the spaghetti plots are quite 'together'
up to Friday (with upper ridge indicated NW Europe), but looks like a
dogs-breakfast by Monday - not unusual
Todays London ensemble seems remarkable for the overall warming trend and lack of ppn after Tuesday
http://www.wetterzentrale.de/pics/MT8_London_ens.html
presumably due to the persistant ridging from the SW,

--
regards,
david
(add 17 to waghorne to reply)

Have you seen the ensemble forecast for Manchester, very odd operational
run from 7-13th June with regards to the rainfall. Hinting at daytime
convection maybe ? If so, it's going for some very heavy showers. Anyway,
too far ahead to take it as gospel.
http://www.wetterzentrale.de/pics/MT...ester_ens.html
ATB, Joe
No I hadn't -where's Manchester ;-) ?
Does look odd I agree.Wonder what set up wld give that(assuming ridging close to the south),

--
regards,
david
(add 17 to waghorne to reply)

"Waghorn" wrote in message
...
Have you seen the ensemble forecast for Manchester, very odd
operational
run from 7-13th June with regards to the rainfall. Hinting at
daytime
convection maybe ? If so, it's going for some very heavy showers.
Anyway,
too far ahead to take it as gospel.
http://www.wetterzentrale.de/pics/MT...ester_ens.html
ATB, Joe
No I hadn't -where's Manchester ;-) ?
Does look odd I agree.Wonder what set up wld give that(assuming
ridging close to the south),

--
With 850mbar temps around 12 or 13C one would expect
surface maxes quite high in the 20s ... reminds me of the first
week of June 1982 ... a sluggish southerly or flat surface ridge,
residual pockets of cool air aloft, a daily crop of thunderstorms,
some of them very severe.

http://www.wetterzentrale.de/topkarten/fsreaeur.html

Philip Eden

"Philip Eden" philipATweatherHYPHENukDOTcom wrote in message
...

"Waghorn" wrote in message
...
Have you seen the ensemble forecast for Manchester, very odd
operational
run from 7-13th June with regards to the rainfall. Hinting at
daytime
convection maybe ? If so, it's going for some very heavy showers.
Anyway,
too far ahead to take it as gospel.
http://www.wetterzentrale.de/pics/MT...ester_ens.html
ATB, Joe
No I hadn't -where's Manchester ;-) ?
Does look odd I agree.Wonder what set up wld give that(assuming
ridging close to the south),

--
With 850mbar temps around 12 or 13C one would expect
surface maxes quite high in the 20s ... reminds me of the first
week of June 1982 ... a sluggish southerly or flat surface ridge,
residual pockets of cool air aloft, a daily crop of thunderstorms,
some of them very severe.

http://www.wetterzentrale.de/topkarten/fsreaeur.html

Philip Eden


Hi Philip,

I replied to David via e-mail, as I didn't want to swamp Martin's
informative thread about the Venus transit, however I mentioned a
situation very similar to what you have brought up here.

I was thinking of a pattern more similar to the beginning of July 2001 ( I
was still 3yrs off being born in '82) where a ridge to the S/SE was being
nudged eastwards by a elongating upper trough to the W. It eventually
formed a cut off low in the English Channel and caused some very severe
thunderstorms, with 104.7mm at Betws-Y-Coed, Wales in a 24hr period.

http://www.metoffice.com/climate/uk/...y2001rain.html

The op run suggests a more blocked scenario with a similar set-up each
day, so I suppose your dates do offer the better option.

ATB, Joe

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/
(GME via: http://www.wetter.com/home/)

Verifying: 2004 June 08 up to ~midday


2004 May 31: D-08: GFS (GME JMA see evolution)
Synoptic:
Low ... (slow-moving/occluded) south of Iceland, with secondary
development along latitude ~50N. Low ... North Biscay at midnight moving
NE, over Wales/SW England by midday/8th. Ridge ... England/Wales moving
NE into N.Sea. Frontal link E/W from Iceland-central Norway. Relatively
High pressure NE France, Low Countries, Germany and eventually Denmark
(after trough moves away east).

