Model output discussion 25th Jan onwards

[bluearmy]

Thanks for clarifying. Could you give an example of a situation where the jet does sink south with all in its wake?

1979 !

[Troubleatmill]

Stratospheric warming encourages high latitude northern blocking to develop, but whether it develops in a favourable location to bring cold weather to Britain, or trough disruption and slider lows allow cold air to reach Britain is a different matter.Minor warmings can take up to 3-4 weeks to have any effect of increasing northern blocking, but sudden stratospheric warmings (huge increases of polar stratospheric temperatures over a small number of days, can increase northern blocking within a week). Although as I said earlier, with a SSW you still need the location of the blocking and trough disruption and slider lows all to fall into place to deliver a cold spell to the UK.

Thanks north easterly, I understand that part, thinking december 2012. what got me a little confused though was that the warming in early Jan just went with no effect or coming down to the trop at all?, just how I read Chios post who I respect the highest with the strat, sure we all do infact sorry mods I dont know how to move, so will ask in the stat thread, always willing to learn Edited January 27, 2014 by Nicholas B

[East_England_Stormchaser91]

Gavin P wasn't that far off with his USA forecast he did say the probability of a strong ridge near to the Pacific North West would encourage cold conditions for central and eastern parts but it all went wrong thereafter saying that our winter could be 'dry if not very dry' and temps close to normal but fair play to him.

As for this evenings ECM although better than earlier today it's still difficult to see how any cold continental air can be advected westwards it's just one big high pressure 1500/2000 miles away acting slightly more as a buffer on this run before the inevitable happens.

Gav seems to have done a better job than all of the models put together!

[Man With Beard]

Using the JMA rather than the GFS for the jet stream (more detail to me) @T192 it is South of the UK and would think it would take any lows, like this week, NW/SE. I would also think and hope that once colder air starts to fill Europe then proper battlegrounds could take place.

 

Completely agree with this. I'm going to argue that we haven't moved a million miles away from the slider low scenario. The ECM in particular threatens to send energy into Europe. This has been the problem of the last three weeks - just how much of each low pressure is going to split under and how much is going to split over. Such scenarios are rarely settled until T72/T96. But the ingredients are still there, even if the model output of the last 2 days has said no.

 

Anyone else noticed how the models are fluctuating in a kind of cycle? A week ago, the ECM was going for a clear Atlantic victory for later this week with a more northerly tracking low. A couple of days later, it swiftly moved to a slider low. By Saturday, it was back to the northerly low - remember that strange run on Saturday morning with a cut-off low in the North Sea? This evening, two days on, this weekend's low does not clear the Hebrides and ends up getting pushed back. 

 

I feel this is going to continue for a while. At some points, it will look as if the Atlantic will get the upper hand back - then eastern blocking will threaten again. This has been the pattern of the last 2 weeks. I think the Northern Hemisphere is undergoing transition with an Atlantic beast and an Eastern beast both vying for supremacy. It's been a stalemate these last two weeks. I believe the PV will eventually lose this battle as the sun gets higher and higher in the sky. We will not go back to December. But because of the extreme cold in the US/Canada this winter, it's taking a bit longer for this transition to happen.

 

So I'm going to predict no change from the last two weeks for the next two weeks. Blocking will remain to our east and the cold line will stay between 300 and 600 miles from the east coast. Lows will keep reaching the UK but not push through. Encouraged by the jet, occasional lumps will break off low pressuresand go into Europe and when a bigger lump breaks off we will see brief colder easterlies. Then, at some point between Feb 5th and Feb 15th, just because I can't believe the Atlantic can continue as relentlessly as the GFS suggests, a lull will appear in the pattern, allowing some warmth will be injected into the western side of the Scandi/Russian High, and blocking will be encouraged move west across the UK and to the North and East. If the block is favourably positioned, it will get cold. Best scenario is the PV keeps some strength and lows continue to attack the block leading to snow on the leading edge.

[MisfitDog3]

FI is FI. doesn't matter if you favour mild or cold, the same very small chances of stuff at +192 hours or whatever verifying carry on. What has been the theme of this Winter? Outside rain, it's been the unprecedented repeat violent swings across a number of the models. Nothing is reliable outside the 5 day window....yes the Atlantic looks very powerful but it takes a brave man or woman to hang your hat on anything in mid Feb....

[Gibby]

Hi everyone. Here is the evening report on the latest 12 noon outputs from the NWP for today Monday January 27th 2014.

