Storm Forecast
Valid: Thu 14 Oct 2010 06:00 to Fri 15 Oct 2010 06:00 UTC
Issued: Wed 13 Oct 2010 21:59
Forecaster: GATZEN

A level 2 was issued for southern Turkey mainly for tornadoes and excessive rain.

A level 1 was issued for the Aegean and Turkey mainly for tornadoes, excessive rain, large hail, and severe wind gusts.

SYNOPSIS

A high is present over the north-eastern Atlantic. A broad trough has developed downstream over the north Mediterranean. It will slowly move eastwards at the southern flank of a polar trough over east Europe. At the surface, the Atlantic high rides into Turkey. The central and east Mediterranean are affected by low surface pressure.

DISCUSSION

East Mediterranean

A south-westerly flow will continue to advect an elevated mixed layer from the Sahara desert into the east Mediterranean. Latest Izmir sounding indicates rather steep mid-level lapse rates and MLCAPE of more than 1000 J/kg on Wednesday. On Thursday, MLCAPE will likely reach 1000-2000 J/kg over a broad region given the rich low-level moisture and the steep mid-level lapse rates ahead of the approaching trough axis.

At low levels, a south-easterly flow is forecast to advect a moist boundary-layer air mass into southern Turkey. From the Aegean Sea, a cold front is expected to spread eastwards. Especially along the southern coasts of Turkey and the cold front, low-level convergence is forecast to support initiation. As a consequence, thunderstorms may affect southern Turkey and the Aegean Sea for most of the period.

Storms that develop will likely organize in the strongly-sheared south-westerly flow ahead of the trough axis. A south-westerly low-level jet exceeding 15 m/s at the 850 hPa level and weak south-easterly winds in the boundary-layer will result in rather impressive 10-20 m/s 0-1 km vertical wind shear and also strong deep-layer vertical wind shear. Additionally, favourably veering profiles can be expected locally.

Well-organized storms are forecast to spread into Turkey and the surroundings. Bowing lines and supercells may develop. These will pose a threat of large hail, severe wind gusts, and tornadoes. The chance of tornadoes is expected to increase along the southern coasts of Turkey in the evening hours, when favourably curved hodographs are forecast by latest GFS ahead of the approaching cold front. Excessive rain is also possible especially due to the rather long impact time of thunderstorms and the high moisture content. The intensity and coverage of storms is expected to decrease behind the cold front.