Storm Forecast
Valid: Wed 08 Apr 2015 06:00 to Thu 09 Apr 2015 06:00 UTC
Issued: Wed 08 Apr 2015 06:24
Forecaster: PUCIK

A level 1 was issued for E Sweden, S Finland, N Estonia and extreme NW Russia mainly for severe wind gusts and to the lesser degree for tornadoes.

A level 1 was issued for Morocco mainly for large hail and severe wind gusts.


SYNOPSIS

An omega-like pattern is observed with a ridge stretching over much of W Europe and two cyclonic vortices at its flanks - one off the W Iberia coastline and another one centered over Greece. Both will be accompanied by isolated to scattered DMC, especially over the sea. Continental Europe will be mostly under stable airmass, too hostile for any thunderstorm. More active pattern prevails over Scandinavia with strong northwesterly flow advecting cold and slightly unstable airmass towards W Russia.

DISCUSSION

... E Sweden through S Finland towards N Estonia and NW Russia ...

Behind the cold front, airmass characterised by lapse rates of 7.5 to 8 K/km in 800 to 600 hPa layer will advect over the area. Lapse rates of this magnitude are confirmed by 00 UTC Orland sounding. However, with meager low-level moisture and mixing ratios around 3 g/kg, only marginal CAPE can be expected, perhaps on the order of 10 to 100 J/kg. With no strong forcing factor (trough already moved over the region), scattered, low-topped DMC is simulated.

Strong vertical wind shear is forecast, but will be mostly confined to the lowest 1 km with around 15 m/s of bulk shear simulated in this layer. Unidirectional shear profiles are forecast with 850 hPa wind speeds between 25 and 30 m/s. In such configuration and with weak instability, sustained supercells are not likely, but are not completely ruled out along with a chance for tornado. However, primary threat should be severe wind gusts, which may accompany any shower or tstm, regardless of its organisation.

... Morocco ...

On the forward flank of the low, strong SW-ly flow is simulated with 20 to 25 m/s of DLS. At the same time, as NW-ly low-level flow advected moist airmass over the land, CAPE values around 500 J/kg should be possible. Due to the strong DLS, supercells and well-organised multicells are possible with attendant threats of large hail and severe wind gusts.