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phil nw.

Model Output Discussion 4th Dec.2013-12z onwards.

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WOW!! that is really shocking for Coldies. Even the coldest outlier only gets down to a one day cold snap, with the mean only drifting down to highs of 7 and lows of 3 during the week before Christmas and  the big day itself. Greenland Vortex tight and spinning, heights to the South.. Pattern locked in for 2 weeks at least - Very Mild, mild, Cooler at various times - but no cold.

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I sense some big changes in the FI charts over then next 2 days, New year onwards to be cold...

I think this thread needs it...CFS model has constantly hinted at cold towards the end of Dec, let's hope it gets it right.

Are we now close enough to Xmas day to say we won't see snow, I think so.

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the trend to the sinking atlantic trough into w europe through week 2 continues. this will raise the possibilities of the north of the uk experiencing cold zonality at times. with secondary lows forming and running in the flow, there could be some surprises in scotland. in general though, this pattern change will take us through to beyond xmas. it could lead to any number of colder patterns or it could be transient and revert back to a 'bartlett type' situation as we have approaching. if the northern arm of the jet relents then i still believe the scuro block will assert itself and drive a scandi block. thats conjecture as nearly all modelling doesnt follow that route. the slowly sinking trough will take the jet south with it in time. that gives the potential for the ridging to drive nw above it which is one of the possible colder patterns. realistically, looking for cold within a fortnight looks a forlorn hope for the moment.

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Thats the gulf stream for you, if it wasn't for that we'd get bitter winters probably every year given our latitude

A bit pedantic but that's not strictly true. The reason is that the jetstream and associated weather systems move from west to east, and the air mass is modified by its passage over the Atlantic to us. That would be true even if the Gulf stream didn't exist, we would still have a maritime climate rather than a continental one, although granted temps would probably be a few degrees cooler. So today for example, Scotland might be getting temps of 7C instead of 11 or 12C. Bitter winters only come from airmasses sourced from eastern or northern quadrants, and I doubt that the lack of the gulf stream would make a huge amount of difference to the frequency of those events.

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Very seldom post in here but for all the doom and gloom regarding no cold etc I can at least say the last 2 days have provided some of the best freezing fog and frost I've seen in years!  Admittedly not raging easterlies with blizzards as desired by most.  Often a good fog has proceeded a memorable freezup.  I can't claim any meteorological insight to this statement though!

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Yes, my own expectations and that of other coldies probably requires a look at December thus far and most likely up to Christmas as a more raging-zonal type like those often seen back in the late 90s and a vast part of the 2000s.

 

For all those interested in my own views, I have simply lessened my expectations back down to earth for the moment. However, there are certain folk in here (not naming names) whom don't appear to add much else than regurgitate old news. Yes, it sure is a bit of a bleak outlook in comparison to more recent years but Temps will still only be average/slightly above at best and often lower on occasion in the coming seven to ten days. Windstorms are also on the agenda and with the FOG unable to clear at home right now, I am currently achieving a maximum of barely 4c in my neck of the woods. When you look a bit deeper, it is no lie that there is currently little wintriness on offer but gut feeling tells me that this will change as we enter the final third of December, watch the ensembles for early signs of this, not just individual charts and as others had said also watch the Jet profiles.

Edited by gottolovethisweather

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Yes Mucka, but even then the 14th, 17th and 20th December all hint at Polar maritime incursions though, granted they might not make it to Southern England. Posted Image  Yes, my own expectations and that of many other coldies needs to look at December thus far and possibly up to Christmas as a zonal type like those seen back in the late 90s and a vast part of the 2000s.

 

For the attention of all, I have simply lessened my expectations back down to earth for the moment, but there are certain folk in here whom don't appear to be doing anything other than regurgitating old news. Yes, a bit of a bleak outlook in comparison to more recent years but Temps will still be average at best and even lower on occasion in the coming seven to ten days. Windstorms also on the agenda and with the FOG unable to clear at home, a maximum of barely 4c ensuing in my neck of the woods. When you look a bit deeper, it is no lie that there is currently little wintriness on offer but gut feeling tells me that this will change for the last third of December.

 

It looks quite likely that this will be the third predominantly westerly December in a row. 2011 was very westerly, 2012 less so to start with but was very zonal in the second half.

