Nick F

Yep, that's where the diurnal home-grown threat looks to develop both Saturday and Sunday. Monday perhaps seeing storms developing further east through M4 corridor during the day, plus some imports into the SE. Mixture of breeze / moisture convergence, surface heating and orographic lift the main mechanism for storm initiation, not a great deal of forcing aloft showing, with the main low displaced over Biscay. Risk of isolated elevated storms flaring-up from time to time over the coming days too away from these areas, more particularly overnight and mornings as isentropic lift of the warm and moist conveyor aloft, a few weak disturbances running north, while upper levels cool nocturnally creates mid-level instability. Some elevated storms possible for western E Channel, SW England, Wales and eventually parts of EIRE Friday night into Saturday morning. Perhaps isolated risk of elevated storms erupting further east across southern areas Saturday and Sunday nights and early mornings, some if it imported - but looks a low risk atm.

Quite dry air / low dew points across the SE this evening. At 6pm, for example, despite Southend airport seeing 16C, the dew point was -5C, giving a humidity of just 25% http://www.weatheronline.co.uk/weather/maps/current?LANG=en&UP=0&R=310&TYP=taupunkt&ART=tabelle&LANG=en&DATE=1462381200&KEY=UK&LAND=UK&CONT=euro&SORT=3&SI=mph&CEL=C&UD=1

Friday sees an area of low pressure push north from the Bay of Biscay toward Ireland by Saturday, with it a plume of moisture spreading north from Iberia and spreading across EIRE and western Britain - so could be some thundery showers / elevated storms in the west and EIRE later on Friday. More uncertainty for the weekend, but it looks as if thundery showers or home-grown thunderstorms forming over SW England, Wales, NW England and Ireland on Saturday afternoon once overnight showers clear, storms that develop further east more isolated, with most staying dry, sunny and warm with temps reaching low to mid 20s. Then Sunday, showers and storms developing more widely during the day across England and Wales, as moisture advection from the south increases further east. 12z EC develops 300 - 800 j/kg CAPE on Sunday widely over E & W, helped by temps hitting 25C and also far north of France from where some storms may develop and cross into SE England. Long way off though and subject to change. Not a great deal of mid-upper forcing or strength in upper flow indicated apart from Friday evening / night in the west, so severe potential looks low for now, but surface wind convergence could be a big player in triggering storms, given slack pressure pattern over the weekend, which would still produce some lively storms.

After a late reminder of winter over the past week, this blog looks at the prospects of early summer temperatures by the end of next week, with temperatures hopefully reaching reach 20C in the south. View the full blog here

Convergence indicated by models towards east coast of England today, so could be some funnel reports today under showers or storms that form here. Eastern England the focus for storms, with a residual cold pool aloft here from the upper trough exiting east. Storm & Convective Forecast Issued 2016-04-30 08:51:44 Valid: 30/04/2016 0600z to 31/04/2016 0600z CONVECTIVE FORECAST - SATURDAY 30TH APRIL 2016 Synopsis Upper trough begins to slide away east from Britain on Saturday, with a ridge beginning to build in from Atlantic across SW Britain and Ireland. A residual cold pool from the upper trough to the east across SE Britain will bring another day of heavy showers and a few thunderstorms to eastern England today. ... EAST and SE ENGLAND ... Upper cold pool across SE Britain will create steep lapse rates here (30-32C between 850-500mb) and will generate a few 100 j/kg CAPE with surface heating late morning and through the afternoon. As a result, heavy showers and some thunderstorms will develop in the above areas, accompanied by hail. Cells will be slow-moving given light steering winds, so heavy rain from these cells may lead to localised flooding. Breeze convergence is indicated by models to develop towards the east coast or just inland from the coast, so storms maybe be focused along these zones. As is typical of convergence zones, stronger updrafts into storms may rotate to form funnel clouds or even isolated brief/weak tornadoes/waterspouts. Storms should quickly fade after dark.

