Storms and Convective discussion - 1st May 2022 onwards

[Sky Full]

Raining quite heavily here now.  No thunder though.

 

[BrickFielder]

The front currently over the South west is bringing in moisture at upper levels. This will lead to some upper level clouds and storms as it slowly sweeps west to east during the day. It should be noted that the boundary layer (surface) is very dry and there will be significant resistance to convective initiation (CIN). What is not perhaps picked up by the models well is the possible second frontal boundary which seems likely to play its part tomorrow as upper level cooler air crosses the southern half of the UK.

By early evening upper level frontal cloud band should reach the midlands and London areas and considering cloud top heights may give a lightning show.

 

The UKV Model also seems to like initiating convection along a low level convergence zone.

 

This is just one model but it does hint at a possibly of a cap going quite explosively. along that zone.

 

Since this is just a hint on one model we should not get too excited and even here the convection is likely to be elevated. Not convinced (overnight soundings were not that positive) but worth keeping an eye on.

 

[Sky Full]

15 minutes ago, Sky Full said:

Raining quite heavily here now.  No thunder though.

 

The rain stopped almost as soon as it started.   I can still hear distant thunder though.

[Sky Full]

Skies here now looking a lot different from yesterday:

South

East

Overhead

 

Must get some more activity out of this, surely?

[Chris K]

I'm guessing this incoming narrow band of thundery rain will suddenly fade out just before reaching Bristol

[DeepSnow]

Not expecting any thunder from it now having see the radar but will be nice if it can keep some precip for here!

[Harry]

Some fantastic videos circulating of positive lightning strikes across the SW this morning. The thunder was fantastic and chimes with one forum member’s experiences in Plymouth this morning

[ChannelThunder]

New radar returns in the area you want them if you're in the central south! This shows that the energy is there to give us at least something late this afternoon 

[AnvilCrawlers]

We finally got rain and a nice breeze just blew through.Wether it turns thundery will have to wait and see.

[Turquoise]

well at least those in the South cant complain about the lack of storms this season, literally every single storm event this summer has been a copy and paste job in the south. And yet again is the case today. 

Hoping for more action up this way later but unlikely.

[Ben Sainsbury]

UKV 9z still wants to kick off an isolated but severe surface-based thunderstorm across East Midlands into NE England next hour or two.

[MP-R]

1 hour ago, Chris K said:

I'm guessing this incoming narrow band of thundery rain will suddenly fade out just before reaching Bristol

If it comes without thunder... good!

[Raindrops]

Just had a nice storm pass by me (Dublin), rather messy and sporadic, some IC and one CG, light rain, mostly coastal, I'm mostly waiting for late night action if at all lucky.

Humidity is high now.

Edited July 19, 2022 by Raindrops
typo

[Mapantz]

Just heard thunder. I don't want any rain here! I have freshly laid concrete..

[Dangerous55019]

Holy cow! I’ve just had a look to see if there was anything kicking off as this Spanish Plume of hell goes out…
 

It might all die out before it gets to those of us in land… But it might not! Here’s hoping! 🌩⛈

[TJS1998Tom]

Are there any storms for Lincolnshire areas later tonight or is it mostly tomorrow?

[IanR]

17 minutes ago, Azuremoon2 said:

well at least those in the South cant complain about the lack of storms this season, literally every single storm event this summer has been a copy and paste job in the south. And yet again is the case today. 

Hoping for more action up this way later but unlikely.

very unlikely,  you may have marginally better chance being closer the the peaks ,  but still highly unlikely    

[alexisj9]

21 minutes ago, Azuremoon2 said:

well at least those in the South cant complain about the lack of storms this season, literally every single storm event this summer has been a copy and paste job in the south. And yet again is the case today. 

Hoping for more action up this way later but unlikely.

SW, doesn't include all south. Although we have had a storm in Dover. 

[DeepSnow]

Some light rain here, sky looks stormy and its very still and muggy but it just doesn't want to go bang unfortunately

[mike5900]

I can here thunder to the south of here.

