Deep Low Hitting UK/Ireland Sun/Mon?

[martinastro]

There's alot of chat going on about the chance of a deep LP system hitting Ireland and UK on Sun/ Mon next week with heavy rain and gales expected inland, perhaps severe gales for the coast and large tides, worth keeping an eye on!

[paulster78]

This storm is still on course to slam into the UK Sunday night-Monday, RTE Weather last night mentioned possible storm force winds and heavy rain, also mentioned another deep low moving in on thursday so an interesting if not rough week coming up!

[JohnC]

That looks like 960mb in the centre - The Great Storm of 1987 was 953-960.  It look as though it's going to be pretty lively.

[martinastro]

The Met Office have an advisory out for all of the UK already 

http://www.metoffice.gov.uk/weather/uk/uk_forecast_warnings.html

[martinastro]

SKYWARN UK SEVERE WEATHER WATCH #001
ISSUED: 1900UTC, FRIDAY 5TH NOVEMBER 2010.

SKYWARN UK HAS ISSUED A SEVERE WEATHER WATCH FOR THE FOLLOWING REGIONS:
NORTHWEST SCOTLAND
SOUTHWEST SCOTLAND
NORTHERN IRELAND
NORTHWEST ENGLAND

IN EFFECT FROM 1500UTC ON SUNDAY 7TH NOVEMBER UNTIL 2100UTC ON MONDAY 8TH NOVEMBER 2010.

POWERFUL LOW PRESSURE EXPECTED TO CROSS THE UK, BRINGING STRONG WINDS AND HEAVY RAIN TO MANY AREAS TOWARD THE LATTER PART OF THE WEEKEND AND INTO EARLY NEXT WEEK.

THERE IS A POSSIBILITY OF SEVERE WEATHER AFFECTING THE INDICATED REGIONS IN THE TIME PERIOD SPECIFIED. THREATS WITHIN THIS WATCH INCLUDE, BUT ARE NOT LIMITED TO:
HEAVY RAIN POSSIBLY LEADING TO FLOODING...WIND GUSTS TO 70mph.

DISCUSSION:
MODEL GUIDANCE IS IN GOOD AGREEMENT AS TO THE EXISTANCE OF A POTENTIALLY SEVERE EXTRATROPICAL CYCLONE AFFECTING THE UK OVER THE LATTER PART OF THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK. THE DEVELOPMENT OF A VERY STRONG 180KT JET STREAK RUNNING NORTH-NORTHWEST TO SOUTH-SOUTHEAST AND LOCATED JUST TO THE WEST OF THE UK THROUGH THE WATCH PERIOD. RAPID CYCLOGENESIS OF A LOW PRESSURE SYSTEM IS EXPECTED TO OCCUR IN RELATION TO THIS JET STREAK, REACHING A MINIMUM PRESSURE OF AROUND 960hPa AS IT TRACKS SOUTH-SOUTHEAST ACROSS NORTHERN IRELAND THROUGH SUNDAY NIGHT INTO MONDAY MORNING. WINDS INCREASING THROUGH SUNDAY AFTERNOON WITH 850hPa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mm EXPECTED AND WITH HIGHER TOTALS POSSIBLE. NORTHWEST SCOTLAND SHOULD BE LESS AFFECTED BY RAINFALL, AS THE DEPRESSION TRACKS TO THE WEST OF SCOTLAND. IN MORE SOUTHERN AREAS JUST REACHING THE REGIONS IN THIS WATCH, A RIDGE OF HIGHER THETA-E AIR EXISTS. CONVECTIVE ELEMENTS ARE LIKELY TO BE PRESENT IN THE FRONTAL SYSTEMS, AND WILL OCCUR IN A SHEARED ENVIRONMENT of 30-50 KNOTS 0-6km BULK SHEAR AND ENHANCED 0-1km SHEAR OVER LAND OF 30-40 KNOTS.

SPOTTER ACTIVATION IS REQUESTED AND SPOTTERS ARE REQUESTED TO REPORT RAINFALL ACCUMULATIONS AND ALL FACTORS EXCEEDING ACTIVATION CRITERIA. ANY WEATHER CONDITIONS...SUCH AS GUSTS THAT DO NOT REACH THE 70mph THRESHOLD...THAT CAUSE DAMAGE ARE ALSO REQUESTED TO BE REPORTED.

THIS WATCH WILL BE SUPERSEDED AND OTHER REGIONS INCLUDED REGULARLY AS THE REGION OF RISK MOVES CLOSER AND WITHIN 48 HOURS.

[markt]

This certainly looks an interesting end to the weekend / start to the new working week - one to keep an eye on...

Noticed the metoffice is also warning scottish highlands of significant snowfall aswell as a result...

[martinastro]

Now another level 1 out...



