Nick F

First widespread risk of hill snow of the season in the north Tuesday afternoon through to early Wednesday, some snow perhaps to lower levels as far south as East Midlands Tuesday night too. View the full blog here

Increasing support now from ENS for a Wly/NWly flow to take over from mid-week next week through to mid-November, as 500mb Polar Vortex over northern Canada shifts east across Greenland combined with a strong Azores high which ridges NE toward UK at times. More unsetttled towards the north of the UK in such a pattern. Gone is any -NAO signal for now. BUT, with the MJO moving through phases 7 and 8 around mid month, maybe even 1 at a push and longer range EC, GEFS and others (GloSea5) hinting that we may see blocking and colder/drier weather return towards the end of the month. So, no point worrying about the pattern change to more mobile next week just yet, could be a temporary thing as the PV still shows no signs of becoming strong or lingering over Greenland.

Following temperatures in the high teens today and as high as 22C in north Wales, the forecast maximum temps of 9-10C in the south on Wednesday will surely be noticeable, even if they aren't exceptional for early November. Perhaps colder still on Sunday, GFS forecast maxes of 7-8C across the south. Not really any signal for snow away from the hills in the north, but it is only early November after all. GFS/EC operationals and GEFS and EPS 500mb mean today still keen to bring a 500mb vortex east into Greenland later in the medium range, which would eventually cause the mid-Atlantic/Greenland/Iceland ridge to collapse south and allow low pressure to drop SE from Greenland eventually feeding into the Euro trough. However, positive signs IMO for coldies longer term, with the latest ECMWF ensemble system MJO forecast moving through colder phases of 7 and 8 towards mid-November. Take in the lag, that would perhaps impact for the 2nd half of November: Also strong indications of an early-season split in the stratospheric polar vortex over the coming weeks which, if it works its way down to the trop, will increase the likelihood of high latitude blocking as we head into early winter. Though whether these blocks, if they form, position favourably will be another hurdle to worry about nearer the time. All to play for if you like your November and early winter average to cold and certainly no signs of mild zonality taking over anytime soon.

As the new month of November starts, the weather changes with cooler conditions spreading south, with overnight frosts returning. Turning even colder next weekend, as colder air from the arctic arrives. View the full blog here

A look at the 00z EC ens mean/anomaly suggests the mid-N Atlantic / Sern Greenland +ve height anomaly relaxing and slipping S/SW by day 10 - as 500mb vortex over Nern Canada shifts slowy E into Greenland. So the 00z deterministic maybe on to something wrt the flow shifting back to a NWly. But ens mean/anomaly charts are by no means a foregone conclusion that far out.

The scenario of the low pressure system dropping SE across Nern Britain then on across N Germany & Denmark in tandem with height rises north to Iceland & Greenland next weekend seems to be common ground for a while now in the models. However, questions marks toward the end of the medium on range over how long the greeny ridge and resultant cold N to NEly flow developing end of next w/e will maintain. A look at the northern hemisphere view from the operationals this morning has GFS maintaining the ridge to the N and NW into the extended range but ECM breaks down the ridge as it has a lobe of the polar vortex over northern Canada drift E across Greenland toward the end of the medium range, which causes low(s) to develop off Sern tip of Greenland then slide SE toward northern Scotland. More runs needed, wouldn't place my money on the 00z ECM operational just yet.

Blocking high pressure looks to continue to dominate the UK weather through to the end of October and perhaps into early November. View the full blog here

UK Severe Convective & Storm Forecast - Issued 2016-10-16 08:55:53 Valid: 16/10/2016 0600z to 17/10/2016 0600 CONVECTIVE / STORM FORECAST - SUN 16TH OCTOBER 2016 Click here for the full forecastCheck the full storm forecast here

