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ASSESSMENT FOR PHASE III

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This is the forecast as given in the press release of the 16th
October, 2007

[ which is the one I am verifying, not the 'shifting sands' updates
that keep coming out from Weather Action. ]



* 24th to 28th November. Storm/hurricane gusts of 90mph to 130 mph.

Probably worst in central/South British Isles. This is the 304th

anniversary of the devastating tempest of 26th/27th November (modern

calendar dates) 1703. Likely track (80% confident) of damage

eastwards: Holland, Denmark, N Germany, South Sweden and parts of

Baltic States and Finland.



[ I have also seen the 'detailed' forecast issued by Weather Action
for this period, which is even more alarming thus:....



" Very heavy rain local floods/major storms and thunder. Probably
worst in West / Central / South Brit Isles. Extremely stormy sea
conditions and alarming build up of swell. Sea defences in South and
West particularly Severn estuary and parts of the South coast likely
to be breached. Winds generally Southwesterly/Westerly or cyclonic,
gales / storms, hurricane force likely in exposed places. Widespread
damage of trees, roofs, buildings, high sided vehicles. Travel chaos
to air sea and road. Exposed buildings in towns near South Coast in
danger." ]



In my view, this forecast has proved to be grossly misleading. It is
clearly wrong in that it singles out areas of the British Isles that
experienced nothing like the 'death and destruction' promised. The
weather type is also obviously wrong: the forecast implies some sort
of 'running/explosively developing' feature across southern Britain
and heading for the Low Countries: the reality was a fairly standard
jet-driven development well away to the north which, once occluded,
allowed enhanced northerly flow to develop.



Whether or not developments this weekend (1st / 2nd December) will
produce problems over populated land areas remain to be seen:
certainly the situation is highly developmental, with the potential
for high winds. However, even if this proves to be true, this doesn't
make * this * particular forecast correct.



(I shall issue a composite summary, and some notes on the climatology
of the period, in a few hours time)



24th: A rapidly occluding frontal system crossed the British Isles
from the northwest and as it did so, the associated veer of wind
brought colder air southward through the day; by midday, occlusion
Humber estuary - St. George's Channel, with strong/loc gale WNW'ly Pm
flow behind & a strong/gale flow ahead of the front in the north. At
the start of the day, gales were widespread across northwestern
British Isles waters (F8), extending across the Viking/Forties 'gap',
where Severe Gales (F9) were reported. Coastal gusts at this time are
not great, being generally 40-45 kn very exposed spots western
Scotland, NW Ireland and around the Northern Isles & far north of
Scotland. However, by 03Z, Severe Gales (F9) were widespread across
the northern North Sea open areas (i.e. affecting many rigs/platforms
here), and the gale-strength winds had now reached the exposed coasts
of SW Norway. For coastal areas of northern Britain (and adjacent
islands), this is the period with maximum gust strengths: generally
45-55 kn very exposed locations (57 kn Foula), but for many, 40-45 kn
the more representative range. The remainder of the day saw the
greatest strength (F8/F9) driving SSE across the North Sea, as winds
eased slightly for western Scottish waters - still very perky Northern
Isles though. By late afternoon, gusts well in excess of 50 kn are
affecting exposed coasts from the Utsires (SW Norway) down to northern
Holland, with some near 60 kn. The Environment Agency had low-level
'Flood Watch' out for locations around some coasts expected to be
affected by the strong winds (& high tides), with two 'Flood Warnings'
in force by 18Z for a couple of stretches along the English North Sea
coast & by 21Z, this number had increased to 9, so they must be
worried about the surge to come down the North Sea coastline. I could
find no reports of ferries, bridges etc., being affected by high
winds, but I can't believe that there were not some delays to berthing
of ferries at least.



