Focussed Model Discussion

[Dean E]

Morning all, glad to see Central, Southern and South Western areas do well from last nights snowfall, including the surprises for Cornwall and Devon earlier in the day!

Moving forward, the ECM and GFS continue to paint an interesting picture in my opinion, especially so into mid next week. 

ECM 0z +144                                                       GFS 6z +144

 

Attempts to build a ridge around the 7th somewhere over Scandinavia is hinted at by both models, indeed the ECM gives this a good go. However the Atlantic Jet is modelled too stubborn next week, throwing lows across the Atlantic towards Iceland, disrupting the ridge and getting the Azores high to send heights into the Med. Given the situation over North America right now, this is not surprising. 

Beyond the 7th and into the following weekend, the trend currently is for more or less the same (ignoring 'standard GFS' with its silly deep lows). 

A lobe of the tropospheric Polar vortex still resides over NE Canada, which in my opinion is delaying any sort of interesting developments in regards to colder weather as we head into February. 

[Man With Beard]

Right fresh from building a 10cm tall snowman (not much snow left here this morning), now back to the longer - term. 

I can only conclude that it is going to take a fair shift to set up a genuine cold pattern again. Low anomalies west, high anomalies south = Atlantic train

[stodge]

Afternoon all

Away from the snow angst in the regional discussions and back to something more sensible and some thoughts on the medium to longer term evolution going towards the middle of the month and beyond.

A couple of days ago we were being teased with height raises to the NE as the PV weakened and displaced and the Atlantic amplified.

However, the GFS 06Z OP is relentlessly Atlantic throughout albeit with signs of the jet coming south in FI - mainly mild but changeable and getting stormier toward mid month.

Little hope for cold on the Parallel either - if anything, a milder and more vigorous Atlantic but a sign at the very edge of FI of some amplification upstream over North America allowing heights to build over NW Europe.

Control keeps a wedge of heights to the north so the jet is further south but even with the PV pushed over to Siberia the Atlantic still fires up again in FI and it goes stormy into mid month.

Looking at the GEFS, the signal for northern blocking isn't dead by any means but is much weaker (perhaps 6 out of 20 by T+300 offering some solution with blocking to the north or east).

Elsewhere, the 00Z ECM ends with a weak ridge building north to the west of the British Isles but it's a curious evolution.

The end of the 06Z NAVGEM raised an eyebrow.

CFS 00Z makes fools of those thinking winter is over with a re-run (not quite) of a very cold and wintry end to February and beginning of March.

So, it seems the prospect of any HP to the east has been swept away and atypically the first half of February is looking quite disturbed with a dominant jet and powerful Atlantic. Perhaps around mid month it gets stormier as the jet eases south but the second half of the month is far from clear and those thinking today and tomorrow mark the end of winter may yet be in for a surprise. 

[Dean E]

12 minutes ago, Man With Beard said:

Right fresh from building a 10cm tall snowman (not much snow left here this morning), now back to the longer - term. 

I can only conclude that it is going to take a fair shift to set up a genuine cold pattern again. Low anomalies west, high anomalies south = Atlantic train

Glad you managed 10cm tall snowman, just up the road here there was enough this morning but commitments annoyingly got in the way!

But overall agree with you here, I think the only 'excitement' we'll see over the next week is another slider setup later next week. The EC suggests this and has been on the same page for a while now. Can't take the GFS too seriously with its 10 day, especially so with yesterdays Scandi block being shown.

Lets hope for an uptick soon.

 

[knocker]

As expected looking at the 1300 chart. Bits and bobs of snow and rain still around central southern and south east England with showers in the north and along the east coast.

[knocker]

The front will finally move away from the south this evening taking what is left of the snow and rain with it. So generally a clear night for most places with the temps plummeting once more, particularly in northern Scotland. But the north, and particularly eastern coastal regions will still be subject to frequent wintry showers and you will note the Pembroke Dangler makes a guest appearance

[chrisbell-nottheweatherman]

Might not be suitable for his thread, but is there any expanation in the stratospheric models, MJO, GLAAM or anything similar as to why the jet seems likely to do a passable impression of an average November after the SSW that was supposed to finish-off the trop. vortex? 

[knocker]

There is a major depression in Mid Atlantic by midnight Wednesday with it's associated front bringing rain and strong winds to the UK A quick look how it developed

At T18 it starts developing in central northern Canada and 18 hours later it continues to develop rapidly as it tracks east and phases with a lobe of the vortex.

Over the next 24 hours it deepens rapidly hitching a ride on 120kt jet

And then where we came in

 

 

[WhiteFox]

Thanks for that Knocker: great explanation of the formation of a storm.

 

 

[knocker]

After the mayhem around here yesterday ( albeit extremely interesting from a meteorological perspective) some green shoots.

[phil nw.]

The latest fax's from the 12z runs showing the Atlantic moving in next week.

Less cold air moving across with the frontal systems so temperatures generally closer to normal in the westerly flow.

ECM mean for day 7 with the nh pattern  showing little change out to the end of next week.

[Dean E]

So the SSW continues to affect the lower troposphere, given the slow down-welling you can expect a slow and steady reversal of mean westerlies in the troposphere over the coming weeks.

You'd think a heighten chance of a colder outbreak? Well possibly yes, but as Dr Amy Butler on twitter has alluded to earlier (she's great and worth a follow by the way), the NAO is stubbornly resisting a change from positive which is where we are at currently. Especially so that the AO is due to head into the very negative territory and HLB popping up in favourable locations over the next 10 days.

