Storm Forecast
Valid: Tue 17 Aug 2010 06:00 to Wed 18 Aug 2010 06:00 UTC
Issued: Mon 16 Aug 2010 23:15
Forecaster: KOROSEC
A level 2 was issued for parts of northern Romania, western Ukraine, western Belarus and Lithuania mainly for large hail, strong/severe wind gusts, excessive convective rainfall and tornadoes.
A level 1 was issued for surrounding areas of level 2 covering areas from Baltic States across eastern Europe into SE Balkans mainly for large hail, strong wind gusts and excessive convective rainfall.
A level 1 was issued for southeastern Spain towards the northern Marocco and Algeria mainly for severe wind gusts, large hail and intense rainfall.
A level 1 was issued for Denmark, parts of northern Germany and western Poland mainly for excessive rainfall, strong wind gusts and brief funnel clouds.
SYNOPSIS
A large upper low with history of severe weather outbreaks across parts of Europe finally weakens while merging with the large long-wave trough coming from the northern Atlantic. Embedded in this large trough, a deep upper low approaches British Isles towards Wednesday. Another small upper low remains stationary centered near Gibraltar. At surface, a N-S oriented cold front across eastern Europe serves as a focus for another day of severe storms.
DISCUSSION
... Baltic States across eastern Europe into SE Balkans ...
Another round of severe storms is again expected ahead of the slowly transforming upper low. Very moist and hot airmass is spreaded across the level 1 and 2 areas, MLCAPEs well exceeding 1000 J/kg up to 2000 J/kg will become available. It seems that overlaping with 15-20 m/s of deep-layer shear is reasonable across the western Belarus and Ukraine. There, organized robust severe storms (numerous strong multicells/clusters and supercells) will become likely along the frontal convergence where storms will rapidly initiate in the afternoon. Those will be capable of producing intense rain, large hail, tornadoes and strong to severe wind gusts especially if any bowing segments will form. A couple of large clusters/large MCS seems likely again, moving ENE-wards along the front later towards the evening/early night hours.
Areas surrounding the level 2 will still experience the severe storms, but those will be more isolated, as models don't show large precips signals and shear is weaker. However, some severe threat exists there as well.
... SE Spain into NW Africa ...
Ahead of the small stationary upper low, strong WAA gets pushed into SE Spain. Large scale ascent suggests that quite widespread activity can be expected in the environment with moderate isntability and around 15-25 m/s of deep-layer shear. Organized strong multicells and a couple of supercells will be possible, posing a threat for large hail and strong wind gusts given the rather high LCLs. However, training effect of the cells could bring some flash floods threat as well.
... Denmark, parts of northern Germany and western Poland ...
The remnants of the transforming upper low will be affecting northern parts of central Europe. On its southern side, a strong mid-level jet streak provides above 20 m/s shear, but only partly overlaping with the marginal instability to its north. However, overlaping seems enough to provide some more organized storms, rising the threat for some strong wind gusts/intense rainfall with the stronger cells. Given the concentrated instability in the lowest levels and low ELs, a couple of low topped supercells could be possible with 10 m/s of LL shear in place. A couple of funnel clouds/brief tornado cannot be completely ruled out either.
A level 1 was also extended into Denmark as some instability well overlaps with the moderate shear near 15 m/s on the northern side of the upper low/trough. Some organized storms will be possible, clustering into larger system later in the afternoon hours.