UK Severe Convective & Storm Forecast - Issued 2016-04-30 08:51:44 Valid: 30/04/2016 0600z to 31/04/2016 0600z CONVECTIVE FORECAST - SATURDAY 30TH APRIL 2016 Click here for the full forecastCheck the full storm forecast here

This cycling HP beast SW of the metro is riding the warm front as it moves north over Oklahoma, lots of moisture streaming in from the south and backed surface SEly winds, but warm front tornadic storms often tend to be messy with rain wrapped tornadoes. I-35 traffic near Norman to OK City Metro grinding to a halt ahead of this storm to the SW, wouldn't like to be stuck on that interstate!

Very strong couplet

Yep, been following the KFOR live feed for last hour, with a very animated Reed Timmer updating right under the hook in his Dominator on the I-44, keeps cycling, but been reports of a rain wrapped tornado in this HP beast. Norman and OK City in firing line. http://kfor.com/on-air/live-streaming/ Severe studios is probably best bet with a few chasers on it: http://www.severestudios.com/live-storm-chasing-map/ Jeff Piotrowski right in the thick of it too: https://www.periscope.tv/w/1nAKEweYzayJL

Storm & Convective Forecast Issued 2016-04-29 08:39:15 Valid: 29/04/2016 0600z to 30/04/2016 0600z CONVECTIVE FORECAST - FRIDAY 29TH APRIL 2016 Synopsis Surface low will drift slowly away from NE England across the North Sea today beneath slow-moving upper low. Wrap around occlusion will bring further sleet or snow to SE Scotland & NE England, while upper cold pool associated with upper low pushes southward across, Ireland, England and Wales ... spreading bands of showers/scattered thunderstorms south during the day. ... N. IRELAND, EIRE, WALES, ENGLAND and SCOTLAND ... Pool of unseasonably cold and dry mid-upper air is evident as a dark stripe pushing south on WV imagery ... this is steepening lapse rates and destabilising the atmosphere and will bring bands of heavy showers, some with hail and thunder, southward across the above areas through the day. Isolated lightning has already been evident across NW England, Wales and NE Scotland so far this morning, thunderstorms will develop more widely / become more numerous through the day as surface heating beneath steep lapse rates creates strong convection - higher cloud tops for charge separation to occur. Vertical shear will be too weak and surface airmass too cold and dry for any severe weather today. Heavier showers and thunderstorms maybe accompanied by hail and gusty winds.

UK Severe Convective & Storm Forecast - Issued 2016-04-29 08:39:15 Valid: 29/04/2016 0600z to 30/04/2016 0600z CONVECTIVE FORECAST - FRIDAY 29TH APRIL 2016 Click here for the full forecastCheck the full storm forecast here

Upgrade to Enhanced Risk for later today: http://www.spc.noaa.gov/products/outlook/day1otlk.html Quite a complicated picture, overnight/morning convection needs to clear sharpish to allow atmosphere to recover, plus profles look weakily capped - so could be a lot of storms popping up and competing with each other, which tends to lessen tornado potential. Warm front moving north over Oklahoma or triple point over W/NW Oklahoma could be best place for backed surface winds and thus tornado potential. Dryline option too, though would be concerned that cold front could overtake it too quickly to allow storms to stay discrete long enough before they line out

Thought I would start a thread for Friday's severe risk across Texas, Oklahoma and perhaps Kansas - which could easily produce more tornadoes than Tuesday's bust. A negatively-tilted upper low at 500mb swings in across the southern Rockies, a strong 500mb 70knt+ jet rounds the base of the trough and enters NW TX and Wern OK atop of a warm sector spreading north across Texas and Oklahoma to east of dryline across Wern TX, with 70F DPs reaching as far north as southern OK by 00z Sat (18z CDT) and mid 60s across the rest of Oklahoma. A surface low moves east across the TX Pahandle while warm front lifts north across OK to the east, GFS develops around 2500-3000 j/kg CAPE along I-40 west of OK City and I-35 corridor south of OK City in the warm sector. Sfc winds backed the most along I-40 at 18z CDT, near the parallel warm front - so west of OK City toward the TX Panhandle could be decent initial target IMO. However, reality may not be as straight forward as the models suggest. Firstly, isentropic lift of warm moist southerly conveyor north of warm front is forecast to produce widespread elevated storms/convection overnight, so the detritus from this may hamper recovery of the atmosphere and hinder development on Friday. And although overnight crapvection should clear northeast from Wern OK and NW TX, the warm sector looks weakly capped, so potential that storms will develop too readily/widespread near the dryline and interact too much with each other to allow tornadoes to form. Also, the cold front could catch up the dryline too quickly to allow storms to stay discrete. But, if storms can stay discrete, they will be well-vented by the strong upper winds to stop them turning HP quickly and the Hodographs look quite favourable for tornadoes too, OK City for example.

