South West and Central Southern England Regional Weather Discussion 01/12/2018 Onwards

[Mapantz]

Uppers are marginal on the 72hr ECM

That would be rain in my location.

[Dorsetbred]

3 minutes ago, Mapantz said:

https://www.weathershop.co.uk/shop/davis-6332-vantage-pro2-anemometer-transmitter

That's a very good price!

I got mine for £170 through a German Davis dealer.

Will you stop it..

[Dorsetbred]

3 minutes ago, Mapantz said:

Uppers are marginal on the 72hr ECM

That would be rain in my location.

Yep, just another 3-4degrees and we would be in for a shout, but they are too warm..

Edited January 26, 2019 by Dorsetbred

[AWD]

3 hours ago, AWD said:

We have 3 possible scenarios;

1)  The low runs into NW France along with the PPN and our region remains largely dry and chilly.

2)  The low deepens and runs along the Channel giving a modest snowfall for many areas of Southern England.

3)  The low deepens further and runs further north giving heavier snowfall for areas north of the A303 and a snow to rain event for areas south of the A303.

There are other possible options to like the low travels much further north and gives rain to our region or the low doesn't form at all but I don't see huge support for these evolutions currently.

As things stand, would give the percentage chance of each scenario:

1)  50%

2)  30%

3)  20%

This is before the majority of the 12z output is out.  I will update after the 12z output is out to demonstrate the volatility of this situation.

The 12z EC is more scenario 3.

Now that the majority of the 12z data is out, let's look at the percentage chance of each scenario again.  We are now looking at something like:

1)  30%

2)  35%

3)  35%

As you can see, all very up in the air still.  The further south you are, the more marginal conditions are for you.  However, it's high risk, high reward as the further north you are, the less PPN there is.

 

Edited January 26, 2019 by AWD
Maths

[Dorsetbred]

8 minutes ago, AWD said:

The 12z EC is more scenario 3.

Now that the majority of the 12z data is out, let's look at the percentage chance of each scenario again.  We are now looking at something like:

1)  40%

2)  35%

3)  35%

As you can see, all very up in the air still.  The further south you are, the more marginal conditions are for you.  However, it's high risk, high reward as the further north you are, the less PPN there is.

 

To summarise, (firstly) not sure about the maths aspect of this but...what you are saying cold rain for folks south of the A303, well that's been the order of the winter so that's pretty much par for the course....

Edited January 26, 2019 by Dorsetbred

[Skullzrulerz]

Looks like I'm out of the game oh well into February I go 

[Dorsetbred]

Some slight movement to wind shifting from the SSW to W / NW, as the front slips further eastwards and the cooler air begins to dig in

Edited January 26, 2019 by Dorsetbred

[AWD]

12 minutes ago, Dorsetbred said:

To summarise, (firstly) not sure about the maths aspect of this but...what you are saying cold rain for folks south of the A303, well that's been the order of the winter so that's pretty much par for the course....

Just edited my post with regards to my maths.  I always did need a calculator when it comes to Arithmetic.

Don't take each scenario to literally, I'm just trying to explain the conundrum regarding Tues/Weds and the scenarios the different modelling is playing around with.

Scenario 3 has indeed increased in likelehood a bit this evening, namely due to the EC Op, although I think the UKMO wouldn't be too dissimilar either.  This scenario would see cold rain for Southern coastal counties and Cornwall into Devon.  Once you go north of the A303 and you meet the Mendips, Salisbury plain etc, there is an increased likelihood of the PPN turning to sleet & snow.

Like I said though, all very up in the air at the moment, with no clear path forward through midweek next week.  I await the high res modelling with interest.

Edited January 26, 2019 by AWD
Grammar

[CheesepuffScott]

Oh balls I'm 14 miles south of the A303 

[Mapantz]

I don't think this is a bad shout from my own forecast:

[Leon1]

ECM looking good. If it is still looking great by this time tomorrow, I think I will go to find out the sledges lol! Uppers just need to be a bit colder and for the precipitation to hit us a few hours later so it's cooled down enough outside.

[Dorsetbred]

20 minutes ago, AWD said:

Just edited my post with regards to my maths.  I always did need a calculator when it comes to Arithmetic.

Don't take each scenario to literally, I'm just trying to explain the conundrum regarding Tues/Weds and the scenarios the different modelling is playing around with.

Scenario 3 has indeed increased in likelehood a bit this evening, namely due to the EC Op, although I think the UKMO wouldn't be too dissimilar either.  This scenario would see cold rain for Southern coastal counties and Cornwall into Devon.  Once you go north of the A303 and you meet the Mendips, Salisbury plain etc, there is an increased likelihood of the PPN turning to sleet & snow.

Like I said though, all very up in the air at the moment, with no clear path forward through midweek next week.  I await the high res modelling with interest.

Yeah, point taken, and appreciate you highlighting the options open as the data becomes available, ..

[Dorsetbred]

16 minutes ago, Mapantz said:

I don't think this is a bad shout from my own forecast:

Wow, that much..I best go find my micrometer, wouldn't want to miss measuring this seasons snowfall once it has happened.... Time for Christmas pud methinks and some brandy cream..cheers...

Edited January 26, 2019 by Dorsetbred

[nettie]

I'm 1 mile north of the A303  

[CheesepuffScott]

6.7°C after a high of 9.3°C today

[Leon1]

Sorry for the IMBYism but my locations forecast for Tuesday night into Wednesday...

 

[Mapantz]

9.1°C and still windy. Pressure down to 989.84hPa.

[Wilxy]

7.1°C, 94%RH, Dew P 6.2°C, 987.2mb Rapidly Falling.

3.6mm Rain 

Edited January 26, 2019 by TomW

[Don]

2 hours ago, AWD said:

Just edited my post with regards to my maths.  I always did need a calculator when it comes to Arithmetic.

Don't take each scenario to literally, I'm just trying to explain the conundrum regarding Tues/Weds and the scenarios the different modelling is playing around with.

Scenario 3 has indeed increased in likelehood a bit this evening, namely due to the EC Op, although I think the UKMO wouldn't be too dissimilar either.  This scenario would see cold rain for Southern coastal counties and Cornwall into Devon.  Once you go north of the A303 and you meet the Mendips, Salisbury plain etc, there is an increased likelihood of the PPN turning to sleet & snow.

Like I said though, all very up in the air at the moment, with no clear path forward through midweek next week.  I await the high res modelling with interest.

I’m about 3 or 4 miles north of the A303 and 400 feet above sea level, so probably touch and go.  However, as said, lots to be resolved still...

[CheesepuffScott]

Temperature back up to 7.3°C

[CheesepuffScott]

1 hour ago, Leon1 said:

Sorry for the IMBYism but my locations forecast for Tuesday night into Wednesday...

 

Rain for me (!) but I got light snow at 3-6am Wednesday morning.

[matt111]

Dropped slightly from what it was earlier but stopped at 8.8°C where it's been for a while now.

EDIT: Went up to 8.9°C as soon as I posted that.

Edited January 26, 2019 by matt111

[Leon1]

6 minutes ago, CheesepuffScott said:

Rain for me (!) but I got light snow at 3-6am Wednesday morning.

Don't worry lots to be resolved still and will probably change again tomorrow and bring those further south back in the game  .

[matt111]

Currently offers me mostly rain but does have this later in the night. Not that it’ll be the same next time I look at it. 

[CheesepuffScott]

ICON 18z, mmm. Looks like we could be in with a fair shot on Thursday too, but could do with some of that snow being a bit further south for those nearer the coast; but let's get Tuesday/Wednesday out of the way first!