 

All models show a slowly filling depression slipping slowly SSE over the UK and down over France by Thursday having largely filled up by then. Over the next 48 hours further very showery weather persists over the UK with showers or longer spells of rain with hail at times and sleet and snow over the high hills of the North. Winds will be brisk from a West or SW point in the South then an easterly point in the North by Wednesday. Thursday then sees a spell of rain and hills now move SW on an occluded front dying out over the SW later in the day. Eastern and Central Britain may see the isolated wintry shower or two briefly before a deepening depression to the NW of Britain sweeeps any cold weather away with freshening Southerly winds carrying rain East across the UK on Friday with some snow over the hills for a time.

 

GFS then shows a very unsettled and windy spell with winds between South and West throughout with showers and longer spells of rain occurring with all too much frequency as deep Low pressure areas successively sweep NE over the UK with temperatures very close to average for early February.

 

The GFS Ensembles show a wet and windy two weeks with the Atlantic in total control of the UK weather with Low pressure after Low pressure ensuring that the weather doesn't allow any  recovery in conditions affecting the flooded areas of the SW. Temperatures will remain close to average and after a short chillier than average spell for a time this week we become rather milder than average in places later.

 

UKMO tonight has conditions on Sunday governed by a Low pressure area moving away to the North taking it's showers with it and allowing a weak ridge of High pressure to cross East and bring a drier spell of weather for many ahead of a new Low pressure area approaching from the SW to start next week.

 

GEM is also painting a very unsettled picture with showers or longer spells of rain in strong SW winds in association with Low pressure encircling over and to the NW of Britain.

 

NAVGEM is very similar with Low pressure well established to the NW of Britain with strong winds and spells of rain and showers sweeping NE on regular occasions from this coming weekend.

 

ECM too is very changeable but perhaps a little less deeply unsettled over the South for a time with average temperatures and winds from the South or SW for most of the time.

 

The ECM 9 and 10 Day Mean Charts show the likelihood of Low pressure being positioned just to the NW of the UK with a cyclonic South or SW flow across the UK in pressure levels at sub 1000mbs over the majority of the UK. With relatively mild winds from the SW and such low pressure we can only expect the prospect of plenty more rain and showers, probably heaviest in the areas that least need it, being the West and South.

 

http://www.wetterzentrale.de/pics/Reem2161.gif

 

http://www.wetterzentrale.de/pics/Reem2401.gif

 

The GFS Jet Stream Forecast maintains the flow close to or over Southern Britain over the coming few weeks. The flow will be just to the South through the firsts week before it shows signs of strengthening strongly again later in the low resolution part of the run.

 

In Summary the Atlantic is gaining supremacy more and more with each run as the embers of the cold spell become reduced to one day on Thursday. With successive deep Low pressure areas spiralling around to the NW of Britain from all output to a greater or lesser degree the weather will remain very unsettled and often wet with showers or longer spells of rain in brisk, sometimes strong SW winds and temperatures recovering back to near or even a little above the seasonal average in the South at times.

[Gibby]

FI is FI. doesn't matter if you favour mild or cold, the same very small chances of stuff at +192 hours or whatever verifying carry on. What has been the theme of this Winter? Outside rain, it's been the unprecedented repeat violent swings across a number of the models. Nothing is reliable outside the 5 day window....yes the Atlantic looks very powerful but it takes a brave man or woman to hang your hat on anything in mid Feb....

I think saying what you say is what happens when we all follow the operational runs of each model as gospel which have of course swung quite quickly from one solution to another of late. However, the ensembles have always been much less susceptible to such swings over recent weeks and at no time have shown anything resembling a full blown Easterly bias within their ensemble group and that is what seems to have come to pass. Follow the operational runs of course but always remember that without the support of it's ensemble group it is far less likely to verify unless of course it's member ensemble group support the operational. Using that basic rule of thumb will set you up for less of a fall when the operational's follow a sensational chart on one run with one that contradicts it's predecessor on the next and could make model watching a lot more enjoyable and less traumatic and less under and overwhelming for new members to the forum trying to learn. I am not a believer in FI is FI and never verifies. These time frames have and continue to provide good guidance to me and are excellent at picking up trends as long as one doesn't dwell on the specifics of each chart until it falls within more reliable time restraints. Of course sometimes even the ensembles don't pick up on trends until we are close to the event but in general you won't see such wild swings day to day as you will within the operational's.

[Earth Wind and Snow]

If all models only went out to + 144 and the majority were showing something like this - we would all be salivating at the mouth. 

