Convective Weather UK

[Coast]

Sorry, bit late in today! (I have a note from my Mum....)

ESTOFEX back on forecasting today with the Western side of the UK and all of Ireland highlighted for a watch, but no specific details of potential for us:

TORRO have nothing for today (I noticed they came in with a late one that I missed yesterday afternoon, so keep an eye out on their site)

Here are some charts to colour in with crayons as appropriate:

I want to say Ireland, but after yesterday I think I'll keep quiet.....

[Stuart]

Storm Forecast Issued: 2010-09-09 01:00:00

Valid: 2010-09-09 00:00:00 - 2010-09-09 23:59:00

Yorkshire, E Midlands, East Anglia and SE England ( Scotland, Northern Ireland, Ireland and C + E England are included in the WATCH )

Synopsis

On Thursday, the United Kingdom sits under a temporary ridge of High pressure between a shallow area of Low pressure "Fe" (FU Berlin) over Germany, and an approaching area of Low pressure from the Atlantic - part of the remnants of ex-Hurricane Earl, which will move across Scotland on Saturday.

In a rather slack westerly airflow, scattered showers are forecast to develop over central and eastern Britain. Through the afternoon, cloud heights appear favourable for a few isolated thunderstorms - the area with best potential appears to be East Anglia. These showers will decay rapidly during the evening hours.

Along the cold front over northwest Ireland, there is a low risk (20%) of embedded convection, and thus a low risk of isolated thunder/lightning. Conditions are more favourable for thunder/lightning along and behind the occlusion which moves across the north Atlantic, approaching western Scotland at the end of the forecast period. Here, numerous showers will be present in the rPm airmass.

http://www.ukasf.co.uk/module-Storm/mode-forecast/id-349/

[Coast]

ESTOFEX not following the UKASF thinking and GFS have 2 or 3 days of very low potential before it goes ultra-quiet:

[Stuart]

and i dont see much happening over the next few days

[Coast]

ESTOFEX have a titchy bit of the NW and some of Ireland circled today:

...Ireland and Scotland after sunset...

A strong wave affects the area during the night. Marginal CAPE evolves as mid-levels cool down in an environment with up to 20 m/s SW-erly winds at 700 hPa. Strong wind gusts remain the main risk with showers/isolated thunderstorms.

UKASF say:

Storm Forecast Issued: 2010-09-10 00:43:00

Valid: 2010-09-10 00:00:00 - 2010-09-10 23:59:00

Regions Affected

Northern Ireland, SW Scotland and N + W Ireland ( Ireland, Northern Ireland and S + W Scotland are included in the WATCH )

Synopsis

A large and complex area of Low pressure over Iceland dominates the weather across the United Kingdom on Friday.

A large area of showers are expected to move over parts of Ireland and Northern Ireland during the evening and night-time hours, moving NE into SW Scotland around midnight (and hence the end of the forecast period). The showers are associated with the remnants of ex-Hurricane Earl, and thus are accompanied by a rather warm and unstable airmass.

Given favourable cloud heights, there is a reasonable chance for a few thunderstorms amongst this large cluster of showers, even after sunset since the lapse rates will be quite steep.

Given the airmass, hail is possible in some of the showers, and may be locally moderate in size (up to 3cm in diameter)

[Stuart]

Storm Forecast Issued: 2010-09-11 00:54:00

Valid: 2010-09-11 00:00:00 - 2010-09-11 23:59:00

Regions Affected

Scotland, Northern Ireland, Ireland, Wales, N England and Midlands ( all of the United Kingdom is included in the WATCH )

Synopsis

Complex area of Low pressure "Gloria" (FU Berlin) located over Iceland will dominate the weather across the United Kingdom on Saturday.

To the north of a waving cold front, which will slowly and erratically sink southeastwards during the forecast period, a cold rPm airmass is advected across many parts of central and northern UK.

Widespread showers are forecast to readily develop during the morning, with a reasonable chance for quite a few pulse-type thunderstorms during the afternoon across highlighted regions. Light upper level winds will ensure showers will be slow-moving, and thus flash flooding may be a primary concern. Also, given the airmass, hail is likely in many of the showers, and in any stronger storms, particularly over Ireland and Northern Ireland, the hail may be locally moderate in size (diameter up to 3cm).

