Astronomy, Photography and Weather

General Category => Weather & Atmospherics => Topic started by: martinastro on November 05, 2009, 08:17:23 pm



Title: Convective Outlook Ireland & UK - Thurs Nov 6th
Post by: martinastro on November 05, 2009, 08:17:23 pm
(http://i33.tinypic.com/24ot1y8.jpg)

Slight Risk of Post Frontal coastal Showers West Ireland & Southern UK 09Z-00Z

Slight Risk of Tornado Development 06Z-00Z Southern Ireland & Southern UK regions 06Z-00Z

Current models predict heavy rain across the UK & Ireland through much of Friday. Particular attention is given to the cold front specifically where embedded stronger cells could develop as an 800 mb dry jet rapidly overruns dynamic forcing along the frontal boundary. Streamlines look to be at a tangent to the cold front suggesting that a squall line will be unlikely, though bowing line segments will be more likely close to the UK south coast as the cold front arcs backwards and dry air is fed into the rear of the cloud tops utilising potential instability to the max. Given that the steering winds will be less than of Tuesday, the progress of the cold front looks to be much slower and hense forcing directly at surface should be less. Thus the risk of tornadoes 'would seem' slightly less!!

Friday nevertheless has certain advantages in that the mid level lapse rate will be steeper, dry air is at the optimum height ie. 800mb upwards. This co incidentally ties in with a strong low level jet stream with much better veer at surface. So all in all any tornado development will have the potential to rotate fast with a slower forward momentum. Typical damage (if any) might show long, broader tracks with better twisting of trees and debris carried aloft for great distances. Any funnel development would be much more visible. In addition to this any man made structures could be subject to much more abrupt changes in pressure with subsequent roof damage. (All hyperthetical at this point)

So in short whilst the risk of tornadoes might seem less ATM. It would not take much to increase the risk to moderate.