Storm Forecast
Valid: Sat 17 Apr 2010 06:00 to Sun 18 Apr 2010 06:00 UTC
Issued: Sat 17 Apr 2010 10:09
Forecaster: VAN DER VELDE
A level 1 was issued for northern Algeria mainly for a chance of large hail.
SYNOPSIS
A band of high pressure covers the central latitudes of Europe, while low pressure affects Scandinavia, Iberian Peninsula, northern Africa, southern Balkan and Turkey. Slight instability is present in various places in southern Europe. Significant wind shear is collocated with instability in northern Africa, as well as central Sweden and Balkan/Turkey areas (partly). Troughs providing lift to destabilize or trigger convection southern Balkan/western Turkey, Algeria, and Russia, while upper lows are found over northern Italy and over/west of the Iberian Peninsula.
DISCUSSION
...northern Algeria...
GFS indicates significantly uncapped airmass with large deep convergence signals and convective precipitation. The area is crossed by a jet stream providing 20-25 m/s DLS and 150-250 mē/sē SREH3. The LCL is on the higher side (>1500m), which together with the kinematics favors large hail growth. Only CAPE is on the low side.
...Greece, W Turkey...
Somewhat enhanced SREH and DLS occur near slight CAPE with likely some local overlap, providing some large hail chance, however in Greece low LCLs are forecast and in Turkey some capping/partial elevated instability.
...central Sweden...
A strong jet overruns some area of low instability and sets up a DLS of up to 35 m/s and some SREH. LLS is about 10 m/s and overall the shear could induce tornadogenesis, but LCLs are quite high and the forcing not certain (cold air advection, but proximity to left jet exit).
...S Portugal and S Spain...
Weak flow and a convergence zone may cause local waterspout development.