During the evening hours the showers are expected to shrink rapidly to coastlines, though the northwesterly prevailing wind will blow them a reasonable distance inland during the overnight period.

http://www.ukasf.co.uk/module-Storm/mode-forecast/id-351/

[Coast]

ESTOFEX showing their thoughts on activity off the East coast and into the North Sea today:

DISCUSSION

... North Sea across southern Scandinavia into northern Germany ...

An intense frontal system enters North Sea during the daytime hours and quite rapidly shifts southeastwards. Models simulate weak instability to build up along/just ahead of the cold front. Accompanied by this trough, strong mid-level jet provides strong deep-layer shear which should support some organized storms. Expect some organized convection mainly along the cold front where convective lines will be possible with the strong wind gusts as the main threat. A level 1 was issued over the areas where this threat seem to be maximized. Behind the front, CAA overspread rather warm SST of North Sea and yields some LL instability and steeper lapse rates. There, as well as around Denmark and northern Germany coastal areas, a couple of funnel clouds/spout type tornadoes cannot be excluded.

Can't load up the forecast from UKASF currently although the map of their idea for today looks like this:

Here's something interesting to keep an eye on:

[Coast]

Well if you like or don't like them, believe or don't believe them, ESTOFEX have a watch area map that includes a slight Kent Clipper today, but conflicting wording.....

DISCUSSION

No prominent area with severe thunderstorm risk is forecast for this day. Especially with the vorticity maxima and deep low pressure system crossing Southern Scandinavia into the Baltic Sea and progressing northwards. Areas with strong synoptic scale forcing along with high values of wind shear lack sufficient amount of instability to promote severe thunderstorm formation. Nevertheless, narrow frontal rainband ahead of the vorticity maxima is possible with its circulation possibly enhancing the wind gusts, which will be mostly induced by a synoptic scale pressure gradient.

UKASF have any even more pronounced coverage down the Eastern side:

Storm Forecast Issued: 2010-09-15 00:53:00

Valid: 2010-09-15 00:00:00 - 2010-09-15 23:59:00

Regions Affected

Scotland, NE England, Yorkshire, Lincolnshire, Norfolk and Suffolk ( majority of the United Kingdom, excluding SW/CS England, is included in the WATCH )

Synopsis

A large and deep area of Low pressure, "Imogen" (FU Berlin), located over the North Sea, will dominate the weather across the United Kingdom on Wednesday.

Widespread showers and thunderstorms are forecast to develop over northern Britain behind a southwards-moving occlusion. Frequent heavy downpours may cause local flooding in places. Given the airmass, small hail is likely in many of the showers.

Showers will progressively shrink to the coastline during the evening hours, with further thunderstorms forecast over the North Sea overnight.

I'm just trying to find some support for it now:

Seems to be more of a threat in the North Sea to me, maybe a touch on the Eastern borders, what do you think?

[Stuart]

Good Morning

Storm Forecast Issued: 2010-09-22 23:57:00

Valid: 2010-09-23 00:00:00 - 2010-09-23 23:59:00

Regions Affected

England, Wales, S Scotland, Northern Ireland and E Ireland ( all of the United Kingdom, excluding N Scotland, is included in the WATCH )

Synopsis

Low pressure "Kathrein" (FU Berlin) located over the United Kindom will dominate the weather on Thursday.

Behind an eastward-moving cold front, widespread showers and thunderstorms are forecast to develop in the rPm airmass. Rather slack upper level winds will allow showers and storms to cluster, sometimes into distinct lines. Gusty winds and hail potentially to moderate diameter (3cm) are likely in many of the showers, and given the relatively light winds, flash flooding may occur during prolonged downpours. There is also a risk of a weak tornado, particularly in southern England.

Showers should decrease in coverage during the evening hours but are likely to continue in some parts overnight.

http://www.ukasf.co....orecast/id-355/

[cyclonic happiness]

Good Morning

Storm Forecast Issued: 2010-09-22 23:57:00

Valid: 2010-09-23 00:00:00 - 2010-09-23 23:59:00

Regions Affected

England, Wales, S Scotland, Northern Ireland and E Ireland ( all of the United Kingdom, excluding N Scotland, is included in the WATCH )

Synopsis

Low pressure "Kathrein" (FU Berlin) located over the United Kindom will dominate the weather on Thursday.