Storm & Convective Forecast Issued 2016-10-15 10:22:26 Valid: 15/10/2016 0600 to 16/10/2016 CONVECTIVE / STORM FORECAST - SAT 15TH OCT 2016 Synopsis Upper and colocated surface will low in the southwest approaches will drift slowly NE across southern Ireland by early Sunday. Associated cold front will lift north across the UK and Ireland during Saturday, clearing N Scotland by midnight. Shortwave trough ejecting NE ahead of upper low and associated frontal wave will bring an area of squally heavy thundery downpours NE across southern England, Midlands, E Anglia and Wales this afternoon and evening, followed by further showers towards southern and western coasts of England, Wales and EIRE overnight that could be thundery. ... S ENGLAND, WALES, MIDLANDS, E ENGLAND AND IRELAND ... Cold front lifting north brought a line of heavy rain and isoated thunder earlier this morning across far SW England, SW Wales and southern Irish Sea. Now Water Vapour imagery, 500mb relative humidity and vorticity charts indicate a marked shortwave trough moving NE towards SW England this morning - stronger lift and dry mid-level air of the shortwave is supporting an area of heavy convective rainfall with embedded isolated thunder and lightning now moving in across Cornwall and Brittany. This area of heavy rain with isolated thunder will continue NE across S England, Wales, Midlands and E England through the afternoon and evening. Strong southwesterly flow aloft and deep layer shear in the order of 30-40 knots will be sufficient for organisation of convection/storms - with a risk of heavy rainfall leading to localised flooding and isolated strong wind gusts possible. Have issued a MARGINAL risk for localised flooding towards S England - where higher rainfall signal is indicated. Further heavy showers will follow this convective/thundery area of rainfall from the southwest to affect southern and western coastal areas of England, Wales and EIRE this evening and overnight, as steep lapse rates overspread southern and western areas. Some heavier showers producing isolated lightning towards coasts where warm SSTs create stronger updrafts/high cloud tops through cold air aloft. Isolated localised flooding, hail and gusty winds will be possible with these showers. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-10-15 10:22:26 Valid: 15/10/2016 0600 to 16/10/2016 CONVECTIVE / STORM FORECAST - SAT 15TH OCT 2016 Click here for the full forecastCheck the full storm forecast here

Low pressure takes control this weekend, turning it unsettled across all parts. But it looks a brief blip before it turns drier again next week, as high pressure returns. View the full blog here

IMO Hurricane Nicole will be instrumental in rebuilding that H500 anomaly over Scandi/Barents as indicated by the 00z GEFS and EPS H500 anomaly charts into the extended range The tropical warmth wrapped in Nicole is indicated to be transported poleward NE toward Norwegian Sea in the mid-levels - which will rebuild the block and cause troughing pushing east across the Atlantic to disrupt SE once the block re-intensifies to the NE: It appears high latitude blocking will be with us until the end of October, 00z GEFS even hints at retrograde of the anomaly, whether it hangs on into November, when the air sources to the east will get progressively colder, remains to be seen. But the persistence of the blocking signal to the NE certainly an early positive sign for coldies as we head into the cold season.

UK Severe Convective & Storm Forecast - Issued 2016-10-13 08:37:02 Valid: 13/10/2016 0600 - 14/10/2016 0600 CONVECTIVE / STORM FORECAST - THURS 13TH-OCT-2016 Click here for the full forecastCheck the full storm forecast here

Cool pool drifting west over warmer N Sea creating pool of steep lapse rates and CAPE which will drift into E England Monday: Storm & Convective Forecast Issued 2016-10-09 22:10:00 Valid: 10/10/2016 0600 11/10/2016 0600 CONVECTIVE / STORM FORECAST - MONDAY 10TH OCTOBER 2016 Synopsis Beneath persistent upper ridge over Scandinavia - an upper low with a deep mid-level cold pool (temps of -25 to -30C at 500hPa) over Denmark Sunday lunchtime will drift west across the North Sea overnight and arrive across E England during Monday. A shallow surface low/wave will also drift west across Low Countries/S North Sea on forward/western side of upper low, with associated wrap around occluded front pushing in across Ern UK by noon Monday. ... E ENGLAND ... Cold mid-level temperatures of upper low atop of relative warm North Sea Surface Temps (SSTs) between 13-17C in the southern part will produce a pool of steep lapse rates / a few 100 j/kg CAPE drifting W into E England during Monday. This will support heavy showers and perhaps some thunderstorms capable of producing hail, squally winds, and isolated minor surface flooding. Vertical shear will be rather weak - so no severe weather is anticipated. However, lower Lifted Condensation Levels (LCLs) over the N Sea thanks to greater moisture and relative warm SSTs along with some wind local convergence near east coasts may allow more buoyant updrafts to rotate to produce funnels or even one or two waterspouts. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-10-09 22:10:00 Valid: 10/10/2016 0600 11/10/2016 0600 CONVECTIVE / STORM FORECAST - MONDAY 10TH OCTOBER 2016 Click here for the full forecastCheck the full storm forecast here

Eye wall just a few miles off the Florida coast now, gust of 100mph recorded USAF tower near Cape Canaveral - risk of 115mph+ gusts along Florida's Space Coast over next few hours.