Storm Forecast
Valid: Sun 07 Nov 2010 06:00 to Mon 08 Nov 2010 06:00 UTC
Issued: Sat 06 Nov 2010 17:44
Forecaster: SCHLENCZEK

A level 1 was issued for parts of Ireland, western UK, NW France and NW Iberia mainly for severe wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

On Sunday there are two weather systems affecting Europe which may pose a risk of severe convective and non-convective weather:

(i) a strong extratropical cyclone initially located northwest of the British Isles will race across the NE Atlantic and the Irish Sea towards the Bay of Biscay while occluding. This low pressure system should gain its maximum intensity on Sunday around 18 UTC between Iceland and Ireland. The origin of this low is a baroclinic wave east of southern Greenland next to an impressive 100 m/s upper jet streak.

(ii) a large upper trough over the Mediterranean with strong upper level winds ahead of it, pointing towards S Italy and Greece / Albania. Moderately warm air on the right side of the jet streak should lead to at least some hundred J/kg MLCAPE, probably with maximum values close to 2 kJ/kg. Increasing 0-6 km shear and 0-3 km shear in the late evening / night hours and sufficient QG forcing from the upper vort-max may lead to widespread severe weather, especially wind gusts and tornadoes.

DISCUSSION

...W Ireland, Scotland and extreme SW England...

After the warm sector has passed the western half of the British Isles in the late evening / night hours, the cold front will approach Ireland and western UK. A few hundred J/kg CAPE / ICAPE are forecast which should allow a strongly forced but rather shallow convective line that may produce severe / damaging wind gusts. As the non-convective gusts will likely reach values around 25 m/s and the CAPE signal is rather weak, a level 1 should cover the risk of convective events properly. As seen in other similar cases, SRH1 and SRH3 tend to reach extremely high values near the cold front and isolated tornadoes may occur within the line.

...Bay of Biscay, NW Iberia, NW France, British Isles...

A broad number of global models (GFS, ECMWF, GME and others) agree that convection will become rather unlikely in these places (except for NW France in the afternoon hours before the cyclone will reach western UK). The warm front / warm sector region of the cyclone may lead to widespread severe wind gusts over Ireland and UK which are mostly non-convective. In the early morning hours on Monday, the cold front of the low pressure system will arrive at NW France but instability should be too low for deep convection. Some convective enhancement of the wind, especially in the southern Bay of Biscay, cannot be ruled out and therefore a level 1 was issued for those regions which are most likely affected.

[paulster78]

Hmmm..wont be holding my breath, although who knows what surprises this large low pressure may throw up.  This system now developing quickly off the southern tip of Greenland and throwing up a load of lightning strikes already.

http://andvari.vedur.is/athuganir/eldingar/index.html?

[martinastro]

Here comes the storm, she looks nice on SAT24...

http://www.sat24.nl/frame.php?html=homepage

66km/hr gusts already reported in the NW.

I can see lines of weak convection here moving in from the SE along with that cirrus shield.

I'm not holding my breath either Paul 

[martinastro]

[martinastro]

TORRO TORNADO WATCH 2010/008

A TORNADO WATCH has been issued at 17:50GMT on Sunday 7th November 2010

Valid from/until: 17:50 - 13:00GMT on Sunday 7th/Monday 8th November 2010, for the following regions of the United Kingdom & Eire:

Parts of (see map)

Eire

N Ireland

Western and southern Wales

SW & Central Southern England

THREATS

Tornadoes; hail; thunderstorm wind gusts to 55 knots; torrential rain; and isolated cloud-ground lightning.

SYNOPSIS

Rather intense Atlantic storm will push an occluding frontal system into western parts of the British Isles overnight. The triple point is likely to cross Eire and thence into the S Wales/SW England area. To the north of this feature, the eastward progression of the frontal system is likely to become very slow, whereas the southern portion of the front continues eastwards across southern coastal counties of England through Monday morning.

Hi-resolution models simulate a forced line of convection along the cold front/occlusion. In addition, there is the suggestion of misocylones along the front, and given the strong vertical wind shear, and sharp veer across the front, seems reasonable. Stong convergence along the front and INVOF misocyclones should promote fairly strong updraughts in the lower atmosphere. The backed flow, and hence increased low-level shear INVOF misocyclones, and perhaps topographical features, suggests a tornado risk. In addition, strong wind gusts are likely, although these may non-convective in nature at times. Close to the triple-point depression, increased deep lift and the advection of reasonably warm air from the English Channel may enhance the thunder risk, and perhaps pose a risk of hail, locally heavy.

Behind the frontal system, showers and thunderstorms are expected across parts of S Eire, SW England and S Wales through Monday.

Forecaster: RPK

[paulster78]

Thanks for that Martin, risk of tornadoes now, this storm is gonna throw everything at us!  The drop in pressure is remarkable and very fast, looks like it will be sub 960hpa in some areas!!   Very windy and lashing rain with me.

[markt]

Its looking rough!  Anymore updates from you chaps further west? 

[jjb]

That's some pic of the low coming in martin looks like its going to be a rough night ahead batten up the hatches....

[martinastro]

Hi Mark, so far there's been strong wind gusts, my lights have blinked, and there's heavy rain and sleet with the heaviest frontal echoes over Ulster at the moment. There's also been c-g sferics over the Irish sea not far from Wales. There should be a clearance later with showers and t-storms so any late night comet observers may see a few flashes.