 

 

Unfortunately this chart is + 24 and its all expected to go pear shaped soon after with the atlantic blasting through and the cold high to the north-east sinking south-east wards. However it is a close call and may still bring something wintry to north-eastern spots before / during the breakdown.

 

The good thing is that we get this close to a bitter easterly despite the raging vortex and unfavorable back ground signals. Sometimes we need two or three attempts before the cold wins the day. Last week the cold reached the north sea - this week the cold will make further inroads to our islands.

 

If the vortex continues to weaken and we get another attempt, I believe we have a much better chance of the cold becoming established - call it third time lucky. These type of battles often become a repeating pattern once established so I would not be surprised to see another attempt in the next 1-2 weeks.

 

Still a long way to go in this winter - hopefully by the weekend the models will be picking up the next attempted mild v cold battle and we can all get upon the next roller coaster ride.

 

Keep the faith coldie friends

 

EWS 

[weirpig]

from what i can see the low on the latest gfs is even deeper. Got a feeling the uk and ireland could be swept away into france at this rate 

[pip22]

I don't think it will be as bad as Christmas though. It is enough to bring a few branches down.

 

 

We still pretty much in the cold air mass on Sat.

Edited January 27, 2014 by pip22

[Mucka]

Next Friday night/Saturday still looks quite interesting day with everything including the kitchen sink probably thrown in the mix. A lot will depend on the track and strength of the low and how much the 850's get modified across the Atlantic but some potential fun and games based on current output.

 

Edited January 27, 2014 by Mucka

[Blake]

Latest GFS showing heights strong over Greenland and slightly better over Scandi. Block coming back? Could be on to something here...?

 

If heights over Greenland build, pushing lows further south before heading across the Atlantic, would be in a better position to slide SE when it hits the Scandi high?

 

12z

 

 

18z

 

[bluearmy]

there is no good news for coldies. if you place any value in the extended ens (and to be fair, they have sung a similar tune for a fair while though the strengthening block to our ne delayed it being played out for about a fortnight), we are looking at the next fortnight devoid of any decent wintry potential (ignoring events into and through the weekend).  troughing to our west, blocking to our north and slowly but surely through week 2 , euro heights rising, especially se europe will lead to a mean souester. no doubt the troughing will edge over us from time to time so not much respite from the unsettled nature of things.  the only hope i can give you is that the block holds on that bit longer (signs on the 12z ops that this is reasonable through to day 8 and we can somehow get another arctic ridge passed across from the other side of the NH.   a pretty measly straw to clutch but we could be destined to reach mid feb whilst still waiting for winter to arrive in earnest (in tandem with much of europe also).

Edited January 27, 2014 by bluearmy

[Weather Boy]

from what i can see the low on the latest gfs is even deeper. Got a feeling the uk and ireland could be swept away into france at this rate

Based on experience dartboard lows from GFS should be taken with a pinch of salt as they are always overdone. Not to say they won't be significant but the GFS will almost certainly exaggerate them.

[pdiddy]

Latest GFS showing heights strong over Greenland and slightly better over Scandi. Block coming back? Could be on to something here...?

 

If heights over Greenland build, pushing lows further south before heading across the Atlantic, would be in a better position to slide SE when it hits the Scandi high?

 

12z

 

 

18z

 

I think that's more a surface feature.  We really need much better heights (greens yellows on the 500s charts) over Greenland for blocking. Try P15 from the 12z GFS...

http://www.meteociel.fr/modeles/gefs_cartes.php?code=15&ech=192&carte=0&mode=0

Edited January 27, 2014 by pdiddy

[Weather Boy]

Latest GFS showing heights strong over Greenland and slightly better over Scandi. Block coming back? Could be on to something here...?

 

If heights over Greenland build, pushing lows further south before heading across the Atlantic, would be in a better position to slide SE when it hits the Scandi high?

 

12z

 

 

18z

 

Sorry but what Scandinavia block? Can't see one on those charts?

[weirpig]

Based on experience dartboard lows from GFS should be taken with a pinch of salt as they are always overdone. Not to say they won't be significant but the GFS will almost certainly exaggerate the

yes i understand that i think im just left a little frustrated with the constant barage of lows this winter, Infact i cant remember a period when i have seen so many sub 980 lows modelled

[Blake]

The split in the low heading NE flattens allowing heights to build again over the top, and the low coming for us could stall but hopefully the NW/SE tilt can rebuild sending it SE.

