Winter Model Discussion 18Z 8/1/13. The hunt for cold (is closer).

[cold snap]

cast your minds back to yesterday ecm followed the gfs.

Gem ecm dont over complicate any shortwaves,its a small window to get greenland heights.

Be interesting if there is any ens support for this outcome ,i believe there will be

[bluearmy]

Are we seeing the standard pre cold spell gfs wobble ? given the recovery on the 00z gefs wrt to yesterday, i wouldnt be concerned as yet. my eye was drawn to the way the ecm mean recovered amplifiaction at the end of its run when one might expect the opposite.

extremely messy and uncertain. the polar opposite to nov/dec 2010 (sorry for the pun!)

[pyrotech]

I merely quoted brum as one example based on tephi. UKMO modified fields don't just restrict potential to there.

Hi Ian,

yes i understand that, but is it the thickness and WB thats giving doubts about anything further South, i would also expect the line to move south as the day goes on and increase with elevation. Its just looking at GFS and your comments the two factors above are what i saw as main forecasted difference between the outputs

[picog]

Hiya

I have very limited knowledge of models and their likely outcomes, so could someone please give me a biginners description of an outlier, a short wave and a toppler please?

I know there's a learners area but a bit short of time at the moment and I'm sure you guys will be able to give a perfect explination!!

Thanks Guys

A shortwave is basically an area of low pressure. Not sure about the others, so hopefully someone else can step in.

[bradymk]

Ian F, if you are around, do you know what the UKMO view is on GFS this morning and whether it's shortwave by Iceland is a plausible and likely outcome or are they leaning towards the ECM option with no shortwave scuppering the pattern? If the GFS didn't have that shortwave (which I am pretty sure is the problem)

[Dexter29]

Please stop saying "one run"

December 2012 was just "one run" and look what happened.

You can't ignore the fact that the 00z and 06z gives us the Atlantic next week just like most of us did not ignore the fact that models were giving us 47' style charts yesterday.

Please please 12z - go back to the stunners of yesterday!

[garbagebags]

My concern is not that the GFS has downgraded (that was always going to happen after a "perfect" run). Its the way its downgrading it doesn't look like a "blip" or a "wobble" it looks like a steady upgrading of the shortwave and to be honest I believe it and its very worrying. I say game over for next week, "pest from the west". Would appear there is no such thing as a "block" anymore...

anyway, heres hoping I'm wrong.

Edited January 9, 2013 by garbagebags

[alexisj9]

That won’t happen until they become short term, mid range models agreeing with one another is the exception rather than the norm at any time of year, the trick is to learn not to care if they don’t agree as most of the time it’s not relevant.

This easterly that seems will happen this weekend was picked up and then droped by both GFS and ECM so I am not yet woried about anything that is showing and then vanishing in fl, it may come back in the reliable. It's a case of wait and see.

[weather eater]

Now let’s watch the 06z ensembles all point in the opposite direction.

[UV-RAY]

Remember tis only weather, not life or death. I see downgrades for next week coming from all the models just nowhere near as bad the 06z. Anyway I' m off out for a nice stroll in the first bit of sunshine we've seen in weeks. Chillax peeps!

[NO LONGER POSTING]

I said yesterday in the South East thread we would see downgrades ETC. It is bound to happen. The models are all over the shop at the moment and I really stress not to look past 1HR tbh (only kidding) but seriously, if somebody made a model that could predict the weather +122hrs then they would be classed as a god..

[wallopweather]

Am I missing something? these are just computer generated models, they don't actually control the weather and nothing they predict is actually cast in stone. I'm amazed at the number of people who seem to be taking these outputs as gospel. We still have a long way to go when it comes to correctly predicting the weather beyond a few days and it is still only wednesday and the constant moaning on the model forums when we miss a bit of a chilly period is one of the reasons I stopped visiting and interacting with the forums.

[Methuselah]

Och well, in the immortal words of Ian Brown, WTF!

[TyphoonNow]

I wondered if anyone posted a detailed report/description of the reasons behind the December 2012 model turnaround? If they noted the signs before (or looked back and traced them) of the eventual outcome amongst the cold train, which was derailed.

Maybe there is something to be drawn from that time?

[Carl46Wrexham]

This easterly that seems will happen this weekend was picked up and then droped by both GFS and ECM so I am not yet woried about anything that is showing and then vanishing in fl, it may come back in the reliable. It's a case of wait and see.

All well and good...but I recall similar comments when the December fiasco was unfolding. I just hope that what is happening this time is not a repeat performance. The last thing this country needs is another rain fest.

[pyrotech]

Hiya

I have very limited knowledge of models and their likely outcomes, so could someone please give me a biginners description of an outlier, a short wave and a toppler please?

