South East and East Anglia Regional Discussion 31st January 2013

[Snowangel-North]

Please use this thread for your regional discussions about the current weather or what is being forecast for the next few days in the South East and East Anglia...

Link to the previous one here:

[gottolovethisweather]

Hello, well I'll set the ball rolling in here with my analysis from yesterday, if you don't mind.

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Hello my long lost friends, well i hope you still are (my friends , I have actually met some of you ) I am still about, but largely I reside over in the CSE and SW thread and it is from there I want to provide a posting.

Have a read guys n gals, JP et. al keep up the good work.

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On top of the wonderful analyses already provided, I wish to add my initial thoughts for the first third of February and perhaps beyond.

As usual, I am basing my evidence on consecutive GFS 12z runs and where need be, additional tweaking from other sources from elsewhere.

As ever, I urge newbies and/or unexperienced model output followers to please view things only from a global perspective. In general, miniscule yet undeveloped surface features often at the >t+96 timescale only serve to confuse your interpretation of the model output. This week, being a special case in point of this, as we have a very difficult forecasting situation at the <48 hour timeframe.

In fact, let us look at where the NH Jetstream was projected to be by todays date (Wednesday 30th January, 12pm), some two days ago. As a consequence, what were the expected associated T850s.

To be expected, it did develop into what we basically witnessed at the surface, a breezy type of day with the NH Jetstream roaring directly above our heads. However, when we move forward another 48 hours to Friday 1st February, 12pm), we were expected to see the following conditions, NH Jetstream and T850s profile wise.

Compared to what is now expected on the hugely anticipated date of Friday 1st February, 12pm.

Not much has changed from the GFS 12z expectations of two days ago, compared to what is now projected. If anything, today's 12z run has upped the anti with the depression. However, the split flow in the NH Jetstream is much more of a talking point because after Friday's event it offers the UK a complete reversal in terms of airflow from tropical maritime to polar maritime, albeit temporarily.

So now what of what on Monday was the t+144 timescale, Sunday 3rd February, 12pm. Previous expectations against todays, having moved forward to t+96 timescale. Firstly in terms of NH Jetstream.

Monday's 12z at t+144.

Todays's 12z at t+96.

How about Sunday's T850s profile wise. Then and now.

What is apparent now is quite a divergence in output, from just the last couple of days.

Two important points to note here IMHO are, that we MUST NOT DISMISS the relatively high chances of backedge snowfall (I guess at a 60% to 70% risk for my location) from the Friday event. This takes place between the previously shown chart above and the current one. What is not shown is the large range of t850s diving South from polar regions, in between the two charts, i.e come the very cold February 2nd as hinted at by AWD.

My second point is such charts, on the face of look rather disappointing springlike synoptics, after a brief tempory excursion from the North, in fact by t+144 (Tuesday 5th February, 12pm) end with us heading towards an ever cooler wintry type of synoptic yet again.

NH Jetstream diving South once again.

Associated T850s profile at Tuesday 5th February, 12pm timeframe.

And then some, come Thursday 7th February, 12pm, courtesy of NH Jetstream and T850s once again.

It would be futile to look in detail, any further than next Thursday, however I firmly believe there will be a significant upgrade in the coming days, when speaking of further cold potential and wintry type synoptics. Three dates seemingly stand out for me as ones to watch at this range, they are Friday 1st February, Tuesday 5th February and yet further potential for yet deeper cold from the 10th February onwards.

• For the more immediate timeframe, regarding the appoach of the potentially dangerous (hopefully trending less so) development, I advise folk to follow posts containing NAE output, NMM output and/or MetO Fax chart updates.
  

Stay safe and stay tuned to this regional for many more updates.

[gottolovethisweather]

Another sound analysis of where we might be heading is given below by AWD, courtesy of the SW & CSE thread.

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Quick glance at the medium to long range potential tonight, leant towards the search for colder, Wintery weather.

We have good confidence now of a mid Atlantic high pressure system setting up next week. Something like this will be typical midweek;

What this does is block the Atlantic depressions from smashing into the UK as they have done so recently. This is also known as zonal. What looks like happening now is the Atlantic depressions look like being deflected north over the mid Atlantic high in the northern arm of the Jet Stream;

You can see above the Jet Stream riding over the high, hence the amplitude in the Jet Stream. These then come back down south in the North Sea and into mainland Europe, forming a Euro trough;

The red in the Atlantic being the mid Atlantic high, the blue over Europe being the Euro trough. What this will bring to our part of the world is colder than average conditions, summed up nicely below;

However, whilst some snowfall is possible on elevated areas of our region, it would still remain very marginal for most of our region due to modified warm sectors raising Dewpoints and WBFL values. Things like this aren't worth speculating until much nearer a potential event anyway, but I wouldn't rule out surprise snowfall cropping up on embedded troughs in the flow for some next week, indeed I half expect it.

