FI Charts ( T120+ onwards) Spring 2021 **READ MOD NOTE IN FIRST POST**

I think if the ECM came off.. temps would definitely be sufficient for snow, even out to sea.

We managed sea level snow here on Friday and Friday evening with -6/-7c 850hPa’s and that’s with a Polar Maritime sourced airmass. Others said that it would only snow at altitude - not true.

This airmass would be from the Arctic, and would have a lower Mixing Ratio, therefore lower dew points.

Nqp15hhu wrote: »

GFS. Extremely low thickness values and a North American style cold front. It would be quite unique and exciting to experience.

-12c at 850hPa, so no higher than 3c Max at the surface in sunshine.





About 512 decametres on the east coast of NI





Lasts until Wednesday



Hopefully this comes to fruition. I can’t imagine temps exceeding 2 or 3c even in sunshine, as the freezing level would be about 300 metres max.

In any showers, the air temperature would be brought down to about -1c or -2c.

GFS 18z still has this event in place from the evening of the 4th April.

So, looking at the GFS model very little has changed from earlier in the week. Here is a summary of the synoptic situation for this cold event.

The cold event actually starts midday Sunday the 4th April (not the 5th as earlier discussed), with a sharp cold Front:



850hPa temperatures fall to -8c by early afternoon:



By evening they are at -11c over Ulster:



And later the Eastern and Central swathes of the island:



850hPa temps warm up to -9c over Ulster and -7c/-8c elsewhere on the 5th. This is still productive for snow.





Cold Spell ends Midday Tuesday.

This airmass is very cold:

Theta E Values (require 10 for guaranteed snow) are as low as the easterly event at +5:



Freezing Level below 400 metres in Ulster by Sunday afternoon:


Even lower by evening:


Moderately low on Monday daylight hours:


This airmass is very cold, I don't see any marginality whatsoever. It is sourced from the Arctic and has very low freezing levels with low Theta e. Definitely all parameters are met for snow to fall down to the surface. However, this is all subject to change and could end up just being cold and sunny.

It is on par with the easterly we had, if not colder synoptically. What will be interesting is the cold front, it looks as though temps drop from 10c to as low as 2c within an hour.




There could be a few centimetres at low levels on Sunday night/Monday night in NW and N parts if showers get going. Again this is all subject to change and is an overview of the situation as predicated at this moment in time.

pauldry wrote: »

I mean the air temperatures so this is just freezing boredom then. Heating Bills etc. Hope the cold stays off for most of Easter Sunday. Wev an Easter egg hunt planned with kids

-11c is the record low max. You’re not going to get that in April.

And ECM showing another arctic incursion on the 9th!

Plenty of opportunities for us to get some snow and possible lying snow! Great!

Latest 18z GFS:

850's are about 1c warmer, however, the cold air lasts into Tuesday evening now.











Quite a cold day on Monday, with higher elevation areas potentially staying below freezing.





Exceptionally low thickness values:



So a window for snow of almost 3 days - I don't see any marginality. I do see the potential for low level areas to get a covering of snow, maybe even of a few centimetres if this plays out as shown.

It's hard to know though. I don't think we've had an airmass as cold as this in April in recent times.