Storm Forecast
Valid: Mon 22 Jun 2026 06:00 to Tue 23 Jun 2026 06:00 UTC
Issued: Sun 21 Jun 2026 14:03
Forecaster: TUSCHY

A level 1 was issued for SW UK mainly for isolated hail and gusts.

A level 1 was issued for NW Spain into far NE Portugal mainly for isolated hail, gusts and heavy rain.

A level 1 was issued for parts of SE Europe mainly for hail, gusts and heavy rain.

SYNOPSIS

A deep barotropic blocking anticylone is centered over SW into W Europe. An extreme warm-up of the lower troposphere keeps most parts of this ridge capped despite a few regions with somewhat enhanced probabilities (Spain/UK).

E of the anticyclone, a southward shifting cold front interacts with an extensive plume of rich moisture and instability, so scattered to widespread CI is forecast. Weak dynamics and kinematic preclude organized DMC activity for most parts.


DISCUSSION

... Parts of Germany to the W Balkans towards Italy and S Belarus ...

Ahead of a slowly southward sagging cold front, rich BL moisture exist with BL mixing ratios in the 12-14 g/kg range. At least partially overlapped by steepened mid-level lapse rates, this supports MUCAPE in the 1500 to 2500 J/kg range. However, especially towards Germany, a drying trend at mid-levels should keep ECAPE much lower.

The whole area is avoid of noteworthy synoptic-scale support, so CI will be mainly driven by orography/mesoscale boundaries or the cold front itself. Scattered pulsating and partially clustering thunderstorms pose a local hail and strong to severe downburst risk, also with heavy rain. A regional clustering of some reports is possible and a confined level 1 was added, where confidence is highest for best updraft strength. Elsewhere, confidence in further upgrades remains too low for adding more level 1 areas.

... NW Spain and far N Portugal ...

Placed beneath synoptic-scale subsidence for most of the day and with lingering capping issues, CI is uncertain and probably more isolated in nature. A few evening/nocturnal storms are still possible, especially with increasing upslope component of the BL flow. Still abundant MUCAPE and modest shear point to a hail and strong gust risk with a level 1 added.

Same for the forenoon risk of thunderstorms mainly offshore of W Portugal. In case a thunderstorm grazes the coast, hail, gusts and heavy rain will be the main issue. No level 1 was added

... Parts of UK ...

This is a low confidence forecast with a northward surging warm front. The warm sector airmass features rich BL moisture and placed beneath a N-ward fanning EML, MUCAPE in the 1000-2000 J/kg range seems plausible for SW-UK. Drier air filters in from the E and limits the warm sector further E.

Substantial warm-up in the lower troposphere with H85 temperature in excess of 20C causes strong capping and with a building ridge, not much background support is forecast. However, a short wave crosses the warm front E but pobably too far N for CI within the warm sector. We still issued a low prob. lightning area for parts of the warm sector to higlight a low chance for incoming elevated convection from the SW to root deeper into the unstable warm sector with better effective shear. Any stronger updraft could temporarily produce some hail and gusts.

This loaded gun situation bears watching closely as CAPE shear space would otherwise be pretty supportive for organized DMC activity. EZ f.ex. is still 2K cooler along the periphery of the cap with much more CI than most other models. Nowcasting is needed for this event as otherwise a strong cap could cause nil CI.

A bit more active CI is forecast next to the warm front itself and this was highlighted by a high prob lightning area. Isolated hail and gusts are possible with eastward moving convection.