Behind an eastward-moving cold front, widespread showers and thunderstorms are forecast to develop in the rPm airmass. Rather slack upper level winds will allow showers and storms to cluster, sometimes into distinct lines. Gusty winds and hail potentially to moderate diameter (3cm) are likely in many of the showers, and given the relatively light winds, flash flooding may occur during prolonged downpours. There is also a risk of a weak tornado, particularly in southern England.

Showers should decrease in coverage during the evening hours but are likely to continue in some parts overnight.

http://www.ukasf.co....orecast/id-355/

not only that, but the whole of the UK is under a weather warning from the meto too!! haven't seen that in a while?

http://www.metoffice.gov.uk/weather/uk/wm/wm_forecast_warnings.html

(p.s. that's not a very nice way to talk about Germany's capital city? )

Edited September 23, 2010 by cyclonic happiness

[TheToastPeople]

Holy crap the met office weather warning page covers almost all of england!!! i bet i will be stuck in class while something thunders over :@

[Gordon]

Holy crap the met office weather warning page covers almost all of england!!! i bet i will be stuck in class while something thunders over :@

those warnings are very misleading as it's not going to be raining/thundering everywhere

the met office seems to have gone mad covering everyone in a blanket forecast which for most will no be what will occur

Edited September 23, 2010 by Gordon

[TonyH]

It will interesting today, to gauge how many places are actually affected by convective 'heavy rain' given the near blanket MO warning of severe rainfall events across the UK.

Misleading or not? That is the question.

A few heavier showers getting going in SW Wales just now so we will see, should prove a topic of interest?

Edited September 23, 2010 by Tonyh

[Gordon]

the other thing to mention is that as these showers are forecast to be slow moving anyone not in the firing line is going to have a largely dry day

the latest forecast on the BBC weather website which was updated at 08.35 has me with a day of sunny intervals with a light shower at 19.00 which is a complete contrast to their TV forecast and their rain forecast maps don't show a lot of rain either locally or nationally

A lot of people might be disappointed with the weather they get today

[staplehurst]

Agreed, quite a few will miss out and no doubt there will be the usual posts by this evening about how the MetO got it wrong again...

(p.s. that's not a very nice way to talk about Germany's capital city? )

I presume it stands for Free University of Berlin which allocate names to all the Low and High pressure systems over Europe.

[Coast]

If you like something just out of reach this morning.......

Storm Forecast

Valid: Mon 04 Oct 2010 06:00 to Tue 05 Oct 2010 06:00 UTC

Issued: Sun 03 Oct 2010 23:22

Forecaster: DAHL

A level 1 was issued across central France mainly for severe wind gusts and tornadoes.

SYNOPSIS

A deep upper-level trough over western Europe has been in the process of closing off into a cut-off cyclone on Sunday evening ... with the remaining short-wave trough lifting into the Norwegian Sea on Monday ... and the cut-off low moving across the western Mediterranean. A SFC low will be maintained ahead of this feature, supporting WAA over western and parts of central Europe on Monday. The next Atlantic system(s) will evolve into an impressively large and intense trough, being accompanied by an equally extensive SFC low, which will cover large parts of the northern North Atlantic by Monday evening.

Certainly worth watching NI/Western Scotland later though

[Harry]

Is that not though the best summary for 2010!?!?

Near, but not near enough!

I think things could be interesting this week however, as the orientation of the LP system draws up some very strong winds straight out of N Africa - nudging against weak continental HP, we could have an interesting mix of warm, humid subtropical air, drier air from the continent, and mild/cool continental air flow - strong winds and lots of weather fronts too!!

[Coast]

I think things could be interesting this week however

I'm going to say the opposite H, not to be awkward, just can't see it being the right mix for us:

[Nick F]

06z GFS indicates some rather warm and moist air advecting north out of Iberia/Biscay on Friday, which may destabilise as the upper trough moves in from the west to create some elevated instability/storms over Ireland and the far SW of England. Long way off, so possible the set-up could change, depending on the orientation/direction the trough makes.

[Harry]

I fear you're right Coast

The reason for my post was the complexity of the setup - slight re-alignments of the LP system, weather fronts etc, could mean the difference between dry and calmer weather, or unstable, humid convective conditions.

Makes for interesting viewing as the week plays out...MetO fax chart indicating a potentially potent storm system developing out to our West Thursday/Friday, not making too much progress Eastwards though, with a fairly strong feed of much warmer air in the meantime...

