Low pressure currently expected across the UK from 17th Jan 2007, bringing gales across the country and gusts to 70 mph.

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Gald i re-inforced my back gate, take a look at the Gulf Stream for Thursday



Here's the wind chart:

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Better nail the Lurchers kennel down!

Don't want him doing a "mary Poppins"

Is all this coming from the Atlantic then?

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Yes it is coming in off the Atlantic, the Mids is right in the firing line too!

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This could get interesting...

Storm Forecast
Valid: Wed 17 Jan 2007 06:00 to Thu 18 Jan 2007 06:00 UTC
Issued: Tue 16 Jan 2007 18:25
Forecaster: GATZEN



SYNOPSIS

Delta of strong westerly flow over northern Atlantic evades eastward into western Europe. While very strong upper jet streak travels over the Atlantic Ocean, a short-wave trough ahead of the jet rapidely moves across Brtish Isles and North Sea into Scandinavia during the period. Another trough that forms the southern part of the delta flow regime is forecast to travel over western Mediterranean and central Europe.

At lower levels, relatively deep rich low-level moisture has developed over western Mediterranean underneath a strong inversion in the range of subtropic ridge. While the upper trough approaches, this inversion is expected to decrease significantly, and CAPE will likely develop during the period.

To the north, rich moisture spreads into France and further into Benelux, while cold/dry air mass is present from Germany eastward and over the Balkans.

DISCUSSION

Interesting situation is expected to develop over British Isles underneath the first upper trough north of propagating jet streak. Moist and convectively mixed air mass is expected in the range of this short-wave trough that rapidely moves eastward into southern Scandinavia. Given strong synoptic forcing due to strong DCVA and only weak CAA, showers and thunderstorms will likely develop.

While DLS is forecast to be not too high, LLS is forecast to be around 10..15 m/s near the coasts of British Isles and southern Scandinavia. 0-1 km SRH values of about 100 J/kg spread eastward during the period, reaching southern Scandinavia in the night hours. Given almost no CIN and forcing, thunderstorms that form will likely profit from this low-level helicity, and shallow mesocyclones and small bowing lines are forecast to develop near the coasts. Marginally severe hail, strong wind gusts and even isolated tornadoes are not ruled out.

Overall threat seems to be high enough to warrant a level 1. It is not clear how far south deep convection will occur. Although latest GFS does not indicate deep instability over southern UK, strong DCVA in the range of the upper trough will also affect these regions. Given rather high low-level instability, showers and thunderstorms may develop along the trough axis/main vort-max, where low-level forcing will likely be strong enough for initiation. Given south-westerly surface winds east of the main vort-max, and about 10 m/s low-level vertical wind shear, mesocyclones capable of producing marginally severe hail, strong to severe wind gusts and even isolated tornadoes are also forecast for this region.

Convection that develops along this trough axis may also affect most of the southern North Sea in the afternoon/evening hours.

European Storm Forecast Experiment - ESTOFEX

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Thursday 1800 run:

This is for 'Convective Gusts' - Sure does look like this one is going pack a punch!
(Convective gusts are strong downdraughts that spread out horizontally when they hit the ground. (This is the easyest explanation i could come up with - feel free to add on))



Data from: Lightning Wizard - weather & photography

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Updated Estofex map showing the strikes so far and a tornado in the Med.



European Storm Forecast Experiment - ESTOFEX

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Here are the latest charts for the 18th. Look how quick that low moves across.

00:00, 06:00, 12:00, 18:00

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LEVEL 2 Estofex:

Storm Forecast
Valid: Thu 18 Jan 2007 08:00 to Fri 19 Jan 2007 06:00 UTC
Issued: Thu 18 Jan 2007 07:52
Forecaster: GATZEN



SYNOPSIS

Delta of strong westerly polar jet is present over Europe, with a trough over central Mediterranean, another over southern Scandinavia, and a subtropical high over Iberian Peninsula.