Beyond next week, I tend you back to a paint job I did a couple of days ago.

Here I mention the probability of the Mid Atlantic high starting to topple over towards the UK after a couple of failed attempts trying to get into the Greenland area. Well, is there a sign of this in the models;

Yep, timing aside, this scenario is gaining support as we enter week 2 on tonight's runs. This then sends WAA (warmer Atlantic air) up towards the Iceland corridor;

Similiar to my paint job chart above. What this does is help start of height rises in the GIN corridor, nearer the Norway side I think however;

Bingo. The last frame of the ECM Det starting to show this develop. Whilst this takes place however, do expect a brief return to near average temperatures as mentioned in the Met Office 5-15 day forecast. This is because whilst WAA is being sent up north, the high has to topple, bringing less cold air for us temporarily.

Now what I expect to happen beyond the ECM is a bit clearer tonight, if indeed the current model output verifies. Back to my paint jobs, it would be something similiar to what I said a couple of days ago. This;

Ignore the black line for now. Height rises becoming a player towards the Iceland/Norway area and a euro trough digging further south into Southern Europe. This scenario would bring the cold air over Europe here;

Westwards over the UK. The ECM anomaly chart for week 2 represents my thoughts well;

So, I'm very happy about where we are heading currently, but it is stil a long term trend that has a long way to go still so caution is most definetly still required. The trend gas gained momentum tonight in the 12z data, that's all we need at the moment.

- coolnext week for the most part, just not quite cold enough for reliable snowfall, however, if everything is timed right, surprise transient/wet snowfall is possible for some, elevation key here

- do expect a recovery to near normal temperatures briefly towards the end of next week as the sypnotic pattern sets itself up for the main event. Also expect drier conditions.

- cold mid February from the east/north east/north still looking good, still my long range punt. How cold and if it will be accompanied on snowfall remains to be seen. My guess at the stage is not mega cold but easily cold enough for snow, which we will see at some point being closer to the Euro trough.

All looking fine still guys. We can but hope.

[Jan_Bromley]

Lovely...................Thanks GTLTW

[john pike]

another ecm chart tailored just for us in the south east

nice

[Paul Ashford]

another ecm chart tailored just for us in the south east

nice

Just give me Sunday's forecast

LOL

[Tamara]

In my humble little opinion I think that the current (reliable) charts are more favoured for the Northern and North Western regions That is not to say that things can't or won't change, but I think we need to see further signs that the pattern is going to amplify enough to let more of a NE'erly element arrive with the colder upper air to the east working with the North Sea to give us snow potential. North or North Westerly winds will give us generally dry and chilly weather, unless there are any low pressure features sliding south from Iceland/Svalbard in the airstream .

Edited January 31, 2013 by Tamara Road

[john pike]

tomorrow

starts raining early morning to late afternoon

winds north westerly veering north then north easterly later

temperatures 6-8 degrees

will not feel it

tomorrow night

bitter north east wind

early evening precipitation that falls will be rain

however as we go into the early morning the cold air has dug in and whatever falls will likely be snow

saturday

a bitter north to north west wind

cold around 3 degrees

any precipitation that falls will likely be snow but at present it looks mainly dry

late afternoon warmer uppers moving in so snow risk falls and temps likely to rise

saturday night

westerly to north westerly weak flow

could stay dry until morning

temps around 6 degrees

sunday

fairly weak westerly flow

dry up to around 2pm then light rain turning to heavier rain late in the afternoon

temperatures back to around 10 degrees

monday

a very strong and cold north westerly wind

potential to stay dry

temperatures around 8 degrees but wind chill will make it feel a lot colder

tuesday

too early to call but a strong and bitter north west wind

troughs being driven down to us from the north west

we are under 528 dam air so potential for wintry showers

temps down again around 3 degrees

ukmo raw fax (bottom right)

is close to a very good chart

more on that tomorrow

[Jason T]

Brilliant post;s JP and Gtltw. Hopefully February could about to deliver the sting for a top finish to Winter 2012/13.

Edited January 31, 2013 by Jason T

[Jason T]

Hmmmmmm. Interesting.

