Nick F

Spain and Portugal still in the grip of a heatwave this week after 44.5C was reached in Cordoba on Sunday. More moderate heat elsewhere in southern Europe, but northern Europe including the UK at mercy of cool Atlantic flow. View the full blog here

Storm & Convective Forecast Issued 2016-07-01 08:59:18 Valid: 01/06/2016 06z to 02/06/2016 06z CONVECTIVE / STORM FORECAST - FRI 1ST-JULY-2016 Synopsis Unseasonably deep upper low moves in across NW Britain on Friday, with a deeply cyclonic southwesterly flow across the UK. Surface low will move slowly NE to the NW of Scotland, cold front clearing SE England in the morning will be followed by a cool and showery maritime flow, with surface heating allowing a few thunderstorms to develop. … EIRE, N. IRELAND, SCOTLAND, N WALES, N ENGLAND, N MIDLANDS … Cold pool associated with upper low moving in across the NW will steepen lapse rates across the above areas through the day … which with surface heating of moist maritime flow will contribute to around 300-600 j/kg CAPE this afternoon. As a result, heavy showers already across EIRE/N. Ireland and western Scotland will become more widespread across the above areas through the day, with increase in surface heating leading to the development of scattered thunderstorms. Deep layer shear will be weak across Scotland and Ireland … so storms will struggle to organise. Better overlap of stronger shear (40-50 knots) near jet stream across the south and instability will exist across N Wales, N England and N Midlands – where storms may potentially organise to bring a risk of localised flooding, hail to marble-size and strong wind gusts. Generally, organised storm risk looks below severe probabilities, given cool temperatures / modest instability. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-07-01 08:59:18 Valid: 01/06/2016 06z to 02/06/2016 06z CONVECTIVE / STORM FORECAST - FRI 1ST-JULY-2016 Click here for the full forecastCheck the full storm forecast here

Not posted in here for a while, as been lurking in the convective threads given the thunderiest June I can remember in my 40 years. But, my goodness, whatever happened to high pressure blocks in high summer that used to bring a week or a few weeks of fine settled weather? OK, I don't expect them every summer, but can't remember the last time we experienced them, recent summers seems to be dominated by cyclonic westerlies. The 00z extended EPS H500 mean showed a trough over the UK throughout to day 15, the current 12z GEFS H500 mean through to day 15 does, so expect the 12z EPS will do too. The weather is certainly reflecting the political mood of the country for now! But with 2 months of summer left and September, if you except the shorter days, plenty of time yet I guess...

Quite a potent storm about 5 miles away about 1/2 hour ago over SE London with a lot of fast rising motion in the updraft area and was spitting out fairly frequent CGs

Occasional rumbles from a cell east of here over SE London, new cell going up overhead. Just returned back from Brighton where there were some angry skies late morning as a storm followed the coast.

My storm forecast for Saturday Storm & Convective Forecast Issued 2016-06-24 21:56:32 Valid: 25/06/2016 06z to 26/06/2016 06z CONVECTIVE / STORM FORECAST - SAT 25TH-JUNE-2016 Synopsis Upper trough axis toward the western side of UK on Friday continues to shift further east on Saturday, with slow-moving surface low pressure centred near the east coast, which will focus greatest instability for showers/storm production further east. ... SCOTLAND, N ENGLAND, MIDLANDS, E ANGLIA, CENTRAL S and SE ENGLAND ... Trough of cold air aloft shifting slowly east atop of moist maritime surface flow warmed by sunny spells will create steep lapse rates and yield 300-900 j/kg CAPE per GFS and ECMWF. As a result ... heavy showers and thunderstorms will readily develop across the above areas after a dry start in many places. A few convergence zones are indicated by models, one from western Scotland southeast across Pennines of England and toward E Anglia ... perhaps another W-E zone across SE England. These zones will tend to focus and allow training of thunderstorms which will bring the threat of locally high spot rainfall totals and localised flooding risk given slow-movement of storms. Also storms may produce hail, frequent lightning and gusty winds. Weak winds aloft and convergence will create ideal conditions for funnel clouds or even isolated brief/weak tornadoes with stronger updrafts. These diurnally driven storms will tend to die out after dark. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-06-24 21:56:32 Valid: 25/06/2016 06z to 26/06/2016 06z CONVECTIVE / STORM FORECAST - SAT 25TH-JUNE-2016 Click here for the full forecastCheck the full storm forecast here

