Pulses of Heavy, Sub-Tropical Downpours Will Run A Boundary Tonight/Friday Across Ireland & UK (Includes Video!)

Written by on August 16, 2012 in United Kingdom & Ireland with 0 Comments

Photo courtesy of Mark Vogan

The low pressure which deepened to an impressive 980mb yesterday off Ireland brought unusually strong August winds with gales for some. It also brought a brief blast of torrential rain northwards across Britain and Ireland as the front swept through followed by heavy downpours. We continue to hold onto our warm, humid air mass with little cooling thanks to the low continuing to spin and remain deep just west of Ireland, this continues and will continue for many days to feed warm, humid air up from the subtropics. While UK sits underneath a boundary and convergence zone which which seperates the low which should hold a steady pressure of 985 to 990mb over the next 36 hours with an intensifying high to the east, we sit right where these air masses converge.

While we stayed fairly warm and muggy again today with many starting the day around 16C, just like recent morning’s, the cold front yesterday allowed the upper levels to cool slightly and so today was a day of sunshine and showers, of which the showers were heavy and thundery.

The boundary we sit beneath ain’t going nowhere thanks to the strong upper ridge over Europe and so the train of deep subtropical moisture will fire from the Azores to UK as the crow flies, starting tonight and could last into Saturday.

Notice in this latest satellite image captured this afternoon how the low remains deep with still a well defined curl of cloud around the centre. Also note the front and rain band well north of the UK which impacted us yesterday and the thing we should pay close attention to now is the trailing mass of cloud which is loaded with subtropical moisture and will spread across us through tonight and tomorrow (Image courtesy of WeatherOnline)

Over the next 24 to 36 hours, starting tonight, we’re going to see our very own, modified version of the monsoon which you can see in the above satellite image taken this afternoon. Notice the mass of cloud to southwest of Britain, that is loaded and heading our way tonight. It’s going to reinforce the warmth and humidity already in place. For days the models had this plume of deep, rich subtropical moisture flowing from the subtropical Atlantic directly into Ireland and the UK in the form of a series of pulses. Anytime you’ve got moisture and subtropical air in the mix, you know the rains will be torrential and likely to cause flooding.

What to expect tonight and Friday

Tonight shall see the radar light up with torrential, thundery downpours over central and eastern Ireland (worst should stay over Ireland and the Irish Sea) and these will push up into Northern Ireland and across the Irish Sea/North Channel into Lancashire, Cumbria and Southwest Scotland, eventually reaching the Central Belt. Don’t be surprised to see flooding, incredible cloud bursts which could drop a very impressive amount of rain within a very short period of time. These pulses could well be accompanied by thunder and lightning as well as strong and gusty winds. Some funnel clouds aren’t out of the question either.

Some that get under a few of the more intense cells will see a lot of rain and the rate at which is comes down is the concern. It will come in waves, not one solid mass so it’s not a uniform 1-2 inches of rain across a broad area but will be in pockets.

As for temperatures, well under the cloud and downpours, it’s naturally cooler but it’s still going to feel warm and very sticky with highs near 20-21C, yes that’s under the cloud and rain! Remember where the air and moisture is streaming up from!

As for Southeast and East Anglia, perhaps extending up to Yorkshire, temperatures in the sunshine will warm nicely towards 25-28C and humidity will be on the rise over the next 3 days.

Front will sit across the UK this weekend seperating warm from downright hot with London eyeing 88-90F, while Paris aims for 100F

A degree of uncertainty remains over the fast approaching weekend as a front will drape across the UK, seperating the increasingly hot and humid air which will bleed off France starting Saturday, from a warm but more comfortable air mass to the north. It would appear that from Manchester north, it could be a somewhat mild to warm weekend with a chance of some showers while south of Manchester and especially from Birmingham down to London, the sun will shine strong, southwest winds will blow and heights are strong enough that we’re going to take a run at the UK’s warmest reading so far this year of 30.7C set at St James Park, London. I am going for a high of 31C in London but this may need altered..

The true heat looks to stay on the other side of the channel where temperatures could well reach 100F (38C) as far north as Paris, perhaps even north of there. I believe records are likely to fall and they could really anywhere from Seville in the South of Spain to as far north as Calais on the North coast of France. We may see some reach new all-time highs with some eastern interior areas of both Spain and France likely to surpass 110F.

Check out this latest ECMWF run issued today. This has looked the same since last weekend!

Weekend warmth will extend into first part of week with turn to cooler and unsettled during second half & next weekend

Looking ahead and into next week, it’s looking nice with high pressure in control and temperatures will remain warm at 26 to 29C in the South all the way out to next Tuesday. The second half of the week will see the trough swing in, slicing heights and low pressure will return.


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