1 Aug 2011 - Storm/convective Forecast, Discussion And Reports

[Darren Bown]

Tomorrow seems quite interesting for my area. It is very muggy here at the moment, air is moving a little, but with the forecast tomorrow as 'muggy with some rain or thunder' (by the symbols) then I'm satisfied

[Staffordshire]

Anyone know if there's going to be any convergance zones, where and for what day

[Costa Del Fal]

Anyone know if there's going to be any convergance zones, where and for what day

In this slack flow very likely. Where is very hard to answer as it could be anywhere really and day - much of the week.

GFS 12z has changed things slightly. Its quite a poor one for the East and after Thursday the potential has diminished but Monday to Wednesday starting to look potentially interesting for the West and Central West zones especially extending to the NE at times as well. Im happy as it is but it WILL change more thats for sure!

My only slight concern is Lapse rates which dont look great at times but given other conditions it shouldnt put out things too badly. Perhaps cloud could be an issue tomorrow?

Edited July 31, 2011 by Blizzards

[Raidan]

Im liking the fact that the west is getting a mention for a change,All you hear or read when it comes to storm potential is about the east,im still sticking to what i said yesterday but at the same time thinking maybe what i said a few weeks ago about when the west do finally get storms there going to be awesome,Good luck all.

[Staffordshire]

And staffs is smiling

[shuggee]

I've opened this thread as there's forecasts about tomorrow with percentage chances of storms beyond 50%. Hope the chaps above don't object to starting-off the thread

[Staffordshire]

Not at all , I don't have a clue about t-storms if I'm honest so any know the areas at risk tommorow? Cheers

[Jane Louise]

Evening folks

I am also curious as to where the storms will be tomorrow.

If I'm right everybody has a chance from Monday until Wednesday.

All I can say is ' Good Luck ' everyone, fingers crossed and all that! here we go again..... :lol:

I don't want to jinx it for Cheltenham so I wont mention what my storm risk is yet , but let's say it kind of looks okish for now Lol

[The watcher]

Not a very good risk for here, seems to get better later in the week. Mainly a mainland event upto Wednesday I think.

[Nick F]

Despite the GFS indicating several 100 j/kg CAPE across central and northern areas tomorrow afternoon, I am rather sceptical there'll be any storms. For a start, there looks to be too much cloud around and lapse rates don't look too conducive - with rather a saturated troposhere. Also forcing is likely to remain weak until later in the evening - when a short-wave trough is inidicated to move up from the SW. Perhaps overnight into Tuesday may see some isolated elevated storms in the west. Tuesday and Wednesday look better, when greater forcing arrives.

[Stuart]

Last Updated: 21:37 Sunday, 31st July 2011

Valid: 00:00 Monday, 1st August 2011 - 23:59 Monday, 1st August 2011

Areas Affected:

E and SE Scotland, NE England/Pennines, NW England and N Midlands (Watch extended to E Wales and remaining Midlands)

Synopsis:

As an upper ridge continues to strengthen to the east of the United Kingdom, a quasi-stationary occluded/cold front continues to nudge slowly eastwards across Central Britain. The main bulk of any noteworthy convective activity will be along this frontal boundary.

Discussion:

To the east of the aforementioned front(s), a warm airmass with high dewpoints (~16C) will be advected northwards across England and Wales. Diurnal heating combined with forcing from fronts and local topography, particularly the Pennines, is likely to destabilise this airmass and develop embedded convection along the boundary. Any storms that do develop will pulse in a NNE direction, and are most likely along and to the north/east of high ground.

GFS is quite keen to develop widespread thundery activity to the east of the Pennines during the late afternoon and evening, but it is suspected this may be exaggerated slightly by the bias towards overcooked dewpoint values. Despite CAPE of ~500J/kg and ELT's as low as -35C, lightning is expected to be quite sporadic, and may be particularly inhibited by cloud cover.

Such storms that do develop are expected to move over the North Sea during the evening hours but are expected to quickly decay later in the evening. High values of PWAT may provide locally high rainfall totals.

http://ukasf.co.uk/storm-forecasts/57

[Static Prevails]

I like that from UKASF. Hopefully I'll see something.

[ZONE 51]

GFS/NAE 18z

Looking at the cloud cover charts it does appear that GFS wants more cloud then NAE-which breaks up the cloud even into Northern areas, what we have is high enough CAPE, fairly unstable airmass-Lifted index showing some negative(yellow) through monday, GFS seems to be under estimating the surface temperatures with NAE liking a more hotter day, also the dew points on GFS are looking a little high maybe as NAE really shoves them down a bit. also watching the feature to move into the SW later in day as shown on the NAE ppn charts, this more likely to turn thundery and enhance the convective possibilitys later!

now the precipitation is quite interesting on the NAE as this shows some rather heavy stuff breaking out in places, it is Northern and Western areas most at risk of thundery activity on monday and overnight into tuesday, at the moment it seems the SE especially staying dry hot and sunny, but the models change so could be a bit different by the morning.

We will need to wait until the mornings model runs to see where any storms might develop, conditions may improve for convective actiivity with higher potential, we have ingredients for storms but a cake wont bake unless someone cooks it.....

-

Edited August 1, 2011 by ElectricSnowStorm

[Coast]

ESTOFEX are showing something pretty well everywhere:

Storm Forecast

Valid: Mon 01 Aug 2011 06:00 to Tue 02 Aug 2011 06:00 UTC

Issued: Sun 31 Jul 2011 22:06

Forecaster: SCHLENCZEK

SYNOPSIS

The most remarkable upper level feature on Monday is a small upper shortwave trough west of Iberia which will move across Iberia towards France. Unstable air ahead of this trough will lead to severe thunderstorms over Spain and the N Maghreb States.