25th: The dominant low continues to fill/slow-moving north Norwegian
coast, with a near-direct ex-Arctic flow extending on it's western
flank right across the North Sea. A High has wandered ENE to around
47N18W in response to the changes in the upper pattern. Gales, or
severe gales are widespread from the Viking/Forties region in the
northern North Sea (including the Utsire region), down to the North
Sea coasts of Denmark, Germany & northern Holland. Some areas very
exposed to the unstable flow are experiencing gusts to at least 60 kn,
but in the main, where there are fairly large settlements, the gust
values are more modest: generally 45 knot or less and not too far away
from exposed coasts, a lot less. For open sea areas, the severe gales
(very isolated storm force/F10) have caused minor problems for a
temporary evacuation of the Thistle Alpha platform in the far north.
Otherwise, apart from a temporary swathe of 'Flood Warnings' down the
east coast of Britain, and similar alerts for some continental coasts,
not major problems are noted due to the strength of the wind coupled
to the high (astronomical) tide. Meanwhile, gales around north British
waters are easing, and by midday have ceased.



26th: High block persists across the west Sole/NW FitzRoy area.
Vigorous cyclonic development around southern Greenland with frontal
systems moving swiftly over Iceland and Denmark Strait. Strong,
unstable flow runs from the high Arctic to the European Alps, to the
west of a slow-moving/filling low in the north of the Baltic. Gradient
has weakened considerably across the British Isles (weak fronts
trailing along the flow), and there has been a slight easing in the
flow over the North Sea. At midnight, gales continue from Viking/outer
Utsires, across much of Fisher & east German Bight, i.e., roughly the
north and east of the North Sea as far as SW Jutland, NW Germany and
the northern coastline of Holland. We're down to 'ordinary' gales now,
with some gustiness enhanced by instability. By midday, only isolated
gusts along the north Dutch & NW German coast to 43kn (which would
qualify using the shipping forecast verification scheme), but
generally no gales now within the area under review & after nightfall,
a further easing of the flow removed even the residual stronger gusts
from coastal regions.



27th: Broad high-pressure belt from SE of the Azores, across
FitzRoy/Biscay and much of France, keeping things relatively quiet
over southern Britain. Frontal systems cross northern UK, with minor
waves on the trailing cold front (extending at least as far as the
Azores). The strong N/NNW'ly flow over the eastern North Sea has
finally eased to well below gale-strength, and now affects the Baltic
and contiguous states.



28th: The high pressure link from the Azores area to Europe is being
broken now as the long-wave pattern changes to the north: a series of
fronts is dominating the latitude band 48N-70N, with a major
development winding itself up north of Newfoundland. In the NW Europe
sector, the Scandinavian low of the past few days is now shunted well
and truly east, with Atlantic lows dominating from the Norwegian Sea
down to Ireland. The SW'ly maritime flow is strong (F6/F7) in places,
but 'proper' gales are hard to find. However, one particular low,
which at 06Z was near Belmullet (NW Ireland) is developing rapidly and
this is producing a strengthening of the gradient to its east in the
warm sector, with isolated gales Celtic Sea (mainly St.George's
Channel), central & eastern English Channel & parts of the North Sea -
all very transitory though and not clear that such strength of wind
affected land / coastal areas.

[ My working notes can be seen at:..........
http://booty.org.uk/booty.weather/Ge...on_FxCheck.htm ]

--
Martin Rowley
E:
W: booty.org.uk

Very heavy rain local floods/major storms and thunder. Probably
worst in West / Central / South Brit Isles. Extremely stormy sea
conditions and alarming build up of swell. Sea defences in South and
West particularly Severn estuary and parts of the South coast likely
to be breached ... Exposed buildings in towns near South Coast in
danger." ]

Well, I was down on the south Devon coast, walking a stretch of the
coast path, on Monday (26th) and there was barely any wind to speak
of. The sea was glassy smooth, with waves perhaps reaching as much as
9 inches along the shingle beaches :-)

____
Rob

wrote in message
...
Very heavy rain local floods/major storms and thunder. Probably
worst in West / Central / South Brit Isles. Extremely stormy sea
conditions and alarming build up of swell. Sea defences in South and
West particularly Severn estuary and parts of the South coast likely
to be breached ... Exposed buildings in towns near South Coast in
danger." ]

Well, I was down on the south Devon coast, walking a stretch of the
coast path, on Monday (26th) and there was barely any wind to speak
of. The sea was glassy smooth, with waves perhaps reaching as much as
9 inches along the shingle beaches :-)


ROFL. You couldn't make it up.

Will
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