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Nick F

Senior forecaster
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Nick F last won the day on January 24

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About Nick F

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    South Norwood, London (home), Hounslow/Heathrow (work)
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    Weather - particularly thunderstorms, growing plants, walking, cycling, cooking and good food, wine.

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  1. Effectively, yes, strong upper winds are important in sustaining and organising storms, not just deep layer shear, strong DLS is required for bowing-line segments and supercell structures that produce large hail, damaging winds and tornadoes though. At least I have a stronger pulse heading towards me in Croydon, flashing away to my southwest though can't hear the thunder quite yet.
  2. Yes, the vertical shear is not particularly strong, 20-30 knots, but the mid-upper flow is fairly strong and, combined with forcing from a shortwave trough, enough to organise storms into clusters forming a few convective systems IMO.
  3. *UPDATE 22Z* to Thunderstorm Outlook covering tonight thru Sunday, as widespread thunderstorms spread NE across England overnight before clearing Sunday morning. More thunderstorms possible for SE Britain on Sunday afternoon. Storm & Convective Forecast Issued 2018-04-21 21:54:57 Valid: 21/04/2018 2200z - 23/04/2018 0600z THUNDERSTORM OUTLOOK - DAY 1 UPDATE (SAT 21ST) & DAY 2 (SUN 22ND) Synopsis An upper trough moving will continue to move east into western Britain from Saturday night into Sunday, a shortwave trough moving NE on the forward side of the upper trough will bring a swathe of thunderstorms, locally strong, NE across parts of England tonight, before clearing NE into the N Sea Sunday morning. During Sunday, occluding cold front moving east ahead of low moving NE between Iceland and Scotland will bring a band of cloud and rain across country with cooler and more stable conditions of Atlantic origin following. However, warm, humid and unstable airmass will hang on across SE England and E Anglia into the afternoon, - which may trigger isolated thunderstorms with surface heating. DAY 1 THUNDERSTORM OUTLOOK Valid 21/2200z - 22/0600Z … N WALES, ENGLAND AND SE SCOTLAND TONIGHT … * Risk of ... hail (isolated large), strong wind gusts, flash-flooding, frequent cloud-to-ground lightning Through the rest of the evening and overnight, increasing large scale ascent and cooling aloft from approaching Atlantic trough from the west interacting with WBPT plume advecting north across England will support scattered elevated thunderstorm activity. One area of scatteres storms will continue to affect N England which may drift NE into the Scottish Border region. Another more extensive area of storms, forming one or two MCS (mesoscale convective systems) will push NE across S England, Midlands, SE England, E Anglia,Lincs and Yorks - driven by a shortwave trough moving NE out of France noted on WV imagery through the day. These elevated storms may produce hail, strong wind gusts, localised flooding and frequent cloud-to-ground lightning. DAY 2 THUNDERSTORM OUTLOOK VALID: 22/0600Z - 23/0600Z ... SE ENGLAND and E ANGLIA ... *Risk of ... Hail, flash-flooding, gusty winds and frequent lightning Warm and humid airmass ahead of cold front moving in from the west will become unstable with surface heating in sunny spells aided by continued cooling aloft steepening lapse rates, surface breeze convergence ahead of approaching front the west combined with large scale ascent of approaching upper trough may support the development of a few thunderstorms with peak heating in the afternoon, provided there is some sunshine. 30-40 knots of deep layer shear, strong SWLy flow aloft and 300-600 j/kg CAPE may allow storms to organise, perhaps strong enough to bring some isolated large hail, localised flash flooding, gusty winds and with LCLs lower than today, a brief funnel or weak tornado can't be ruled with storms forming or crossing along wind shift. Issued by: Nick Finnis
  4. UK Severe Convective & Storm Forecast - Issued 2018-04-21 21:54:57 Valid: 21/04/2018 2200z - 23/04/2018 0600z THUNDERSTORM OUTLOOK - DAY 1 UPDATE (SAT 21ST) & DAY 2 (SUN 22ND) Click here for the full forecastCheck the full storm forecast here
  5. 00z EC looking more promising for some storms to develop over northern France this evening then moving NE across SE England and East Anglia ... the EC CAPE charts, not shown, showing area of 1000 j/kg+ CAPE spreading into Kent/Sussex overnight, so could be quite electrically active with some hail.
  6. Storm & Convective Forecast Issued 2018-04-20 22:07:48 Valid: 21/04/2018 6am TO 22/04/2018 6am THUNDERSTORM OUTLOOK - DAY 1 (SATURDAY 21ST APRIL) Synopsis An upper trough moving across the Atlantic will arrive across the far west of the British Isles on Saturday, as upper level high on near continent retreats. A surface low will drift NE to the south of Iceland beneath the upper trough arriving to the west. Backing of the flow to a Sly direction across England and Wales on Saturday will draw in an increasingly warm and moist but unstable airmass out of France, with an increasing risk of thunderstorms developing northeastwards across England and Wales during the forecast period. … ENGLAND and WALES … * Risk of ... hail (isolated large) strong wind gusts flash-flooding frequent cloud-to-ground lightning Plume of warm moist air, characterised by high wet bulb potential temps (WBPT), will advance across S England and Wales Saturday morning, a shortwave trough moving up from NW France looks to destabilise this plume and support the development of thundery showers and increasingly a risk of elevated thunderstorms moving N/NE, initially isolated across SW and S central England in the morning, then more widely across Wales, Midlands and parts of N England into the