The Most Thundery Time of Year in Your Back Yard

[MP-R]

Spring is just around the corner and so my attention turns more to convective possibilities while expectations of wintry weather lessen as March wares on. It got me thinking when to most expect thundery weather / thunderstorms. Looking back through my records, May is the most thundery month of the year here, accounting for the spike in average rainfall in the otherwise drier half of the year. Specifically, the time around the 05th-15th seems to attract thunderstorms:

2016:

2011:

2008:

2006:

  

2004:

 

2001:

2000:

 

1998:

 

A common theme with most of the above is the easterly flow, a direction my location does quite well out of. Cyclonic SE-NE can be good for here, and these tend to peak in May most years. A particular surprise looking back through the archives was May 2004, a 'warm' northerly sourced from a chilly northern Russia.

What time of year have you noticed to be most thundery in your neck of the woods?

[Thundery wintry showers]

I think in Tyneside it is roughly evenly split between June, July and August with May very close behind (~1.5 thunder-days per month).  I recall reading in a couple of Philip Eden's articles that some parts of the country have a maximum in August, including the Manchester area; this could be to do with the seas surrounding the UK getting to their warmest.

This is only a hypothesis but I have a suspicion that in some areas of the south-west, May ends up the most thundery month on average because of the weaker Atlantic prior to the "June return of the westerlies", resulting in a relatively high frequency of easterly winds.  Easterlies tend to bring low cloud into eastern areas and warm sunshine and the possibility of thunder to western areas, and imports from the continent also tend to be directed towards the south-west. 

Later in the season the majority of thunderstorms come from Spanish plumes and from shallow low pressure systems with a predominantly westerly flow, and both of those setups tend to favour central and eastern parts of England over the south-west due to the tendency for storms to generate over the land mass or head across the English Channel from the continent.

[Supacell]

I tend to find spring isn't that good here. May does bring some storms but there are usually more June/July around these parts. Whilst chasing I have witnessed storms in every month from April to October but have never seen a storm in March.

[cheeky_monkey]

Mid June to beginning of August ..90% of summer rain comes in the form of thunderstorms here

[Thundery wintry showers]

I saw a thunderstorm in Lancaster on the 1st March 2003, from a cyclonic south-westerly setup.  It was one of those where the showers banded together over the Irish Sea and sferics started popping up as they passed over the land mass.  The storms penetrated into parts of north-east England also.

Manchester had 4 days with thunder during March 1995, probably due to the high frequency of cold polar maritime airmasses that came in from the west that month, passing over the relatively warm Irish Sea.

In the Vale of York I saw a weak thunderstorm with some quite impressive hail on 23 March 2014 from a slack north-westerly, and later in that month the Tyne and Wear area had thunder and hail from an easterly; it was one of those paradoxical setups where there wasn't much of a contrast between the 850hPa temperature and the North Sea temperature, but a strong upper cold pool was enough to set off deep instability over the North Sea.

I recall the London area having homegrown thunderstorms from a westerly on one day in February this year.  It's not very common but it would seem that particularly towards the south-east, February's weak sun combined with upper cold pools can generate sufficient instability on rare occasions.

Edited March 2, 2017 by Thundery wintry showers

[Weather-history]

Mid to late summer but this decade has been really poor for thunder.

[MP-R]

2 hours ago, Thundery wintry showers said:

I think in Tyneside it is roughly evenly split between June, July and August with May very close behind (~1.5 thunder-days per month).  I recall reading in a couple of Philip Eden's articles that some parts of the country have a maximum in August, including the Manchester area; this could be to do with the seas surrounding the UK getting to their warmest.

This is only a hypothesis but I have a suspicion that in some areas of the south-west, May ends up the most thundery month on average because of the weaker Atlantic prior to the "June return of the westerlies", resulting in a relatively high frequency of easterly winds.  Easterlies tend to bring low cloud into eastern areas and warm sunshine and the possibility of thunder to western areas, and imports from the continent also tend to be directed towards the south-west. 

Later in the season the majority of thunderstorms come from Spanish plumes and from shallow low pressure systems with a predominantly westerly flow, and both of those setups tend to favour central and eastern parts of England over the south-west due to the tendency for storms to generate over the land mass or head across the English Channel from the continent.

I also think it's the declining frequency in easterlies that contributes to this. June is often too anticyclonic for frequent thundery weather here in recent years. no coincidence that the most unsettled June end up being the thundery ones here. 