 

I think 2009 and *that* December made us forget about this sort of bilge that we're having to endure.

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It looks quite likely that this will be the third predominantly westerly December in a row. 2011 was very westerly, 2012 less so to start with but was very zonal in the second half.

 

I think 2009 and *that* December made us forget about this sort of bilge that we're having to endure.

 

Yes, Meteorological Winter is in its very early days and so far in Newbury I've only had one double-digit Max in the first ten days but I guess I can expect a few more yet. Accordingly one third in, the comparison against the 1981-2010 averages shows my location at only 0.3c above average which is hardly mild, excepting for the fact I've had just two slight Frosts in ten days. Anyway, best leave it to others to post back on topic with the first of the afternoon suites just over half an hour away.

Edited by gottolovethisweather

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Today's NAO update show it at either natural or slightly positive for the rest of the month

 

Posted Image

Edited by Summer Sun

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I just want to indicate the start-off point for today's afternoon runs as the current forecasted UK t850 uppers show this.

 

 

 

Posted ImageGFS 12z 111213 UK 850s & SLP at 1500 hours - t+3.png

 

Look outside your window in your patch and what is the reality, for me it is far far removed from what the current charts suggest, at the surface. To repeat, the experienced among us do not take charts as gospel i.e. at face value, the reasons for this are very complex beyond the realms of my understanding. Currently with 9c uppers it would be expected for me to be sitting mild surface conditions, it is currently 3.7c after a daytime max of just 3.9c due to thick fog.

 

Here endeth gottolovethisweather's sermon. Posted Image  The models are simply guidance tools and each one of us is open to differing interpretations of said developing weather pattern. Now, let's give that PV a good beating and let the Atlantic floodgates push those Euro highs back across to Russia. I commence my Eastern seaboard watch herewith and will wait to hear our netweather correspondents thoughts on the coming days and week's weather. Posted Image

Yes you posts can be some what difficult to digest. Anyway, as you say surface temps and very much different to 850's etc. Not got above 7.2 here.

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Jet attempting to dig South in the Atlantic at t+111. Posted Image

 

Look to this timeframe as being where all NWP output will begin to differ, which is only 16th December right now. Posted Image

Edited by gottolovethisweather

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I just want to indicate the start-off point for today's afternoon runs as the current forecasted UK t850 uppers show this.

 

 

 

Posted ImageGFS 12z 111213 UK 850s & SLP at 1500 hours - t+3.png

 

Look outside your window in your patch and what is the reality, for me it is far far removed from what the current charts suggest, at the surface. To repeat, the experienced among us do not take charts as gospel i.e. at face value, especially the deeper into Fi you get. The reasons for today's situation are very complex and are generally beyond the realms of my understanding. Currently with 9c uppers, you would be expected to be sitting mild surface conditions, whereas in Newbury it is currently 3.7c after a daytime max of just 3.9c due to thick fog which never relented. The models are simply guidance tools and each one of us is open to differing interpretations of said developing weather pattern. Here endeth gottolovethisweather's sermon. Posted Image

 

 

Now, let's give that PV a good beating and let the Atlantic floodgates push those Euro highs back across to Russia. I commence my Eastern seaboard watch herewith and will wait to hear our netweather correspondents thoughts on the coming days and week's weather. Posted Image

 

 Not hard to unerstand IF you can follow the skew-t diagrams (if not then take a look at the Guide on them), see below for the Watnall ascent 12z today.

http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=GIF%3ASKEWT&YEAR=2013&MONTH=12&FROM=1112&TO=1112&STNM=03354

 

The 850mb is shown as +12C or so with the surface at just above zero C. What is called an inversion or what some like to call  by other clever names that are meaningless. Surface cold beneath an inversion from a ridge of high pressure-a not uncommon happening. Even where the fog cleared then a maximum of about 8C close by that ascent would be expected.

below is the ascent for the far north of Scotland

http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=GIF%3ASKEWT&YEAR=2013&MONTH=12&FROM=1112&TO=1112&STNM=03005

850mb T there is approximatelky 4/5C with winds from the SW hence another weather phenomena called the fohn effect occurring in some eastern places with maximum up to 15/16C, and the actuals showing 13-14C.

