Good evening. Here is the report on the midday outputs from GFS, UKMO, GEM, NAVGEM and ECM for tonight Monday July 22nd 2013.
All models show a breakdown in the hot spell over the coming 48 hours. There is a growing risk of thunderstorms across the UK in the coming 48hrs with probably more Northern and Eastern parts likely to see some severe and noteworthy storms later tomorrow. Cooler and fresher conditions will be making some inroads slowly in from the SW through the rest of the week with further thundery showers or rain at times but still with a fair amount of dry, bright and reasonably warm weather in between. There looks little to change this overall showery period over the weekend either with some bright and dry weather at times too.
GFS shows no large changes next week too with slack Low pressure over the North or to the West with further showery rain at times as well as further warm conditions at times in the SE. Things thereafter do turn more generally cooler and unsettled as they have shown to be for umpteen runs now with rain and strong winds at times and average temperatures for all areas late in the run.
The GFS Ensembles tonight show a cool off under way over the coming days. The main cooling event does not show its hand much before the 29th with a showery week to that point before a more Westerly feed delivers fronts and occasional rain moving West to East across the UK.
The Jet Stream is soon to realign across the Atlantic troughing South to the West of the UK and returning North over the UK enhancing very warm air still on the continent. The unsettled and cooler weather will affect Western areas most with some fine and warm weather still to be found on the returning flow in the East.
UKMO still continues to show slack Low pressure over and to the West of the UK with a mix of drier intervals and heavy, thundery showers at times continuing over the UK through the weekend.
GEM tonight shows a showery spell too at the weekend with temperatures still well up to and a little above average. Through the following week winds turn more Westerly with cooler temperatures bringing rain fronts across the UK in average temperatures by then.
NAVGEM tonight shows a very showery spell too as Low pressure very slowly migrates from the SW approaches to Northern Britain to begin next week.
ECM shows a new surge of thundery Low pressure moving slowly North at the weekend with warm and humid weather with thundery rain, especially in the SE gradually being replaced on Sunday by cooler and more showery weather moving north over Southern Britain. Later in the run Low pressure retains the upper hand swinging up close to Western Britain and North to Scotland with some wind and rain for all. Warm weather is maintained close to the SE with temperatures above average at least and a thundery Low looks likely to affect these areas with more showers and thunderstorms at the end of the run.
In Summary the biggest shift in output over the past few days has been the slow shift West of the UK trough with the hot plume heading North over Europe with potentially record breaking heat over there around the weekend. For us the shift means that Eastern and SE Britain could tap into this air and find temperatures still in the very warm category with the potential for further thundery weather as cooler uppers buffer the heat over the East. Further North and West the weather though cooler than of late will never be cold with occasional rain and showers around here too.
Originally Posted by: GIBBY