NAO Observation/ Forecast                            AO Observation/ forecast

                     

Reasoning for this remains a head scratcher for now, however my thoughts lie with the winter killer of the Northern Canada tropospheric vortex. Its been there most of this winter and still continues to sit, stead fasting the jet stream across the Atlantic and promoting height rises from the Azores over to the Mediterranean. Whilst there have been many historical severe winter cold events with a vortex located over Canada and a +NAO, it has certainly been a curse rather than a miracle.

I believe that, for now, our only hope is from systems sliding over Western areas like we've seen this week. Now this isn't an issue for snow lovers, as these events can bring large amounts of snowfall across the UK and Ireland. But for prolonged and deep cold (akin to December 2010), the Canadian vortex needs to uproot and move out of there to promote HLB across the North Atlantic/Scandinavia.

Of course, weather and nature do not follow a model, so things can and will change. EC monthly and developments with the AO and MJO *may* help alter our path or be diluting our model outputs over the next few weeks. But one thing is for sure, I believe this down welling of the SSW has only just started.

 

 

Edited February 2, 2019 by Dean E

[knocker]

Outlook - After a cold weekend becoming less cold and as always with slow transitions, some wintry interest

The 500mb and surface analysis for midnight and the 0300 WV image.

Still some remnants of the front around in the south east but that will clear and after a cold and icy start today will be cold with wall to wall sunshine in many areas, The exception being the north and eastern coastal regions with frequent wintry showers likely to be of snow as they slip inland, but becoming less frequent as the day progresses. The Pembroke Dangler could also effect the far south west this morning/

With the showers dying out and the winds abating tonight will be clear and very cold with a widespread frost, icy patches and some freezing fog. But by morning cloud and rain will arrive in the far west, courtesy of an occlusion which is part of a complex area of low pressure in the eastern Atlantic

Bands of rain, sleet and snow (the latter general on the higher ground) will cross the country on Sunday as the aforementioned low pressure area edges east introducing slightly warmer air in the south west/

Still some rain around on Monday with a shallow low over Scotland but this will clear away later so another cold night. But way out in the western Atlantic a deep depression has arrived on the scene (see post above from last evening)

After a cold start on Tuesday rain and strong winds will arrive from the west, courtesy of a frontal system associated with the aforementioned  low resulting in a wet and windy day although the warmer air has arrived.

The fronts and rain have moved away to the east by Wednesday but the eastern atlantic is now under the auspices of low pressure so remaining unsettled.

Edited February 2, 2019 by knocker

[knocker]

To continue briefly with the gfs but just to note it's handling of the major low is at odds with Exeters. Anyway by t144 the main low is filling north of Scotland and another system has arrived in mid atlantic and this will deepen and tack east to be 979mb Stornoway by midday on Friday. Thus another very wet and windy day. This moves away east but another major trough has emerged from Canada and is south of Iceland by Sunday so continuing unsettled with periods of rain and snow on the high ground in the north and perhaps gales in exposed areas.

[knocker]

By Friday midday the ecm has filled the previous Atlantic low but another has appeared on the scene south west of Iceland and the associated fronts are bringing strong winds and rain to the northern half of the country. These quickly move away to the east but a much more active system brings rain and strong winds more generally on Sunday

[knocker]

Looking at the change, or not, of the EPS ext mean anomaly would suggest some amplification of much the same pattern. TYhis wepuld portend a quieter period vi weather inclining towards a N/S split with temps a tad above average.

[knocker]

Showers down the east coast and the blasted Danger this morning

A reflection on Thursdays shenanigans

[knocker]

I see the next cold plunge across the pond takes the Arctic air down to California

[feb1991blizzard]

5 minutes ago, knocker said:

I see the next cold plunge across the pond takes the Arctic air down to California

The other day a run had the -15c practically in the deep south, can you believe in some parts of the US where the average temperature is a good 5c higher than Britain, the record low is a good 3c lower, yet their record high for January is our summer temperature!!

GUTTED!!

Edited February 2, 2019 by feb1991blizzard

[chrisbell-nottheweatherman]

4 hours ago, knocker said:

Looking at the change, or not, of the EPS ext mean anomaly would suggest some amplification of much the same pattern. TYhis wepuld portend a quieter period vi weather inclining towards a N/S split with temps a tad above average.

Bartlett set-up?

[Singularity]

Seems to me the models are making a complete hash of handling the MJO propagation in the coming week, hence PNA response in the 8-14 day range. So I'll be watching out for any trends toward a -PNA pattern emerging after all, something that would drastically alter the N. Atlantic-Europe pattern toward something much more conducive to HLB in our vicinity.

[knocker]

Good news Sidney Spring is coming early. Cousin Punxsutawney didn't see his shadow

[knocker]

This evening the coastal showers will tend to die out leaving clear skies so temps will start to plummet particularly in the north. And by morning some areas in the south will be quite nippy as well so ice will be a problem

But during today a wave has formed on the occlusion to the west and by tomorrow morning is south of Iceland and the occlusion will bring rain and snow to Norther Ireland and western Scotland by midnight. This will spread east and further south over the rest of the night to effect most of Scotland, NW England, Wales. and the south west

Edited February 2, 2019 by knocker

[knocker]

nice high res MODIS at 1245

[Dean E]

3 hours ago, knocker said:

I see the next cold plunge across the pond takes the Arctic air down to California

Never a bad thing in my mind. Promotes a stronger Jet over the mid west and NE Seaboard, which can help promote WAA into Greenland.