Storm Forecast
Valid: Thu 24 Feb 2011 06:00 to Fri 25 Feb 2011 06:00 UTC
Issued: Wed 23 Feb 2011 19:51
Forecaster: GATZEN

SYNOPSIS

A broad and deep trough covers Europe at the western flank of a ridge over western Europe. At Thursday, this ridge will expand north-eastward into northern Europe. With the northerly low-level flow, cold and very dry air masses will spread into the Mediterranean. Higher boundary-layer moisture can be found near the center of the mid-level trough. Increasing low-level moisture is also expected over south-western Europe.

DISCUSSION

East Mediterranean/Turkey

Underneath the trough center neutral lapse rates and quite rich low-level moisture of 7 g/kg mixing ratio are forecast over the east Mediterranean and are expected to lead to some low-level CAPE that can be found in the latest soundings as well. Low-level convergence is expected to be most intense to the south of Greece and Turkey near the center of a surface low. With almost no convective inhibition, moist convection will likely form and is forecast to reach equilibrium level temperatures below -20°C, indicating a potential of thunderstorms. With weak vertical wind shear, severe thunderstorms are not likely, but waterspouts may occur near the coasts due to the steep lapse rates.

Daytime heating over Turkey is also forecast to be strong enough to produce deep moist convection. With weak vertical wind shear, the potential of severe weather is weak, but locally strong downdraft gusts and small hail may be possible.

Besides the main activity, some isolated thunderstorms are also possible over the southern Mediterranean as well. This activity is expected to weaken from the north as the dry air masses from the central Mediterranean spread southward.

West Mediterranean

With northerly low-level winds, a tongue of higher moisture that has remained over the west Mediterranean is advected towards the African coasts. Especially over eastern Algeria and Tunisia, this moist air will overlap with rather cool mid-level air masses, and weak CAPE is expected by latest numerical models. At mid-levels a strong northerly jet streak initially pointing towards eastern Tunisia will move southwards, and some lift is likely at its anticyclonically sheared entry. Further lift can be expected near the coasts due to upslope flow. Showers are forecast that can also be capable of producing isolated lighting. Gusty winds are likely given moderate northerly winds, but severe limits are not expected to be reached given the lack of instability and only weak forcing.