Potential for wind and snow (NW) 4th, 5th December - DISCUSSION ONLY

Deep Easterly

Deep Easterly wrote: »

it really is odd why met.ie used 'recent snow' in the report when it was obviously sleet by our standards. I am flummoxed anyways!

Just thinking about this further, I wonder does code 83 also represent snow and rain falling at separate intervals in the time leading observation report as well as snow and rain falling together at the same time? In one of the showers earlier this morning, we had rain starting off, then rain and snow falling at the same time, which then turned into snow fully before clearing away (which it did, quite quickly). Overall, I would have classed this particular shower as being 'sleety' despite the fact that snow proper fell for a very brief period, but I am not an official observer. So, if the same type of showers occurred at Belmullet (rain, then sleet turning to snow briefly) then does code 83 allow for this, and still be in line with the 'recent snow reports' as seen on met.ie??


Who knows.. !!

Edit: just looking at the 00z synop as well, Code 26 is down for present weather which is 'Showers of snow, or of rain and snow' (in the preceding hour) in the WMO guide, which doesn't really help either as not very specific. (72682)

Su Campu

Remember, code 83 refers to present weather, so it says nothing about the hour leading up to the observation. The fact that it is used instead of 85 or 86 means there was snow mixed in with rain, i.e. Sleet.

Using 26 would mean the same thing happened, only it was stopped by observation time. Otherwise they would use 25 (recent rain showers).

Deep Easterly

So the 'mixed' used in codes 83 & 84 is a fixed rather than loose term. Code 26 for example does not use this definition but uses instead 'showers of rain & snow' whereas 83 and 84 state that the showers are 'rain & snow mixed'.


I'll get it yet.

Here is one coded weather report that we are unlikely ever to see being reported from Belmullet: 73590

Su Campu

Deep Easterly wrote: »

So the 'mixed' used in codes 83 & 84 is a fixed rather than loose term. Code 26 for example does not use this definition but uses instead 'showers of rain & snow' whereas 83 and 84 state that the showers are 'rain & snow mixed'.


I'll get it yet.

There are only 10 codes available for reporting "Past weather" (20-29), whereas there are 60 to chose from when reporting "Present weather" (40-99).

40-49: Fog
50-59: Drizzle
60-69: Rain
70-79: Snow
80-90: Showers
91-99: Thunderstorms.

These are the "past weather" codes that refer to showers:

25 Shower(s) of rain
26 Shower(s) of snow, or of rain and snow
27 Shower(s) of hail*, or of rain and hail*
28 Fog or ice fog
29 Thunderstorm (with or without precipitation)

and these are the "Present weather" codes that refer to Showers. One of these weather events will have occured during the past hour for one of the codes above to be reported:

ww = 80–99 Showery precipitation, or precipitation with current or recent thunderstorm

---

80 Rain shower(s), slight
81 Rain shower(s), moderate or heavy
82 Rain shower(s), violent
83 Shower(s) of rain and snow mixed, slight
84 Shower(s) of rain and snow mixed, moderate or heavy
85 Snow shower(s), slight
86 Snow shower(s), moderate or heavy
87,88 Shower(s) of snow pellets or small hail, with or without rain or rain and snow mixed (87=light, 88=heavy)
89,90 Shower(s) of hail*, with or without rain or rain and snow mixed, not associated with thunder (89=light, 90=heavy)

If there were only rain showers, then 25 would be used. But it wasn't.

Using 26 means that one or more of 83-86 occured (87-90 contain hail, so code 27 would be used for those). The fact that 83 was used as "Present Weather" in some reports (as it was happening at the time of observation), plus the other temperature and dewpoint data, would strongly suggest that it was this that occured in the "Past weather" too, and not 85 or 86.

Now when this gets reported on the met.ie site, it obviously need to be translated into a shortened form. I think the word "sleet" will only be used if it's occuring now, as it can be inferred from the 83 type in the synop that is being decoded for the site. I don't think I've ever seen "Recent Sleet" used. When referring to past weather, the options are greatly reduced, and therefore a 26 would have to be written as Recent Snow, for the reasons stated above.

I need a beer! :rolleyes:

Tom Cruises Left Nut

Su Campu wrote: »

I need a beer! :rolleyes:

This should quench your thirst :pac:

Deep Easterly

Su Campu wrote: »

I need a beer! :rolleyes:

and why in the Belmullet 00z report was past weather used in the current weather group?

and and and....

Only messin. Thanks

PS, good point about the 'recent sleet'. Don't recall ever seeing it being used on met.ie.

Su Campu

This thread has run its course now so I'm closing it. The Snow Reports thread will stay open for another 24 hours.