Ahhh so easy to understand now thanks Idefix you are doing a great job :-)

Hi, I wonder the meaning of these two times and which one should I use

Let say that I am looking at NEW SNOW layer using the picker for my location.

If I choose let say 12hrs / 24hrs / or 3 days

The 24 hrs are starting at the reference time or at the last update of the model ?

In my case here reference time is 00.00.00z
but the last update was 3am easter time

Zulu reference time and update time arent matching obviously

so the 24hrs new snow forecast start at Z time or 3 am eastern time ?

Finally what the reference time purpose is ?

thanks guys and sorry for my broken Frenchglish :-)

@idefix37 Ok great thank you !!! There is always something to learn ...its a lot more complicated than The Weather Network but its more fun :-)

@idefix37 Ok I think I got it , since english isnt my first language let see if I really got it : The snowfall forecast is telling me in theory the intensity of the snow fall EG, 1 cm per 3 hrs or 0.6 per 3 hrs etc etc , am I right ?

Now if I use the picker with the NEW SNOW layer I'll get the approximative accumulation at the rate of 1mm of water for 1 cm of snw without taking into account the real density of the snow , am I right ?

Finally , the SNOW DEPTH is the most realistic amount of snow that we will get ? Am I right ?

Where I am not sure again is, if I look at the picker now for my location on Tuesday feb 18 it says, snow depth 42.8 cm according to the snow fall and the density of the snow determined by the model, so I am assuming that it is the total amount of snow and height we have received so far up to feb 18 this winter, am I right ?

so for 18 hrs on the same day we are supposed to get according the the forecast apprx 13.9 cm so if I started the day with the snow depth picker at 42.8 and if I add 13.9 , the snow depth would be 56.7 by the end of the day on tuesday, but since the density of the snow vary, the snow depth layer picker is giving me 51.4 , so in reality the amount of snow received would be ( 51.4 - 42.8) 8.6 cm instead of the 13.9 shown in the forecast, am I right ? .... ok I have an headache, what about you ? :-) anyway thanks a million for your help Idefix

Hello, what is the most reliable way to look at new snow ? If I look at the forecast for my location the total of the forecasted snow equal let say 15 cm over 24 hrs , so they may say .3cm at 3 then 1.5 at 6 than .9 at 9 and so on and the total will be 15cm. Now if I use the new snow icon with the picker for the same period they say 17.5 or else, the number are never or rarely the same ... why is that ? what is the most accurate number, the one under the picker or the one described in 3 hrs segment in the forecast ? Thanks !!

Korina thanks !! Let me ask you 2 more please ... what is the difference between the reference time and the forecast time ? Im in eastern canada , the reference time shown is changing twice a day at 00:00:00z (19Hr) and 12:00:00z(7HR). However ECMWF seems to update twice a day at 3am and 3 pm eastern time . Even if I convert the forecast time reference time and reference time , the hours dont match . Last question. For the total new snow, should I really look at the reference time or at the last update of the forecast time for the most accurate reference ? Thanks !!!!

Got it, thanks again !!

Reference time being the last update of a particular model ? Ok Thanks ...why I didnt figure that out by myself :-) anyway thanks again

@Gkikas-LGPZ Tell me now , the 24hrs period started at the exact time you are looking at the map, or at 00.01 of that very same day ? Also, often this map is not showing the same amount of precipitation to receive when compared to the main forecast page for my location where it shows the precipitation by the 3hrs period.... why is it that ? Thanks

Hi, wonders how to read this. When looking for the new snow accumulation how should I read the 12 hrs / 24 hrs / 3 days etc . I wonder if per exemple if the 12 hrs is from the time I am watching or if it is from midnight of the same day. IM asking because if I look at my forecast they say 10 cm between 3pm and 9 pm m but if i look for the next 12 hrs they say 2.5 cm .... so when I should start to use the 12 hrs forecast if its per exemple its 10am ? For the next 12hrs or from the midnight before or at noon of the same day or at midnight .... Ive tried many way to look at it and the forecast for new snow seldom match the 12/24/3/5/12 daus of precipitation page thanks