Storm Forecast
Valid: Wed 27 Jun 2018 06:00 to Thu 28 Jun 2018 06:00 UTC
Issued: Wed 27 Jun 2018 06:02
Forecaster: PUCIK
A level 1 was issued across Spain for large hail and severe wind gusts.
A level 2 was issued across NW Turkey mainly for large to very large hail, severe wind gusts and excessive rainfall.
A level 1 was issued across W and N Turkey mainly for large hail and severe wind gusts.
A level 1 was issued across Greece, E Bulgaria and E Romania mainly for excessive rainfall.
A level 1 was issued across NE Romania, Moldova and parts of Ukraine mainly for excessive rainfall and tornadoes.
SYNOPSIS
Synoptic-scale situation will be dominated by two features, a large cyclonic vortex at mid to upper troposphere centered over the S Adriatic Sea and an extensive high pressure system at the lower troposhere, stretching across much of NW and N Europe. While the high is associated with stable conditions, abundant DMC has been observed with the vortex, particularly at its E flank in the WAA regime. Several short-wave troughs are rotating around it and will impact the setup during the forecast period. To the W, a quasistationary low is located over the Atlantic Ocean with an ill-defined thermal boundary residing over Iberia.
DISCUSSION
... Spain ...
Similarly to Tuesday, scattered DMC is forecast to initiate in weakly capped environment and MLCAPE values locally exceeding 1000 J/kg. With DLS between 10 and 15 m/s, multicells will be the prevalent convective type. Stronger updrafts may be capable of large hail, while forecast soundings reveal locally dry and deep boundary layer, suggestive of downbursts. Thus, a Lvl 1 is issued particularly for late afternoon and evening hours. Convective activity will likely subside during the night.
... NW Turkey ...
NWP is in good agreement regarding the overlap of moderate buoyancy, with CAPE values around 1000 J/kg, and of strong DLS, exceeding 20 m/s. Long, linear hodographs can be found in the forecast wind profiles, suggestive of splitting supercells. SRH is forecast to increase towards the evening, when pressure falls ahead of the approaching short-wave trough are expected. At first, isolated convective mode is most likely, but coverage may quickly increase towards the evening as synoptic-scale lift erodes the remaining CIN. Thus, a transition from isolated supercells to an MCS is likely at some point. Large to very large hail will occur with supercells, while MCS may be accompanied by severe wind gusts and excessive rainfall.
... Greece to E Romania ...
Forecast soundings reveal environment conducive to heavy rainfall with skinny CAPE, high RH in low to mid-troposphere and rather slow storm motion. A lvl 2 was considered for N Aegean, but was dismissed due to the model discrepancies regarding the simulated precipitation. Nevertheless, this region has the highest threat of rainfall with moist onshore flow and several rounds of convection possible during the entire forecast period.
... N Romania, S Ukraine, Moldova ...
In contrast to the other regions of interest, large model discrepancies preclude confident forecast for this one. Models agree on the WAA regime, advection of moister airmass towards NW and a belt of strengthening flow towards the late afternoon and evening hours. However, due to the differences in lower tropospheric moisture, the N and W-ward extension of available buoyancy and also the locations of CI are rather uncertain. Neverthless, will keep a Lvl 1 for the combination of heavy rainfall and tornado threat. The latter will be enhanced as LLS exceeds 10 m/s with rather low cloud bases. However, it is questionable whether convection will be surface based (particularly towards the northern edge of Lvl 1) and whether isolated supercells would form given rather weak shear beyond the lowest 1 - 2 km of troposphere.