Such a shame and frustrating too as the chase season is getting into full swing when they decide to pull the plug. Can't think of many alternatives with so many chasers streaming live, severe studios is ok if you use a laptop/desktop but the streams may not run on tablets or phones given the software they use. ChaserTV - not many seem to use as a platform. Will have a look around to what others there are, certainly plenty of streams on different platforms, but not lots on one like TVN.

Had a few rumbles of thunder here in south London in the last hour, nothing overhead though.

The shear profiles really didn't help yesterday's cause, good explanation of why the high probabilities for tornadoes issued by SPC in their PDS warning didn't materialise I read here: https://www.facebook.com/TornadoTitans/?ref=stream Friday's risk over the southern Plains worth keeping tabs on, may turn out a better day for chasers than yesterday's hyperbole for tornado potential. Oklahoma looks prime spot looking NAM parameters.

Another day of good convective skyscapes, with heavy showers throwing a wintry mix of rain. soft hail, sleet and snow accompanied by the flash and bang. Storms probably more concentrated towards the east today - where lapse rates are forecast to be steepest. Storm & Convective Forecast Issued 2016-04-27 09:03:35 Valid: 27/04/2016 0600z to 28/04/2016 0600z DAY 1 CONVECTIVE FORECAST - WEDNESDAY 27TH APRIL 2016 Synopsis Large upper low overspreads northern Europe, with a slow-moving surface low centred over Denmark, an unseasonably cold and unstable N to NWly flow covers the UK and Ireland. ... EASTERN SCOTLAND, CENTRAL, SOUTHERN AND EASTERN ENGLAND ... The coldest mid-upper level temperatures associated with upper low will be across eastern UK and North Sea - so here will see the steepest lapse rates (30-32C between 850-500hPa) and strongest instability developing with surface heating in sunshine. So like Tuesday, showers from the word go this morning across northern and western areas exposed to the NWly flow, then as surface heating increases in the sunny spells, showers becoming widespread inland, bringing a mix of rain, sleet, hail/soft hail and hill snow. Cloud tops gaining sufficient height for scattered thunderstorms to develop too in the above areas - where aforementioned lapse rates / CAPE will be highest. Given weak vertical shear, lack of surface warmth/moisture and high cloud bases, no severe weather is forecast. Any storms will quickly fade after nightfall.

UK Severe Convective & Storm Forecast - Issued 2016-04-27 09:03:35 Valid: 27/04/2016 0600z to 28/04/2016 0600z DAY 1 CONVECTIVE FORECAST - WEDNESDAY 27TH APRIL 2016 Click here for the full forecastCheck the full storm forecast here

Should be some good photogenic convective skies in the cold and clear arctic air today, have issued a convective / storm forecast - as lapse rates have become rather steep today, so some thunder is possible in the showers. Storm & Convective Forecast Issued 2016-04-26 09:50:19 Valid: 26/04/2016 0600z to 27/04/2016 0600z DAY 1 CONVECTIVE FORECAST - TUESDAY 26TH APRIL 2016 Synopsis Highly amplified upper flow persists over the Atlantic and Europe with deep upper trough extending south from the arctic across northern Europe and an upper ridge extending north over the Atlantic and across Greenland. Surface low will remain slow-moving today to the east of the UK, centred near Denmark / Nern Germany, with a strong, unseasonably cold flow across the UK - unstable to surface heating leading to showers and scattered weak thunderstorms. ... ENGLAND, WALES and SCOTLAND ... Upper trough extending down North Sea and eastern UK, with unseasonably cold mid-level temperatures (below -35C at 500mb), will create very steep lapse rates between the surface and mid-levels. Heavy showers, wintry in the north, are already ongoing across coastal areas exposed to the northerly wind ... strong late April sunshine warming the ground will allow more widespread convection/showers develop inland too as the day wears on. GFS indicates a few 100 j/kg CAPE, so some well scattered weak thunderstorms will develop amongst the showers almost anywhere across mainland UK, particularly inland where surface heating is maximised. Dry surface flow will mean showers/storms will be high-based, which combined with weak vertical shear and lack of warmth/moisture will mean there is no risk of severe weather. However, showers/storms will be accompanied by hail and gusty winds locally. Forecast online on Netwx website: http://www.netweather.tv/index.cgi?action=convective;sess=