I've noticed that certain periods in the year repeat in close'ish' clusters. E.g. late June / early July 2001, late June 2003, late June / early July 2005 and early July 2006 were thundery via plume scenarios. Another example would be mid August e.g. 2001, 2002, 2004, 2006, 2012 and 2014, nearly all of which followed warm or hot spells.

By September, with the seas at their warmest, and it still fairly warm, there are so many options on the table there is no particular pattern to link thundery weather to. In 2004 it was from a cyclonic SWerly, 2005 a plume, 2006 a cyclonic southerly, 2008 a strong westerly, 2010 a cyclonic SWerly etc.

February is the least thundery month here. Between 2007 and 2016 there was no instance of thunder in February at my location.

[lassie23]

June here recently

[Dami]

21 minutes ago, lassie23 said:

June here recently

yes June. We had 3 storms last year. 

[B87]

Between April and September. 

[Summer of 95]

May, June, July, August all seem roughly equal. 

The classic thunderstorm setup here of times gone by would involve an active cold front coming usually from the NW (sometimes W or N) hitting hot air that has been entrenched for days, and it goes bang. The memorable storms of July 1995 and June 2005 came from this, there were also fine examples in May and June 1992.

It never happens anymore, that setup. The hot air can't establish itself as securely and the fronts just blast through it in a wave of rain, wind and 17C temps, with no bangs. It's also noticeable how what I see as the winter equivalent (fronts engaging cold anticyclonic air, giving snow) doesn't happen these days either: it just rains and rains, even if it hits subzero air. The dates of the last "classic" thunderstorm and last "classic" battleground snow from the W are not far apart: June 2005 and March 2006. Something definitely happened in late 2006/early 2007.....

[stainesbloke]

1 hour ago, Summer of 95 said:

May, June, July, August all seem roughly equal. 

The classic thunderstorm setup here of times gone by would involve an active cold front coming usually from the NW (sometimes W or N) hitting hot air that has been entrenched for days, and it goes bang. The memorable storms of July 1995 and June 2005 came from this, there were also fine examples in May and June 1992.

It never happens anymore, that setup. The hot air can't establish itself as securely and the fronts just blast through it in a wave of rain, wind and 17C temps, with no bangs. It's also noticeable how what I see as the winter equivalent (fronts engaging cold anticyclonic air, giving snow) doesn't happen these days either: it just rains and rains, even if it hits subzero air. The dates of the last "classic" thunderstorm and last "classic" battleground snow from the W are not far apart: June 2005 and March 2006. Something definitely happened in late 2006/early 2007.....

Agree, something changed post 2006 big time where thunderstorms are concerned, including here in the SE. 

April-September would generally see most storms here, though thundery showers would occur at least several times over the winter months too. The best warmer month storms would usually occur after a good few days of warmth and when a cold front would gradually move in from the SW or W. 

 

[Weather-history]

There were some pretty decent thunderstorms during May in the 1990s: eg 1992, 1997 and 1999, little surprise that 2 of those 3 were warm Mays. May 1997 was particularly thundery but since 2000, thunder during May feels though it has markedly dropped off. They seem to be systems coming up from the SSW as well such as the storm that hit here during late May 1995 and a storm causing a fatal air crash that same day in Yorkshire where 12 people were killed. It was the day Harold Wilson died.

Not sure what is was with the 1990s but it did feel a thundery decade. 

 

Edited March 3, 2017 by Weather-history

[Terminal Moraine]

June just edges it as the most thundery month of the year here, with an average of 2.6 days with thunder heard, but there's not much difference between June, July and August with the latter two having an average of 2.4 and 2.3 days respectively.

The most thundery day of the year, over the last 40 years, is August 23rd with thunder heard on 9 occasions. This is followed by July 6th, July 31st and August 3rd with 7 occasions and then May 10th, June 2nd, 3rd and 30th and July 2nd with 6 each.

[MP-R]

On 3/3/2017 at 15:09, Weather-history said:

There were some pretty decent thunderstorms during May in the 1990s: eg 1992, 1997 and 1999, little surprise that 2 of those 3 were warm Mays. May 1997 was particularly thundery but since 2000, thunder during May feels though it has markedly dropped off. They seem to be systems coming up from the SSW as well such as the storm that hit here during late May 1995 and a storm causing a fatal air crash that same day in Yorkshire where 12 people were killed. It was the day Harold Wilson died.

Not sure what is was with the 1990s but it did feel a thundery decade. 

 

Interesting to hear. How thundery was May during the 80s? I think the thundery nature of the 90s was what triggered my interest in the weather as I was growing up then. The thunderstorms of May 1999 are etched in my memory - two absolute belters on the 27th and 29th.