[Guest]

Thunder heard in Bournemouth, not a strike within 40miles. Sound is being carried on the strong southerly wind?

[Methuselah]

5 minutes ago, Alderc said:

Thunder heard in Bournemouth, not a strike within 40miles. Sound is being carried on the strong southerly wind?

Or you've been to Specsavers?

[Raindrops]

Day 1 Convective Outlook

VALID 06:00 UTC Tue 19 Jul 2022 - 05:59 UTC Wed 20 Jul 2022

ISSUED 06:12 UTC Tue 19 Jul 2022

ISSUED BY: Dan

An incredibly hot, dry airmass continues to cover Britain on Tuesday associated with a deep well-mixed layer generally suppressing surface-based convection. Above this mixed layer scattered elevated showers and thunderstorms are possible in the morning over SW England and into Wales and perhaps SE Ireland along a NW-SE aligned instability axis drifting gradually eastwards through the day on the forward side of an upper low over Biscay. Most model guidance suggests activity along this zone will wane by the afternoon hours, however the instability axis remains as it tracks eastwards across England through the afternoon and evening and any subtle forcing/moistening may be sufficient for additional elevated showers/thunderstorms to develop. However, confidence is rather low on exactly when and where - a blend of guidance suggests there may be an uptick in activity across SE England, East Anglia and the E Midlands during the evening hours. Meanwhile, ahead of this feature the UKV (and to a lesser extent the ECMWF) continues to flag the potential for a few scattered showers/thunderstorms over Cen N and NE England and SE Scotland during the afternoon and early evening hours, exiting to the North Sea. In the model world these have a surface-based look to them forming within the surface trough axis, but in reality their bases would be incredibly high (same level as elevated convection essentially) and given the incredibly deep hot, dry layer such surface-based convection would likely struggle for moisture. Therefore this scenario is deemed rather unlikely, with elevated convection probably the more favoured mode (if anything does indeed develop). Any strong, isolated elevated convection that does develop at any point during this forecast period poses the risk of starting a fire given potential for dry thunderstorms and tinder dry vegetation, and perhaps also some heat bursts. Thunderstorms could produce quite frequent lightning given the magnitude of instability above the EML.

Perhaps better consensus is for an active complex of thunderstorms to quickly develop over parts of northern Scotland and the Moray Firth during the late afternoon and early evening hours, on the leading edge of the approaching cold front as PVA arrives from the southwest. This may become messy given a mixture of convective and dynamic precipitation, but could be rather active for a few hours before weakening on approach to Shetland. Overnight, there may also be an increase in elevated shower/thunderstorm activity in the vicinity of the Celtic Sea and portions of Wales/SW England (perhaps W Midlands/W Country) on the northern periphery of the approaching Biscay upper low. 

convectiveweather.co.uk

[The Tall Weatherman]

False strike near Milton Keynes

[Raindrops]

Storm Forecast
Valid: Tue 19 Jul 2022 06:00 to Wed 20 Jul 2022 06:00 UTC
Issued: Mon 18 Jul 2022 23:51
Forecaster: BEYER

A level 2 was issued for S to C France for large to very large hail, severe wind gusts, and excessive precipitation.

A level 1 was issued for parts of Spain and France into far S Belgium extending the level 2 for overnight activity mainly for excessive precipitation and to a lesser extent for large hail.

A level 1 was issued for the W Alps and the Sea Alps mainly for excessive precipitation and to a lesser extent for severe wind gusts.

A level 1 was issued for parts of W Russia mainly for excessive precipitation and to a lesser extent for tornadoes.

A level 1 was issued for S Russia adjacent to the Caucasus Mountains mainly for excessive precipitation and to a lesser extent for tornadoes.

SYNOPSIS

An unusual strong long-wave ridge is present over C Europe and moves slowly eastward during the forecast period. At the same time, a cut-off upper-level low is present over the Bay of Biscay moving to the English Channel during the night to Wednesday. On its forward flank, a hot airmass is advected far to the North. This record-breaking heat will bring new temperature records to many parts of W and C Europe.