Fortunately for eastern Florida the strongest winds are on the eastern flank of eye wall well out at sea, land interactions lessening winds inland over eastern Florida. Still risk of hurricane force winds for Florida's space coast though. Love this twitter comment

Category 4 or even 5 Hurricane Matthew to hit Florida early Friday - bringing destructive winds, life threatening storm surge and flooding rains. View the full blog here

Trend west of #Matthew track continues:

Storm & Convective Forecast Issued 2016-09-30 22:09:05 Valid: 01/10/2016 0000 TO 02/10/2016 0000 CONVECTIVE / STORM FORECAST - SAT 1ST-OCT-2016 Synopsis A well-defined upper-level low/trough in the strong belt of upper westerlies covering northern Europe will shift east across the UK during Saturday. At the surface, a shallow area of low pressure will cross S Ireland Friday night, then S Wales and S England on Saturday, slightly deepening to around 1003mb as it does so. Wrap around occlusion moving east with the low will bring outbreaks of heavy rain and also airmass will become sufficiently unstable for some thunderstorms. ... IRELAND, ENGLAND and WALES, S SCOTLAND ... Water Vapour imagery Friday evening shows a well-defined dry air vortex of upper low/trough crossing S Ireland, with associated lift and increasingly colder mid-level temperatures atop of relatively warm SSTs increasing low-level lapse rates/CAPE and enhancing convection over western areas. Heavy showers and a few isolated thunderstorms will drift east in across Ireland, S England, Wales, Midlands and NW England Friday night. Then thundery downpours could occur across much of England and Wales and perhaps S Scotland during Saturday wherever lift is enahnced and/or pockets of instability occur where the sun comes out / or over warm SSTs beneath cold air aloft spreading east. These heavy showers and perhaps storms will organise into bands locally due to combination of large scale ascent aloft with passage of upper low, local surface wind convergence near slack low pressure centre moving east and lift along wrap around occlusion. And with low-to-mid-level winds becoming light as upper/surface low passes through, showers/storms will become slow-moving bringing a risk of localised flooding where cells train over one area. Storms may also be accompanied by hail and gusty winds too. Although deep layer shear will become weak under upper low passing through, low-level shear will be enhanced by backing of winds with passage of low ... particularly near coastal areas ... and also enahnced by wind convergence. This increase in LL shear locally may allow more stronger/bouyant updrafts over warm SSTs to rotate and tighten to form isolated tornadoes or waterspouts. Other than the potential for some very localised areas of flooding, the risk of severe weather looks minimal due to cloud cover and extensive non-convective rainfall limiting potential instability to give a signal for a low/isolated storm coverage - so a general thunderstorm risk will suffice for now. Issued by: Nick Finnis

UK Severe Convective & Storm Forecast - Issued 2016-09-30 22:09:05 Valid: 01/10/2016 0000 TO 02/10/2016 0000 CONVECTIVE / STORM FORECAST - SAT 1ST-OCT-2016 Click here for the full forecastCheck the full storm forecast here

UK Severe Convective & Storm Forecast - Issued 2016-09-30 07:27:33 Valid: 30/09/2016 0600 to 01/10/2016 0600 CONVECTIVE / STORM FORECAST - FRI 30TH-SEPT-2016 Click here for the full forecastCheck the full storm forecast here

After a cool down over the next few days, parts of the UK look set to see an Indian Summer during the first week of October on the back of one of the warmest Septembers in recent years. View the full blog here

More for northern Britain and EIRE really, but as well as winds gusting to 50-60mph over Scotland, perhaps 60-75mph far NW Thursday morning, some lively and perhaps thundery showers too: Storm & Convective Forecast Issued 2016-09-28 22:48:32 Valid: 29/09/2016 00z to 30/09/2016 00z CONVECTIVE / STORM FORECAST - THURS 29TH-SEPT-2016 Synopsis Long-wave upper trough to NW of UK edges SEward across the UK during Thursday. A deep area of low pressure passing close to northern Scotland overnight runs east and merges with low pressure complex over Norway. Cold front associated with this low will clear SE UK Thursday morning, with a cool Pm flow following which will become increasingly unstable across Scotland and N. Ireland. ... SCOTLAND, N. IRELAND, EIRE and NW ENGLAND ... Cold front sliding SE across England and Wales is unlikely to produce any strong convection, due to poor lapse rates/ warm mid-upper temps above front. Forward side of large-scale upper trough pushing SE across the UK will introduce sufficiently cold and dry mid-level air atop of warm seas and modest land heating to create an increasingly unstable Polar maritme airmass across northern mainland UK and EIRE. So across the above areas expect scattered or numerous heavy showers, some of which will be accompanied by hail and thunder. Vertical deep layer shear will tend to become weak as the greater instability arrives from the NW in the morning and into the afternoon. Though one or two troughs and occluded fronts in the strong westerly flow could organise convection sufficiently to bring a risk of localised flooding. There is also a risk of strong and perhaps isolated damaging convective gusts associated with downdrafts bringing down strong upper winds within heaviest showers or storms across central Scotland in particular. Therefore have issued a MARGINAL risk of severe weather here.

UK Severe Convective & Storm Forecast - Issued 2016-09-28 22:48:32 Valid: 29/09/2016 00z to 30/09/2016 00z CONVECTIVE / STORM FORECAST - THURS 29TH-SEPT-2016 Click here for the full forecastCheck the full storm forecast here