Storm Forecast
Valid: Sun 07 Feb 2010 06:00 to Mon 08 Feb 2010 06:00 UTC
Issued: Sun 07 Feb 2010 00:28
Forecaster: SCHLENCZEK
A level 2 was issued for SW / W Turkey mainly for widespread excessive convective rainfall and to a lesser extent for severe wind gusts, tornadoes and large hail.
A level 1 surrounding the level 2 was issued mainly for excessive convective rainfall and to a lesser extent for tornadoes.
A level 1 was issued for SW Greece / S Adriatic and Aegean Sea / Crete mainly for isolated excessive convective rainfall and the chance of an isolated waterspout.
SYNOPSIS
The dominant feature for deep moist convection on Sunday will be an upper cut-off low over the S Adriatic. An upper jet streak with 80 m/s at 300 hPa stretches from S France via S Sardinia towards Crete and SW Greece, its left exit region should be centered over the Aegean Sea / Bosporus region on Sunday morning. The upper low should move eastwards towards W Turkey until Monday morning.
An upper shortwave trough over the N North Sea will travel SSE-wards into N France / Benelux countries in the second half of the forecast period. In the wake of this trough, cold maritime air is advected into W-central Europe. Some showers and thunderstorms are forecast near the upper cold core of an upper low, centered over NW Scandinavia.
DISCUSSION
...Sicily, central Mediterranean...
Some showers and thunderstorms will develop in the vicinity of the upper cold core. Lightning activity should remain rather sparse as CAPE is confined to 100 - 200 J/kg and subsidence is expected. The chance of an isolated waterspout is given but overall threat should be below the level 1 threshold.
...SW / W Greece, Albania, Crete...
A plume with unstable air is advected towards the S Adriatic and the S Balkans on Sunday morning. The heavy rain threat from Saturday will continue at least until Sunday afternoon with expected 12 hour precipitation sums around 30 - 40mm. At the southern tip of Greece, deep layer shear should be strongest with 20 - 30 m/s forecast around midday and the chance of an isolated supercell with marginally severe hail should be maximised there.
Steep LL lapse rates and rich BL moisture over the S Adriatic may allow an isolated waterspout.
...Aegean Sea, SW Turkey, Bosporus...
In an environment with a few hundred J/kg CAPE, strong QG forcing will lead to convective initiation over the Aegean Sea. Strong southerly LL flow with 15 - 20 m/s at 850 hPa may lead to isolated severe wind gusts due to downward transfer of momentum. Even though directional shear is not that strong, SRH3 values around 300 - 400 mē/sē and 15 - 20 m/s deep layer shear are forecast which should be sufficient for mesocyclogenesis. An isolated tornado / large hail event is not discounted. The organised multicell / supercell mode should be dominant between 12 UTC and 18 UTC over SW Turkey.
Storms will be advected onshore and large sums of convective precipitation are forecast for SW / W Turkey from Sunday 12 UTC till Monday 06 UTC by both ECMWF and GFS. The accumulated 18-hour precipitation is forecast between 80 and 150 mm which will likely cause widespread flooding near the coastlines. A level 2 for widespread excessive rainfall should be warranted. The surrounding regions where the duration of this precipitation event should be somewhat shorter will need a level 1.
