The hunt for cold - Model discussion (late November)

[ZK099]

One thing I'm noticing this year is a distinct lack of a Canadian and Greenland PV in modelling. Normally the vortex is raging in those regions in particular, and I saw an old chart I had saved from last year and the difference is astounding. One thing that's for sure is the NH atmosphere is behaving strangely this year, ever since that SSW... 

[booferking]

Updated ICON is an improvement.

[bluearmy]

14 minutes ago, ZK099 said:

One thing I'm noticing this year is a distinct lack of a Canadian and Greenland PV in modelling. Normally the vortex is raging in those regions in particular, and I saw an old chart I had saved from last year and the difference is astounding. One thing that's for sure is the NH atmosphere is behaving strangely this year, ever since that SSW... 

Eps mean day 15 ...... apropos of nothing 

[Geordiesnow]

12 minutes ago, ZK099 said:

One thing I'm noticing this year is a distinct lack of a Canadian and Greenland PV in modelling. Normally the vortex is raging in those regions in particular, and I saw an old chart I had saved from last year and the difference is astounding. One thing that's for sure is the NH atmosphere is behaving strangely this year, ever since that SSW... 

I don't want to sound to pedantic but the PV has actually been quite strong over Greenland and especially Canada this Autumn, hence below average temperatures over Canada during September in particular and that Hudson Bay ice is forming a bit more extensive than normal and there is a strong PV there right at the moment. 

All that said, this is going to change after midweek for that part of the world with above average temperatures(although still will be cold for our standards!) set to dominate, how long that lasts for and what impact if any on our weather remains to be seen. 

[Spah1]

26 minutes ago, booferking said:

Updated ICON is an improvement.

Why? How? What’s improved? 

[Mike Poole]

Been busy so just checking the charts, bottom line a moderate swing back to cold from the 12s...

As we wait for the pub run to get going, here's the last 5 CFS runs for December, pressure anomaly - very much suggesting blocked, -AO month...

[booferking]

12 minutes ago, Spah1 said:

Why? How? What’s improved? 

Follow the isobars lines from scandi and the blocking compared to 12z is stronger both charts below

850s also below

Edited November 19, 2018 by booferking

[jules216]

@nick sussex I know you would like to hear this, today update from NOAA:

The MJO slowed down and weakened over the past few days, partly due to interference with both the base state and a strong equatorial Rossby wave over the West Pacific.  Dynamical model MJO index forecasts depict continued robust MJO activity during the next two weeks. The GEFS forecasts indicate a high amplitude event crossing the Pacific during Week-1 and the Western Hemisphere during Week-2, while the ECMWF has a faster propagating and less amplified event. Statistical guidance also supports robust MJO activity.  As the MJO enhanced phase crosses the Pacific, it will begin constructively interfering with the base state that is transitioning towards El Niño conditions.  The MJO is likely to play a role in tropical-extratropical teleconnections over the next several weeks. A high amplitude Pacific MJO event tends to favor a transition to a negative NAO pattern and colder conditions over the eastern CONUS, which is fairly consistent with long range dynamical model forecasts

 

I think its better news then worse, no?

[Mike Poole]

Block stronger on this one and burgeoning low looks more elongated at T114, then T120 from the 12z for comparison 

[feb1991blizzard]

EC46 - zonal weeks 3 and 4 - worst update of the winter so far

[Always a red]

Just now, feb1991blizzard said:

EC46 - zonal weeks 3 and 4 - worst update of the winter so far

It`s a good job they change more often than the weather then and are about as reliable! (see what I did there) 

[booferking]

1 minute ago, feb1991blizzard said:

EC46 - zonal weeks 3 and 4 - worst update of the winter so far

Not good to hear but EC46 can flip flop like any model it's far from bullet proof.

[Man With Beard]

Now this is a good one

If you had to pick one place away from the mountains to have 2cm of snow by midnight tomorrow, where would you pick? 

If you DIDN'T choose the Isle of Wight... you'd be wrong, according to the last EURO4

Look closely! 

Edited November 19, 2018 by Man With Beard

[bluearmy]

Just now, feb1991blizzard said:

EC46 - zonal weeks 3 and 4 - worst update of the winter so far

Upper ridge anomaly arlound the uk weeks 3 and 4 though this is from the south ....... the dam lines tend to be quite flat by week 4 in our part of the NH .....

[feb1991blizzard]

On the plus side - a good GFS coming up here - more of a dig on the trough.

[Mucka]

GFS 18z still going for heights to be sucked NW rather than drain SE a la ECM

Much prefer GFS solution tbh even though ECM has a potential Scandi high.

[SMU]

Updated 18z is finally onboard with the UKMO slider @144 keeping the colder air flowing SW ...

Edited November 19, 2018 by Steve Murr

[northwestsnow]

6 minutes ago, feb1991blizzard said:

EC46 - zonal weeks 3 and 4 - worst update of the winter so far

Not suprising Feb...

Things beginning to unravel?

Hope not..

 

 

Edited November 19, 2018 by northwestsnow

[Mike Poole]

GFS finally getting hang of the slider! definitely going under here T144:

All power to the southern arm of the jet, should be good run this.

[feb1991blizzard]

1 minute ago, bluearmy said:

Upper ridge anomaly arlound the uk weeks 3 and 4 though this is from the south ....... the dam lines tend to be quite flat by week 4 in our part of the NH .....

That just looks much like a slightly displaced Bartlett further North though, even if you take the anomalies rather than the contours as the features.

[Allseasons-Si]

Hi the hunt for cold gang

i have done a Nick Sussex van gogh squiggle of the NH view from the latest cpc 8-14 day 500mb outlook,ok i know it's a mean anomoly but you get the gist,

just look at all the northern hemisphere blocking+ve height's over the pole and all the -ve heights over the mid latatudes,the purple arrows indicative of -AO reversal and the black arrows roughly where the PJF(polar jet front)is

the NAO/AO still tanking negative but look at the AO in particular av around -4 with a couple going off the scale

lets have a look at the De-Built ens(temps,dewpoints and wind direction)

and clearly there are uncertainties early on esp the dewpoints and wind direction.

 

 

[bluearmy]

1 minute ago, feb1991blizzard said:

That just looks much like a slightly displaced Bartlett further North though, even if you take the anomalies rather than the contours as the features.

Will wait to see the T2m anomalys (much later) to see what mean flow is expected 

[Man With Beard]

I'm really getting into the minor models tonight - our old friend the HIRLAM is on the case for snow in the south tomorrow night

[feb1991blizzard]

5 minutes ago, northwestsnow said:

Not suprising Feb...

Things beginning to unravel?

Hope not..

 

 

The one positive can take right now is the wavelength number, height and poleward flow lately would mean that even if we go pseudo, quasi or even fully zonal for a short while, it might not be too long before we get more bites of the cherry.

[Mike Poole]

Nope, it's blown that low into a bowling ball, even after it was disrupting.  T180:

Will eat my underpants if that verifies...