Model output discussion 13th Feb onwards

[Frosty.]

BRrrrrrr minus 6 in late march puts our recent winter to shame. Now we finally get the northern blocking we craved for the last four months..it seems the uk weather has a sense of humour after all. :-)

[SLEETY]

typical .Ecm showing what we wanted all winter Thats what I love about uk weather though is its  unpredictability.

[bluearmy]

I wonder if what we are seeing in the model output at the moment is tied in with a

late SSW?

Zonal winds are forecast to be reversed right through the stratosphere by days 7-8..

ecmwf10f168.gifecmwfzm_u_f192.gif

A very interesting GFS 06z run this morning with height rises over Scandinavia which

retrogress to our north-west by 240 hrs which then allows a stonking Northerly.

gfsnh-0-120.pnggfsnh-0-240.png

Seems to tick quite a few of the SSW boxes.

it certainly looks like a possibility. the second week april looks like it could bring a wintry blast - though it takes an incredible combination of sypnotics and uppers to bring real winter to the southern half of the uk come mid april. plenty of water to flow under the bridge yet and the ens are well spread on their placement of the upper ridges and surface extensions. however, i expect a momentum to build in this direction over the next few days. whether that is merely another tease for nw europe remains to be seen but first half april looks like being very chilly for scandinavia. Edited March 23, 2014 by bluearmy

[johnholmes]

The last couple of 6-10 day outputs from the anomaly charts, NOAA and ECMWF-GFS do tend to support the ECMWF synoptic 00z run. So far the 8-14 shows no sign of this but I suppose it is possible for this to start to show in 2-3 days time. At the moment, based on NOAA, then I would suggest the high shown to the NW is unlikely to be there in 2 weeks time but may be there between 7 and 10 days?

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

[Polar Maritime]

GFS, ECMWF, and UKMET all showing strong signals for blocking taking place towards the end of the month now, very interesting model watching over the next week to see if the signal evolves. GFS has done very well picking this trend up first a few days ago..

 

[Frosty.]

Yes PM..I think the GFS has been the best performing model during the last 4 months, the much trumpeted ecm has performed abysmally.

[Polar Maritime]

Certainly has Karl, especially since the models upgrade last year, although the GFS always seems to handle these set ups better what with such a Westerly bias.

Edited March 23, 2014 by Polar Maritime

[Frosty.]

We never saw temperatures as low as this during that pathetic winter and the charts for the next few weeks show Easterly winds dominating, eventually turning warmer later as winds back SE'ly.

 

Today will see a shift in balance with the showers pushing across to the eastern side of the uk, some heavy and thundery with snow on the highest ground whereas the western side of the BI will dry up and become sunnier with lighter winds..but tonight, skies clear and winds fall light everywhere with a widespread sharp frost..minus 6 celsius for the coldest spots.

[Summer Sun]

The lowest temperature last winter was just -7.7 ^oC at Altnaharraon on February 17th we could go pretty close to breaking that tonight in some sheltered parts

 

[Summer Sun]

Some big temperature contrasts looking possible on Tuesday

 

 

 

Wednesday looks like it will be a chilly day for all

 

 

Temperatures slowly rise on Thursday

 

 

By Friday it turns mild again in the south

 

 

Its a similar picture on Saturday

 

Edited March 23, 2014 by Summer Sun

[bluearmy]

amazingly, yet again Gfs is the best model out there in the 10 day plus range!

[Polar Maritime]

amazingly, yet again Gfs is the best model out there in the 10 day plus range!

 

Yes BA, good to see you back posting now something of interest is showing in the charts, I thought you had given up..

[Thundery wintry showers]

The GFS is projecting widespread light precipitation from the upcoming easterly spell.  I don't expect sunshine and showers from it though, for with 850hPa temperatures generally above the -5C mark, it will be quite a stable flow- I think widespread stratiform cloud and light rain is most likely to be the result.  Sheltered western areas may get a fair amount of sunshine though and so may parts of the south, due to the relatively short track over the North Sea.

 

The 8-14 day outlook from NOAA persists in showing us under low pressure:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

This is quite consistent with what the GFS is showing in its extended timeframe.  The implication, to me, is that we can expect a spell of easterlies, followed by a temporary build of pressure to the NW, which may or may not last for long enough to give us a northerly for a couple of days, and then falling pressure to the north allowing weather systems to head in from the west as we head into April.

[bluearmy]

Yes BA, good to see you back posting now something of interest is showing in the charts, I thought you had given up..

Not been much to say pm. I noted the likelihood of a couple of colder days after the 20th and that has come to fruition. I cautioned against the mid month cold snap shown by the models. this pattern change to HLB has caught my eye due to the fact that it ties in with strat activity. of course it may well end up a west based neg NAO or be pushed to our east come the time. not impressed if it does turn cold. Don't mind chilly in april but cold isn't nice. very cold ........ now that would possibly be worth a look! However, after a dismal winter for coldies, a warm spring and summer would be wonderful.

