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mildmuck

Understanding Continental Weather

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Just lately I'm very much interested in continental weather and climate, specifically speaking USA/Canada.

I understand a little meteorology but find certain topics really quite difficult.

 

How and why is continental weather more extreme ?  ,… also following on from this rainfall tends to be more severe even in relatively inland states like Nebraska.  A lot of states receive very heavy falls of rain -‘’Rainstorms’’. Even in France when I was on holiday I was surprised at how bad it can get.  

 

Why is this when UK is surrounded by sea?.

 

What are the main causes of this, .. High dew points, Temperature ,humid-instable air? ..Or other factors?  More interestingly regarding precipitation.

 

 

 

Sorry for my bad English, thanks for reading, any feedback much appreciated.

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The reasons being are the long fetch over a big landmass which is powerfully heated by solar energy from the sun in the summer months (diurnal heating/insolation), this happening over France, into Benelux and Germany. That is why they get those huge MCS's in the summer that we always complain about but admire at the same time!! 

The English Channel modification of the really hot and unstable air is to blame for the less intense stuff, although it can occasionally happen that we do get really intense storms, particularly with favoured upper airflow SSE-NW or S-N and not SW-NE (as that gives a Kent clipper scenario at best), high SST's and a surface wind within the range of ESE to SSW to bring the really juicy humid air off the continent. This is the best route for the most unstable air possible for the UK and happened more often in the 90's era! Although the last 2 years have seen a comeback of some kind fortunately! 

 

The most common place for thunderstorms in the UK being Lincolnshire happens the same way, with a predominant SW flow providing a large heated landmass for air to travel across and become most unstable when it hits the flat lands of Lincs and East Anglia. 

 

As you say, higher Dew points and temperatures fuel the extremities of the storms, with other factors such as cloud top temperatures (the colder, the more extreme), steep lapse rates and PWAT values etc. 

 

Being surrounded by cooler waters here in the UK, it makes it very rare to see anything like what the USA gets and even the likes of France and Germany.

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The reasons being are the long fetch over a big landmass which is powerfully heated by solar energy from the sun in the summer months (diurnal heating/insolation), this happening over France, into Benelux and Germany. That is why they get those huge MCS's in the summer that we always complain about but admire at the same time!! 

The English Channel modification of the really hot and unstable air is to blame for the less intense stuff, although it can occasionally happen that we do get really intense storms, particularly with favoured upper airflow SSE-NW or S-N and not SW-NE (as that gives a Kent clipper scenario at best), high SST's and a surface wind within the range of ESE to SSW to bring the really juicy humid air off the continent. This is the best route for the most unstable air possible for the UK and happened more often in the 90's era! Although the last 2 years have seen a comeback of some kind fortunately! 

 

The most common place for thunderstorms in the UK being Lincolnshire happens the same way, with a predominant SW flow providing a large heated landmass for air to travel across and become most unstable when it hits the flat lands of Lincs and East Anglia. 

 

As you say, higher Dew points and temperatures fuel the extremities of the storms, with other factors such as cloud top temperatures (the colder, the more extreme) and PWAT values etc. 

 

Being surrounded by cooler waters here in the UK, it makes it very rare to see anything like what the USA gets and even the likes of France and Germany.

 

Interesting ... a great insight. Many thanks  :)

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Interesting ... a great insight. Many thanks  :)

You're welcome my friend. I'm still a rookie compared to some senior forecasters on here  :rofl:

 

People such as Nick L and Nick F, Steve Murr, TEITS (Dave) on here could go much deeper into this I'm sure. 

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Can't argue with any of that! As has been said it's down to the landmass. Land has a lower specific heat capacity than the sea, meaning that it cools down/heats up much quicker. The plains of the US are also a battleground for several different airmasses: polar air to the north, hot and dry desert air to the west and warm and moist air to the south, all of which contribute to the massive storms you see over there.

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One thing I can't help noticing when I look at European compared to British weather: Just why is the North Sea such a prolific cloud-making machine? We can get clearances coming off the Atlantic or over the Channel, or down from the Arctic, but everything off the North Sea is cloudy. Look at satellite pics when a large anticyclone sits over northern Europe and everywhere is clear, except England and eastern Scotland. The Baltic doesn't seem to have the same effect; you don't see masses or low cloud over eastern Sweden and Denmark in these setups. Yet it's colder than the North Sea, especially in spring and early summer, so would be expected to produce even more cloud when it meets warm airmasses. Compare Stockholm's sunshine totals with Aberdeen's and you see just how bad the North Sea can be for our climate. When we get plagued by its muck (that's another thing, why does it get 100 miles inland) I often wish the land bridge still existed...

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One thing I can't help noticing when I look at European compared to British weather: Just why is the North Sea such a prolific cloud-making machine? We can get clearances coming off the Atlantic or over the Channel, or down from the Arctic, but everything off the North Sea is cloudy. Look at satellite pics when a large anticyclone sits over northern Europe and everywhere is clear, except England and eastern Scotland. The Baltic doesn't seem to have the same effect; you don't see masses or low cloud over eastern Sweden and Denmark in these setups. Yet it's colder than the North Sea, especially in spring and early summer, so would be expected to produce even more cloud when it meets warm airmasses. Compare Stockholm's sunshine totals with Aberdeen's and you see just how bad the North Sea can be for our climate. When we get plagued by its muck (that's another thing, why does it get 100 miles inland) I often wish the land bridge still existed...

 

Your reasoning is the wrong way around here.

 

If it's colder at the surface than above, it will be more stable. The North Sea is a relatively warm body of water during cold spells, and as a result of this lapse rate it creates an unstable layer and helps form a layer of stratocumulus. If we are under high pressure with a temperature inversion aloft, this unstable layer will be shallow, and the stratocumulus will be heavily "capped" by the inversion above. Thus the cloud becomes stubborn and won't move much until the synoptic pattern shifts.

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Tis true on the Canadian prairies and the northern part of the states especially in early summer the land warms very quickly where as high aloft the air is relatively cool/cold due the artic still being ice bound..therefore as the heated air rise it collides with the cold air aloft causing huge storms..this is particularly true when the jet runs straight across the 50 degree parallel..sometimes the jet can get stuck and 'wobble' across the Prairies which causes a prolonged spell of Thunderstorms and tornadoes as happened in June and July 2010..when there were severe storms almost daily where I lived in Edmonton. In the UK we rarely get these huge clashes of air types because of the effect of the ocean...same is true of Vancouver they do not suffer from big storms or huge snow events because of the proximity of the Pacific.

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