Run-to-run evolution: We've gone back to something like we had a couple
of days ago, with main centre-of-gravity (cog) of low in NE Atlantic,
and some sort of baroclinic development running up from Biscay into
southern Britain. It looks very much as if the run yesterday was an
'outlier', BUT, it is interesting to see that HP is poised very close to
the areas of interest, and this is a recurring theme from some other
models which approach this time-frame.
(GME up to 24hr before event ... trough Scotland - Brittany moving east
with cold ridge behind, ahead of next developing wave-depression ... JMA
for similar time shows broadly progressive W/SW type, with low NW of
Scotland and wave well to WSW of British Isles.)
Looking at the GFS Ensemble means and spaghetti plots, there seems to be
some convergence onto the theme of relatively HP over the continent, and
LP to the NW of the British Isles. The mean 500hPa trough is sharpening
as it comes east, which must indicate developmental tendencies, given
other conditions being in place. (However, you could argue that this is
nothing more than mean climatology!)

Inference: With these ideas, again we would have to threaten many
southern areas (of Britain), along with NW France, with cloud/rain from
the development coming up from the SW, and far NW parts of the British
Isles also rather cloudy. Elsewhere, (and across Wales & much of England
before the middle-level cloud arrives), good conditions for sighting.
Thicker overcast clearing from SW Norway, Denmark, with well-broken
cloud developing. Other areas adjacent mainland NW Europe OK, once
morning fog/low cloud evaporates.



--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

.... just a 'heads-up': with more models to look at and as we get closer
to the event, I'll not be posting the updates until into the afternoon -
I'm finding it difficult to give enough 'considered' time during the
morning.

Martin.


--
FAQ & Glossary for uk.sci.weather at:-
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[ ... do you wish you had never started something ....;-) ]

Unless otherwise noted below, the discussion is based on products
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http://www.wetterzentrale.de/topkarten/
(GME via: http://www.wetter.com/home/)

Verifying: 2004 June 08 up to ~midday

2004 Jun 01: D-07: GFS EC GME (JMA n/a)
Synoptic:
GFS: Low ... (slow-moving) SW of area Shannon. High ... Norwegian Sea.
High ... northern North Sea, with ridge extending across NW Germany,
intensifying. Trough ... N.Biscay/Brittany - SW Ireland early, moving
NE, lying Cotentin peninsula - SW Wales - central Ireland by midday/8th.

EC (yesterday's 12Z): Low ... south of Iceland. Low ... (thundery?)
Biscay. High ... Heligoland Bight into Germany. Frontal trough ... SW
England - West Wales - Forth.

GME: Low ... SE Biscay. Low ... (complex) SSW of Iceland. High ... just
east of Scotland. Trough ... N/S Denmark/South Norway.

Run-to-run evolution: all deterministic runs show relatively high
pressure North Sea, Low Countries, NW Germany & NE France. GFS/EC show
the idea (as the GFS yesterday) of some sort of 'plumey' development
Biscay to NW France - across SW Britain, extending NE'wards. (NB: some
of our earlier runs also indicated such). These runs all tend to support
a rather 'blocked' pattern, with HP the dominant theme NW mainland
Europe, but tendency to slightly more mobility towards the
westnorthwest. (Have just seen the 06Z GFS run and this doesn't develop
the plume so much from / across the SW!)

Inference: main areas at high prob (80%) of extensive & persistent
cloud cover based on these output would appear to be: Brittany, all SW
England, much of Wales (though with a fine start), and perhaps into CS
England, the Midlands and parts of southern Ireland. All other areas
should have a 60% of sighting, *at some time*, though with a slack flow
and moist low level air, some cloudy infill is indicated for
central-northern France and SE England, with medium-level unstable cloud
also likely to be a factor. Also, low cloud may be a problem for east/NE
England and E/SE Scotland with a flow off the North Sea. Some far NW
parts of both Ireland & Scotland may also have large amounts of cloud.



WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/
(GME via: http://www.wetter.com/home/)

Verifying: 2004 June 08 up to ~midday

2004 Jun 02: D-06: GFS EC GME JMA UKMO NGP GEM
Synoptic:
GFS: Low ... well to WSW of Shannon. Trough (possibly thundery) ...
moving/developing NE slowly across NW France / western Channel /
southern Britain. High ... west Norwegian Sea. Ridge ... central Europe
to Viking. (broad ideas confirmed by 06Z run).
EC: Low ... (slow-moving) well to west of Ireland. Low ... (thundery?)
Biscay at 12Z/8th (i.e. well after event has finished). High ... in
broad belt from Italy / central Mediterranean to NW Europe to much of
British Isles to High cell Norwegian Sea.
GME: Low ... (complex / thundery) FitRoy to Biscay. High ... between
Iceland and Faeroes, with ridge towards Low Countries .. changes small
in following 24hr, possibly intensifying high pressure. (similar to
JMA).
JMA: Low ... north of the Azores. High ... between Faeroes and Iceland.
Ridge ... Shetland to southern North Sea. Broad upper ridge much of NW
Europe (note, trough Biscay not as pronounced as GME).
UKMO: Low ... (slow-moving) well to west of Ireland. Low ... NW Iberia.
High ... North Faeroes to Norwegian Sea, with strong ridge towards Low
Countries.
NGP: similar to GEM (below)
GEM: Low ... well to west of Biscay, but trough extending eastwards
towards western France (upper ridge aloft in east). Low ... Finland.
High ... in irregular belt from central Mediterranean across NW Europe /
British Isles to N/NE Atlantic.

Run-to-run evolution: the GFS is on its own as the most pessimistic
model showing the near-classic plume breakdown as contour heights fall
and very warm, humid air is advected northwards. All other runs are
nothing like as pessimistic, with variations on the 'HP' theme under a
rounded upper ridge across much of NW Europe - differences in the Biscay
/ Brittany area though, with some models showing a trough underneath
neutral or slightly cyclonic flow aloft. The German model in particular
has consistently indicated this rather optimistic (for our purposes)
pattern.
Looking at the GFS mean 500hPa pattern, the mean trough is well to the
west at 080000Z and reasonably sharp, with the mean ridge axis from
north of Shetland to Denmark to NW Italy. The trough does come east over
the next 24hr, with a decrease of contour height British Isles, but the
sphagetti plots appear to indicate that the slight majority favour the
trough not coming east too quickly - some solutions keep the upper ridge
firmly over NW mainland Europe, and near enough to much of BI to
influence developments. At this range, models often introduce this type
too quickly but .....
The GFS does have a good track record at this range, so the inference is
biased towards that: BUT, I wonder if that might prove to be the
*pessimistic* view, given the output from the other centres.


Inference:
- much of W & NW Germany, Low Countries, NE France ... 70% chance of
good sighting - morning fog/stratus should clear readily, and there may
be build of medium/upper cloud for some.
- southern Norway, Denmark ... old frontal link, fragmenting .. 60%
chance of some sighting, with Jutland in particular perhaps 80% chance
of fine skies.
- NW France / SW Britain .. subject to Biscay developments (see caveats
above), so have to indicate often extensive medium/upper cloud, with
thundery rain/convective clusters; also coastal/hilly areas may be
misty/foggy (humid low-level air mass).
- East/NE England, E & NE Scotland .. with large areas persistent cloud
on/near coast, and extending inland, but breaking here with time. NE
Scotland / Shetland though more problematic.
- Ireland / west coastal & much NW Scotland .. large areas cloud, but
breaking from south. ~60% chance of some sighting during event.
- Remaining areas (includes large parts of central & SE England, N Wales
& NW England, and perhaps large areas of west and Highland Scotland) ..
areas medium/upper cloud - some scattered showers, but often well-broken
cloud cover, with at least 60% chance of seeing something ... and if
this proves the most pessimistic scenario, perhaps 80% chance.





WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

You can get direct links to those and other long range forecasts on my
weather portal.
Hope this is of use to you. If there are other charts you would like listed,
let me know.


