Storm Forecast
Valid: Sun 19 Jan 2014 06:00 to Mon 20 Jan 2014 06:00 UTC
Issued: Sun 19 Jan 2014 04:12
Forecaster: VAN DER VELDE
A level 2 was issued for southern Italy and west Balkan coast mainly for a combined threat of excessive convective rainfall, tornadoes, severe wind gusts and large hail.
A level 1 was issued for surrounding areas for similar phenomena.
SYNOPSIS
A blocked weather pattern is present over Europe with high pressure over Scandinavia and Russia and low pressure stretching from Iceland to southern Italy. The main low pressure system lies over Italy with an upper shortwave trough and intense mid to upper level winds in the presence of unstable, relatively warm air airmass which is advected over Italy and the western Balkan. Another system affecst the southwestern Mediterranean with good quasi-geostrophic forcing and weaker instability, reaching Italy Monday morning. Furthermore a band of slightly unstable cool airmass extends between Ireland and southwestern France.
DISCUSSION
...Italy and the east coast of the Adriatic Sea...
Despite CAPE not being alarmingly high, only 500-1000 J/kg, strong deep layer and low level bulk shear vectors are creating a kinematic environment for severe storms consisting of mutlicell complexes and supercells. The two main focus areas are southern Italy, mainly until the late afternoon as result of the shortwave trough movement, and the Adriatic coast the entire period but mainly evening and night.
Predicted storm motion can be faster than 25 m/s over southern Italy making it easy to create severe wind gusts at the ground. The Adriatic storms will be more stationary and therefore likely more a threat of excessive precipitation. Tornadoes and large hail appear likely, given storm-relative helicity in the 200-400 mē/sē range and 0-1 km shear of about 15 m/s. 0-6 km shear is 25-30 m/s.