Joe laminate floori

Good point @Piers_Corbyn ! Stratwarm under conventional 10mb,30 mb 70-100 mb great for blocking.. winters a rocking

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[gottolovethisweather]

In my humble little opinion I think that the current (reliable) charts are more favoured for the Northern and North Western regions That is not to say that things can't or won't change, but I think we need to see further signs that the pattern is going to amplify enough to let more of a NE'erly element arrive with the colder upper air to the east working with the North Sea to give us snow potential. North or North Westerly winds will give us generally dry and chilly weather, unless there are any low pressure features sliding south from Iceland/Svalbard in the airstream .

I think your humble little opinion would be quite right, but we do need these baby steps in order to get to the holy grail that a whole lot of us still yearn for. JP will have a tasty Fax chart or two to post in the coming days methinks.

JP, have a gander at Tuesday's one when you can. T'was one of my dates to watch as well.

Edited January 31, 2013 by gottolovethisweather

[john pike]

I think your humble little opinion would be quite right, but we do need these baby steps in order to get to the holy grail that a whole lot of us still yearn for. JP will have a tasty Fax chart or two to post in the coming days methinks.

JP, have a gander at Tuesday's one when you can. T'was one of my dates to watch as well.

tuesday

too early to call but a strong and bitter north west wind

troughs being driven down to us from the north west

we are under 528 dam air so potential for wintry showers

temps down again around 3 degrees

hi gtltw

it is a good chart

but will hold until tomorrow to firm up

i have a feeling the low to our north east will be further south

all in all

looking good

[gottolovethisweather]

tuesday

too early to call but a strong and bitter north west wind

troughs being driven down to us from the north west

we are under 528 dam air so potential for wintry showers

temps down again around 3 degrees

Perhaps it's an out of date chart, but I had seen a different one to you upon which AWD made a comment, see below.

http://forum.netweat...80#entry2580302

Edited January 31, 2013 by gottolovethisweather

[john pike]

Perhaps it's an out of date chart, but I had seen a different one to you upon which AWD made a comment, see below.

http://forum.netweat...80#entry2580302

hi gt

its the same chart

unless there is a system error somewhere

on second thoughts we have said the same thing

the tues fax only came out tonight so has to be the same

Edited January 31, 2013 by john pike

[john pike]

http://www.meteociel.fr/cartes_obs/gens_display.php?x=319&y=150&run=18&runpara=0&type=0&ext=1

short term ensembles looking good

[john pike]

[gottolovethisweather]

http://www.meteociel...=0&type=0&ext=1

short term ensembles looking good

Not a lot wrong with the long-term either, aye JP.

[john pike]

Not a lot wrong with the long-term either, aye JP.

hi gt

i think we have a lot to look forward to

the reason i have reserved too much comment on tuesday is if you look to the south-south east

the wind isobars spread we need a very strong wind to gain from a north westerly

not too say we cannot see snow from it though

what i think is the low to our north east will be a lot further south

see if i am right tomorrow

[gottolovethisweather]

BANK.

[john pike]

nae for saturday

some will be happy with that

[gottolovethisweather]

hi gti think we have a lot to look forward tothe reason i have reserved too much comment on tuesday is if you look to the south-south eastthe wind isobars spread we need a very strong wind to gain from a north westerlynot too say we cannot see snow from it thoughwhat i think is the low to our north east will be a lot further southsee if i am right tomorrow

Yes, I think for most areas, bar the North and perhaps some Western regions (in the NW'ly flow), it will be case of taking one step at a time. Overall, damn good synoptics for our little island, given the deluges this past week. I actually have an inkling it may end up pretty cold and dry for most come Mid February but I'd settle for a few days of SNOW before then, that's for sure. Edited February 1, 2013 by gottolovethisweather

[john pike]

gfs at warmer end of the ensembles from the 4th

cold on the 5th right through to the 10th

fi on the 10th which is resonable agreement for these

now we wait to see how cold next week gets

BANK.

i knew you would like that

[john pike]

Yes, I think for most areas, bar the North and perhaps some Western regions (in the NW'ly flow), it will be case of taking one step at a time. Overall, damn good synoptics for our little island, given the deluges this past week. I actually have an inkling it may end up pretty cold and dry for most come Mid February but I'd settle for a few days of SNOW before then, that's for sure.

hi gt

agree but what i reckon will happen is the jet will be further south than shown

if you look at tuesdays fax and put the low to our ne 500 miles south

you will see what i am thinking

also once we get the cold in as we always say

the snow will come

[john pike]

heres a ramp chart

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=12&mode=0&carte=0

nice run

[alexisj9]

wow this thread has been quiet today, thank you for the good posts JP and GTLTW, very informative. How can you work out the expected temps from the fax charts?, have never figured that part out.

Night all, CYA tomorrow.