Classic 552 isopleth rule. When the 552 isopleth hits the coast of greenland blocking almost always endures, and it just manages it at 30hr and again at 45hr compared to not at all on the 0z.

The 6z solution should not and cannot be discounted, there has been consistent if not strong support on the ensembles for this, I do not consider it a blip or even a U turn, just another minor upgrade. But once you get to a tipping point it really only takes a minor upgrade.

JUST FOR FRUSTRATION - I do not believe in this chart but it does look good in FI: - More or less similar if not identical to Feb 1991 cold spell.

http://www.wetterzentrale.de/pics/Rtavn3841.gif

Another possibility:

Either way FI keeps us in a cool NW'ly flow or bitterly cold easterly.

Yep, see what the models look like in 5 days or so, not getting too expectant yet. If anything similar like this happens i'll be in hospital and probably miss seeing it.

I was supposed to stick a  On the end of that 

If this run was showing raging zonality by Friday I would expect multiple posts about how the 6z GFS is useless. Is that not the case anymore? 

I'll take that one. Similar to ECM theme.

Indeed. The ENS are the only tool needed as there are so many scenarios and each op will show different. I know everyone knows that (or they should!) but people still get drawn into it all  The vast majority of GEFS shows a pressure build with HP very close to the UK. 850s will of course paint a misleading picture but I still think a gradual return to average temperatures will follow. Despite colder nights, day temperatures will creep up, along with the rising sun and unlike now, there will be a greater diurnal range.

I still think the METO have the right idea in that unsettled weather will clip the N with the best of the dry weather in the S. This is what GEFS is reflecting and the ECM too.

No, it is still useless. 

here is 2 intrestin post by steve murr over at NW. 

Ok so theres 3 ways to go it would seem....

2 deliver cold sustained, 1 delivers the mild middle ground.

* Scenario 1- Sustained Easterlies-  likely 30%

Whilst I dont like the 06z taken at face value its a fantastic run.-  I posted ( I think yesterday with the red circle ) that when you get those deep italian lows modelled in Easterly scenarios often a second wave is throw west to the UK

The 06z GFS shows this particularly well & puts a wave exactly where the red circle was on my diagram

http://modeles.meteo...gfs-0-168.png?6

Coming through the low countries ejecting west.

This most certainly bings with it the potential of a decent snow event similar to Feb 09 for England - so worth keeping an eye on. Its not amplified at all, however doesnt need to be -

* Scenario 2 - the deep cold polar outbreak, A la 2010 ( but not as amplified)

The UKMO today @ 144

http://www.meteociel...44-21.GIF?01-06

& indeed the 06z NAVGEM

http://modeles.meteo...0-144.png?01-11

both these models are looking to take a scoop of polar air down across western Scandi that may well infuence the UK at day 7-8

The more amplified the pattern goes the further west the cold is backed.

Of Note is how the GEM control looks like the UKMo @ 144 & then moves on to a cold scenario

http://www.meteociel.../cmc_cartes.php

Current risk around 30% - of evolution bringing -8c line back into the Uk from the NE

* Scenario 3, - the halfway house... 40%

the high pressure sits neither to far north to allow the Bitter Easterlies in nor retrogrades far enough west to allow the cold to back up into the Uk, so we end up in the south cold & dry & the north becomes increasingly milder & windy from the west-

Something like this-

http://www.meteociel...&mode=0&carte=0

Ultimatly we are very finely balanced this morning between any of these 3 outcomes, with the GFS resurecting the sustained easterly flow from the ashes.

the non descript halfway house may end up the solution as usually thats our luck, but it is a very evenly shod 3 horse race...

 AND ANOTHER

Something to keep one eye on over the next 24 hours is how the mid term of the models develops

the 06z which is notoriously bad has moved to a more favourable solution for snow in the SE

for those of you who want snowy easterlies wind direction is KEY

If the parameters are right for snow - thats low 500 heights sub 540 DAM & sub -10c air then it all boils down to wind direction.

To get widespread snow here we need as close to an direct easterly as possible.

Imagine this.

East is 90 degrees, NE is 45 degrees- the westward propergation of snow showers into London, Susses, Essex & surrey is 100% correlated to how close to 90 degrees the windflow is

so take 90 degrees-

EVERY county gets hit-  thats sussex both, kent, london, essex , & suffolk + Herts.

Swing that dial to 75-80 degrees & you have wiped out most of the NW part of the region as well as western sussex

Move the swingometer around 65-75 degrees & you wipe out most of London & essex & NW kent.

The further you get round to 45 degrees you really only swipe east kent & suffolk....

for reference

the Thames streamer is usually 85-95 degrees

the Mid kent streamer is usually 60-80 degrees

the east kent streamer is usually 30-60 degrees              - there are some overlaps.

With that in mind if you are a novice & want to snow will it snow in the easterly IMBY use this 1 link on the GFS high res.

http://www.meteociel.../850-hpa/3h.htm

it shows the uppers & the windflow. -

here is the 00z for the BEST window this week.

http://modeles.meteo...100-0-102.png?0  -8 to -9c air & windflow 40 degrees

would equal an east kent streamer only.

Now review the 06z from the link above

http://modeles2.mete...20-7UK.GIF?01-6

this shows friday morning as a very strong 75-80 degree windflow - bringing a lot more in the way of snow showers across the SE corner.

http://modeles2.mete...-779UK.GIF?01-6

then again further down the line

http://modeles2.mete...98-7UK.GIF?01-6

So IF your still hunting for anything decent then follow that link & see how we fair....

Had to delete a few posts in here. On topic please :)

The Op wont be alone with its thoughts of an Easterly

Is it just me, or the extended ensemble is late completing today?  

Out to 300 hours, lots of variations on the general theme in evidence. 

Meto talking about a band of snow moving down the country on Tuesday but can't see it on any forecasts. In fact there's very little snow modelled anywhere now from this cold spell unless the GFS 6z is correct which I would give about a 1% chance

The Met have a watch out for snow for Central and Eastern areas on Wednesday.

Control backs up the Op and some very interesting ens members, some showing another polar outbreak like Steve mentioned

Lets hope the trend continues with the 12z though I fear we may be brought back to earth with a bump

Well hopefully Wednesady could be the day then. Hopefully be cold enough by then to be all snow. 

Indeed.  Yesterday afternoon there was widespread snow forecast for the east but it didn't materialise.  Not a surprise (ha ha) but the actual detail is so hard to pin down where there are showers involved. Long live the pleasant surprise!

5 or 6 very cold easterlies in there maybe the Op run wasn't so drunk after all!

http://www.wetterzentrale.de/pics/MT8_London_ens.png

And staying there according to N Miller