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

None of the 2300Z TAFs forecast snow tomorrow, even at Knock. Only sleet and hail showers.

For those of you seeing snow tonight, enjoy it. It very well may be the last snowfall you will see for at least 7-10 days. The worst of the wintry weather will occur overnight and during the first half of Monday. The Thursday-Friday cold snap is not looking promising in terms of widespread wintry showers, with the exception of coastal counties in the west and north. Nighttime frosts may be severe on Wed, Thur nights also. Beyond that it will turn much milder over the weekend. Of course, models will upgrade and then downgrade in between but there is no sign of any significant wintry weather in the next week or more.

We look like remaining in this cold, mild, cold, mild... setup for the next 2 weeks at least with the nw and n being favoured to see any significant wintry weather.

Deep Easterly wrote: »

A couply wet snow showers earlier on which melted on impact. Slop!

Belmullet is reporting 'Recent Snow' on the 10 pm reports, with a temp of 6c and a Td of 3.6c. Trace amounts.

http://www.met.ie/latest/reports.asp

In the 1 and 2 am synops this morning, the code used for present weather was 83, which by WMO definition (Page 417) is

"Shower(s) of Rain and Snow mixed, Slight"

which is really sleet, as there is no code for "Sleet" in the official list, and if they were purely of snow then Code 85 or 86 would have been used instead. I wonder if these are what are reported as the "Recent Snow", given that of the two types, snow must always be given preference, though I wonder why it's not just put down as "Recent Sleet" on met.ie then??

darkman2 wrote: »

That is immediate west coasts which I always said were unlikely to see just snow.

Me too, which is why I was baffled at it. Maybe the explanation above might be valid.

I live a few meters above sea level here in the East near Malahide. My area had a snow shower last night. I am as close to sea level as you can get on the coast.

By your own admission it was "just a flake, but a flake nonetheless". But yes, we have seen some snow make it to near sea level, albeit very briefly. On the whole though I would not call rain with brief intermittent snow on the snowline. For me, snowline means where precipitation is only falling as snow, and that for me was around 100 m and above.

P.S that other thread I cannot understand why that has been closed. Now we are missing a forecast thread for this week. Which is Monday to Friday btw. Threads like that, IMO, should not be closed because a particular poster disagrees with the forecast. If said poster disagrees the least they can do is start a new thread with their own forecast for the week and put as much effort into it as the poster of the thread they wanted closed. Comes across as a bit ignorant really. If the forecast turns out to be wrong then it's best to discuss that after the time period of the forecast is over. That is the first time I have seen a forecast thread closed here before the time of the forecast expired.

To open yet another thread would be a nightmare. Your one already wasn't really needed as it could well have been part of the Winter 2011/2012 discussion as it was a week away when you opened it, but it was let run all the same. As Wolf said, people are now posting all over the place, and seeing as the threat of the widespread frost looks like not materialising, it is best to close it and let people go back to the Winter 2011/1012 one to avoid confusion and keep things tidy.

Lucreto wrote: »

I was watching the temperature go down to 0.8c at 11pm and I checked again around 1pm it was 1.7c.

It was 3c at 3pm with moderate sleet/hail showers where I am yesterday. At midnight it was 4.5c and raining. Must watch 'The Man Who Went Up A Hill and Came Down A Mountain' to get some tips on how to improve my altitude.

Another vid from Mark Vogan today. Taken north of Glasgow

Su Campu wrote: »

In the 1 and 2 am synops this morning, the code used for present weather was 83, which by WMO definition (Page 417) is
which is really sleet, as there is no code for "Sleet" in the official list, and if they were purely of snow then Code 85 or 86 would have been used instead. I wonder if these are what are reported as the "Recent Snow", given that of the two types, snow must always be given preference, though I wonder why it's not just put down as "Recent Sleet" on met.ie then??

I suppose with the term 'sleet' having different connotations in various parts of the world it was probably wise not to include it in the WMO definitions. But yep, 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!

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 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:

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.