16 July 2011 - Storm/convective Forecast, Discussion And Reports

[Jane Louise]

There's a possibility for some of us to see storms today myself included.:lol:

Please discuss here for any potential.

To start the ball rolling. I'll post up this one for starters. Good luck y'all

This is from UKWW courtesy of Tony Gilbert :

8.40pm Fri

Moderate Risk of Thunderstorms UK & Ireland (as per map) 09Z-21Z

Risk of Funnel Ob's Eastern Scotland yellow box

Risk of Stronger Convection red box 12Z-18Z

Earlier build up to this outlook looked rather benign according to the NMM a GFS. Though on a personal note I could see more potential here than the models were maybe ingesting at the time!

Moderate risk of thunderstorms looks to be in place for isolated parts of the UK, north of the Thames Valley and for much of Ireland. Once again it needs to be noted that the risk box is broad. Whilst in reality only a small portion of this risk coverage will in fact see storms!

Quasi stationary low over Scotland maintains a partial polar maritime unstable flow across the UK. Most recent UKMO forecast synopsis looks rather messy IMO. These maps are drawn freehand and when they look like this it usually means there is some uncertainties here!!

Based on what I can see ATM initial occluded front likely to bring heavy persistent rain to much of the UK & Ireland through the morning. Some post frontal troughing looks to develop within the wake of the initial frontal rain. It is within this period for the UK that we have the chance of a significant upper jet streak peeling off across the southeast quadrant of the UK. Winds look straight lined at all levels and models are currently having trouble extending instability into this sector. My opinion suggests that based on the sudden and abrupt incursion of mid level dry air, moist low level advection and surface insolation we should see higher CAPE values across central regions than are in fact currently predicted. With this in mind the risk for stronger convection looks to have the potential to reach much further SE than is currently predicted.

In short a bit hit and miss ATM but hopefully the risk will become more clearer in the morning! Hense the red box may need extending further SE?

Edited by Tony Gilbert 15/7/2011 21:05

http://www.ukweatherworld.co.uk/forum/forums/get-attachment.asp?action=view&attachmentid=73155

http://www.ukweather...w.asp?tid=43981

[Costa Del Fal]

Interesting thoughts from Tony Indeed, nice to see here in the thought zone for stronger storms. The Models are certainly coming round slowly to the availability of more instability.

Good luck folks.

[Mesoscale]

the north keeps getting the storms! what happened to the south being the most lightning active? lol Ive seen two storms this year one being quite a good one and ive heard thunder on two other days so I am happy with what I have got so far as i know alot of people haven't seen a storm in years. the only thing im missing this year is a good old wardrobe shaker at 4am in the morning. its the only real type of storm I can remember from my childhood when I was petrified of storms.

[paul m]

Not this part of the north gets them its further up north. Bloody northerners

the north keeps getting the storms! what happened to the south being the most lightning active? lol Ive seen two storms this year one being quite a good one and ive heard thunder on two other days so I am happy with what I have got so far as i know alot of people haven't seen a storm in years. the only thing im missing this year is a good old wardrobe shaker at 4am in the morning. its the only real type of storm I can remember from my childhood when I was petrified of storms.

I love storms but those night time ones still freak me out. To be woken from a nice dream by a sudden bang is enough to freak anyone out

[Stuart]

ok my last post before bed

Areas Affected:

North and East England, Scotland and Ireland

Synopsis:

An unseasonal area of low pressure (987mb) centred just to the west of Scotland during the day is forecast to be the dominant feature of the weather. A marked upper level trough both at mid and upper levels is associated with this low pressure, along with a noteworthy (>120KT) diffluent jet just to the west of the UK. Active frontal systems associated with the low pressure are forecast to bring a zone of frontal precipitation from west to east, before clearing to leave a very unstable west or north-westerly air mass across many parts.

Discussion:

Extensive frontal cloud and precipitation is forecast from all sources across parts of the north and east of the UK during the early stages of Saturday. This zone of precipitation is forecast to bring some potentially heavy rainfall, but little or no significant convective activity is expected to be associated with the fronts. As the fronts clear away to the east, into the North Sea, by late morning brighter conditions then allow for the development of a more convective, showery type during the rest of the day.