I've certainly noticed the drop in thundery occurrences in April however, and an overall decline in the typical sunshine and showers days.

[cheese]

May-September. 

[MP-R]

9 minutes ago, cheese said:

May-September. 

I'm assuming all of those months are very thundery in your area then cheese?

[Mapantz]

The most thundery time, here, that I can remember in recent times, was December 2013 and January 2014. It was showers following on from the constant flow of low pressure systems. I remember having 5 or 6 consecutive days of thunder in January. I have found that the Winter months have given more chances of thunder than the Summer (apart from last year)

[cheese]

4 hours ago, MP-R said:

I'm assuming all of those months are very thundery in your area then cheese?

No month of the year is 'very thundery' in my area. Those months are simply the ones that are most likely to have thunderstorms, in my experience.

Edited March 5, 2017 by cheese

[Nick L]

11 minutes ago, cheese said:

No month of the year is 'very thundery' in my area. Those months are simply the ones that are most likely to have thunderstorms, in my experience.

Yep, I don't think thunderstorms are frequent enough anywhere in this country for there to be a season per se, but as you'd expect they're more common in late spring through to early Autumn. Although I have heard thunder in most months.

[Weather-history]

10 hours ago, MP-R said:

Interesting to hear. How thundery was May during the 80s? I think the thundery nature of the 90s was what triggered my interest in the weather as I was growing up then. The thunderstorms of May 1999 are etched in my memory - two absolute belters on the 27th and 29th.

I've certainly noticed the drop in thundery occurrences in April however, and an overall decline in the typical sunshine and showers days.

Almost as thundery, May 1983 was particularly thundery. I remember a good thunderstorm during May 1989 that lasted a couple of hours, I think it was the 19th May. 

There is a school of thought of a connection between thunder activity and sunspots. 

[Terminal Moraine]

With regard to the decadal averages of days with thunder heard for May to August, here are the stats for my location. The 60s are the average for the 6 years 1964-69 and the 10s are for the 7 years 2010-2016.

              May             June           July        August          Total

60s         4.3               3.5             2.5            3.8             14.1

70s         2.3               2.1             2.3            2.4              9.1

80s         2.9               3.3             2.4            1.5             10.1

90s         2.0               3.1             1.6            2.6              9.3

00s         1.8               1.8             3.2            3.3            10.1

10s         0.5               2.4             2.7            1.6              7.2

Notable points are how thundery the 60s were,  May in particular, and the lack of thunder in the current decade, again May in particular.    

[Despicable Weather]

10 hours ago, Mapantz said:

The most thundery time, here, that I can remember in recent times, was December 2013 and January 2014. It was showers following on from the constant flow of low pressure systems. I remember having 5 or 6 consecutive days of thunder in January. I have found that the Winter months have given more chances of thunder than the Summer (apart from last year)

In total agreement with you there on that *nods*

I figure due to constant sweeping low pressure systems off Greenland hitting the warmer EuroSlug air from mainland is maybe what caused that. I was very surprised at the thundery element so early in January during 2014 and even noted some similar thundery days during Jan 2015. Both summers were a shocking let down with almost nothing but grey crud racing by on a southerly stream after massive storms in northern France.

Oh I have all fingers and toes crossed for a better and delivering season in 2017 but I won't hold my breath 

[MP-R]

10 hours ago, Mapantz said:

The most thundery time, here, that I can remember in recent times, was December 2013 and January 2014. It was showers following on from the constant flow of low pressure systems. I remember having 5 or 6 consecutive days of thunder in January. I have found that the Winter months have given more chances of thunder than the Summer (apart from last year)

What an exceptional period of weather! I remember that first week in January of convective weather. A particularly fierce hailstorm moved through on the 06th or 07th here.

I'm far enough west to benefit at least sometimes from the winter coastal thundery activity but not coastal enough for regular such activity. The wind direction had to be specifically WSW through the Severn Estuary for that.

[cheeky_monkey]

On 3/4/2017 at 14:28, MP-R said:

Interesting to hear. How thundery was May during the 80s? I think the thundery nature of the 90s was what triggered my interest in the weather as I was growing up then. The thunderstorms of May 1999 are etched in my memory - two absolute belters on the 27th and 29th.

I've certainly noticed the drop in thundery occurrences in April however, and an overall decline in the typical sunshine and showers days.

i remember those storms of May 1999 its the only time apart from Snow on Xmas day 2000 that i have filmed a weather event ..due to the fact i purchased my first and only camcorder the week before