Storm Forecast
Valid: Wed 23 Feb 2011 06:00 to Thu 24 Feb 2011 06:00 UTC
Issued: Tue 22 Feb 2011 22:16
Forecaster: PUCIK

No threat levels have been issued.

SYNOPSIS

A significant blocking situation is underway over Europe with a large and deep trough stretching from Scandinavia into the Southern Mediterranean. A strong temperature gradient on its rear flank results in a quick northerly jet-stream at mid and upper levels of troposphere. To the east a ridge stands out in the geopotential fields, but temperature analysis of 500 hPa reveal rather cool airmass even within this feature. The trough will remain stationary but as the ridge approaches from the west, driven by a strong zonal flow in its wake, it is expected to start filling in.

Closer to the surface, a complex system of high pressure dominates Europe, being centered over Russia and stretching towards the Iberia and further into Atlantic. A shallow low is forecast close to the southern flank of the trough, over the Ionian and Aegean Sea. It will be this region that might experience thunderstorms.

DISCUSSION

...South-Central Mediterranean...

The first area with isolated thunderstorm activity will comprise a proximity of the center of the surface low, which should track in vicinity of Sicily and over the Ionian Sea later on. Low-end instability built-up will realise thanks to the cold mid-level temperatures and at the same time an upward synoptic scale motion on the forward flank of the trough. With very weak instability and insignificant wind shear, severe threat with these low-topped thunderstorms will be almost non-existent. Storm activity will slowly shift east/southeastwards during the day, in conjunction with the movement of the surface low and the trough.

...Eastern Mediterranean...

The second area will comprise the western and southern coasts of Turkey and adjacent seas. The degree of instability will be higher in this region, partly thanks to the presence of moister and warmer airmass at lower levels due to the WAA. To the south of Turkey, a region of enhanced, moderate instability (with simulated CAPEs around 1000 J/kg) will partly overlap with strong DLS, suggesting a potential for well-organised convection. Nevertheless this overlap will be most significant outside the forecast area and thus no Level is introduced. Some low-end threat of excessive precipitation might develop close to the western coasts of Turkey as numerous rounds of showers/thunderstorms are possible during the forecast period.