The NMM WRF, GFS and ECMWF are all signalling a convective threat through Saturday afternoon across Scotland, North and East England and Ireland in particular. Latest forecast soundings across Scotland, Northern England and Ireland are predicting complete instability with surface temperatures near 16C or 17C and dew points around 10C or 11C. At the moment cloud development up to 20,000ft is a distinct possibility, but potentially >25,000ft across parts of Scotland during the course of Saturday afternoon.

Steep lapse rates are predicted beneath the low pressure centre. As a result parts of Northern England and Scotland do seem to be at the greatest risk of some deep instability during the course of Saturday afternoon. SBCAPE values of up to and over 700 or 800j/kg is predicted, but with a more modest 300 or 400j/kg of MLCAPE, along with LI values lower than -2. DLS and LLS are greatest across parts of Central and Southern England tomorrow, so primarily away from the main convective areas. In fact forecast soundings for Central Scotland predict no more than 10KT wind speeds 850mb level and just 30KT at the 500mb beneath the low centre. As a result more signal celled storms are predicted during the day, but given the deep instability, then there is a threat of some localised torrential downpours leading to excessive rainfall totals in a short space of time and localised flooding. Some medium sized hail may also be possible, along with temporary gusty winds, particularly in association with any thunderstorms nearing maturity.

A greater amount of DLS (30KT to 40KT between 0-6KM) in particular is expected across Northern England, which may well aid to organise some storms into lines of heavy and perhaps thundery showers. A trough is also forecasted to move across parts of Scotland and Northern England during the day and this may also aid to increase the risk of organisation, given a zone of increase voriticy/PVA.

There is a threat of some localised funnel clouds, particularly given low LCL’s and the risk does seem to be greatest across parts of Northern England where shear is greatest, despite poor or low helicity values.

So in summary after a zone of more persistent frontal rain has cleared to the east on Saturday, a showery and convective weather type is expected for many areas of the UK. Scattered moderate or heavy showers may well develop in many areas during Saturday afternoon, but the focal point of thunderstorm activity, some of which could lead to locally severe weather conditions, is likely to be across North and East England, Scotland and Ireland

http://www.ukasf.co.uk/storm-forecasts/41

[Nick F]

Convective / Storm forecast - Issued 15/07/2011 22:30

16/07/2011 06:00 - 17/07/2011 06:00

Headline: ...THERE IS A RISK OF THUNDERSTORMS FORECAST...

Synopsis

Atlantic depression will move in across Nern UK and become slow moving over next 36-48 hours. Occluding front will clear E England around 12z with an unstable rPm flow circulating around low pressure centred over Scotland.

... UK and IRELAND ...

In wake of frontal rain clearing eastern England late morning, an unstable rPm airmass characterised by steep lapse rates will move in from the west across much of the UK and Ireland, as upper trough shifts east. Models suggest heavy showers and scattered thunderstorms are likely to develop with insolation quite widely across the UK and Ireland away from far SE and S England. Vertical shear will be rather weak generally, though the jet streak and dry mid-level air intrusion towards the SE overlapping CAPE across the Midlands and E England may allow some organisation with perhaps a risk of one or two stonger storms here ... capable of producing strong wind gusts and hail, with a risk of stronger storms possibly extending further south across southern England if cloud and rain clears more quickly than anticipated by models. Storms across Ireland and N Ireland are most likely during the morning and early afternoon, before instability susbsides in the afternoon.

Issued by: Nick F - Forecaster for Netweather

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

[Stuart]

Still looking good for some of us today good luck who still in no storm club like jane and the rest of you :lol:

[NorthNorfolkWeather]

Still looking good for some of us today good luck who still in no storm club like jane and the rest of you :lol:

Good luck Stu ( and all the others). This frontal rain is definitely moving very quickly, the sooner it's through, the more chance we have of some storms

[Static Prevails]

I wish I could be watching the radars right now, but I can't as my laptop is broken. Later on, will anybody tell me if there's anything coming towards Chesterfield? I'll post this again later.

[Coast]

Morning all!

Strangely ESTOFEX, TORRO and SkyWarn have nothing forecast for today? So here's some other indicators:

21st OWS map in line with Nick's NW one

Their UKMO interpretation being more to the North

Blimey, this looks meaty coming up The Channel and over Scotland!

and here the Eastern side of the country gets convection

Is there enough CAPE?

