Storm Forecast
Valid: Thu 22 Oct 2015 06:00 to Fri 23 Oct 2015 06:00 UTC
Issued: Thu 22 Oct 2015 07:56
Forecaster: GATZEN
A level 2 was issued for the Ionian to Aegean Sea region including Greece mainly for excessive precipitation and to lesser extent large hail, severe wind gusts, and tornadoes.
SYNOPSIS
Low geopotential is present across eastern Europe. Embedded cut-off lows progresses eastward from the Ukraine to Russia and from Italy to Greece. Upstream ridging affects south-western Europe. At its northern flank, a strong polar jet stream expands into Europe. A first short-wave trough moves across the North Sea and amplifies into the southern Baltic States. At lower levels relatively cool air masses have spread into the forecast region. A frontal boundary is present ahead of the Italian trough, and latest soundings indicate some steeper lapse rates over Greece. These lapse rates overlap with rich Mediterranean moisture and some CAPE is expected.
DISCUSSION
Aegean to Ionian Sea region including Greece
A strong mid-level jet streak spreads across the south-east Mediterranean. Ageostrophic flow below the exit of this jet causes low-level warm air advection. Lift can be expected due to QG thinking and lapse rates increase during the period, especially across the Aegean Sea region. These lapse rates overlap with a moist air mass with a 0-1 km mixing ratio around 11 g/kg, and latest GFS predicts CAPE in the order of 1000 to 1500 J/kg. Storm have formed along the cold front in a strongly sheared environment with 20 m/s 0-6 km bulk shear and around 7.5 m/s 0-1 km bulk shear. Additional storms are going on across Greece where upslope flow supports initiation, and further upstream near the base of the trough across Italy.
Current thinking is that storms will go on during the day. Best potential of well-organized storms is forecast along and ahead of the cold front where strong vertical wind shear and veering profiles are present. Linear organized storms are the dominant mode along the cold front, but supercells are also not ruled out especially across the Aegean region where SRH will be near 200 mē/sē. Large hail and severe wind gusts are forecast, together with a chance of tornadoes which is highest across the Aegean Sea region including Crete. Additionally, there is a potential of excessive precipitation especially where upslope flow is present. Altogether a level 2 threat is issued.
