Valid: Wed 29 Mar 2017 08:00 to Thu 30 Mar 2017 06:00 UTC
Issued: Wed 29 Mar 2017 07:58
Level 1 has been issued for parts of N and E Poland mainly for severe wind gusts.
SYNOPSIS and DISCUSSION
A ridge of higher geopotentials is stretching from
NW Africa to Iberian penninsula and parts of W Europe. Around the ridge, a belt of strong, SW-ly to W-ly flow is simulated with windspeeds above 20 m/s at 500 hPa. A short-wave trough is embedded in the flow, translating from Denmark towards Poland during the day. Towards SE Europe, a low filled with cold mid-tropospheric airmass contributes to development of isolated to widely scattered DMC, including some weak tstms, not warranting a Lvl issuance due to the lack of significant instability and/or sufficient vertical wind shear. An arctic airmass with very steep lapse rates will spill over Russia, but mixing ratios below 3 g/kg will likely be too low for any thunderstorms to occur.
Situation will be different over parts of Poland, in conjunction with the aforementioned short-wave. In the exit region of the jet-streak at its base, stretching thanks to the upward motion may result in locally steeper lapse rates juxtaposed above the tongue of moister lower tropospheric airmass ahead of the advancing cold front. In such case, marginal latent instability would be realised with a formation of a band of DMC, possibly electrified. Due to the strong DLS and LLS, this band may be well organised and pose a risk of severe wind gusts as 850 hPa flow exceeds 20 m/s. This scenario is not completely certain atm, but warrants a Lvl 1 issuance.