Storms and Convective discussion - July 2023

[JR319]

Both Met Office and BBC Weather mention thundery showers on Saturday. What effect will the strong gusts have on these for any that do develop? 

[CoventryWeather]

Saturday seems like a day of interest for me, might be some severe storms possible, even if the CAPE profiles do not look anything exciting. Wind shear aloft seems very strong. Not an expert so not going into too much detail, but would expect others to comment on this day soon.

Very convective day expected (and I'm off to Fairford for an airshow)

[Wilxy]

24 minutes ago, CoventryWeather said:

Saturday seems like a day of interest for me, might be some severe storms possible, even if the CAPE profiles do not look anything exciting. Wind shear aloft seems very strong. Not an expert so not going into too much detail, but would expect others to comment on this day soon.

Very convective day expected (and I'm off to Fairford for an airshow)

 

I'm also off to RIAT this weekend and it doesn't look great at all does it! I even wondered if they would consider cancelling Saturday as this could be the worst weather I have seen forecast for the event in all the years Iv'e been except the ones that got cancelled! 

[Rufus Butterfield]

I’ll make a highlights video once I string together the clips from friends and family and get chance to edit. This was from last weekend (8th July), very close strike. 

 

Obviously I wasn’t there (I return back from Spain tomorrow).

[Harry's House]

9 hours ago, Eagle Eye said:

I actually play cricket in Great Chart. Small world I guess.

So sorry to hear about your wife's oldest brother.

Heather's youngest brother used to lay cricket for Great Chart many years ago. He has since emigrated to Australia.

[Eagle Eye]

15 minutes ago, Harry's House said:

Heather's youngest brother used to lay cricket for Great Chart many years ago. He has since emigrated to Australia.

Really is a small world. A few people might even have known him. The chairman of 50 odd years still plays for us occasionally so I imagine he knew him right from the start till the end of when he played for us.

[Harry's House]

52 minutes ago, Eagle Eye said:

Really is a small world. A few people might even have known him. The chairman of 50 odd years still plays for us occasionally so I imagine he knew him right from the start till the end of when he played for us.

He is Nick McNaughton.

[Jamie M]

Would pray for shear like that in a proper storm scenario 

[alexisj9]

7 hours ago, JR319 said:

Both Met Office and BBC Weather mention thundery showers on Saturday. What effect will the strong gusts have on these for any that do develop? 

Well I'm guessing the se has a wind warning Saturday for a reason. Expect preshower strong winds, or perhaps a squally element.

[Eagle Eye]

Convective Outlook

A band of heavy showers might turn into elevated thunderstorms in places, but the confidence is very low. This is given very low instability with a band of rain which could have a few rumbles within the band, especially with the back of the cold front. An initial, decaying warm front probably won't hold much instability with the first band. However, there's a cold front close to it which may have some instability associated with the back of it. High shearing parallel to the advancing cold front should allow for organisation of any CAPE. Possibly enough to upgrade to a slight risk tomorrow and expand the low if MLCAPE forecasts trend further north. 

Instability will build across Ireland later, MLCAPE in excess of 1000 J/KG in some areas should spark a few fairly active storms. Some elevated storms to the north of initial surface based storms along a Theta-W plume with some post APBL WAA. A lifting occluded front rises with the Theta-W along a QG plane, forcing stronger convective forcing in a line along the PV lobe with widespread 700+ J/KG of MLCAPE and locally sourced 1000+ J/KG of MLCAPE could provide for some high LCL embedded storms. Lightning probably won't organise due to the high LCL's and mostly fairly low EL's despite the fairly high shearing. This is because that weakens the ECAPE the storms can take up, fairly weak. South of the lifting QG plane, surface heating should provide for fairly large SBCAPE and a few storms to form despite weak shearing.

[Eagle Eye]

10 hours ago, Eagle Eye said:

Convective Outlook

A band of heavy showers might turn into elevated thunderstorms in places, but the confidence is very low. This is given very low instability with a band of rain which could have a few rumbles within the band, especially with the back of the cold front. An initial, decaying warm front probably won't hold much instability with the first band. However, there's a cold front close to it which may have some instability associated with the back of it. High shearing parallel to the advancing cold front should allow for organisation of any CAPE. Possibly enough to upgrade to a slight risk tomorrow and expand the low if MLCAPE forecasts trend further north. 

Instability will build across Ireland later, MLCAPE in excess of 1000 J/KG in some areas should spark a few fairly active storms. Some elevated storms to the north of initial surface based storms along a Theta-W plume with some post APBL WAA. A lifting occluded front rises with the Theta-W along a QG plane, forcing stronger convective forcing in a line along the PV lobe with widespread 700+ J/KG of MLCAPE and locally sourced 1000+ J/KG of MLCAPE could provide for some high LCL embedded storms. Lightning probably won't organise due to the high LCL's and mostly fairly low EL's despite the fairly high shearing. This is because that weakens the ECAPE the storms can take up, fairly weak. South of the lifting QG plane, surface heating should provide for fairly large SBCAPE and a few storms to form despite weak shearing.

