Storm Forecast
Valid: Sat 11 Aug 2012 06:00 to Sun 12 Aug 2012 06:00 UTC
Issued: Sat 11 Aug 2012 06:17
Forecaster: PUCIK
A level 1 was issued for Bulgaria and Romania mainly for excessive precipitation and marginally large hail.
a level 1 was issued for Northern Turkey mainly for large hail and severe wind gusts.
SYNOPSIS
An omega-block situation is simulated to develop over Europe with a major ridge covering much of Western and Northern Europe. On its forward flank, a sharply defined short-wave trough will travel towards south/southeast, slowing down its progress during the second half of the forecast period. Large scale trough will be covering much of Eastern Europe and another trough will begin affecting British Isles later in the evening hours. Closer to the surface, an extensive high pressure system centered over the Northern Sea dominates weather conditions with a shallow low over Southeastern Europe/Turkey and Atlantic. Cooler airmass is advected over much of Central Europe in the wake of the progressing short-wave trough and a cold-front crossing Iberia in the night hours will weaken the heatwave conditions over the region.
DISCUSSION
... Spain ...
Very hot and dry airmass is present over the region with extremely steep mid-level lapse rates, reaching over 9 K/km. Tuesday 12 UTC soundings from the region suggest that some instability is present over the region, however much of it strongly capped with DMC staying in elevated mode. Inverted V profiles point to the possiblity of dry downbursts with some of the storms. Higher CAPE values are simulated by NWP close to the eastern coastline of the Mediterranean Sea. Approaching cold front and height falls might help in removing some of the capping layer, but very high uncertainity remains regarding the storm coverage. If any DMC develops, best conditions for severe weather will be present over extreme NE Spain during late evening/night hours, where DLS values might exceed 20 m/s. So far Level 1 does not seem to be warranted with CI being isolated at best.
... Romania / Bulgaria ...
Moderately unstable airmass is present over the region, thanks to the cold mid-level temperatures associated with the trough. Surface flow will likely have a strong easterly component, while mid to upper levels will be characterised by a southwesterly flow, as shown by Bucuresti 00 UTC sounding. This factor should yield moderate wind shear over the region and induce rather slow storm motions. Combined with the airmass having high RH values, well organised multicells might possess a heavy rainfall threat. Moreover, the approach of the short-wave trough from northwest might spark DMC reintensification also during the night hours. Marginally large hail is not ruled out in case that storms will become well organised in the DLS values around 15 m/s.
... Northern Turkey ...
Surface northeasterly flow should advect moister airmass from the Black Sea over the region with steep mid-level lapse rates contributing to the moderate latent instability. 15-20 m/s of DLS should be present with storms having potential to become well organised, including possiblity of supercells. Large hail should be the primary threat owing to higher LCLs, steep mid-level lapse rates and good storm organisation. Downbursts seem to be possible too in this setup. Albeit coverage of DMC remains different by various NWP simulations, a Level 1 seems to be suitable in this case.