Quite how folk can say weather is boring when all one has to do is look for something interesting is beyond me.

 

The 12z Fax chart shows the surface set up, high pressure east of the country with quite a frsh flow from about SW in western and northern parts.

http://www.weathercharts.org/ukmomslp.htm

Edited by johnholmes

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Back to the models, the UKMO chart at t+120 below shows a continuing Southward trend with surface features which may be something to keep an eye on in future runs, given that the GFS 12z concurs with the Jet digging South at times, even in the relative near-term.

 

post-7183-0-60918600-1386778871_thumb.gi

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The GFS 12 looks more progressive on the face of it, but this time yesterday it did much the same with the 'Icelandic Beast', only to unwind things again on the 18, 00 and 06.

 

Still one to watch with interest though.....

Posted Image

Edited by shedhead

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 Not hard to unerstand IF you can follow the skew-t diagrams (if not then take a look at the Guide on them), see below for the Watnall ascent 12z today.

http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=GIF%3ASKEWT&YEAR=2013&MONTH=12&FROM=1112&TO=1112&STNM=03354

 

The 850mb is shown as +12C or so with the surface at just above zero C. What is called an inversion or what some like to call  by other clever names that are meaningless. Surface cold beneath an inversion from a ridge of high pressure-a not uncommon happening. Even where the fog cleared then a maximum of about 8C close by that ascent would be expected.

below is the ascent for the far north of Scotland

http://weather.uwyo.edu/cgi-bin/sounding?region=europe&TYPE=GIF%3ASKEWT&YEAR=2013&MONTH=12&FROM=1112&TO=1112&STNM=03005

850mb T there is approximatelky 4/5C with winds from the SW hence another weather phenomena called the fohn effect occurring in some eastern places with maximum up to 15/16C, and the actuals showing 13-14C.

Quite how folk can say weather is boring when all one has to do is look for something interesting is beyond me.

 

Thanks John, still learning and haven't attempted to understand skew-t diagrams but I'll no doubt pop over to the learning area sometime in the future. What I was trying to press home is the apparent obsession (to strong a word but you'll get my meaning) to overanalyse the details, i.e. looks like 16c max at t+148 hours whereas the reality will most likely be not even similar. Add to that, how we all seem to know everything about anything when the weather and climate simply continues to ignore us and teaches us the ultimate fact that we don't know everything. Did that last sentence make sense? Posted Image Posted Image

Edited by gottolovethisweather

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Real feel: 3-5C Snow showers for high ground and western/northern areas:

Posted ImagePosted Image

Edited by Panayiotis

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The NH profile is interesting on the 12z. On the 6z, low pressure had successfully breached northward through the area of high pressure spanning the Bering Straits by this stage. On the 12z this hasn't happened yet. I don't know what the implications are, if any, so input would be welcome!

Posted Image

EDIT - the jet is also very amplified over the Western side of the United States at 240hrs

Posted Image

Edited by Joe Levy

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Nice Arctic high at 216hrs, should yield at better outcome regarding cold later in the run...

Posted Image

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PV looking slightly less threatening around early FI, though we need to see the core shift from Canada/Greenland area

 

Posted Image

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Back to the models, the UKMO chart at t+120 below shows a continuing Southward trend with surface features which may be something to keep an eye on in future runs, given that the GFS 12z concurs with the Jet digging South at times, even in the relative near-term.

 

Posted ImageUKMO 12z 111213 SLP & HGT500 at t+120.gif

 

The t+144 not so promising but some variation on a theme I reckon, a definite ramping up of the Atlantic into next week with alternating PM and TM influenced weather patterns emerging. The final third of December is currently up for grabs IMHO. Forget prolonged cold and think colder incursions is how I currently see things.

Edited by gottolovethisweather

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Northerly for Christmas? Arctic high evidently the cause of the movement of the PV from Canada/Greenland to SIberia on this run:

Posted Image

Edited by Panayiotis

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GFS starts the pattern change about day 9 tonight and by deep FI it's well under way. Given the 12z outputs yesterday evening and now this from GFS, the tide MAY be starting to turn

 

Posted Image

 

 

Jet digging further and further S in FI due to pressure from Pacific ridging.

Edited by CreweCold

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