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61  General Category / Weather & Atmospherics / Re: Spanish Plume/Severe Storms? - England/UK - Mon & Tues June 27th & 28th on: June 27, 2011, 10:56:06 am
Updated Monday 10:51 AM

SKYWARN UK SEVERE THUNDERSTORM WATCH #031
ISSUED: 2130UTC SATURDAY 25TH JUNE 2011 (GJ)

SKYWARN UK HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR THE FOLLOWING REGIONS:
NORTHERN ENGLAND
NORTHEAST WALES
WEST MIDLANDS
EAST MIDLANDS
EAST ANGLIA

IN EFFECT FROM 1100UTC UNTIL 2100UTC SUNDAY 26TH JUNE 2011

WARM MOISTURE PLUME DESTABILISED UNDER JETSTREAM FORCING

THERE IS A POSSIBILITY OF SEVERE THUNDERSTORMS AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:
HEAVY RAIN...STRONG GUSTS...HAIL...LIGHTNING...FLASH FLOODING...FUNNELS/TORNADOES

DISCUSSION:
THERE IS NOW STRONG SHORT-RANGE CONFIDENCE IN A POSSIBLY SEVERE CONVECTIVE RISK AFFECTING MOST OF THE NORTHEN HALF OF ENGLAND DURING SUNDAY AFTERNOON AND EVENING. A WARM AND MOIST AIRMASS IS IN PLACE ACROSS THE UK, WITH A STRONG FLOW OF WIND THROUGH THE UPPER LAYERS ALONG THE RIGHT EDGE OF THE JETSTREAM. CAPE VALUES OF OVER 1000J/KG MAY BE ACHIEVED IN STRONG EARLY AFTERNOON SUNSHINE, WITH INCREASING DEEP LAYER SHEAR PROVIDING ORGANISATION FOR STRONG STORMS. THE RISK COVERS ALL AREAS, BUT STRONGEST STORMS ARE EXPECTED AROUND THE EAST MIDLANDS PRIMARILY, WITH POSSIBILITIES OF MODERATE HAIL SIZES EXTENDED TO THE NORTHEAST OF ENGLAND AND THE PENNINES. SUCCESSIVE STORMS MAY LEAD TO INSTANCES OF FLASH FLOODING. PLEASE MONITOR TRAVEL INFORMATION AS NECESSARY. THIS WATCH MAY BE UPGRADED.

Current data from my Davis Pro Weather Station 27 June 2011 10:53:00

Temperature Temps 28.8įC
Heat Index       30.8
Dew Point        20.5
Rel Humidity     61%

Pressure (hPa):
Current          1012.36
Trend (per hour) -0.23


62  General Category / Weather & Atmospherics / Re: Spanish Plume/Severe Storms? - England/UK - Mon & Tues June 27th & 28th on: June 27, 2011, 12:55:43 am



Storm Forecast
Valid: Mon 27 Jun 2011 06:00 to Tue 28 Jun 2011 06:00 UTC
Issued: Sun 26 Jun 2011 22:34
Forecaster: DAHL

A level one threat has been issued across the SE UK mainly for large hail, damaging wind gusts, and tornadoes.

SYNOPSIS

A high-amplitude upper flow pattern exists over Europe, with a longwave trough setting up over the eastern Atlantic. Another long-wave trough is present over eastern Europe and will close off into a cut-off cyclone on Monday. At low levels ... the eastern Atlantic trough supports advection of warm/moist air into western and central parts of Europe, as well as the northward expansion of an EML plume atop this warm/moist air mass.
The SE European trough is accompanied by a rather intense SFC low, but elsewhere rather quiescent synoptic-scale surface conditions prevail.

DISCUSSION

... SE United Kingdom ... N France ... Benelux ...

It seems that some instability will develop in the pre-frontal air mass across the southern British Isles and western continental Europe as the mid-level lapse rates increase in response to the northward spreading EML. The GFS CAPE values are not to be trusted given suspected problems in the surface-flux scheme that overestimates the diurnal latent-heat flux cycle. ECMWF shows that some 500 - 1000 J/kg of CAPE will develop over the SE British Isles and up to 2000 J/kg over France and the Benelux countries, which seems to be more reasonable than what GFS is advertising.

First storms should develop over the SE British Isles amidst the 850 hPa thermal gradient, probably in the afternoon hours, gradually increasing in coverage as the day/evening progresses. The activity should migrate across the Channel region and expand southwards during the night, when the convection will likely become slightly elevated. It seems that upscale growth into one or more elevated MCSs may occur, affecting extreme N France and the Benelux countries early Tuesday morning.

The severe threat with the convection over the British Isles in the afternoon and evening hours should be dominated by well-organized multicells and supercells given DLS of about 20 m/s (increasing from about 15 m/s over the extreme SE parts of the UK to over 25 m/s over the central portions of the UK) and rather strong LLS (exceeding 10 m/s over the extreme SE UK). However ... CAPE should be weakest where shear is strongest, and vice versa. Also, the LLS maximum is expected where DLS is weakest. Despite these somewhat negative factors, it seems that isolated large hail and damaging winds will occur, and perhaps also a brief tornado or two. At this time, a LVL1 threat seems to be sufficient, though an upgrade to LVL2 may be required if the CAPE and shear fields become aligned more favorably, or if CAPE proves to be higher than currently anticipated.