Better than a big, walloping, fat Mid Atlantic ridge sitting there I think we can all agree (unless of course you prefer the colder, cloudier prevailing conditions you get from such a yucky and boring mid atlantic ridge setup)

Edited October 4, 2010 by Harry

[MP-R]

Though there is always room for surprises regarding a setup like this and convective potential. For instance, we had a good storm in the afternoon on this day with lots of loud thunder, flickery lightning and very heavy rain in quite a similar setup:

http://www.wetterzentrale.de/archive/ra/2006/Rrea00120061016.gif

[knocker]

Better than a big, walloping, fat Mid Atlantic ridge sitting there I think we can all agree (unless of course you prefer the colder, cloudier prevailing conditions you get from such a yucky and boring mid atlantic ridge setup)

Like this you mean although I'm rather stretching the definition of ridge.

http://www.ecmwf.int/products/forecasts/d/charts/medium/deterministic/msl_uv850_z500!Wind%20850%20and%20mslp!192!Europe!pop!od!oper!public_plots!2010100500!!/

[Coast]

I bet you kinda want this level 2 to go a little further North and East eh?

Storm Forecast

Valid: Fri 08 Oct 2010 06:00 to Sat 09 Oct 2010 06:00 UTC

Issued: Thu 07 Oct 2010 18:01

Forecaster: TUSCHY

A level 2 was issued for the far eastern Atlantic mainly for damaging wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

Impressive warm seclusion is in full swing over the far eastern Atlantic at the outset of the forecast with pressure drop gradually settling down somewhere between 950 - 955 hPa and a constant filling thereafter. This shallow warm-core structure features two damaging wind maxima, one bound to the back-bent occlusion in the western fringe of the depression's center and another one along the warm conveyor belt. Otherwise, strong ridging/LL high pressure area affect most parts of Europe with stable conditions forecast.

DISCUSSION

... Portugal and Spain ...

A gradually eastward moving warm conveyor belt with favorable access to a (sub) tropical moisture pool to its south causes a band with strong precipitation. Thunderstorms are most probable along the coast of Portugal and SW-Spain with stratiform rain more inland. LL shear is strong with up to 15 m/s and LCLs quite low (locally below 500 m), so a few tornado reports are well possible despite the rapid clustering trend of thunderstorms. Strong to isolated severe wind gusts remain confined to the coastal areas, where boundary layer air mass will be somewhat better mixed than inland. There, WAA/isentropic lift disconnects surface winds from intense winds above. The main risk however will be strong to locally excessive rainfall mainly over Portugal and the SW coast of Spain, which caused the issuance of a broad level 1.

... W-Bay of Biscay northwards ...

A sharp trough axis and attendant surface wave race northward along the eastern fringe of the main vortex. Coupled to some mid-level dry air overspreading the western fringe of the moist warm conveyor belt and abundant lift cause a sector with modest CAPE/intense shear overlap. A rare E-Atlantic level 2 was introduced to highlight the chance for tornadoes and severe wind gusts with that activity, which probably peaks around noon with decreasing action thereafter.

[Stuart]

Storm Forecast Issued: 2010-10-22 20:28:00

Valid: 2010-10-23 00:00:00 - 2010-10-23 23:59:00

Regions Affected

Wales, Midlands, East Anglia, SE, CS + SW England and Ireland (all of the United Kingdom is included in the WATCH)

Synopsis

Low pressure "Ursula" (FU Berlin) centred over the North Sea will dominate the weather across the country on Saturday.

Behind an eastward-moving cold front, clearing the east by late morning, a cold rPm airmass is advected across the majority of the country, steepening lapse rates. Scattered showers and isolated thunderstorms are forecast to affect many parts of the country, particularly nearer the coasts.

Given the airmass, hail is likely in many of the showers, perhaps locally large in diameter, particularly (but not exclusively) in southern counties of England. There exists the potential for a spout to form. Gusty, blustery winds will accompany heavier showers.

Showers are forecast to decrease in coverage rapidly during the evening hours, becoming increasingly confined to the coasts

http://www.ukasf.co.uk/module-Storm/mode-forecast/id-356/

Edited October 22, 2010 by Stuart

[Nick F]

Netweather storm forecast for tomorrow issued here:

http://www.netweather.tv/index.cgi?action=convective;sess=