesting topic especially being a weather professional. Here in the states Nation Weather Servive probability of precipitation is based on a grid system, ( I believe between 25sq miles (( urban areas)) and up to 100+ sq miles or more in remote areas of the US. What the probability of precipitation means is that if their is a 50% chance of showers or whatever - that the forecaster expects roughly 50% of the grid system to receive at least measurable amount of (in this case rain) - measurable mean more than a Trace. If roughly 50% of the grid received measurable rainfall the forecast is considered to have been very good. But for that 50% of the grid that saw Trace or nothing are left wondering what happened. So it's more a coverage thing and not so much amounts. The 0-10% chance sounds a little low but maybe the grid system (if used by Inreach ) is so large in the above examples that it was just an unlucky 10% of the grid. Like pop up thunderstorms in FL, but something seems amiss, POP ( Probability of Precipitation ) is probably the one weather forecast element that depends most on human interaction. My .02 Actually, the probability being expressed is something different: “The "Probability of Precipitation" (PoP) describes the chance of precipitation occurring at any point you select in the area. How do forecasters arrive at this value? Mathematically, PoP is defined as follows: PoP = C x A where "C" = the confidence that precipitation will occur somewhere in the forecast area, and where "A" = the percent of the area that will receive measureable precipitation, if it occurs at all. So... in the case of the forecast above, if the forecaster knows precipitation is sure to occur ( confidence is 100% ), he/she is expressing how much of the area will receive measurable rain. ( PoP = "C" x "A" or "1" times ".4" which equals .4 or 40%.) But, most of the time, the forecaster is expressing a combination of degree of confidence and areal coverage. If the forecaster is only 50% sure that precipitation will occur, and expects that, if it does occur, it will produce measurable rain over about 80 percent of the area, the PoP (chance of rain) is 40%. ( PoP = .5 x .8 which equals .4 or 40%. ) In either event, the correct way to interpret the forecast is: there is a 40 percent chance that rain will occur at any given point in the area.” Explaining “Probability of Precipitation” |
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boonie |
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AmarilloJim |
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TechnoScout |
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ArrowheadPaddler |
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mpeebles |
Safe travels......... |
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AmarilloJim |
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ArrowheadPaddler |
With rain in the forecast tonight for Duluth, I did a little test this afternoon comparing the National Weather Service and inReach forecasts. The NWS had 100% probability of rain overnight, and the inReach 70% heavy rain. Although they didn't agree precisely, the two forecasts were similar in a general sense. The NWS is calling for about 1" and the inReach about 1.75". Radar now shows a huge blob of precip moving towards Duluth. Along with others' experiences, this gives me more confidence in the device. Must have been luck of the draw, or lack thereof on our trip. Still had a wonderful trip, beautiful area. |
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WhiteWolf |
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WhiteWolf |
Forecast Advisor |
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jillpine |
ArrowheadPaddler: "Thanks for the responses everyone, sounds like most of you have had positive experiences. I am not sure what location it was drawing the forecasts from. I was updating my position for every weather request, but maybe as some of you mentioned, the forecast was for a specific location that may not have been nearby. I will look into it some more, perhaps will send an email to the company." Other than a really long wait time (like half-hour), the phone support I received was outstanding - resolved the issue immediately (stuck synchronization with iPhone). After solving the issue, the rep then went on to suggest some additional helpful tips and resources for using the device. Maybe that route may help your question. |
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ArrowheadPaddler |
WhiteWolf: ") I stumbled across this site -- Forecast Advisor-- that will also show you the accuracy of the major weather forecasters, including Accuweather, The Weather Channel, WeatherBug, Weather Underground, CustomWeather, Foreca, and the National Weather Service. ( Dark Sky also)--- kind of cool to play around with though I would really like to see an examination of forecasted snow/rain amounts from 1-3 days out compared to what actually accumulated. I think most of the apps in that regard what fall well below NWS accuracy - but that is just me. Interesting site, although I wasn't expecting the NWS to be so low on the list. They seem to be the most accurate of weather prediction sites, or maybe that is just my perception. |
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Marten |
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TechnoScout |
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jillpine |
Opposite experience - impressed with the accuracy with respect to precip, wind and temps ("basic" not premium). n=6: 3 BWCA area (EP's: sawbill, baker, cross bay EP's and associated areas) and 3 NW Wisconsin (Washburn, Bayfield and Polk counties). Maybe it's location? |
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Jaywalker |
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WhiteWolf |
PRECIPITATION PROBABILITY The probability of precipitation forecast is one of the most least understood elements of the weather forecast. The probability of precipitation has the following features: ..... The likelihood of occurrence of precipitation is stated as a percentage ..... A measurable amount is defined as 0.01" (one hundredth of an inch) or more (usually produces enough runoff for puddles to form) ..... The measurement is of liquid precipitation or the water equivalent of frozen precipitation ..... The probability is for a specified time period (i.e., today, this afternoon, tonight, Thursday) ..... The probability forecast is for any given point in the forecast area To summarize, the probability of precipitation is simply a statistical probability of 0.01" inch of more of precipitation at a given area in the given forecast area in the time period specified. Using a 40% probability of rain as an example, it does not mean (1) that 40% of the area will be covered by precipitation at given time in the given forecast area or (2) that you will be seeing precipitation 40% of the time in the given forecast area for the given forecast time period. Let's look at an example of what the probability does mean. If a forecast for a given county says that there is a 40% chance of rain this afternoon, then there is a 40% chance of rain at any point in the county from noon to 6 p.m. local time. This point probability of precipitation is predetermined and arrived at by the forecaster by multiplying two factors: Forecaster certainty that precipitation will form or move into the area X Areal coverage of precipitation that is expected (and then moving the decimal point two places to the left) Using this, here are two examples giving the same statistical result: (1) If the forecaster was 80% certain that rain would develop but only expected to cover 50% of the forecast area, then the forecast would read "a 40% chance of rain" for any given location. (2) If the forecaster expected a widespread area of precipitation with 100% coverage to approach, but he/she was only 40% certain that it would reach the forecast area, this would, as well, result in a "40% chance of rain" at any given location in the forecast area. |
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ArrowheadPaddler |
Marten: "We just returned from just north of the Bloodvein River in Manitoba. InReach weather was right on for three weeks." Well, I guess that settles the question as to location. Sounds like it was largely just luck of the draw with the bad forecast. Otherwise, the device performed flawlessly. Thanks for the tip on precip amounts Marten, hope you had a good trip. |
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ArrowheadPaddler |
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WhiteWolf |
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Marten |
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ArrowheadPaddler |
AmarilloJim: "OT question. Do you have to send messages to an e-mail or can you text a mobile phone?" You can send messages to either a mobile phone or email address. If desired, you can send and receive the messages from your own phone with the inReach app. It requires a bluetooth connection. I just use the device itself. If you were composing long messages, the smart phone app would be more convenient. You also can download high resolution maps view on your phone to use with the GPS function on the device. There is a built-in GPS, but the resolution is a little low. For most uses, though it is just fine. |
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egknuti |
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andym |
The "persistence" forecast is pretty good for San Francisco. It is downright lousy for Ely. Giving credence to the bring your rain gear into the BW no matter what advice. For both areas, the Weather Channel (which provides the weather for the default iphone app) beats Dark Sky, sometimes by a meaningful margin. |