Model output discussion - 5th December 2016 - Into Winter we go

[Seasonality]

3 minutes ago, feb1991blizzard said:

Some support from the parallel for this evolution too.

Are you feeling ok? You just suggested a cold outcome had support...  Must be the festive season!

[Methuselah]

-10C uppers to within 100 miles of the SE - at the very end of the run - eh? What's the betting that, by the time that date arrives, there'll be +15C uppers coming all the way from Africa? That said, I wouldn't mind them either!

Edited December 12, 2016 by Ed Stone

[Paul]

For those who may be interested, here's what's going on with the GFS para (expected to be implemented May 2017). 

Quote

Changes to assimilation:

Introduction of Near-Surface Sea Temperature (NSST) describing near surface oceanic vertical temperature structure due to diurnal warming and sub-layer cooling physical processes. SST, satellite data assimilation and weather forecasting will be improved by using advanced GSI data assimilation techniques to analyze SST together with atmospheric analysis variables.

Changes to observations:

Radiances

Include Megha-Tropiques SAPHIR radiance assimilation

Monitor GPM/GMI radiance assimilation

Changes to land surface type specification for CRTM

AVHRR radiance and in situ (buoys & ships) sea water temperature observations are added to analyze SST

SATWND observation changes

Assimilate VIIRS winds

Log-Normal wind QC for winds

Assimilate GOES clear-air water vapor winds

Other changes

Assimilate extra GNSS-RO observations

Fix cloud water increment bug

Readiness for CrIS Full Resolution Data and add/extend RARS and

DBNET capability (JPSS, GOESR)

Forecast model:

NEMS software superstructure and infrastructure

SST diurnal variability is resolved with the NSST model.

Land surface changes

IGBP 20-type 1 km land classification

STASGO 19-type 1 km soil classification

MODIS-based snow free albedo

MODIS-based maximum snow albedo

Diurnal albedo treatment

Unify snow cover, albedo between radiation and land surface model

Increase ground heat flux under deep snow

Stability parameter constraint in the Monin-Obukov similarity theory to prevent land surface and atmosphere from fully decoupling leading to excessive cooling of 2m temperature during sunset. Modification of the roughness-length formulation in the surface layer.

Changes to cumulus convection

Scale-aware, aerosol-aware

Rain conversion rate decreases with decreasing air temperature above freezing level

Convective adjustment time in deep convection proportional to convective turn-over time with CAPE approaching zero after adjustment time

Cloud base mass flux in shallow convection as a function of mean updraft velocity

Convection trigger condition to suppress the unrealistic summertime spotty precipitation over high mountains.

Convective cloudiness enhanced by suspended cloud condensate in updraft

Rayleigh damping applied to model layers above 2 hPa reduced by 50%.

Surface reference pressure for the two-time-level semi-implicit semi-Lagrangian scheme changed from 800 hPa to 1000 hPa.

Changes in the land surface and stability parameter should reduce a near surface wintertime cold bias, a rapid temperature drop during sunset and reduce a blockiness apparent in some near-surface fields. Some nighttime warm biases were introduced. Changes in convection should reduce a positive bias in light amounts of precipitation and unrealistic summertime spotty precipitation over high mountains and increase skill in forecasting precipitation. NSST is expected to improve tropical forecasts and may affect mid-latitude oceanic storms. Reducing Rayleigh damping improved wind and temperature forecast in the upper stratosphere. Applying the revised reference pressure reduced model computational noise in the upper atmosphere.

 

[feb1991blizzard]

Just now, Seasonality said:

Are you feeling ok? You just suggested a cold outcome had support...  Must be the festive season!

because it has!!!   -   funny how ive been told I'm the biggest cold ramper on here in seasons past! -  If you go through all the threads of years gone by, you will see that I predict cold and mild, I'm still calling this odds against btw, it will need more than 50% of ens members across all suites showing a potent protracted Easterly as being the favourite before I call it that way - whats wrong with that?

[knocker]

Streuth

Oh dear........................the shock!

