Storm Forecast
Valid: Thu 25 Jun 2026 06:00 to Fri 26 Jun 2026 06:00 UTC
Issued: Wed 24 Jun 2026 20:39
Forecaster: TUSCHY
A level 2 was issued for N Ireland into parts of Scotland and England mainly for large hail with peak size in excess of 5 cm possible. An isolated strong tornado event is possible over N Ireland and SW Scotland.
A level 1 surrounds the level 2 mainly for large hail, some gusts and heavy rain.
A level 1 was issued for NW and SW France mainly for hail, gusts and heavy rain.
A level 1 was issued for N Spain mainly for hail, gusts and heavy rain.
A level 1 was issued for SW Russia mainly for large hail, strong to severe gusts and heavy rain.
Numerous level 1 areas were issued for parts of the CNTRL Mediterranean mainly for isolated heavy rain, hail and gusts.
SYNOPSIS
The main player over Europe remains a warm-core blocking anticyclone ober W Europe, which gradually drifts E towards CNTRl Europe. Ongoing intense WAA regime affects most of W/NW Europe with probably historic heat peaks all over the place.
This anticyclone gets framed by numerous troughs. One crosses Iceland east and it grazes far NW Europe with improving synoptic-scale lift and mid/upper level winds.
The long-lived trough W of Portugal lifts N only a bit but a lead impulse affects the Bay of Biscay and probably W France/SW UK later in the forecast.
Finally the positive tilted low pressure channel over SE Europe persists with a structuring IPV maximum SW of Greece, which drifts E/NE.
A well defined warm front over Ireland to England lifts N/NW during the day and affects also Scotland from the S. Otherwise this will be another day for many parts in Europe, where orography or mesoscale dynamics dictate the general thunderstorm risk.
DISCUSSION
... Ireland and UK ...
A pronounced warm front lifts N during the day with impressive moisture readings along the front itself but also in the open warm sector. In fact, PWAT runs in record territory for this time of year. BL mixing ratios in the mid tens along the edge of a northward fanning EML yield MUCAPE in the 1000-2000 J/kg range for Scotland, increasing to more than 3500 J/kg towards Ireland. These are extreme values for these areas and well highlighted in latest EFI MUCAPE SOT forecasts in excess of +8!
During the day, capped conditions should preclude CI for most parts. One exception will be the tightening frontal boundary NW/N of Ireland and W of Scotland with cross sections revealing a strongly sloped front towards the NW. The eastern fringes of the sloped front turn very unstable (but still capped) during the day as the hot/humid airmass intersects the front from the SE. Strong/persistent lift beneath a more anticyclonic shaped upper flow regime causes a SW-NW aligned band of heavy precipitation with a few embedded WAA driven elevated thunderstorms. This activity remains non-severe.
During the late afternoon onwards, the N/NW-ward sweeping very unstable airmass continues to pile up along the sloped front with extreme and probably record breaking BL moisture content f.ex. over Ireland (e.g BL mixing ratios up to 16 g/kg with 2m dewpoints in the mid twenties).
The combined effect of a gradual cool-down along the cap and persistent cross-isentropic ascent in a WAA regime just ahead of an IPV lobe from the W should increase CI chances during the late afternoon/early eveing onwards over N Irland
into W Scotland.
Kinematics stay impressive during the forecast with DLS in the 25-30 m/s range and a tad weaker for the 3 km shear layer. Capping will initially lower shear magnitude substantially but updrafts probably grow deeper into the BL as they intensify, so latest expectation is for thunderstorms to erupt in an extremely favorable CAPE/shear space (SOT up to +8!). Main caveat will be how far S into Ireland and Scotland storms can evolve with the first round (until midnight).
Fat mid-level CAPE with adequate shear and tropospheric moisture most likely support severe haistorms with hail diameter in excess of 5 cm well possible. Heavy to excessive rain will be another issue as well as strong to possible severe gusts although the rather stable BL could lower that risk somewhat. Finally a tornado risk exists over N Ireland, where BL turns more unstable with a very fvorable LL CAPE/shear overlap. A strong event is possible.
A similar CAPE/shear space exists over parts of Scotland with all kind of hazards forecast. The large to very large hail risk dominates the hazards but a regional augmented tornado risk also exists near Glasgow and further W/NW, where LL capping weakens.
Beyond midnight, we see improving synoptic scale lift beneath the right entrance region of an intensifying 120 kt upper jet to the NW. Upper divergence spreads deeper into the unstable warm sector, so expect scattered CI over N-England into S Scotland. Abundant MUCAPE and modest shear support severe thunderstorms with large hail and heavy rain. Once again, any updraft, rooting deeper into the BL could produce hail in excess of 5 cm and severe gusts. Heavy to excessive rain will be another hazard. We therefore expanded the level 2 more to the SE to cover also this activity.
More elevated convection (partially also advected from France) could affect SW UK beyond midnight, probably also incoming from the S. Stronger cap should turn the focus more to large hail and heavy rain. MUCAPE in the SW still exceeds 2000 J/kg with shear improving from the S betimes, so again very large hail events cannot be ruled out. That's why we expanded the level 2 towards SW UK. Storm coverage becomes more uncertain but should justify a level 2 upgrade with latest NWP guidance.
The level 1 and 2 areas were also expanded far NE over the North Sea, as maturing supercells or bow echoes cross the NE-ward sprawling CAPE plume towards SW Norway. Large hail and severe gusts will be a hazard for offshore activities. This also includes offshore areas off NE England during the end of the forecast.
... France ...
The lifting trough and lead impuls spark scattered elevated thunderstorms during the afternoon onwards and numerous growing clusters evolve over W France. Part of this activity could move N towards the English Channel into SW/S UK, inducing CI in that area. Deep BL mixing support a strong to severe gust risk next to hail with a more pronounced heavy rain risk over NW France.
Another day with mountain convection along the SW Alps spreading into SE France with heavy rain, hail and gusts.
... N Spain ...
A pronounced trough axis lifts N with scattered CI from noon onwards. Clustering convection with strong to severe gusts, some hail and heavy rain affect N Spain before spreading offshore towards the Bay of Biscay.
This convection probably sparks clustering convection over SW France (see paragraph above).
... Far SW Russia ...
An eastbound moving trough crosses an unstable and sheared airmass with point source soundings indicating up to 2000 J/kg MUCAPE and 15 m/s DLS. Organized multicells and isolated supercells bring large hail, strong to severe gusts and heavy rain.
... CNTRL Mediterranean ...
Elsewhere (mainly over the CNTRL Mediterranean) another active day with diurnal thunderstorm activity is forecast. Small level 1 areas were added, where ingredients point to the highest risk of some hail, heavy rain and gusts.