Storm & Convective Forecast Issued 2016-06-24 08:42:35 Valid: 24/06/2016 06z to 25/06/2016 06z CONVECTIVE / STORM FORECAST - FRI 24TH-JUNE-2016 Synopsis Upper trough/low moves eastward above the UK and Ireland on Friday, with a shallow surface low drifting E/SE across Scotland. A slack and unstable SWly or Wly flow covers much of the UK. ... NORTHERN, CENTRAL AND WESTERN UK + EIRE ... Upper low and associated cold mid-level tempeatures will create steep lapse rates across the above areas as it edges east. As a result, strong sunshine creating surface heating of fairly moist maritime flow will yield CAPE values of 300-700 j/kg quite widely over land. So diurnally-driven scattered heavy showers and thunderstorms will develop late morning and through the afternoon. 0-6km wind shear will be weak across northern and western areas and with light winds aloft, storms will be slow-moving across Scotland and EIRE/N. Ireland - bringing a localised risk of large spot rainfall totals in a short space of time leading to localised flooding. Storms here may also be accompanied by hail and gusty winds. Surface breeze convergence over Scotland near centre of low drifting SE combined with light winds and low cloud bases will create conditions favourable for funnel clouds or even brief/weak tornadoes too. Wind shear across E Wales, N England and Midlands will be somewhat stronger, 30-40knts, thanks to being on the edge of strong SWly jet aloft. So some organisation of storms into clusters is possible, bringing a localised risk of torrential rain leading to flash flooding, strong wind gusts, frequent lightning and perhaps isolated marginally large hail. Have issued a MARGINAL risk for these areas. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-06-24 08:42:35 Valid: 24/06/2016 06z to 25/06/2016 06z CONVECTIVE / STORM FORECAST - FRI 24TH-JUNE-2016 Click here for the full forecastCheck the full storm forecast here

I think that's it it I'm afraid, may get the odd heavy shower, but generally the atmosphere is stabilising behind the storms clearing E Anglia. Some violent storms over northern France, Belgium and southern Holland yet again this evening. Been a disappointing day with no thunder here other than in the early hours of this morning ... that's the problem with SWly flows it seems, to much cloud cover streaming off the Atlantic to allow surface storms to fire with any vigour ... If the flow was being sourced from the south off the large continental landmass of France rather than Atlantic, I'm sure we would have seen skies clear more readily but still with the moisture and instability. Much of the near continent has seen clearer skies today away from NW France ... hence the severe storms developing in the humid plume present.

Drizzle has cleared with cloud thinning, brightness and even hints of sun in south London, worth keeping any eye over northern Home Counties, appear to be some convective returns developing on recent radar scans over Herts. Thundery rain pushing NE out of France appears to have weakening lightning wise on northern extent.

Severe drizzle here in south London

Yep, those storms sliding out of Brittany maybe the saviour later, as the cloud is looking too stubborn to allow any surface-based storms, for now. Storms over NW France should head toward and make landfall over Hants and W Sussex on current loop trajectories.

