Pocket grib

ghostlymoron

ghostlymoron

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I've been using this phone app for a few weeks both UK and in the med. I've found it very useful although it doesn't do all it claims. Temperatures and wave heights aren't shown. I now have the paid for version which gives 5 days forecast (but with decreasing accuracy as with any forecast). Does anyone else use it and do they share my experience?
 
ghostlymoron said:
I've been using this phone app for a few weeks both UK and in the med. I've found it very useful although it doesn't do all it claims. Temperatures and wave heights aren't shown. I now have the paid for version which gives 5 days forecast (but with decreasing accuracy as with any forecast). Does anyone else use it and do they share my experience?
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I have been using Pocket Grib (paid version) iPad and iPhone in Greece for a couple of years. I like being able to see the patterns of the wind forecast over several days, and particularly how the wind varies at night. The rain forecast has been very accurate in Preveza this last week, and the pressure charts are useful - you can see a big fall coming.
We also use Poseidon which is better because it adds local info on top of the gribs, but Poseidon is not always reliably up to date.
 
Remember that Windguru, PocketGrib and many others are just different displays of the same information.

Poseidon is based on the same data but it does use a smaller grid length and so can represent topography better.

I do not think, but cannot be sure, that Poseidon uses a detailed data analysis. Their prediction of weather detail, therefore, is compromised.

The Greek Met service does say that they start with a detailed analysis. So does the Croatian service.

I think that you will get a better service than Poseidon, PocketGrib, Windguru or any that you pay for by using
http://212.175.180.126/DTS/sea.php. Although issued by Turkey, it is ECNWF output. They have the best global model and it runs on the smallest grid (0.125 degree lat/lon) of any. The data are at the model grid points. The US GFS (ie PocketGrib etc) uses a 0.25 degree grid but only provides data on a 0.5 degree grid.

Links to many (most?) services of these kinds are at http://weather.mailasail.com/Franks-Weather/Grib-And-Objective-Forecasts-Reviewed.
 
scoty said:
WINDFINDER
I find very reliable,,,,gives two diferent posibilities for personal interpretation, been using it in the spanish Med, almost 8 years
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Windfinder uses the US GFS as their “large area” forecast. Their Superforecast model starts with the GFS. They use no more input data but interpolate to a 11 km grid. They handle topography quite well but lack any detailed weather input.

The Turkish/ECMWF forecast at http://212.175.180.126/DTS/sea.php should be better. I say that because ECMWF analyses and outputs on a 0.125 degree grid. The GFS is far coarser. ECMWF take more time over their data analysis. That gives them a lead over the rest. The downside is that they run their models a little later and only twice a day.

For the next 24 hours, I would expect the Spanish, http://www.puertos.es/content/prediccion-del-oleaje-mapas, perhaps the Italians, http://www.lamma.rete.toscana.it/modelli/vento-e-mare, the Croatians, http://prognoza.hr/nauticari_e.php?id=jadran&param=uv10_&it=03 and the Greek surface wind maps, http://www.hnms.gr/hnms/english/navigation/navigation_html all to outperform Windfinder. Beyond 24 or so hours ECMWF is almost certain to come out best on average.

Having said all that, Windfinder nor any of the others will greatly mislead you. In general terms none will be markedly better than any other. Which you prefer will largely depend upon which presentation you prefer rather than the quality of the forecasts.

One point I will make is that there is no point in paying for allegedly “precise”, “accurate to 1 km” etc forecasts. They will be no better than the free services. They are unlikely to be better than those that I have given links to above. Like Windfinder most, if not all, will be based on the GFS. None, as far as I am aware, starts with as detailed analysis as the ECMWF nor the other national Met services that I have mentioned.
 
Hi Frank,

As ever your replies and comments are most enlightening. What you say confirms my own understanding of these services. Whilst I like to use pocket GRIB it is only as an over view of what might happen. I still find that the MSLP and 500Mb charts give me the best look at what is likely to happen.

Simes
 
Simes said:
Hi Frank,

As ever your replies and comments are most enlightening. What you say confirms my own understanding of these services. Whilst I like to use pocket GRIB it is only as an over view of what might happen. I still find that the MSLP and 500Mb charts give me the best look at what is likely to happen.

Simes
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Although some GRIB Apps do give other models, they all give the GFS as the main source. PocketGrib is no exception.

Agreed that surface charts are worth keeping an eye on. I find upper air charts, jet stream etc are more for interest than much real use these days. After all, the models know about weather at all levels and all the information that we tried to use when I was first a forecaster, are taken fully into account. I have a dog, so why bark myself?
 
My understanding of grib files (limited) is that they are what all weather forecasts are based on. So as long as the info is presented in a comprehensible form, it doesn't matter whose app you use. Pocket Grib suits me, its very quick to download the forecast as long as you've got wi fi access. And the presentation is good.
Its important to remember that whilst the forecast for the next few hours is likely to be spot on, day five is unlikely to be so good.
 
ghostlymoron said:
My understanding of grib files (limited) is that they are what all weather forecasts are based on. So as long as the info is presented in a comprehensible form, it doesn't matter whose app you use. Pocket Grib suits me, its very quick to download the forecast as long as you've got wi fi access. And the presentation is good.
Its important to remember that whilst the forecast for the next few hours is likely to be spot on, day five is unlikely to be so good.
Click to expand...


Correct. And, if I was using an iPad, PocketGrib would be my choice for the same reasons. As I usually use a laptop, I use zyGrib.

There are some slightly different GRIB files - COAMPS is one, that run on shorter grid lengths and shorter times.

There are similar products that require browsers - iPad or laptop which are better than the GFS. see one of my earlier posts,
 
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