Model Output Discussion - heading into April

[Mike Poole]

An interesting period coming up for sure, let's take a look about T 168, first GFS T162:

Max cold on this suite, and still possible.  And thanks to @Steve Murr for highlighting this possibility in recent days, and making us think, even for a second, that snow might happen, and that we are not in this coronavirus nightmare....

Other models, T168, ECM, GEM and JMA:

All these push the high pressure over us before any significant northerly can take hold.  JMA briefly cold at same time:

Moving on to T240, ECM and GEM are starting to show the direction of travel I expect, that is, to warm settled:

[Frosty.]

Good to see the eastward correction / shunt beginning on the Ecm 12z operational, predictable too of course but now we are into May i would rather be looking south than north for my weather!

[MATTWOLVES 3]

And just to back up Karl's post above, the mean continues that trend.. With a cracking build of pressure following.. How do ya like them apples GFS! 

[Mike Poole]

4 minutes ago, JON SNOW said:

Good to see the eastward correction / shunt beginning on the Ecm 12z operational, predictable too of course but now we are into May i would rather be looking south than north for my weather!

Yes, Karl, once this cold shot is through it is all eyes to the SW for pressure rises, and look to the south for heat, and reloads, summer starts in my opinion, after this cool or cold shot next week, which is a direct result of the strat final warming, it was benign, so it's effects shouldn't linger.  Good to see the ECM tending towards the longer range models at this range...

[damianslaw]

1 hour ago, Mike Poole said:

Yes, Karl, once this cold shot is through it is all eyes to the SW for pressure rises, and look to the south for heat, and reloads, summer starts in my opinion, after this cool or cold shot next week, which is a direct result of the strat final warming, it was benign, so it's effects shouldn't linger.  Good to see the ECM tending towards the longer range models at this range...

Wouldn't be too sure about a quick return to warm and settled, the models suggest direction of travel is for the atlantic to break through on a westerly trajectory.

[Scorcher]

4 minutes ago, damianslaw said:

Wouldn't be too sure about a quick return to warm and settled, the models suggest direction of travel is for the atlantic to break through on a westerly trajectory.

You think so? I can't see much evidence of the Atlantic being particularly active on the ECM 12Z run. The GFS (which seems to have lost the plot tonight to a degree) is showing a very quiet Atlantic indeed.

[ANYWEATHER]

Evening All! Hope you are all well. The upcoming cold spell is unusual in its severity but certainly not unknown. May 1996 saw some brutal cold across the nation, for this time of year, lots of snow fell in over the moors and tors of Cornwall and Devon.  Sunday into Monday looks very interesting,  snow at low levels possible even as far south as Cornwall And the Channel  Islands  and the Scilly Islands. Models agree at short range , !

[damianslaw]

34 minutes ago, Scorcher said:

You think so? I can't see much evidence of the Atlantic being particularly active on the ECM 12Z run. The GFS (which seems to have lost the plot tonight to a degree) is showing a very quiet Atlantic indeed.

Orientation of any build of heights from the west will allow the jet to ride over the top and hold them down - longer term jetstream profile shows this, westerly/north westerly airstream tilt.

[Scorcher]

6 minutes ago, damianslaw said:

Orientation of any build of heights from the west will allow the jet to ride over the top and hold them down - longer term jetstream profile shows this, westerly/north westerly airstream tilt.

Perhaps this could happen later on, a long way off though. ECM hints at something like that after day 10, so very little certainty.

[Djdazzle]

16 minutes ago, ANYWEATHER said:

Evening All! Hope you are all well. The upcoming cold spell is unusual in its severity but certainly not unknown. May 1996 saw some brutal cold across the nation, for this time of year, lots of snow fell in over the moors and tors of Cornwall and Devon.  Sunday into Monday looks very interesting,  snow at low levels possible even as far south as Cornwall And the Channel  Islands  and the Scilly Islands. Models agree at short range , !

The models certainty don’t agree, and it’s not exactly short range. It’s only GFS which so showing anything notable. I’d be stunned if there is any snow away from high ground in the north.

[Scorcher]

23 minutes ago, Djdazzle said:

The models certainty don’t agree, and it’s not exactly short range. It’s only GFS which so showing anything notable. I’d be stunned if there is any snow away from high ground in the north.

It just looks dry to me- can't see where any snow is coming from. All that will be notable is the wind chill.

[damianslaw]

13 minutes ago, Scorcher said:

It just looks dry to me- can't see where any snow is coming from. All that will be notable is the wind chill.

Would convection not kick in with such cold uppers. Serious hailstorm showers.

[Geordiesnow]

1 hour ago, damianslaw said:

Would convection not kick in with such cold uppers. Serious hailstorm showers.

Only if thicknesses are low enough but most models go for the instability to head in the North Sea. It all reminds me of the April Northerly where there could be a few showers in Eastern areas and alot more cloud(and not cumulus cloud, just boring flat clouds) and inland sheltered areas sunny with patchy cloud. As an weather enthusiast, If a northerly happens, I rather it be a direct hit and not a glancing blow but it looks like that what it will be. 