Warm and moist air remains over eastern Europe and leads to showers and thunderstorms over a broad area. Locally, up to 2 kJ/kg MLCAPE are forecast and some isolated large hail is possible.

Ahead of an approaching low pressure system, some instability is expected over the British Isles and also over S Scandinavia.

Remnants of an upper low which moved across E Ukraine will lead to an overlap of low instability and strong shear over Turkey which is likely to result in some large hail reports.

DISCUSSION

...British Isles...

Showers and thunderstorms may develop during the afternoon in an environment with low-end instability and weak shear. Severe weather is not expected to occur.

UKASF say:

Forecaster: Dan

Last Updated: 21:37 Sunday, 31st July 2011

Valid: 00:00 Monday, 1st August 2011 - 23:59 Monday, 1st August 2011

Areas Affected:

E and SE Scotland, NE England/Pennines, NW England and N Midlands (Watch extended to E Wales and remaining Midlands)

Synopsis:

As an upper ridge continues to strengthen to the east of the United Kingdom, a quasi-stationary occluded/cold front continues to nudge slowly eastwards across Central Britain. The main bulk of any noteworthy convective activity will be along this frontal boundary.

Discussion:

To the east of the aforementioned front(s), a warm airmass with high dewpoints (~16C) will be advected northwards across England and Wales. Diurnal heating combined with forcing from fronts and local topography, particularly the Pennines, is likely to destabilise this airmass and develop embedded convection along the boundary. Any storms that do develop will pulse in a NNE direction, and are most likely along and to the north/east of high ground.

GFS is quite keen to develop widespread thundery activity to the east of the Pennines during the late afternoon and evening, but it is suspected this may be exaggerated slightly by the bias towards overcooked dewpoint values. Despite CAPE of ~500J/kg and ELT's as low as -35C, lightning is expected to be quite sporadic, and may be particularly inhibited by cloud cover.

Such storms that do develop are expected to move over the North Sea during the evening hours but are expected to quickly decay later in the evening. High values of PWAT may provide locally high rainfall totals.

SkyWarn:

Severe Weather Risk: Low

Warm across the southeast, cooler and cloudier to the northwest with potentially heavy showers. Increasing thunderstorm risk in to the new week.

Here's a sprinkling of other info for the day:

One to watch, but I'm not very confident about today - where or even if!

[VillagePlank]

[London,SE]

Strong surface heating required, today, to enhance the rather marginal indices (K,LI,TT) and tap into the CAPE. Doesn't look likely, I'm afraid, with stubborn cloud around all day. Nice big convective clouds will form if the clouds clear, but that's not the forecast.

Going to feel muggy and uncomfortable, though.

Edited August 1, 2011 by Sparticle

[Coast]

Going to feel muggy and uncomfortable, though.

Dew points already up around 15.1 DgC down here, sticky!

[Stuart]

it sticky here to Dew points 10.7

[Jane Louise]

According to my weather station the dew point is showing at 15.8. There is still a lot of cloud cover here but it looks like it's brightening up.

[P-M]

Update From UKWW's Tony Gilbert:

8.44am Mon

Slight Risk of Thundery Showers UK Regions anywhere north of Midlands 12Z-21Z

Risk of Embedded Low Level Mesocyclones as per red box

Atlantic depression maintains polar maritime unstable flow across the UK through period. Only weak influence from upper trough to the west is offset by stronger insolation at surface. UKMO FAX chart suggests a small wave developing through NE UK and SE Scotland where it is expected that some stronger convection could well develop. Storms approaching NE coast will likely overrun a sharp turn in surface vector of 90 deg where some short lived mesocyclones could well develop. Upper flow remains only marginally supportive of storm cell longevity and the straight lined vector aloft results in rather weak mid level Positive Vorticity. This combined with saturated vertical moisture profiles puts some limits to the overall severity of the forecast.

Prime threat isolated CG's. Am unable to rule out the risk of some funnel ob's within red box!

Unable to update today. Though other forecasters could please monitor the current situation as there is nevertheless some scope for a potential upgrade!

See http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=44210&posts=1 for map areas.

[Harry]

Have to say GFS looks really quite grim for my area over the coming days, with any potential imports looking like staying well and truly over the continent. Home growns look exceptionally difficult to nail down given the rather complex frontal picture shown by UKMO. However, some different charts are showing more promise for the SE.

Could be a difficult one for the forecasters in the coming days IMO.

[VillagePlank]

[London,SE]

Strong surface heating required, today, to enhance the rather marginal indices (K,LI,TT) and tap into the CAPE. Doesn't look likely, I'm afraid, with stubborn cloud around all day. Nice big convective clouds will form if the clouds clear, but that's not the forecast.

Going to feel muggy and uncomfortable, though.

Skies are clearing ->24T_c, 14T_d !!

[peterf]

sun is out now,loads of convection happening also.could be interesting mid afternoon.

[Raidan]

Not looking good here today on the first day of a supposed stormy week,Grey and overcast skies no sign of the sun and feels alot cooler than yesterday,Seems we are set to miss out today but tomorrow looks better,Good luck all.

[Jane Louise]

My storm risk has increased for today Even tomorrow and Wednesday's looking good. It's gonna be a good few days I reckon.

The sun is out now breaking the clouds away, it's eyes to the skies from now on Yay.

[NUT]

The temperatures might not be particulairy high here........but boy it is humid! I just wonder if that could do something later tonight................