afternoon, as mid-level temperatures continue to cool aloft from the west, steepening lapse rates. These elevated storms may bring some hail, frequent lightning and localised flooding. Although there will be some capping of the surface airmass by the Elevated Mixed Layer of the plume, surface heating combined with orographic forcing and/or breeze convergence may allow the cap to be overcome to allow some surface-based thunderstorms to develop where skies clear – particularly over north Wales, north Midlands and northern England. Any surface based storm that develops could tap into 500-900 j/kg CAPE – which could allow some isolated large hail, torrential rain leading to flash-flooding, frequent CG lightning and strong winds gusts … the weak vertical shear (20-30knts between 0-6km) will limit severe potential, so will abstain from delineating a severe risk area. During the evening, increasing large scale ascent and cooling aloft from approaching Atlantic trough from the west interacting with WBPT plume advecting north is forecast by a number of models to form a wave of elevated storms developing over the English Channel / N France initially before spreading northeast across parts of S and SE England along with E Anglia in the evening and overnight. Also ongoing storms further north over the Midlands and N England for a time, before clearing NE in the night. These elevated storms may produce hail, strong wind gusts, localised flooding and frequent cloud-to-ground lightning. Issued by: Nick Finnis https://www.netweather.tv/weather-forecasts/uk/convective
  7. UK Severe Convective & Storm Forecast - Issued 2018-04-20 22:07:48 Valid: 21/04/2018 6am TO 22/04/2018 6am THUNDERSTORM OUTLOOK - DAY 1 (SATURDAY 21ST APRIL) Click here for the full forecastCheck the full storm forecast here
  8. The warmest April day for 70 years yesterday, but for most we are not in a heatwave. View the full blog here
  9. Yes, atmosphere strongly capped today and tomorrow across England from upper level high close to the east and the associated subsidence, despite a few 100 j/kg CAPE being shown by GFS. So worth remember to not alway assume there will be storms by going on the CAPE charts alone. However, over the weekend, the upper high will retreat east and heights / surface pressure will fall, bulge north of plume of warm/moist air from France on Saturday likely to destabilise on northern and northwestern edge over western and central areas as upper trough interacts and temps cool aloft to destbilise it and form thunderstorms. Not a great deal of vertical shear on offer from models, so severe potential limited and storms could be elevated, but if home-grown surface-based can form, might be some large hail.
  10. UK has been on the cold side of the jet stream, but next week it shifts north over the UK, bringing warmth for all parts. View the full blog here
  11. Well chances are slim for storms away from Kent and E Anglia, but the grey skies are not really a contributory factor to lack of, as SE England storm risk will be imported from France tonight, if they make it across the sea they will be elevated.
  12. Storm & Convective Forecast Issued 2018-04-12 11:13:38 Valid: 12/04/2018 6AM TO 13/04/2018 6AM THUNDERSTORM OUTLOOK - DAY 1 (THURSDAY 12TH APRIL 2018) Synopsis A negatively-tilted upper trough extends SE and E across France, Spain and the western Mediterranean, with an upper level omega-shaped high extending north over NE Europe. Surface low pressure system covers central and western Europe beneath a ridge of high pressure over Scandinavia - with a strong SEly breeze off the North Sea bringing low cloud and cool temperatures to eastern UK, while warm air advection over central and eastern Europe brings increased instability to northern mainland Europe on northern edge of upper trough. ... AN ISOLATED RISK OF THUNDERSTORMS IS FORECAST TODAY AND TONIGHT ... * Risk of hail, lightning, gusty winds and localised flooding ... ... DEVON & CORNWALL ... Sunny spells here this afternoon bringing surface heating of moist airmass combined with sea breeze convergence inland from the Atlantic and Channel coasts may, as per model guidance, trigger some heavy showers with a risk of isolated lightning and also large spot rainfall totals leading to localised flash-flooding. These showers should fade after dark. ... E ENGLAND ... A shortwave trough in the NWly mid-level flow, visible on WV imagery across Switzerland, NE France and SW Germany this morning moving NW, is forecast by models to trigger a band of thunderstorms across northern France and Low Countries this afternoon/evening, as it brings lift to warm moist surface-heated airmass. Some of these storms could spread NW across SE England, E Anglia, Lincs and NE England tonight, though there is a good deal of uncertainty over the extent of, if any, lighting activity, if strong enough mid-level instability can move across the North Sea. However, any strong elevated, perhaps electrified, convection making it to E England may pose of a risk of hail, gusty winds and localised flooding. Will not go higher higher than an isolated risk of thunderstorms for now. https://www.netweather.tv/weather-forecasts/uk/convective
  13. UK Severe Convective & Storm Forecast - Issued 2018-04-12 11:13:38 Valid: 12/04/2018 6AM TO 13/04/2018 6AM THUNDERSTORM OUTLOOK - DAY 1 (THURSDAY 12TH APRIL 2018) Click here for the full forecastCheck the full storm forecast here
  14. Hi, yes, a lot of lightning activity over southern Holland and far west of Germany atm, ECWMF, ARPEGE, HIRLAM take an area of heavy thundery west across SE England/London/ southern E Anglia then M4 corridor and parts of S Midlands tonight and Wednesday morning. Whether there will be any lightning in it by the time it's crossed the sea from Belgium is anyone's guess though.
  15. Radar shows heavy rain over me near Ashord in Kent, where I'm staying tonight, but it's dry or very light, must be evaporating!
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