At 300 hPa, a 100 m/s jet streak that has formed over western Atlantic rapidly spreads into western and central Europe during the period, providing strong DCVA at its northern flank, where cyclogenesis is forecast. Associated intense surface low is expected over the Baltic States on Thursday.

At low levels, a tongue of very moist maritime air mass is advected into Europe ahead of a cold front that will cross British Isles, Germany, and Poland during the period.

DISCUSSION

British Isles to Poland

Strong cyclogenesis is expected in these affected areas, with intense precipitation in the WAA regime, very moist air mass and very strong LLS/SRH in the warm sector, strongly forced convection along the cold front, dry intrusion above the cold front/cold sector air mass, as well as some convection in the range of the following surface trough and embedded back-bent occlusion. Latest satellite images show an impressive dry intrusion making its way to the east.

Surface observation from British Isles indicate dewpoints of about 11..12 C in the warm sector air mass and relatively deep moisture. Following the ingredients-based theory of severe convection, it seems that an outbreak of severe convection may be possible, but it is more likely that instability will not be sufficient for such a scenario.

Low-level moisture in the warm sector air mass as well as in the convectively mixed polar air mass W of the cold front will be sufficient for weak instability given neutral lapse rates at least. Favorable vertical wind shear of about 25 m/s LLS, 60 m/s DLS, around 600 J/K 0-1 km SRH will be present E of the cold front as well as in the range of the following short-wave trough and embedded back-bent occlusion.

Additionally, strong forcing will likely occur especially along the cold front. Great uncertainty exists about mid-level lapse rates that will be rather poor in the warm sector initially and are expected to improve significantly when the dry intrusion of the low reaches the warm sector ahead of the following trough.

Current thinking is that at least weak instability will be present sufficient to allow a strongly-forced convective line along the cold front that moves eastward over southern/central British Isles, northern France, Benelux, northern Germany, and northern Poland.

Given that forcing and vertical wind shear will be maximized from Benelux to northern Poland, thunderstorms are expected especially in this region, where models show a narrow region of low LIs. To the south, cold front will likely become parallel to the flow. Increasing distance to the trough center and dry intrusion will likely lead to rather shallow instability and chance for thunderstorms will be lower.

Given up to 50 m/s winds @ 850 hPa and around 35 m/s winds @ 950 hPa, vertical momentum transport inside of the downdrafts along the convective line will likely produce severe wind gusts at the surface, even when convection will not be well-organized. Expect a strongly-forced convective line, we decide to issue a level 2 that implies the widespread character of severe wind gusts along the cold front as a combination of strong synoptic-scale pressure gradient and convection.

A second scenario may come true when steep lapse rates of the dry intrusion will spread across the warm sector, leading to significant CAPE. This is now shown by latest GFS00 model run.

Convection that forms may merge into a well-organized linear MCS as strong vertical wind shear will be able to balance the forming cold pool. Such a convective line may produce even higher wind gusts due to mesoscale low-level jets in the range of the cold pool.

This scenario includes widespread severe wind gusts as well as a couple of very high wind gusts of more that 40 m/s. This will mean that the highest gusts of this event will occur along the cold front over most places. An upgrade may be warranted when such a system evolves during the afternoon/evening hours.

In both scenarios, high low-level SRH values will be present in the warm sector. Embedded mesocyclones may form along the convective line, capable of producing isolated large hail and tornadoes. There is also a chance for non-supercell tornadoes along the leading gust front given high background helicity and locally favorable low-level buoyancy.

In the range of the following trough, slight instability in the convectively mixed air mass may be sufficient for a few convective cells. Given strong vertical wind shear and helicity underneath the trough, showers and thunderstorms will likely organize into mesocyclones and/or bowing lines capable of producing severe wind gusts and possibly tornadoes. However, latest models guidance seems to indicate relatively stable conditions in the range of the back-bent occlusion, and development of convection is questionable at this time.

European Storm Forecast Experiment - ESTOFEX

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