 

12z

 

 

18z

 

[Purga]

Over the last month I have lost count how many times I have half read a post

before realising it is the same post just reworded differently.It also amazes

me how many claim to have known how bad the winter was going to be with lines

like "we knew it would be February or even later before things turned interesting".

Hindsight makes great long range forcasters out of all of us.

Even with a westerly QBO noboby could have foreseen how poor this winter has been

or how wet and also how strong the vortex has been.I know I certainly didn't.

Yesterday I said that by next Sunday there will be a lot of happy cold weather

lover on the forum excited by the runs they are seeing.I still think that but it

is all down to the forecasted strat warming. If this turns out to be another damp

squid then apart from a couple of days cold here and there perhaps that is the

best we will likely see during February. However I stand by what I posted yesterday

with great expectations for February.

A forlorn hope as there is no support for any Strat warming from the main METO models in the foreseeable future.

Anyway, 18z starts february on a snowy note for most

Good for a laugh I guess.

[Blake]

Sorry but what Scandinavia block? Can't see one on those charts?

 

If you read it carefully it says heights are slightly better over Scandi. The block isn't currently there but could rebuild as the low heading NE flattens. You can see the lines becoming more vertical on the 18z over Scandia whereas SW/NE on the 12z and marginally further west compared to the 12z.

[Nick F]

Ironic that when the airmass becomes favourable across most areas for snow to fall on Thursday, the precipitation dries up as the low sinks south. Though could be snow mixed in any precip around on the northern flank of low across central and northern parts of England Weds night, as the colder air starts to move in from the east.

It feels like the weather has been rather immoral this winter so far across parts of the Northern Hemisphere. Most notably across N America and Europe. The UK has experienced relentless rainfall, eastern Canada and N/NE USA has seen days of brutal cold, while much of SW USA, especially California, suffers extreme drought conditions from lack of winter rains off the Pacific.

It's all linked of course, stubborn PNA+ ridge affecting Americas west coast, stubborn PV wedge/deep troughing over Ern N America with the downstream impact of a steep temp gradient over the NW Atlantic driving a persistently strong jet towards the UK. Now this month we have the addition of blocking to the east, so the zonality has stopped, but the UK still remains at the end of a strong Atlantic jet. So lows pile in and stall against the block over the UK, 18z GFS, like its predecessors, continues the ominously wet theme. These wave ridge wave patterns have been and continue to be very slow to change so will unfortunately may continue the extremes of rather different kinds of weather over N America and western Europe.

Is there any signs of change? Well, latest update of CPC MJO forecast suggests a weak and incoherent MJO with little eastward propagation from most model guidance, though PNA looks to head into -ve territory, so indication of a break down of the NE PAC ridge. But NAO remaining +ve and looking at the anomalies over the Arctic, the AO perhaps headed to +ve territory too. No strong signal for strat warming have any impact on the PV. So no positive signals for an end to the stalemate between the Atlantic and eastern block, with UK kept out of reach of sustained cold over eastern Europe. The continuing strong flat jet coming across the Atlantic showing run after run of the models is testament to the lack of impetus for change. Need some amplification desperately!

Wish I could find any shred to point towards a pattern changer, but not coming up with anything for now.

Edited January 27, 2014 by Nick F

[Timmytour]

The rain for friday evening into saturday looked bad enough from the 12z, but the 18z seems to be pushing it across the country more slowly.

Some places look like they could be getting 9 hours plus of pretty intensive rainfall.....and those are principally areas that could well do without any more!

Edited January 27, 2014 by Timmytour

[Jason M]

First lets look at the positives tonight...............

Now that's out of the way.......

I'd see two ways forward from here.

1. A big push of southerlies with a plume of warm 850s heading due north out of Iberia. In response heights rise over scandi leading to us getting a roll of the dice.

2. Pressure rises over SE Europe leading to a Bartlett type set up through feb.

The question is which IMO.

Edited January 27, 2014 by Jason M

[weirpig]

The rain for friday evening into saturday looked bad enough from the 12z, but the 18z seems to be pushing it across the country more slowly.Some places look like they could be getting 9 hours plus of pretty intensive rainfall.....and those are principally areas that could well do without any more!

through the whole of that run the striking part is the amount of rain that will fall. When will it end?

[Tim Bland]

18z GFS sums up exactly why we need the Atlantic to bash through and reset the pattern. With the block in place the Atlantic grinds to a halt and persists it down over the UK for weeks on end. Meanwhile the sun is gaining strength....