All that said, a northerly for us in the UK usually means a warm Arctic and my goodness some of the synotopics that are being projected are just extraordinary. We shall see if the models maintain it like that or not but in the medium to longer term, there is basically hardly any PV left and we are not even in mid May yet. 

[Methuselah]

Changes are afoot, peeps!

    

    

    

    

    

No heatwave of course, but more vitamin D-friendly weather to come. Whatever happened to all those extra (Grand Solar Minimum) condensation nuclei?

Stay safe and (in the words of Nanci Griffith) Keep a Distance!

[Frosty.]

Looking at the 0z output, in my opinion the eastward correction / shunt of the colder air at the end of this week / start of next week continues, it’s more and more of a glancing blow looking at the GFS 0z op / GEFS mean / Ukmo / ECM 0z op...I think there should be much more focus on the very warm settled weather than the non event cooler blip from the north that follows it!

Edited May 5, 2020 by JON SNOW

[Singularity]

Never been much support for more than a brief punch of well below normal 850s and day temps.

Main cause for concern is overnight heavy frost potential Sun-Mon & Mon-Tue, depending on how much of a breeze there is to work against that.

As the tropical cycle progresses on, mid-Atlantic ridging should be encouraged to ‘spill’ east across the UK, much as the models are now suggesting for D7-D10.

NAO should then tend to turn more positive during 2nd half of May, remains to be seen how well high pressure remains in play across the UK then. South favoured for it by then.

[carinthian]

1 hour ago, JON SNOW said:

Looking at the 0z output, in my opinion the eastward correction / shunt of the colder air at the end of this week / start of next week continues, it’s more and more of a glancing blow looking at the GFS 0z op / GEFS mean / Ukmo / ECM 0z op...I think there should be much more focus on the very warm settled weather than the non event cooler blip from the north that follows it!

Looks like that on the latest charts and what is being now spoken of on this mornings media TV weather presentations.

C

[Griff]

Anyone else reckon we have made it into April and beyond now? I know, pedantic... 

For the sake of my plants and lockdown sanity, here's hoping it's nothing more than the previously mentioned glancing blow. 

At least regrowing everything from seed will give me something to do, but would it be too much to ask for sunny sky with the occasional but needed shower? What do you mean mother nature doesn't do requests? 

Edited May 5, 2020 by Griff

[Zak M]

Good afternoon all, after the cold plunge that is expected this weekend you might not need to wait too long for warmer and settled weather, because the GFS 06z places that right on the cards for day 10! It shows that there could be the chance of some rain from the SW once again from a low in the Bay of Biscay, but other than that, that is the weather we certainly want for May and the upcoming summer... enjoy the rest of your afternoon 

                  

[LRD]

Well, thank goodness this wasn't Dec, Jan or Feb:

What once looked a really potent cold shot downgraded again. Massive meltdown on here (including from me) if this was winter. Frosty though

[Frosty.]

The watering down / eastward shunting of the cold air continues on the Gfs 6z operational, I expect further eastward adjustment will occur, it’s just so predictable but at the same time good news..in the meantime, enjoy the sunshine and rising temps during the coming days..that’s the main story this week!

Edited May 5, 2020 by JON SNOW

[Kentish Man]

Last night's 12z GFS forecasted 0C minimums in my area  early next week - now up to 4C at the lowest as the true artic blast (as so often) heads further east in the latest models. Quite happy about that as late frosts are potentially very damaging but it also suggests it was unwise of  some broadcast forecasters to over-egg the pudding too early. Of course things can change but I'm struggling to think of many occasions in the past where once a northerly downgrade kicks off it goes into reverse.  

[Djdazzle]

37 minutes ago, LRD said:

Well, thank goodness this wasn't Dec, Jan or Feb:

What once looked a really potent cold shot downgraded again. Massive meltdown on here (including from me) if this was winter. Frosty though

I’m glad. Not just because I don’t want cold weather in May, but because it would be like the weather gods were rubbing it in our faces! Like Jim Bowen in Bullseye, “If only it was winter, here’s what you could have had . . . “

[lassie23]

We may still have another bite of the cherry in a couple of weeks and the building blocks are in place for some snow in June

[MATTWOLVES 3]

47 minutes ago, Kentish Man said:

Last night's 12z GFS forecasted 0C minimums in my area  early next week - now up to 4C at the lowest as the true artic blast (as so often) heads further east in the latest models. Quite happy about that as late frosts are potentially very damaging but it also suggests it was unwise of  some broadcast forecasters to over-egg the pudding too early. Of course things can change but I'm struggling to think of many occasions in the past where once a northerly downgrade kicks off it goes into reverse.  

That's a good point you make, I was quite surprised how confident the beeb was in forecasting significantly colder Conditions at that range, they are normally the first to play it down at any time of winter let alone spring. I think the 6z mean continues with that theme of moving the coldest conditions East... So if you wanna see a true Arctic blast perhaps head for scandy.. High Pressure looks set to build for next week too.. In the short term some rain in the SW today, but hopefully better for you tomorrow, elsewhere plenty of sun, but a keen wind... Enjoy.. Stay safe. 

Edited May 5, 2020 by Mattwolves