[Seasonality]

Just now, feb1991blizzard said:

because it has!!!   -   funny how ive been told I'm the biggest cold ramper on here in seasons past! -  If you go through all the threads of years gone by, you will see that I predict cold and mild, I'm still calling this odds against btw, it will need more than 50% of ens members across all suites showing a potent protracted Easterly as being the favourite before I call it that way - whats wrong with that?

Nothing wrong at all, I meant it in the best of spirits. However, and I DOn't know for certain, but I suspect someone may be along with a useful 384h mean chart that proves definitively that the outcome will be mild.

[Man With Beard]

22 minutes ago, Mucka said:

Unfair. I think it is pretty clear what was meant.

We likely would not even get a frost out of the chart you posted with daytime temps around 6C to 8C

It is actually more disingenuous for you to call me out and say we will get an Easterly that I didn't predict based on a single chart that shows a slack continental flow that was actually in charts when I posted!

I even mentioned temporary slack S/SE flow. 

If we get a genuine Easterly I will be the first to hold my hands up.

 

Sorry Mucka, I thought you were having just a bit of fun, so I thought I would join in!! Some on here may recall I said I would run down the street naked if we didn't get a heatwave during a part of August ... I got a lot stick on here when it was clear it wasn't going to happen!! 

Certainly if the UKMO is closer to the mark tonight, we'll be less likely to get an easterly. 

 

Edited December 12, 2016 by Man With Beard

[BLAST FROM THE PAST]

5 minutes ago, Ed Stone said:

-10C uppers to within 100 miles of the SE - at the very end of the run - eh? What's the betting that, by the time that date arrives, there'll be +15C uppers coming all the way from Africa? That said, I wouldn't mind them either!

Streuth what Knocker......how cold Egypt and Arabic states are? 

 

BFTP

[daz_4]

Now get that easterly under 100h because GFS is downgrade machine when it comes to cold air from east 

[phil nw.]

The later frames of the GFS op are certainly full of Christmas cheer although of course just for fun at that range.

What it does show though is the way to get an easterly from the current setup.Not perfect ,we could with the high a tad further north and more trough disruption underneath but a step towards a really cold pattern with sub zero uppers about to land in the se.

One consistent trend does continue though and that is signal for a Euro/Scandi block so that the Atlantic can't make any head way into Europe or indeed much of the UK.

 

[bluearmy]

The ending of the gfs ops is now getting interesting - not because it's the far end of an ops run which is usually worth little or no attention but because given the current gefs/eps theme, I think it's the only feasible way we could get deep cold to our shores pre new year. It fits the ext ens in broad terms but it relies on a few things going our way

[Methuselah]

3 minutes ago, BLAST FROM THE PAST said:

Streuth what Knocker......how cold Egypt and Arabic states are? 

 

BFTP

Have you changed my name, Fred?

Edited December 12, 2016 by Ed Stone

[carinthian]

GFS still keen on cold continent flow around Christmas with Scandinavia block in place.  Looks like Atlantic now wants to undercut  rather than going over the top. Will be cold in that surface flow with DP well below zero across England and Wales. C

Edited December 12, 2016 by carinthian

[mountain shadow]

1 minute ago, bluearmy said:

The ending of the gfs ops is now getting interesting - not because it's the far end of an ops run which is usually worth little or no attention but because given the current gefs/eps theme, I

The GFS MJO forecasts are keener on Phases 7/8 if I recall which is maybe why we are getting these scenarios from the GEFS. The ECM ens keep the MJO in the COD and therefore and not offering these solutions.

Time will tell who will be right.

[offerman]

Those charts while looking good are way too far out in FI as usual and has often been the case this winter. If these charts verify within a week then that`s reason to start getting more enthusiastic IMHO. 

How many times have we all got excited by FI charts only to be let down time and time again.  Ignore them at those distances as too much can change.

[Day 10]

Finally some interest right at the end of the run! Let's see if this kind of evolution can move forward into the 200's over the next few days. Got to start somewhere on our next road to find that pot of gold. I'll post that chart again like everybody else has to keep up the spirits as it's nice to look at.

