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Dave Clarke

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Posts posted by Dave Clarke

  1. Copied across from UKww

    PJB

    Location: Southbourne, Bournemouth, Dorset

    First signs of destabilisation of the plume in Central Biscay, some growing AcCast visible on Rapid Scan HRV imagery. Trajectories suggest this is the growth Region for any storms in the far SE later tonight.

    -----

    Paul Blight

    UKww Manager - Education/Warnings

    Associate Fellow Royal Meteorological Society

    Southbourne, Dorset, 1M ASL.

  2. More pages of doom casting I see happening over & over again. Latest forcast I have just seen on bbc news 24 said highly elevated storms forming during the evening into the early hours from the wash sw towards southampton. The emphasis on his forecast saying they'd be highly elevated with not much rain getting to ground level, but a lot of lightning present. This indicates the trough will start to destabilise the mid levels and moist plume currently in place over the se & ea.

    As opposed to hopecasting yeah? ;)

    The forecasts being rolled out on BBC are using this mornings runs....

  3. :lol: sorry but thats just made me laugh.. ok im going back to my normal routine now and hope we get another chance in this summer. just hope he's wrong.. but the way the weather is splitting (if u look on radar) everything is splitting up and going north or south off us, and looks like he could be right, now ive got this overcast blanket on me.. doesnt look good now, but i sure hope he is wrong and i do get a rude awakening!! :diablo:

    Paul Blight is one of the best forecasters I know, and rarely gets it wrong, but I hope today is his off day ;)

  4. Another cross post from Paul Knightley to keep you guys up to date with what's happening at our gaff ;)

    Posted 27/6/2011 12:29

    Subject: Re: Convective Outlook - Monday 27 June 2011

    Online

    Location: Reading

    Yes, main area of interest does appear to be across E Anglia/SE England, and perhaps Cent S England overnight, especially later tonight, and for a time tomorrow morning. As Paul mentions, the current area of mid-level activity over the SW should spread NNE through today - as this is indicative of an area of ascent, it's not out of the question that further activity forms from the boundary layer within this mass further NE, with isolated activity building back into more southern areas - any such activity will be subject to reasonable shear and so may be fairly organised.

    Overnight, it looks like the activity will be rooted above a cooling boundary layer (surface flow veers to a northerly component) - 850 flow and above remains with a southerly component, and so isentropic lift of the warm/moist layer around 850 mb should help lift parcels to their level of free convection. Cloud layer shear on the order of 20-25 knots should allow for some organised storms to form - indeed, slight veering of the flow could help aid in mid-level mesocyclone development, so there is the chance of some large hail with overnight activity.

  5. Cross posted from us, just so you know what we're up to ;)

    UK THUNDERSTORM POTENTIAL Monday 27th June 2011 Click for latest updates

    11 BST Update Monday 27th June 2011

    Poor Model Guidance at T+3 from the 06Z Models renders model guidance pretty useless in the short term. The GFS is almost completely missing the area of Thunderstorms and Heavy Showers over SW England. The NAE and HIRLAM are better but a bit slow. Low pressure has formed over SW England and the complex trough visible on WV imagery currently has become complex with two main forcing centres, one crossing Brest now and the 2nd coming NNE over Biscay generating the 2nd area of activity. The main upper trough has buckled a little overnight allowing for a somewhat slower progress much has hinted at by the ECMWF over the last couple days and the slower progress is preferred at this time IMO.

    Sferic activity is waning currently as the Diurnal minima is reached relative to the convective cycle. Both the HIRLAM and NAE break out Showers and isolated storms over N England this afternoon, and these could cause local heavy downpours esp over NE England. However this is relatively straightforward relative to activity further south.

    Model guidance is frankly next to useless atm, as none of the 06Z Guidance has correctly placed the activity over the SW (remember my big ?? from yesterday) Trajectories from MSG Imagery take these these NNE across the SW into Wales and the SW Midlands over the next few hrs - though degenerating into an area of heavy rain with time. However Storms may reform over the SE slice of this area later today - from Inland CS England to Lincs and the Vale of York. These are Medium level storms and as such not much rain initially reaching the ground. Moistening with time will allow some heavier rain to penetrate to the surface, but earlier French Obs did not indicate much rain at the surface.

    The 2nd area of Forcing over Biscay moves NNE and will act as the trigger for destabilisation over NW France, Normandy and then crossing to the SE of England later today, this evening and esp overnight when the main upper trough also moves in and adds additional cooling and destabilisation to the profiles. Heavy Storms (again largely derived from above the B.L) will trigger lots of Lightning and appear very active but will take some time to moisten the lower layers. Areas SE of Wash to Lyme Bay at risk - though a zone from Norfolk, through London and the Home Counties to the IOW and Sussex appear most at risk tonight. The situation is highly complex and prone to significant error.

    Convective.jpg

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