UK Severe Convective & Storm Forecast - Issued 2016-04-26 09:50:19 Valid: 26/04/2016 0600z to 27/04/2016 0600z DAY 1 CONVECTIVE FORECAST - TUESDAY 26TH APRIL 2016 Click here for the full forecastCheck the full storm forecast here

It's looking cold for the London Marathon on Sunday, but will it snow for the first time in its history like some of the media has been suggesting? View the full blog here

Warmest day of the year so far on Thursday, with 20.3C at Porthmadog, Wales. But winter bites back as cold arctic winds sweep south across all parts by the weekend, with the cold lingering through next week. View the full blog here

Some nice breaks and warm sunshine developing here and the Cu con is popping up all over the shop in the moist airmass. Low risk of storms for S England today, but if you catch one could have hail and chance of funnels along southern counties as that low tracks east and creates convergence. Storm & Convective Forecast Issued 2016-04-15 08:38:12 Valid: 15/04/2016 0600z to 16/04/2016 0600z CONVECTIVE FORECAST - FRIDAY 15TH APRIL 2016 Synopsis Broad upper trough extends SW across UK and Ireland, with a cyclonic SWly veering Wly flow across Sern UK, veering Nly further north. An area of low pressure will drift east along southern England on Friday. A cold Nly flow sweeps south across the UK behind the low overnight. ... S ENGLAND and E ANGLIA ... To the south of frontal rainfall spreading slowly north overnight, sunny spells developing across parts of southern England and a moist airmass will allow for some instability to develop in the above areas this morning and afternoon. A few 100 j/kg CAPE forecast and weak capping will allow heavy showers and perhaps a few thunderstorms to develop, though storms will likely be isolated. Vertical shear will be rather weak, so no severe weather is anticipated, though storms will be slow-moving leading to a risk of localised flooding and may also be accompanied by hail locally. Surface convergence along southern counties in vicinity of low pressure moving east may allow funnel clouds and even brief/weak tornadoes to develop with stronger updrafts into storms.

A light S to SWly steering flow over most of England and Wales, though veering Wly over far north of England. Showers and storms likely slow-moving though.

Breeze convergence zone shown on GFS below, likely to be the focus for storms developing across central areas today: Netweather storm forecast for today: Storm & Convective Forecast Issued 2016-04-14 08:47:43 Valid: 14/04/2016 0600z to 15/04/2016 0600z CONVECTIVE FORECAST - THURSDAY 14TH APRIL 2016 Synopsis Broad upper trough extends SW across northern and western Europe, an area of low pressure to the SW moves NE towards SW England by midnight, shallow low pressure centred over the N Sea. A slack, warm, moist and unstable flow covers England and Wales. A cool and stable flow covers Scotland. ... Sern EIRE, WALES, MIDLANDS, Sern N ENGLAND, LINCS, E ANGLIA ... Cold mid-level temperatures and surface heating will create sufficiently steep lapse rates for showers to become increasingly heavy and turn into thunderstorms locally in the above areas. Given weak synoptic forcing, storms will likely be focused near a E-W breeze convergence zone indicated by models to extend from central or north Wales towards Lincs/Norfolk. Thunderstorms maybe accompanied by hail, with an isolated risk of large hail >1.5 cm. Also there is a risk of localised flooding, given weak winds aloft leading to slow-moving nature of storms and large spot totals from heavier downpours. In mind of this, have issued a MARGINAL risk of severe weather for above areas. Funnel clouds and even brief/weak tornadoes or waterspouts can't be ruled out with stronger strorm updafts given weak upper winds/surface convergence.