Hi everyone. A little late today but here is the report from the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday September 17th 2013.
All models show a cool and unstable airflow over the UK with a wave depression running SE then East across Southern and SW areas of the UK through the day with a period of rain, sometimes heavy here. The North and East will continue bright and showery and all areas away from the far SW will be cool. Tonight sees changes as the rain steadily clears East out of the South tomorrow with rising pressure over the UK to give a dry and bright day tomorrow with just isolated showers here and there in the North. Through Thursday a new depression will be crossing East to the North of Scotland with it's fronts crossing the UK with rain followed by clearer weather again with a few showers in the NW. It will become somewhat less cool. Friday should be a dry and bright day for most with just isolated showers possible in the North. Then on Saturday winds back SW and warm and moist air is filtered NE on a warm front bringing low cloud and drizzle for a time to many parts to start the weekend, especially in the North and West. By Sunday this is shown to be pulled away North with skies breaking over the UK with some warm or very warm sunny spells developing on Sunday as High pressure centres close to the SE.
GFS then shows a sustained fine spell for quite a while in the second half of it's run with dry, bright days with misty and sometimes foggy nights. Late in the output Low pressure from the Atlantic does gradually exert it's influence towards Northern and Western Britain and the strongest warmth late in the weekend and start of next week does ease away but all in all not a bad GFS operational run today.
UKMO shows warm SE winds wafting NW over the UK from Europe with High pressure close to the SE. Most if not all areas would be fine and warm by day with sunny spells and patchy mist and fog problems overnight.
GEM is very anticyclonic today with High pressure having arrived at the weekend sustained for the rest of it's run close to or over the UK with fine and quite warm conditions but again with fog problems quite hazardous overnight, slow to clear in the morning's locally.
NAVGEM paints the same picture with High pressure dominant over the UK at the start of next week.
ECM also shows High pressure over the UK dominant next week before it shows signs of slipping further North later next week with fronts queuing up to the SW with rain knocking on the door of the far West late next week. As with the other output fairly warm conditions by day would be balanced by cool and misty nights and mornings.
The GFS Ensembles show a distinct and sustained period of above average uppers from the weekend and through next week only easing off to more average levels at the end of the run. Rainfall is very limited for all areas as the High pressure becomes influential picking up a bit in quantity at the end of the run as low pressure battles the high for supremacy. With such mild uppers above and radiation loss under clear skies at night mist and fog near the surface could become quite a hazard night and morning.
The Jet Stream Ensemble show the current NW to SE flow over the UK backing over the next few days SW to NE as well as being pumped north clear of the UK at the weekend and through much if not all of next week.
In Summary a settled spell is on the way. We have more or less universal support now for a spell of fine and potentially warm early Autumn weather next week though we will be reminded that we are now into Autumn by the chance of extensive mist and fog problems night and morning almost anywhere. High pressure is shown by all models to settle over or near the UK for quite some time this morning with the longer range models only showing incremental evidence of a potential breakdown from the West later in their outputs. So when compared to the early Autumn type weather at the other end of the spectrum that we will all experience through the remainder of this week it is a good example how September in the UK can offer some diverse and wide ranging of weather types.
Originally Posted by: GIBBY