Storm Forecast
Valid: Mon 15 Feb 2016 06:00 to Tue 16 Feb 2016 06:00 UTC
Issued: Mon 15 Feb 2016 00:20
Forecaster: VAN DER VELDE
A level 1 was issued for Sardinia, central Italy and the western Balkan mainly for chances of isolated tornadoes, severe convective wind gusts and chances of excessive convective precipitation.
A level 1 was issued for coastal areas of Morocco and Algeria mainly for isolated tornadoes (waterspouts) and chances of excessive convective precipitation.
SYNOPSIS
A deep long-wave upper trough filled with cold unstable airmass has slipped into the western Mediterranean region. A longitudinal flow carries cold air from the North Sea southward towards Morocco, while advecting warm air between Tunesia and Ukraine northeastward.
DISCUSSION
...coastal areas of Morrocco and Algeria...
Under the influence of cold air advection the airmass is drying in terms of mixing ratio. However, the persistence of convection near the African coastline could locally produce excessive precipitation. Models also seem to produce a possible MCS or persistent curl of convective storms south of Mallorca moving towards Algeria which can enhance excessive precipitation chances.
...Sardinia, central Italy and the western Balkan...
In the low-level warm air advection regime under the edge of the upper PV gradient, a persistent frontal zone can trigger convection. Being under the jet stream, 35 m/s 0-6 km shear and over 250 mē/sē of 0-3 km SREH due to veering winds in the WAA regime are present mainly over central Italy and the western Balkan. This supports development of mesocyclones in storms adding to chances of tornadoes. Also severe gusts may be observed in downdrafts. Onshore advection of moist air can trigger isolated convective precipitation, but with less than 20 kg/m2 precipitable water the chances are lower than the typical situation in autumn.
