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South East England and East Anglia weather discussion/chat - 15th November 2015 onwards


Captain Shortwave

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Estofex also out with a Level 1..

 

 

 

Storm Forecast
Valid: Tue 17 Nov 2015 06:00 to Wed 18 Nov 2015 06:00 UTC
Issued: Mon 16 Nov 2015 22:35
Forecaster: GROENEMEIJER

A level 2 was issued for the Benelux countries, a large part of Germany, the NW Czech Republic and W Poland mainly for severe wind gusts and to a lesser extent for tornadoes.

A level 1 was issued for and area surrounding the level 1, including S Ireland, the S United Kingdom, larger parts of Poland and the Czech Republic, all of Germany and parts of Denmark, France, Switzerland, and Austria, mainly for severe wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

During the forecast period, a strong mid-level jetstreak will rapidly enter western Europe from the Atlantic Ocean. On the southern flank of an associated eastward moving area of low pressure, a strong wind field develops and moves across South Ireland, the southern UK, Benelux, Germany and later Western Poland. Within the seasonably mild and humid air-mass organized severe convective storms are expected.

DISCUSSION

S Ireland, S UK, North Sea, Bneelux, N France, Germany, Poland, Czech Republic, W Poland, N Austria...

Upon approach of a strong mid-level jet, upward vertical motion will ovespread the mild and humid warm sector (with dew point temperatures of 11-14 C) first across southern Ireland, then the southern UK and subsequently further eastward. In response, surface-based convection coverage will increase and probably organize linearly. These storms will be embedded in a strong wind field and gusts that they produce will likely attain severe levels (> 25 m/s).

According to the GFS model, the strongest upward motion should be in the left exit region of the jet streak that becomes particularly focused during the evening. This area of upward motion will move from west to east across the indicated level 2 area, i.e from the Benelux Countries to W Poland in the 21 - 06 UTC time frame. It appears likely that well-organized linear convection with a particularly high risk of severe wind gusts will develop there as the system moves eastward. This will happen in an environment that - per GFS - will boast 200-400 J/kg CAPE, which is quite substantial for the time of year. 

The environment of the convection is characterized by strong wind shear (~ 30 m/s 0-6 km) particularly in low levels (~ 15 - 18 m/s 0-1 km). If mor or less isolated convective storms are able to form, a high tornado threat would be present, but it appears more likely that a line will be the dominant mode given the strongly localized forcing and absent CIN. 

As it presently seems unlikely that a large wind shift will occur across the line, the risk of tornadoes wih the line seems to be redduced, in accrodance with the results of Clark and Parker. Nevertheless, a few tornadoes cannot be ruled out given the otherwise favourable circumstances including high wind shear, very low LCL and the strong forcing for upward motion that may locally steepen lapse rates considerably.

Behind the area of greatest convective activity, strong non-convective winds are expected occur with similar or even higher gusts.

post-12648-0-65729600-1447751402_thumb.p

 

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Posted
  • Location: Bedfordshire 33m above mean sea level
  • Weather Preferences: Snowy and thundery.
  • Location: Bedfordshire 33m above mean sea level

Heavy drizzle here, no wind perfect day for taking bubs school project into school. NOT.

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Posted
  • Location: St rads Dover
  • Weather Preferences: Snow, T Storms.
  • Location: St rads Dover

Latest surface obeservations showing the low now down to what looks like 978mb, although it's hard to tell with the chart so busy

wow that's much lower than what was showing on the models.

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Posted
  • Location: Boxley - Kent 133.9 m ASL
  • Weather Preferences: Sunny Days and a little Snow.
  • Location: Boxley - Kent 133.9 m ASL

Wait a minute!

 

the 06Z has gone nuts!

 

uksnowrisk.png

uksnowrisk.png

uksnowrisk.png

If that comes off I'll meet you at The Strand for a snowball fight ;)

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Posted
  • Location: Alresford, Near Colchester, Essex
  • Weather Preferences: As long as it's not North Sea muck, I'll cope.
  • Location: Alresford, Near Colchester, Essex

I think the weather over the weekend will be more notable, from a cold perspective and possibly for strong winds here too. I think tonight's event might be not a lot more than a nuisance sleep disturber, for the south of our area - more windy for more northern areas though.

 

We could be lucky that we're in a neap tide phase this weekend.

 

post-11059-0-87197000-1447760509_thumb.p

Edited by Steve C
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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

Wait a minute!

 

the 06Z has gone nuts!

 

uksnowrisk.png

uksnowrisk.png

uksnowrisk.png

Glory to God! This thread would implode temporarily. :clap:

Regarding dew points I'll look into that now...

Surrey it should be sub zero for such a cold airmass.

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Posted
  • Location: Alresford, Near Colchester, Essex
  • Weather Preferences: As long as it's not North Sea muck, I'll cope.
  • Location: Alresford, Near Colchester, Essex

What's dew point looking like Saturday?

 

Pretty good on the face of it. Here is 18:00 from NMM.

 

post-11059-0-45380500-1447763785_thumb.p

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Posted
  • Location: Moreton, Ongar Essex,
  • Weather Preferences: love snow and frosty mornings
  • Location: Moreton, Ongar Essex,

Winds picking up here and starting to rain  :)

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Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

post-19153-0-07883600-1447763858_thumb.gpost-19153-0-97634000-1447763869_thumb.gpost-19153-0-58920200-1447763840_thumb.g[post-19153-0-29261000-1447763909_thumb.g

DP are not of a concern here for the very bulk of the day aside from early in the morning progressively colder air working its way towards us through the course of the day.

Edited by Daniel*
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