Perhaps later

Wind sheer better down South, with something windy coming up The Channel

Convergence better up in the North

Rain, rain, rain!

Note lapse rates in Wales and to the West:

This is the one I'm concentrating on:

Windy too!

Blimey, it could be anywhere today with Scotland (and later NI) in the firing line but something brewing (low risk) across the Southern half maybe later?

[UKVoodoo]

Finally after over 4 months (and just in time for first game of footy lol) rain has arrived and its a very heavy downpour

Edited July 16, 2011 by UKVoodoo

[P-M]

Not sure where to put this?

UKww Flash Warning for Heavy Rain over Northern Britain

Issued Sat 16/07/2011 0900GMT

Areas affected - Cumbria and SE Scotland (Sat) , Northern and Central Scotland (Sun)

Valid from: 1000GMT Saturday 16th July 2011 - 0000GMT Sunday 17th July 2011

General evolution: Rain from a slow moving low pressure system developing and crossing northern Britain which is expected to persist until at least Sunday night.

During Saturday the heaviest rain is expected to be over Southern and especially SE Scotland and higher ground in Cumbria. Rainfall totals in excess of 40mm are expected over parts of Scotland.

For Sunday the warning area is extended to include NE & central Scotland with 50-65mm of rain expected. Models are indicating the Inverness area consistently.

Please listen to local radio/television broadcasts for up to date information on travel conditions.

UKww will monitor this watch and update/upgrade when necessary.

Issued by PLJK for UKww, 0900GMT 16/07/2011

[Coast]

Not sure where to put this?

Dewpoints already high across the UK this morning:

http://www.netweather.tv/index.cgi?action=current;type=maxd

[A.J]

Morning Robin....blimey it's wet out there!......It's positively filthy out there, but radar suggests the frontal rain should clear from here in the next hour or so, hopefully then the sun will break through and give some nice surface heating to tap into the post frontal instability, add that to the steepening lapse rates and hopefully things might go *BANG* later on this afternoon

[Jane Louise]

Still looking good for some of us today good luck who still in no storm club like jane and the rest of you :lol:

Cheers Stu, good luck to you too and to the members of the NSC . Some nice rain here at the moment.It's lovely to see rain again.

I wish I could be watching the radars right now, but I can't as my laptop is broken. Later on, will anybody tell me if there's anything coming towards Chesterfield? I'll post this again later.

I'll try and keep you updated Johnny.

[A.J]

Cheers Stu, good luck to you too and to the members of the NSC . Some nice rain here at the moment.It's lovely to see rain again.

Morning Jane , you been at those Jamaican Woodbines again?....:lol:.....It's horrible out there!...driving rain and slate grey skies, yuk!

[Jane Louise]

Morning Jane , you been at those Jamaican Woodbines again?....:lol:.....It's horrible out there!...driving rain and slate grey skies, yuk!

Morning aj,

hmmmm, now how did you guess that Lol.

No, seriously we have been in much need of rain here it's been so dry and humid. I'm loving it :lol:

[Stuart]

Thanks coast for that 10.7 dew pont in greenlaw all reday :drinks: :drinks:

[Staffordshire]

I don't know why but I have a very good feeling about today, I AM getting out of the no storms club! And now I've just jinxed myself!

Edited July 16, 2011 by Staffordshire

[TonyH]

But you have had storms in Lichfield?

At least two

[Staffordshire]

But you have had storms in Lichfield?

But you have had storms in Lichfield?

At least two

Have I? I recall an evening April or may? probably about a mile away from me, nothing other than that, had some very heavy downpours... no direct storms...

Edited July 16, 2011 by Staffordshire

[Coast]

Thanks coast for that 10.7 dew pont in greenlaw all reday :drinks: :drinks:

When do you move Stuart? Perhaps there's more thunderstorms in Inverness? :unsure:

[Chris.R]

Very heavy frontal rain here also, but the temp is 18.7c as it has been all morning. Must be to do with the cloud and me being on the coast. Hope I get a storm this afternoon, there's sertanly a lot of moisture out there.

[Stuart]

When do you move Stuart? Perhaps there's more thunderstorms in Inverness? :unsure:

soon coast and i be in the no storm club more

[NL]

ESTOFEX have released their forecast for today.

http://www.estofex.org/