MarkDJ
http://www.stronge.org.uk
Mobile UK Weather


"Martin Rowley" wrote in message
...
Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/
(GME via: http://www.wetter.com/home/)



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Unless otherwise noted below, the discussion is based on products
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http://www.wetterzentrale.de/topkarten/
http://www.westwind.ch
and http://www.wetter.com/home/

Verifying: 2004 June 08 up to ~midday
2004 Jun 03: D-05: GFS EC GME JMA UKMO NGP GEM
Synoptic:
GFS: Low ... (slow-moving) well out in Atlantic, but frontal trough
across Shannon - Fastnet - Brittany (?thundery at this point). Low ...
(complex) Baltic - North Russia. High ... north of Faeroes with ridge to
Low Countries/NW Germany. Trough ... Jutland - south Baltic.
EC: Low ... Baltic States, with trough SW Norway - Schleswig - low
centre. High ... Iceland to Hebrides, with broad/irregular ridge
dominating British Isles, and discrete tongue of HP Low Countries to
southern Germany. Suggestion of weakness (under a ridge axis) western
France. Low ... (difficult to pick out) somewhere west of Portugal.
GME: Low ... southern Finland (slow-moving) with cold front SW Norway,
north Jutland, moving south. Low ... (thundery?) Biscay. Low ... well
out in the Atlantic, but trough from same to NW Iberia. High ...
Norwegian Sea, north of the Faeroes.
JMA: Low ... St. Petersburg, with trough S Norway - low centre. High ...
Iceland to Faeroes, with rregular ridge towards Heligoland Bight and
central Germany. Trough ... (from slow-moving low in Atlantic) Shannon -
SW Britain under post-upper ridge field.
UKMO (unmodified): Low ... (slow-moving) well out in the Atlantic. Low
.... Russian arctic. High ... Norwegian Sea, with irregular ridge across
North Sea, the Low Countries and down towards the central Mediterranean.
Trough ... SW Approaches - Brittany - northern France (but isobaric
pattern is ridged SW Britain and Channel region.)
NGP: Low ... well out west into Atlantic, with weakly defined trough
towards FitzRoy. Low ... Arctic Russia, with trough to south Norway,
where possibly a separate secondary. High ... SE Iceland, with broad
ridge for much of British Isles - Low Countries - NE France - central
Europe / European Alps.
GEM: Low ... well west into Atlantic, with trough ESE'wards to Sole and
Biscay. Low ... Gulf of Finland, with trough/frontal SW Norway to
Kattegat to south Baltic. High ... Norwegian Sea to SE Iceland, with
ridge across much of north / NW British Isles to NE France, Belgium and
thence to Italy.


Run-to-run evolution:
The models are convergent now on a 'common' broad story with the
following elements:
1. Low slow-moving in the NE Atlantic, well to the west or southwest of
Ireland.
2. Low (some complex) over Baltic or Finland with frontal trough coming
south across southern Norway/Sweden.
3. Troughing (but high variability) in the Biscay/FitzRoy areas.
4. High pressure in belt from Iceland - Faeores - 'NW Europe', but with
variability - some nice fat ridge keeping the trough/high thetaE (or
thetaW) plume to SW at bay; others a narrow feature allowing
encroachment of same.

Inference:

- much of W & NW Germany (except perhaps Schleswig), Low Countries, NE
France ... 70% chance of good sighting - morning fog/stratus should
clear readily, and there may be build (or advection in) of medium cloud
from the north, particularly Netherlands and much of northern Germany.
- southern Norway, Denmark, Schleswig .. trough/frontal link, with
extensive cloud - poorer prospects than indicated yesterday as trough
stalls in this region ... ~30% of sighting.
- NW France / SW Britain .. highly subject to activity over Biscay /
Western Channel: areas middle and upper level cloud, with thundery
clusters, but also some breaks potentially, more especially NW France &
Channel Islands. Prospects *poor* on current ideas, but no reason to
doubt that 'fitful' sightings might occur.
- East/NE England, E & SE Scotland .. mainly cloudy - prospects poor
along / inland of coast, but better (~60%) chance of some sighting away
from coastal plain.
- N Scotland, Northern Isles and perhaps much of western Scotland - much
better than indicated yesterday, with cooler/less humid air, high
pressure etc. ~ 70% or greater prob. of sighting.
- southern half of Ireland .. generally large areas cloud, with poor
prospects, except perhaps at first.
- northern half of Ireland, along with NW England .. reasonable
prospects .. circa 70%, but clouding up from the south during morning.
- remainder of England (including large parts of Midlands, SE England,
East Anglia, also for N Wales .. probably a decent few hours, then
increasingly cloudy from the southwest. 20% for sighting the whole
event, but 60% for some activity.




WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm