Convective/Storm Discussion Thread - 8th July onwards

[Norfolk Sheep]

Frankfurt is looking nice!

http://www.citycams.tv/en/germany/frankfurt-am-main/

[matt_in_dudley]

Had 30 seconds of monsoon rain here earlier. Wasn't pleased...had to run out and get the washing in and i'd just watered the plants! lol. 

[TJS1998Tom]

This is more like it

[Thunderstruck]

Rather a slow start to the day here, but a lot going on in Northern France...

[LightningLover]

Good Morning!

[Justin123]

Can see today's precipitation pushing north from NE France , looks like the only extremely SE/E coast will have any chance of a storm the rest will just b showers, sorry everyone up north, but you got to share ! LOL

[Chris.R]

 If I had anything to share here I would, unless you like drizzle because that's all i've had here this year. ;  that and relentless  sticky heat when the drizzle is not there. 

Edited July 10, 2017 by Chris.R

[Justin123]

I'm just reminiscing on the huge cells last Thursday and yet again another Bust for us then even when we had a MDT and SVR convective forecast. So I hope today feeds my storm starve appetite.

[Chris.R]

1 minute ago, Justin123 said:

I'm just reminiscing on the huge cells last Thursday and yet again another Bust for us then even when we had a MDT and SVR convective forecast. So I hope today feeds my storm starve appetite.

 Yep same here, 3 busts in a row here. It's so frustrating. Certainly for the north-west it's been a terrible year. 

[Justin123]

Just now, Chris.R said:

 Yep same here, 3 busts in a row here. It's so frustrating. Certainly for the north-west it's been a terrible year. 

I am definitely one for the decline in storms in recent years, however, when they happen they tend to be quite big and tend to be edging towards severe however nothing like the old French imports we used to receive all summer back in the day.

[tomp456]

Looking forward to today's storms!

 

Oh...I'm in the UK, not France.

 

Looking forward to today's bust 

[Dami]

It absolutely chucked it down last night, watched it build ( I posted the pics) Heaviest rain I have seen for a while. No thunder. 

 

[Nick F]

Storm & Convective Forecast

Issued 2017-07-10 08:46:33
Valid: 10/07/17 06z to 11/07/17 06z

DAY 1 CONVECTIVE / STORM FORECAST - MONDAY 10TH JULY 2017

Synopsis

Upper trough will move east across the UK on Monday, clearing eastern England this evening. At the surface, a shallow area of low pressure will be centred just off the east coast of England today, before eventually drifting east towards Denmark tonight. A weakening cold front moving east clears eastern England by midnight, a warm and humid airmass, which is unstable to surface heating, resides across E England ahead of this front.

… SE and E ENGLAND …

Upper trough moving east will introduce cooler air aloft atop of warm and humid airmass (dew points of 15-16C) towards eastern England – creating steep lapse rates and thus an unstable airmass here. Modest large-scale ascent ahead of upper trough moving east and surface heating of moist airmass will support development of scattered heavy showers and isolated thunderstorms later this morning and through the afternoon / early evening during peak heating. Thunderstorms are most likely near forecast convergence zones developing across SE and E England – where lift will be maximised. Vertical shear will be weak, so no severe weather is expected … however, there is a risk of localised surface water flooding / hazardous driving conditions from any storms, given high moisture content of airmass storms will be tapping into. Any storm should fade tonight.

Issued by: Nick Finnis

Edited July 10, 2017 by Nick F

[BrickFielder]

  Looking at the forecast models for today then I can see some marked low level wind convergence for parts of the south east and East. The suggestion is that some thunderstorms may develop in this region from mid morning through to early afternoon. Key areas are likely to be along east cost areas with perhaps somewhere like Suffolk having the greatest risk of a storm.

  For the rest of the UK no storm are forecast for today as a weak cold front begins to sink across the rest of the UK. This weak cold front brings drier warmer air in aloft which will reduce mid level lapse rates which limits the ability of low level warm air rising.

  What I have noticed is that some models yesterday kind of liked the look of storms developing at the leading edge of that cold front and they don't like it today. Typically the models are updated with a lot of up to date information over night which usually makes the forecast more accurate. The question we should ask ourselves is whether this is always true.

  This is where I want to go a little of track and explore something which nobody should constitute as a forecast. It occurs to me that overnight cloud cover may affect models accuracy negatively in special circumstances. As the atmosphere cools a little overnight you are likely to get a little more cloud forming. If this was fed into models then there is a possibility that cloud cover could be increased in the modelling and temperatures could be forecast a little on the low side for the following day.  The first test of a theory has to be measuring actual against forecasts and the only thing we can rely on is surface temperatures. If temperatures are close to approaching 20C now in many areas, is it realistic to expect them to top out at around 23C today. So what happens if temperatures are a little higher than forecast and cloud cover is a little weaker.Looking at the castor bay (northern Ireland) sounding from last night then it looks to me like thunderstorms are possible along the leading edge of the occluded cold front when temperatures reach about 26C (maybe in the late afternoon towards the south east).

  The people who work out how forecast models work are pretty smart people and I am sure they have made allowances for such things, but there is always that one small scenario where they could improve. Just maybe that is today, or more probably those smart people have actually got it spot on.

[Flash bang flash bang etc]

Convection going off here in the park by Chelsea Royal hospital, towering cumulus all around and milky blue between. I'm optimistic :-)

[Another Kent clipper]

The defiant optimism for cumulonimbus is the gas in my tank

[Flash bang flash bang etc]

1 hour ago, Another Kent clipper said:

The defiant optimism for cumulonimbus is the gas in my tank

I wondered what that smell was

[marshallfarm]

Storms firing near Cambridge

 

[Carl46Wrexham]

I know I'm not in an area down for storms but shower just gone through intensified big time.

 

Looking East:

[Windblade]

Total bust yesterday. So far things are not looking too great. There's come cumulous around but nothing substantial so far. I think there may well be a cap in place limiting development.

[Windblade]

2 hours ago, BrickFielder said:

  Looking at the forecast models for today then I can see some marked low level wind convergence for parts of the south east and East. The suggestion is that some thunderstorms may develop in this region from mid morning through to early afternoon. Key areas are likely to be along east cost areas with perhaps somewhere like Suffolk having the greatest risk of a storm.

  For the rest of the UK no storm are forecast for today as a weak cold front begins to sink across the rest of the UK. This weak cold front brings drier warmer air in aloft which will reduce mid level lapse rates which limits the ability of low level warm air rising.

  What I have noticed is that some models yesterday kind of liked the look of storms developing at the leading edge of that cold front and they don't like it today. Typically the models are updated with a lot of up to date information over night which usually makes the forecast more accurate. The question we should ask ourselves is whether this is always true.

  This is where I want to go a little of track and explore something which nobody should constitute as a forecast. It occurs to me that overnight cloud cover may affect models accuracy negatively in special circumstances. As the atmosphere cools a little overnight you are likely to get a little more cloud forming. If this was fed into models then there is a possibility that cloud cover could be increased in the modelling and temperatures could be forecast a little on the low side for the following day.  The first test of a theory has to be measuring actual against forecasts and the only thing we can rely on is surface temperatures. If temperatures are close to approaching 20C now in many areas, is it realistic to expect them to top out at around 23C today. So what happens if temperatures are a little higher than forecast and cloud cover is a little weaker.Looking at the castor bay (northern Ireland) sounding from last night then it looks to me like thunderstorms are possible along the leading edge of the occluded cold front when temperatures reach about 26C (maybe in the late afternoon towards the south east).

  The people who work out how forecast models work are pretty smart people and I am sure they have made allowances for such things, but there is always that one small scenario where they could improve. Just maybe that is today, or more probably those smart people have actually got it spot on.

I think there could be some truth to this and could explain why the weekend was forecast to be nice and cool (18-23c) and ended up being absolutely boiling (AGAIN) with temps from 27-32c. 

Edited July 10, 2017 by Windblade

[poseidon]

Seems to be going ballistic on the Suffolk coast atm. Small shower just came thro here, nothing particularly impressive, but can see some pretty big cumulus out West - may be part of that shower convergence line.

[Justin123]

Some very impressive clouds apes out here today, extremely hot and humid, today it think is the day !! 

[Flash bang flash bang etc]

15 minutes ago, Windblade said:

Total bust yesterday. So far things are not looking too great. There's come cumulous around but nothing substantial so far. I think there may well be a cap in place limiting development.

There is - seen towers rising and falling all morning.

Problem with the convective opportunities around our way is that it takes all day to do something - anything - remotely interesting but by then all the CAPE has usually mixed-out.

We seem to be living under a cap all the time!

[Pursuer of Storms]

Things have built up very quickly here over the past couple of hours. At little dull and overcast above but lots of bubbly towers going up in the distance, so hopefully might lead to something later. 

Edited July 10, 2017 by Pursuer of Storms