[knocker]

11 minutes ago, bluearmy said:

The ending of the gfs ops is now getting interesting - not because it's the far end of an ops run which is usually worth little or no attention but because given the current gefs/eps theme, I think it's the only feasible way we could get deep cold to our shores pre new year. It fits the ext ens in broad terms but it relies on a few things going our way

Yes this scenario has come up before as you know but  i take it you noticed the transformation upstrem in just a couple of days. Rapid amplification, doing away with the vortex (neatly), ridging from the Caribbean connecting to the European HP, etc, etc, I'll believe it when I see it.

Edited December 12, 2016 by knocker

[Mucka]

17 minutes ago, Man With Beard said:

Sorry Mucka, I thought you were having just a bit of fun, so I thought I would join in!! Some on here may recall I said I would run down the street naked if we didn't get a heatwave during a part of August ... I got a lot stick on here when it was clear it wasn't going to happen!! 

Certainly if the UKMO is closer to the mark tonight, we'll be less likely to get an easterly. 

 

No worries mate.

I'm all for the banter of your first post, it was the second post that I thought was misleading readers because you appeared to be serious about the idea I was backtracking.

The trouble is that it is a perpetual struggle not to have posts misconstrued or misrepresented or taken out of context so while I took your first post as tongue in cheek the second suggested you were more serious than I thought so I felt further clarification was needed because we are in a public forum not PM.

It's just forum life. 

I honestly would rather get a nice cold Easterly and snow for Xmas than be right.

I'm just hoping GFS will eventually bring one of these retrogressing high scenarios forward instead of continually pushing them back into deepest reaches of fI.

Edited December 12, 2016 by Mucka

[carinthian]

9 minutes ago, carinthian said:

GFS still keen on cold continent flow around Christmas with Scandinavia block in place.  Looks like Atlantic now wants to undercut  rather than going over the top. Will be cold in that surface flow with DP well below zero across England and Wales. C

Further to the above post Looks like the main Atlantic jet wants to dive SE into Iberia and Morocco. Big shift between Christmas and New Year . Maybe the models are finding another route to dislodge the block. An undercut could produce the winter goods many want to see on here. More runs yet, hopefully GFS is on to something.

 C

[frosty ground]

12 minutes ago, offerman said:

Those charts while looking good are way too far out in FI as usual and has often been the case this winter. If these charts verify within a week then that`s reason to start getting more enthusiastic IMHO. 

How many times have we all got excited by FI charts only to be let down time and time again.  Ignore them at those distances as too much can change.

Who is getting carried away? Or who is showing to much enthusiasm?

It would be nice if we could read this thread without having to read stuff like this that only serves to stop the poster in question getting disappointed. 

[bluearmy]

4 minutes ago, knocker said:

Yes this scenario has come up before as you know but  i take it you noticed the transformation upstrem in just a couple of days. Rapid amplification, doing away with the vortex (neatly), ridging from the Caribbean connecting to the European HP, etc, etc, I'll believe it when I see it.

I think the retrogression probably overdone on that run as well as the potential undercutting. However, as you are aware, even the extended eps have sharpened the Atlantic trough and dropped the low anomoly further south over the past couple runs in conjunction with the uppper ridge persisting over s scandi. It's not an evolution that is inconceivable although it's likely the cold end of the envelope 

[Summer Sun]

Looking at the GFS ens and the high isn't over as much of the UK for Christmas as it was on the 06z                                                            

Edited December 12, 2016 by Summer Sun

[Mucka]

Merry Christmas from p5

[frosty ground]

3 minutes ago, Summer Sun said:

Looking at the GFS ens and the high isn't over as much of the UK for Christmas as it was on the 06z

12z                                                                 06z

I only see two 12z charts should there be an 06z to compare?

[Summer Sun]

2 minutes ago, frosty ground said:

I only see two 12z charts should there be an 06z to compare?

Yep for some reason It didn't put the 06z one over I have now removed it

Anyway, the GFS ens doesn't support the Op with its SE'ly

Op                                                               Ens

 

Edited December 12, 2016 by Summer Sun