Yorkshire, Lincolnshire And The Pennines Cold Spell Discussion

[Lewis]

Hi guys, sorry for neglecting this thread recently, like many others my time has been pinned inside the model discussion thread.

Firstly WOW! what a busy 6 days with the models, no doubt this will continue to cause excitement, depression, and headaches!

The cold air is stating to push in now, with the really colder uppers hitting us around 6-7am tomorrow.

With this sort of setup East will do best generally, with a fair few showers about with what will become a very unstable flow. Check John Holmes PDF on the thickness, pressure and convective potential, his methods are purely the best.

There's already some features that has been picked up by the UKMO, the current fax charts show a couple of troughs affecting us over the next 48 hours, this is when West Yorkshire and areas further inland come into play, more on that tomorrow.

I noticed Paul wanted me to give some information regarding the 0c isotherm, it's basically the freezing level at any given height. 0 meters being perfect which is supportive of snow right down to the surface. 100-200m 0C isotherm is supportive of snow if the 850 upper temps are of -5 are below, what is also important is how heavy the precipitation is, during heavier precipitation the freezing level will drop.

Here's a couple of post's i have made today in the model thread, i hope they come in handy. But firstly i have a couple of NMM model charts for 7am tomorrow morning;

Sub 528 thickness (DAM) hits the east coast around 6-7am tomorrow according to the NMM model;

850 temps colder in the east and are at -8 even right on the coast, so this is supportive of snowfall given the lower sst's.

Showers at that time pushing will inland across EA and the SE as the day goes on heavy snow showers affecting Yorkshire/Lincs/NE England;

Dew points;

Shows it as very marginal, but tbh, 0.5c is still fine if the 0C isotherm is low enough, although it's when you tend to get the larger wetter flakes.

0C Isotherm;

generally 300-400m, as low as 100m further North.

As we go through tomorrow the isotherm drops too 100-150m quite widely. Dew points drop off slightly 0 - -1c in places.

Below are the conditions which support snowfall, these are very important. Just keep checking your local conditions and if they match or are better than the estimations below, expect to see snow <_<

1. Is the dew point ok? "0c below"

2. Is your temperature ok? "2c-3c is still fine"

3. What are the 850's like "-8 + to avoid any marginal situation especially for coastal areas" -5 to -6 sufficient enough for areas inland.

4. Is there any modification off the North Sea? Is the flow slack? and coming off the North Sea, if it is expect some mixing.

5. Is the 500-100 thickness (DAM) at least 530 or sub 528

6. Last but not least the most important, the 0C isotherm. (0(being pefect)-200M is ok if you have pretty cold uppers and heavy precipitation, anything above a little marginal to support snow down to the surface so it would be more likely to give a wintry mix) Of course the 0C height will drop in heavier precipitation, this is why on the NAE precip charts it shows it turning to snow, as it's during the heavier precipitation.

They could be some interesting snowfall tomorrow night and Tuesday. I'll see what the models have to show tomorrow.

Over all looking extremely good for Yorkshire and Lincolnshire, The further East your are the better.

Any questions just ask me, or John Holmes.

Regards,

Lewis

Edited February 8, 2010 by Storm Force Lewis

[Schnee]

Thank you for that Lewis. Only just heard there's a cold spell coming again. Hopefully it's not as bad as what the papers are saying lol.

February is meant to be our snowiest month. Lets see what happens.

[gobbyash]

Snowing here at the moment.

[johnholmes]

the 1000-500mb thickness is less important than the 1000-850mb thickness.

in the former its the number 528dm which is often quoted as the 'magic number' certainly not 530dm.

for the latter then the figure of 1293dm gives a 50% chance of snow at low level inland, with it increasing to 90% with a value of 1281dm

[Beverley Lass]

Snowing here at the moment.

Yes, same here Gobby tho it's very light.

1.3*C and not settling .. as yet.

BL :blush:

[Thornwick36]

Snowing Here, quite heavy

Turned to very light snow

very heavy again

[galba]

Had a light dusting here in the last hour...temp is currently -1°C.

Nice little streamer edging in just north of the Humber and according to NW radar some of these showers are making it into Lancashire.

[grab my graupel]

Morning everyone

Had a slight dusting of snow earlier this morning which, apart from on my car roof, has melted

[Snow Angel]

the post is below as a pdf

Skew-t for doncaster for week 7-11 feb 2010.pdf

Thank you John for taking the time to do this, it really helps the learning process to see what information you used to make your forcast. I just wanted to ask if you had time would it be possible for you to provide the same for just Thursday/Friday when it is in a more reliable time frame? I want to print both sets out to study and see if I can see the changes and understand what caused the changes.

I have been following NW for years now and may never be able to read the charts but I want to keep trying, one day it may make sence

Cheers

[NW Leeds Russ]

Morning everyone

Had a slight dusting of snow earlier this morning which, apart from on my car roof, has melted

Morning all.

Woke up to dusting of snow everywhere. Now just rooftops and grass.

Light snow at present. Temp 1.6c. Wind NE

[johnholmes]

Thank you John for taking the time to do this, it really helps the learning process to see what information you used to make your forcast. I just wanted to ask if you had time would it be possible for you to provide the same for just Thursday/Friday when it is in a more reliable time frame? I want to print both sets out to study and see if I can see the changes and understand what caused the changes.