Update to the risk map. Did mention the possibility of it.

[Windblade]

Nicks forecast is out as well...

[Eagle Eye]

1 hour ago, Windblade said:

Nicks forecast is out as well...

Oddly nothing in parts further north in Ireland given quite a few models still supporting that QG forcing that I talked about along with decent MLCAPE.

[Windblade]

52 minutes ago, Eagle Eye said:

Oddly nothing in parts further north in Ireland given quite a few models still supporting that QG forcing that I talked about along with decent MLCAPE.

Yeah, different forecasters using different data and/or having different opinions I guess! 

[Eagle Eye]

Just now, Windblade said:

Yeah, different forecasters using different data and/or having different opinions I guess! 

True true. Its downgraded since last night to be fair. Relies on local maximas which even the most high resolution models won't pick up.

Edited July 14, 2023 by Eagle Eye

[Windblade]

Just now, Eagle Eye said:

True true. Its downgraded since last night to be fair.

I'd love to do my own forecasting but I've always been much better at raw instincts than using data!

Edited July 14, 2023 by Windblade

[Eagle Eye]

5 minutes ago, Windblade said:

I'd love to do my own forecasting but I've always been much better at raw instincts than using data!

Can totally understand. All the big words are just for practising for University for me (hopefully). QG (Quasi-Geostrophic) forcing local maximas just mean, the changes in landscape or pressure deformation affecting storm formation. Most models won't pick them out to their true extent. Though the high resolution models will generally get a better idea of positioning of course. The pressure deformation (shortwave trough) is the main reason here. Though it's a bit further south than it was modelled yesterday and weaker.

 

[Windblade]

1 hour ago, Eagle Eye said:

Can totally understand. All the big words are just for practising for University for me (hopefully). QG (Quasi-Geostrophic) forcing local maximas just mean, the changes in landscape or pressure deformation affecting storm formation. Most models won't pick them out to their true extent. Though the high resolution models will generally get a better idea of positioning of course. The pressure deformation (shortwave trough) is the main reason here. Though it's a bit further south than it was modelled yesterday and weaker.

 

Interesting. However, I think I need to increase my knowledge of dissecting all the various data more first though before I start doing my own forecasts! Tell you what, if I had my time again I'd definitely consider either becoming a Meteorologist or an Astronomer. I find both subjects utterly fascinating.

Edited July 14, 2023 by Windblade

[Lynxus]

So, Er.. Just seen the forecast on BBC for Gloucester tomorrow, Thunder pretty much all day....

Certainly looking interesting with some pretty blustery showers coming from the South West...

Pretty humid air also... So maybe they are correct for a change!

[Harry]

UKV has consistently been showing a line of torrential downpours swinging across London and the SE this evening…

[East_England_Stormchaser91]

I’m getting increasingly interested in what tomorrow May hold. Quite a fair bit of speed shear especially in the E/SE tomorrow. Going to be interesting seeing what the forecasts are by the morning. Looks to me like an environment for a supercell and even a tornado. The CAPE looks to be there, overlapped by quite a screaming jet for the time of year. 

[IanT]

I’m interested too. I like interesting…

[Eagle Eye]

11 hours ago, Eagle Eye said:

Oddly nothing in parts further north in Ireland given quite a few models still supporting that QG forcing that I talked about along with decent MLCAPE.

Well it did happen this evening. Had a good shower go through but when I was at work. Now I know how the others who have storms at work feel.

[alexisj9]

7 hours ago, Harry said:

UKV has consistently been showing a line of torrential downpours swinging across London and the SE this evening…

Yep over me now, first bit of proper rain all day.

[Eagle Eye]

Convective Outlook

3CAPE in excess of 150 J/KG with locally 200+ J/KG along the inner portion of a jet streak with large and suitable moisture transport for some active storms to form. These will likely form on PV lobes and from orographic forcing.

Local QG forcings with pressure deformation will allow for some active storms to potentially form in areas. Despite fairly weak SBCAPE because of local surface buoyancy maximas associated with Quasi-Geostrophic forcing mentioned before, pulse-type storms could become active in areas.

Clustering may occur with +VE PV rolls stretched in a line given mostly QG forced storms, however, that tends to weaken storms I find. So the less clustered they get, the better for forecasting verification.

Along the jet streak, strong wind gusts could take place and given the moisture advection, surface flooding may also occur. An isolated brief tornado may occur given the extent of LLS in some areas. Very strong LLLR's could give the risk for some non-severe hail size.