I know there's a learners area but a bit short of time at the moment and I'm sure you guys will be able to give a perfect explination!!

Thanks Guys

Shortwave, = low pressure

outlier is when a operational run, or control run is against the other runs. Gfs might run 20 different scenarios with different starting data by day four they are normally going in very different directions, an outlier is one that goes totally away from most of the other runs(members)

Toppler, this is where we get a brief Northerly that is disrupted by high pressure spoiling it.

[Tim Bland]

Grrr as soon as ECM is onboard GFS jumps ship! Should be a mild outlier though

[TAFKAP]

I'm afraid I only see this going one way today! Mild! Expect ECM and ukmo to follow suit. I just think this winter was doomed since December. Ain't getting the brakes I'm afraid.

What a well thought out response to the model output there and thank you for backing up your thoughts with such a detailed analysis and providing us with such illustrative charts. Your input is very helpful indeed!

[bradymk]

A big GEFS suite coming up, which the GEFS 00z was a big improvement on the 18z so I wouldn't worry too much yet, no other model supports this shortwave. Even then, I will be pretty surprised if it turns out like the 6z because even if we did lose the cold, it would not be that quick in my opinion.

[peterf]

what time for the ensembles 11am?

just found it 11.50

[Weather Boy]

Predictable and ridiculous over-reaction by some members to a poor 06z.

What we have to remember is Monday is, and has always been FI and that probably won't change for at least a day or two. We were never going to get run after run of snowmaggedon on all models.

The ECM may be right. The GFS may be right. But we know that it will turn wintry over the weekend -highly likely- and thereafter is anybody's guess. It has never been clear what the weather will be like next week, as Ian F and the METO have made clear. To assume the 06z is correct makes no sense at all, even though it of course might be.

Might I also comment that whilst the 06z is a horror show in the current context, it would have got folks majorly excited had it been during the middle of the recent zonal outbreak.

[garbagebags]

Historically speaking what are the % chances of shortwaves being downgraded vs being deepened, once they have been picked up?

[Paul_1978]

As regards the SSW, the guys in the strat thread are still very pleased.

It was said a day or so ago by Ian F that the models are not yet taking into account and reflecting SSW influences.

So my question is this - when will the effects of the SSW start showing in model output?

Given the possible effects of the SSW with regards to cold weather, I think there is a hell of a lot to look forward to in the next 6 weeks of winter.

No one would write off the rest of summer based on model output on 8th July so we should not do it now.

[Alexis]

Every chance it could have completely vanished by the next run.

[nick sussex]

At this time any news from upstream which rubbishes the GFS is fine by me! So this is the best I can do at the moment!

SATURDAY NIGHT...LATEST MODELS DEPICT A WAVE LIFTING NORTHEAST

THROUGH THE BAROCLINIC AXIS WELL TO THE SOUTHEAST WHICH WOULD

SPREADING LIGHT PRECIPITATION INTO IL...AND POSSIBLY INTO SE IA. THE

GFS IS AN OUTLIER WITH A MUCH STRONGER AND MORE NW TRACKING SYSTEM...

WHICH RESULTS IN OUR FORECAST KEEPING CHANCE POPS FOR LIGHT SNOW

ACROSS THE SOUTHEAST.

That nw tracking system is the one that heads towards western Greenland and phases with troughing in the west Atlantic.

SUNDAY INTO TUESDAY...COLD HIGH PRESSURE BUILDS OVER THE REGION

WHILE THE UPPER LEVEL TROUGH TRANSITIONS EAST OVER THE AREA. THIS

WILL RETURN TEMPERATURES BACK TO NEAR OR BELOW NORMAL. MODELS

DIVERGE EARLY IN THE WEEK...WITH THE GFS DEPICTING A LONGWAVE UPPER

TROUGH OVER THE CENTRAL U.S. AND ANOTHER SYSTEM BRUSHING PAST TO THE

SOUTHEAST BY MONDAY NIGHT...WHILE THE ECMWF IS LESS PHASED WITH MORE

OF A SPLIT FLOW PATTERN...KEEPING SYSTEMS WELL TO THE SOUTHEAST.

I should also add though that NOAA didn't think much of last nights ECM operational run in terms of what it did with the PV in the USA.

LATE DAY 6 TUE THRU DAY 7 WED FOLLOW A 70/30 WEIGHTING OF THE 12Z

ECMWF/18Z GEFS MEANS GIVEN ROBUST ENSEMBLE MEAN AGREEMENT AND

VERIFICATION CONSIDERATIONS IN FAVOR OF THE 12Z ECMWF MEAN. THE

12Z ECMWF BRINGS ITS NRN CANADA VORTEX WELL SWD OF CONSENSUS BY

WED.