Storm Forecast
Valid: Sat 17 Oct 2015 06:00 to Sun 18 Oct 2015 06:00 UTC
Issued: Fri 16 Oct 2015 19:35
Forecaster: DAFIS
A level 1 was issued for Portugal and W Spain mainly for excessive rainfall, large hail, severe wind gusts and tornadoes.
A level 1 was issued for E Croatia, Montenegro, Bosnia and Herzegovina, Serbia, Hungary and W Romania mainly for excessive rainfall and severe wind gusts.
SYNOPSIS
The blocking pattern continues during Saturday, with two high pressure systems located over the British Isles and W Russia. A cyclonic vortex is approaching Portugal during the forecast period with its center some hundreds of kilometers offshore. The large cut off upper-air low over central Europe continues to swirl over Germany and unusually cold conditions will continue to affect most of the continent. In central Mediterranean basin southwesterly flow advects unstable air masses which become saturated over land and rain is forecast for a large part of the West Balkans.
DISCUSSION
.... Portugal and West Spain ....
The NWP models forecast that the center of the cyclone West from the Iberian Peninsula will remain offshore and will assist the abundant influx of moisture from the Atlantic. Some CAPE is forecast in the southwestern parts of the level 1 where MLCAPE will reach the 1200 J/kg according to GFS, overlapping with DLS of up to 20 m/s, so any storm that is formed in this environment may become severe. A MCS will be able to travel all the way north to northern parts of Portugal and W Spain with a probability of excessive rainfall (PW will be over 40 mm) and severe wind gusts, mostly near the shore. Furthermore, SREH0-3km thermodynamic parameter will be around 400 mē/sē during the morning and the formation of a well organized storm is possible with a large hail threat or large amount of small sized hail. Moreover the presence of LLS up to 17 m/s and SREH0-1km around 300 mē/sē are enough for a tornado / waterspout threat.
.... E Croatia, Montenegro, Bosnia and Herzegovina, Serbia, Hungary and W Romania ....
A plume of moist air is moving North from the Ionian and Adriatic Sea where some hundreds of CAPE are forecast. The upper-air cut off low just NW from the level 1 area creates enough shear for any storm to become organized and produce excessive rain, especially over N Serbia and S Hungary where the PW exceeds the 30 mm and the DLS is forecast up to 20 m/s, overlapping with 400-600 J/kg of MLCAPE. The probability of severe weather is higher during the morning hours over Montenegro, Croatia and Serbia and for the rest of the day, any MCS would be able to move NE but after 15z the most of the rainfall will be stratiform, but still heavy.