This hot airmass is also characterized by a strong elevated mixed layer with steep lapse rates (1 to 4 km) but a very dry BL. A dry surface trough with strong cold air advection is passing France during the forecast period from W to E and reaches Germany during the night.

Strong synoptic lift is forecasted with the upper-level low that influences especially S France.

Further to the east, an upper-level trough influences W Russia and parts of E Europe with rather cool and unstable airmasses. Several short wave features can be found along the flanks of the UL low. A pronounced short wave trough is moving southward on the W flank of the trough during the night hours.

DISCUSSION

... France ...

As already mentioned in the synopsis the hot and record-breaking airmass is characterized by a deep elevated mixed layer but also very dry BL with low dewpoints and values of specific humidity. The forming surface trough that extends from Great Britain to N France and is moving eastward, will thus pass completely dry with a sharp shift of LL winds and a strong pressure rise further upstream that may bring a few strong wind gusts but no convection.

Further to the south the strong southerly to southwesterly flow that crosses the Pyrenees will lead to lee cyclogenesis just N of the Pyrenees. Strong moisture pooling is forecasted in that region. The strong lift due to the approaching UL low in combination with the orographically induced lee cyclogenesis is forecasted to initiate several storms N of the Pyrenees.

At the same time, mid-level and deep layer shear is strengthening from the west. Low-level wind profiles show a nice veering and up to 200 m^2/s^2 of SRH0-3 is forecasted. As a result, the initiated storm may rapidly develop into rotating supercells.

These mesocyclonic storms may bring large to very large hail taking into account the steep mid-level lapse rates and MUCAPE values of 2000 to 3000 J/kg.

At the same time, DCAPE values of around 500 J/kg are present having an inverted-V low-level profile. Thus also severe wind gusts are possible. LAMs point to wind gusts of well above 25 m/s with those initiated storms.

During the late evening and night hours, the convection is forecasted to move further north related to the synoptic scale forcing of the trough. Having rather parallel shear vectors (pointing S to N) along the organizing feature convection is forecasted to cluster into a linear MCS. Precipitable water has values of up to 40 mm and convection may repeatedly move over the same region. As a result, there is an enhanced threat of excessive precipitation while the chance for large hail is decreasing during the night hours.

At the end of the outlook period, convection should reach NE France and S Belgium but the threat of severe weather is decreasing.

... W Alps ...

Synoptic scale forcing in this region is rather weak but thanks to the orography somewhat enhanced LL moisture (advected with S winds from the Mediterranean) can overlap with the steep lapse rates. As a result CAPE values of up to 1000 J/kg are forecasted to develop.

Given very weak wind shear clustering convection along the orography is forecasted to develop in the afternoon hours. Storms are forecasted to be only slow-moving and therefore excessive precipitation is a prominent threat in this region. In addition, low levels are dry with inverted-V profiles. Thus, especially at the beginning, also strong to severe wind gusts cannot be excluded.

... parts of W Russia ...

A lot of convective activity due to the UL trough is forecasted over W Russia. Strong and persistent convergence is predicted in the region of the surface low that is situated perpendicular below the mid to upper-level low. Precipitable water is forecasted to have values well above 30 mm. Repeated convection enhances the threat of excessive precipitation in the LVL 1 area.

In addition, there is a chance for one or two type-II tornadoes having weak low to upper-level converging winds around the low-level center as well as very low LCLs.

... S Russia ...

Some CAPE can develop close to the Black Sea due to a very moist BL that can develop with somewhat steep lapse rates from further inland. Thus some storms close to the E coast of the Black Sea are forecasted to develop. These may locally bring excessive precipitation given the high values of precipitable water.

Low-level winds are forecasted to be rather weak and LCLs are close to the surface. As a result, we would not exclude waterspouts from these storms.

Further inland almost no CAPE is forecasted. However persistent and strong precipitation can be found in some of the models. These precipitations may be convectively enhanced. Thus the LVL1 was extended further inland to account for an enhanced threat of excessive precipitation also having in mind the high values of precipitable water (40 to 45 mm).

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