63  General Category / Weather & Atmospherics / Convective Outlook - Sunday 26th June 2011 on: June 25, 2011, 08:19:02 pm



Slight Risk of Isolated Thunderstorms 15Z-21Z Central & Central East UK 15Z-21Z

Prime Threat Moderate Sized Hail and CG's

Based on the GFS and MMN model there would appear to be some scope for convection (possibly strong) central east regions by late afternoon as some weak influence from upper troughing slides further SE. Upper flow would appear marginally supportive of cluster or even an isolated cell or two if and when  a thermal trigger level is breached. The latest GFS run certainly says this will be possible but in reality the GFS can often be bullish regarding these requirements! Hence some suggestion that convective initiation may well be a lot later than what the GFS currently predicts. Current UKMO FAX chart synopsis shows very little in the way of surface troughing though maybe the detail is too fine and between runs ATM!

Winds look fairly straight lined though increase with height is numerically steady ATM. Dry air is noted at 500mb upwards allowing for full potential instability to be utilised if this level can be reached by any building storm cell. The map below shows a fairly broad region of risk though in reality storm are likely to effect a very small portion of the zone. A yellow box highlights a region where solar heating is strong and is overlaid with some workable shear aloft. This is nevertheless not necessarily the most unstable sector for the day, but is realistically more likely to produce storms. In addition to this, based on surface heating and surface vector there would seem to be some small chance for convergence. ATM this is not seen by the GFS or MMN though the combination of cool seas to the east and relatively light winds inland the risk for backing winds is certainly a prospect worth monitoring. Whilst I currently do not see any prevalent risk of tornadoes likely any shift in the surface vector from the SE will certainly bring the risk fully into the equation.

Credit Tony Gilbert







64  General Category / Photography / Re: Cornwall again on: June 23, 2011, 11:51:20 pm
Thanks for the comments Paul. The 10 stop filter does create some interesting results like image No2 not the easiest filter to use but more you use it more you learn in timing the best exposure time to create a different style image.

Cheers.
65  General Category / Photography / Re: Cornwall again on: June 23, 2011, 07:43:00 pm
Thanks John, I had a few hours work Tuesday PM for Cornwall Council and once the work was completed I headed up the coast and stayed over at Porth http://www.glendorgalhotel.co.uk/
Lovely hotel with great sea views well recommended. It is crazy the mileage I cover to obtain work but it also provides me time to explore with the camera.
66  General Category / Weather & Atmospherics / Re: Spanish Plume/Severe Storms? - England/UK - Mon & Tues June 27th & 28th on: June 23, 2011, 07:26:51 pm
It only gets better, seriously thinking on travelling east on Monday to capture any action even though it is some way from home but less miles than Cornwall so thatís a bonus. Travailing North tomorrow around Yorkshire / Humberside. Martin I will post any developments over the weekend if things change and if you want to PM your mobile number I can also text you if things start to develop sooner, I have access to Netweather charts and 5min radar.
67  General Category / Weather & Atmospherics / Re: Spanish Plume/Severe Storms? - England - Mon June 27th on: June 23, 2011, 02:34:24 pm
Incredible looking charts could this be the big of the year lets hope so. Martin I will post CFS chart Monday, looks as if Ipswich & Norwich are currently seeing very frequent sferics.
68  General Category / Photography / Re: Cornwall again on: June 23, 2011, 09:39:27 am
Thanks Mark & Richard.

Richard the 2nd image was taken looking towards the village of St. Agnes North Cornwall famous for Cornish Tin mining, if you look you can see one of the old tin mine pumping stations in the top left. I think you remember of my previous images of Clovelly in Devon they do look very similar both wonderful locations.

Thanks
69  General Category / Astronomy & Space / Re: Iridium on: June 23, 2011, 09:37:29 am
Like this one Richard, dark sky no LP and a clear Iridium flare captured great stuff.
70  General Category / Photography / Cornwall again on: June 22, 2011, 05:52:49 pm
Went down to Cornwall yesterday and took a few more images using the 10 stop filter. Its a long way to go from home for a few images but well worth it.







I must remember to stick to the main roads !!!!



I have posted more images on my web here
http://redditchweather.com/cornwall.html

Thanks
71  General Category / Weather & Atmospherics / Re: 2011 Noctilucent Cloud Season on: June 20, 2011, 11:39:56 pm
Well Iím proud of you Paul even with beer glasses on you obtain perfect focus and great captures too. Love the first image with the overhanging trees and the post and rail fence looks perfect framing
72  General Category / Astronomy & Space / Re: AR11236 - Light Bridge, Dark Filament on: June 20, 2011, 11:32:53 pm
Fantastic Mark you are the master of solar imaging great detail captured.  Smiley
73  General Category / Photography / Re: Toome Bridge Night Exposures on: June 20, 2011, 11:29:39 pm
Night photography rocks Martin and you make it work so well, I too like taking night time images so appreciate how difficult it can be to obtain a perfect image and these pictures just prove how low light images can be so rewarding when done correctly.   Smiley
74  General Category / Weather & Atmospherics / Re: Sun Pillar on: June 20, 2011, 03:48:23 pm
That is a monster pillar Richard, love the vivid colours well caught chap.
75  General Category / Weather & Atmospherics / Re: Saturday's unstable skies on: June 20, 2011, 03:46:11 pm
Totally agree with Martin, great images John.
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