I do hope everyone appreciates the sarcastic nature of my gfs post. I wouldn't want anyone thinking that I meant it.

[East_England_Stormchaser91]

Look at that on ECM. Wouldn't it just be sods law that a Greeny high forms throughout April...

[Polar Maritime]

Yes BA, the models especially the GFS have handled this cold snap very well indeed and was the first to pick up the signal and maintain it, From a model watches point of view "whatever the outcome".. there is at least something different of interest other than the West based weather pattern we have been stuck in all Winter.

 

Yes a warm Spring would be nice, but looking at the signals we may have to wait until Summer !

Edited March 23, 2014 by Polar Maritime

[Cloud 10]

I do hope everyone appreciates the sarcastic nature of my gfs post. I wouldn't want anyone thinking that I meant it.

 

 

 

Speaking of the GFS,the 06z operational and the 06z gefs control run seem in a hurry to get those heights to our NW at 168 hrs.

 

 

Meanwhile the jet looks to be taking a hike waaaay south.

 

[Summer Sun]

06z ensembles show the 850's trending above average from the 29th but before than we have a chilly week coming up especially in the east parts of NW Scotland could do well later in the week with more sunshine likely 

 

Edited March 23, 2014 by Summer Sun

[damianslaw]

ECM showing classic retrogression of heights towards Greenland - text book stuff, warm air advection western side of Greenland and Cold air advection over Scandanavia with associated deep trough and a very southerly tracking Jetstream.

 

GFS 6Z goes on a bit of a strange course post 144hrs, at the 120 hr timeframe it too shows heights building to the NW and a southerly Jetstream but then somehow manages to squeeze a trough SW-NE across the country into what are strong developing heights in all directions.. mmm not sure about this run.

 

UKMO appears to be following the ECM route.

 

In the reliable timeframe quite a chilly easterly - the models are showing quite a long draw from a NE direction, no import any continental warmth, though NW parts could see localised warmth under sunshine.

 

The charts today are showing the most 'wintry' synoptical evolution all 'winter season' - I said yesterday these kind of evolutions are much more likely as we hit Spring than during winter and therefore not unusual and in many respects have a much higher chance of verifying now than they would have 2-3 months back when the atlantic traditionally wins out. In Spring the battle lines between a continental or northerly influence are evens against the atlantic.

[gottolovethisweather]

Just my take on things from a broadly Southern England perspective, if anything probably a drier signal further North as a HP cell tends to develop over this region. A right ole mix of Temperatures about over the forthcoming week but nowhere becoming especially warm.

 

http://forum.netweather.tv/topic/79573-south-westcentral-southern-england-regional-weather-discussion-27214-18z/?p=2949034

[draztik]

Just my take on things from a broadly Southern England perspective, if anything probably a drier signal further North as a HP cell tends to develop over this region. A right ole mix of Temperatures about over the forthcoming week but nowhere becoming especially warm.

 

http://forum.netweather.tv/topic/79573-south-westcentral-southern-england-regional-weather-discussion-27214-18z/?p=2949034

 

If I was back home in my native Ulster, im sure id be hearing 'its a wee bit nippy out' ... because as you say, nowhere looks like being overly warm. Certainly the ecm ens are promoting the idea of a cool start to April, with the 850's below normal into the mid term.

 

temp anomaly 2-7April.

[Summer Sun]

The north of the UK is likely to see some of the driest weather later in the week with low pressure becoming more of influence in the south

 

[vladthemert]

There shallow low expected wednesday comes from think poland area looking map slams into bridlington area uk.  What sort trouble expected with sea swells.

 

[gottolovethisweather]

There shallow low expected wednesday comes from think poland area looking map slams into bridlington area uk.  What sort trouble expected with sea swells.

 

 

Nothing to be overly concerned about, Vlad. Will no doubt bring about an increase in swells but nothing exceptional at this stage.

Edited March 23, 2014 by gottolovethisweather

[johnholmes]

Hi TWS. Can I ask: if you're discussing the stability of the profile why are you referring to the temperature at 850mb?  There continues to be a real focus on the temperature at that level yet no-one is looking further up in the atmosphere to see if we're situated under an upper trough or ridge.  This is key because it's that point that determines whether the profile is going to be an unstable one, not how cold the low-level temps are.  Indeed, you can have a scenario where the temperatures at 850mb are -10C but still have a relatively stable profile if there also happens be a weak ridge aloft.  So, in that regard, I think your assessment of the period in question is a little off.  Toward the latter half of next week, as the flow at the surface becomes uniformly easterly, we are still situated under relatively low geopotential heights and cold upper air for a time (-30C at 500mb), which keeps mid-level lapse rates steep.  This maintains an unstable profile, therefore potential for heavy showers with low thunder risk exists. Of course, things can change, but that's what current model output would indicate at this stage.

Best you look at the t-phi profile. For the full picture. If there is an inversion in the lower layers then the 500mb t is not a good guide.