I have been following NW for years now and may never be able to read the charts but I want to keep trying, one day it may make sence

Cheers

thanks-glad its helping

I'll try and do a similar one for Thur-Fri sometime tomorrow. If its not appeared by Tue evening drop me a pm to remind me please?

just a few flurries here now and then in the past 30-40 minutes

[Snow Angel]

thanks-glad its helping

I'll try and do a similar one for Thur-Fri sometime tomorrow. If its not appeared by Tue evening drop me a pm to remind me please?

just a few flurries here now and then in the past 30-40 minutes

Thank you John - much appreciated

[russh]

i have been having Very light sleet and hail not expecting much YET

johnholmes: thanks for taking you time to do the PDF's. looking forward to thus/fri

Edited February 8, 2010 by russh

[Lewis]

Waiting for the 06z NMM,

The 00z showed an organised line of precipitation in the form of a trough early hours of tomorrow morning pushing quite far inland, with the heavier precipitation around 11am - 12pm.

[russh]

Waiting for the 06z NMM,

The 00z showed an organised line of precipitation in the form of a trough early hours of tomorrow morning pushing quite far inland, with the heavier precipitation around 11am - 12pm.

Hi Lewis

is this liable to fall as snow at lower levels, this morning has been more sleet than rain

cheers

Russ

[Lewis]

Hi Lewis

is this liable to fall as snow at lower levels, this morning has been more sleet than rain

cheers

Russ

Even now, any heavy precipitation would fall as snow. To get light snow and sleet with such light precipitation is a very good sign, especially with the current heigh of the 0c isotherm which would also drop in the heavier precipitation.

I would say it will fall as snow to all levels, just keep an eye on dew points. If its at 0c or below at the time of the precipitation expect snow.

[Lincs Observation]

Hi All

At work at the mo but a dusting of laying snow between Louth & Horncastle on the wolds on the way in this morning, Still snow, Sleet & Drizzle here looks like its pepping up on the radar for this part of Lincs (Coningsby)

LO

[Lewis]

06Z NMM has just come out, i looked at precipitation for the next 24 hours. I don't think anyone in East Yorkshire/N Yorkshire/ NE Lincs will be dissapointed

Below is a total convective precipitation chart over a 24 hour period, from now +24.

Also, don't worry about dew points, the NMM model suggest a +1c dew point for me now.

Current dew point: -1.2

Lewis

[Craigers]

just had a very light sleety flurry! its 1.4c at dew-0.0c

[russh]

Even now, any heavy precipitation would fall as snow. To get light snow and sleet with such light precipitation is a very good sign, especially with the current heigh of the 0c isotherm which would also drop in the heavier precipitation.

I would say it will fall as snow to all levels, just keep an eye on dew points. If its at 0c or below at the time of the precipitation expect snow.

thanks for you prompt reply Lewis

looking at the precip charts country file weather seams to be spot on so far, i am still not expecting a vast amount untill later in the week any more would be a bonus

cheers

Russ

[yorkieblade]

Light Snow flurries here,a dusting above 200 M in Sheffield, looking on my snow radar, a sleet/snow band due from 12:30 - 15:00, mainly from the wash across to Peterborough /Corby area. highest it will get is Lincoln or Mansfield.

[Lewis]

The models are up in the air with regards what happens from Wednesday onwards.

The GFS is showing the HP (High Pressure) much further South, with the ECM and UKMO having it further NW. If the GFS output is correct, then we will miss the worst of the weather, with the odd heavy snow showers from wednesday onwards.

If the ECM/UKMO is correct and we get that evolution, we will see more in the way of precipitation (heavy snow showers).

Nail biting times, let's see what the 12z GFS and 12z ECM has to say. I feel if the GFS continues this trend with the HP, and the ECM shifts slightly in favour we will stay mainly dry, but very cold.

From now until wednesday there's going to be plenty of showers about, more especially tomorrow morning onwards, the metoffice are not really showing much interest and have the showers falling as rain/sleet for coastal areas, and snow on higher ground. This could be due to the isothem, in all honesty i don't know what they are doing.

One thing though, i do sadly expect a downgrade on the next fax charts. The current severe weather warning issued for the SE and EA clearly shows the uncertainity. If the HP does sustain it's position according to the GFS (which is much further South) the main risk zone would be of course EA/SE, so the metoffice have issued a severe weather warning for them areas, because the HP is probably showing it's most Southern position, and probably won't push any further South. Nothing dead certain at the moment, the big guns UKMO/BBC are clearly playing their cards close to their chest.

Exciting times ahead, the model discussion continues.

What will it be? a EA/SE event, or more or less and entire U.K event (with all eastern areas doing well). Place your bets now.

[sunny scunny]

Light snow flurries this morning which was good to see,although they didn't last very long.

[Harsh Climate]

I think as things currently stand, snowfall amounts mon-fri next week will be pretty trivial... maybe with the exception of the north york moors.

http://www.wetterzen...cs/Rtavn421.png

http://www.wetterzen...s/Rtavn1261.png

These flows really are quite dry/drizzly flows and with the air being cold rather than being on the right side of very cold, I would except temporary accumulations to thaw inbetween showers. Obviously these charts arent going to be spot on at this stage, so there is a lot of potential down the line

We need a flow where where at the focal point of the squeeze of NE/ Easterly winds, something like this: http://www.wetterzen...00120090202.gif

This would allow for showers to 1.develope in the north sea widely, 2.spread right inland 3.not being under any part of high pressure allowing full convective cababilities...

As things stand at the moment heavy snow mon-fri will be confined to Kent, il try n do a map later

Still think this is how things are looking im afraid.....

[Thornwick36]

snowing here in hull

very light

Edited February 8, 2010 by Thornwick36