Storm & Convective Forecast Issued 2016-06-23 09:54:51 Valid: 23/06/2016 06z to 24/06/2016 06z DAY 1 CONVECTIVE / STORM FORECAST - THURS 23-JUNE-2016 Synopsis Upper trough moving over EIRE today and extending south into western Iberia will drive a strong WAA regime across western Europe, band of storms have propagated NE overnight along the western periphery of a warm/moist plume from N Spain across NW France, SE UK and on into the Low Countries. The storms have developed where upper trough engages the plume's edge. Overnight storms have now cleared SE UK, but will re-develop this afternoon across SE England and E Anglia and may also be joined by further storms moving NE from the Bay of Biscay. Storms should clear out into the N Sea by early hours of Friday, as cold front clears east and introduces fresher conditions. ... SE UK ... UKMO fax charts indicate slow-moving waving cold front will lie SW-NE from Weymouth to The Wash midday Thursday, ahead of this front – a warm/humid airmass characterised by dew points of 16-19C / PWAT values of 1.2/ - 1.6 inches. Overnight thunderstorms that have cleared SE England and E Anglia have left a legacy of low cloud cover … but eventual cloud breaks will allow instability to rebuild as surface heating of humid airmass increases beneath steep mid-level lapse rates. GFS indicates 500-1000 j/kg CAPE across the above areas in the afternoon/early evening. Thunderstorms are indicated to redevelop as surface heating combines with approaching upper trough and surface convergence ahead of cold front to create forced ascent of humid airmass. Storms will form in an environment of veering and strengthening flow aloft that will be characterised by 40-50 knots of deep layer shear, so storms will likely organise quickly … initially a few supercells or bowing line segments are possible … though unidirectional winds aloft will tend to line out storms. Nonetheless, all severe weather hazards are possible from storms … mainly the risk of isolated large hail (2-3cm diameter), damaging wind gusts, flash-flooding, frequent lightning and perhaps even a brief tornado where winds back SEly and increase SREH (Storm relative helicity). Further storms, mainly elevated, downwind across the Bay of Biscay and NW France this morning may move NE across the far SE later too, brinigng a risk of flash-flooding, strong wind gusts, hail and frequent cloud-to-ground lightning. Given uncertainty of how widespread storm development will be have issued a SLIGHT risk of severe weather for now, though may upgrade to MDT in later updates if organised severe storms become widespread. … EIRE/N. IRELAND and SCOTLAND … Atlantic upper trough axis moves in across Ireland and W Scotland on Thursday, associated cold mid-level temperatures will create steep lapse rates atop moist maritime surface airmass, with surface heating creating 200-500 j/kg CAPE in the afternoon – so scattered heavy showers and a few thunderstorms look likely to develop across the above areas. A few organised storms can’t be ruled out … producing a risk of hail, flash flooding and gusty winds locally … though modest instability and shear will limit severe risk. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-06-23 09:54:51 Valid: 23/06/2016 06z to 24/06/2016 06z DAY 1 CONVECTIVE / STORM FORECAST - THURS 23-JUNE-2016 Click here for the full forecastCheck the full storm forecast here

storm incoming here in south London, some very close CGs with gun shot thunder to frighten people out their sleep!

Storms now eased away here in south London, was a little disappointing for lightning intensity as it came over, no really close cgs like a few weeks back when storms came up from the south during the day/ Shouldn't complain, as many will see nada tonight away from the SE.

Storm arriving here in south London now, some close CGs to the south and heavy rain starting, seems to be interrupting Sky TV too ...

Beginning to see lightning flickering to the south of here near Croydon, gonna be a long night me thinks

Airmass imagery clearly shows storms firing all the way from northern Spain NE to Belgium along the western edge of the high theta-e plume cloud tops from these storms reaching 200mb! second wave of storms south of Hants and Dorset seem to be expanding in coverage, could be an MCS forming ...

Very active storms electrically between Dover and Calais and further NE across northern Belgium and out across the southern N Sea ... Would love to be on a cross channel ferry right now!

Newhaven between Brighton and Eastbourne has two decent cameras looking out to sea, seen a few flashes out at sea: https://www.newhavenwebcams.co.uk/

Trajectory of current storms would still take them mainly east of IoW in my opinion with NEly steering flow ... though depends on whether new cells can erupt father NW. Thunder being reported in Guernsey now.

12z HIRLAM indicates perhaps 2 waves of storms. 1 late evening then another from 5/6am across the far SE ... 21z and 00z 03z and 06z Thurs