Valid: Sun 04 Mar 2018 06:00 to Mon 05 Mar 2018 06:00 UTC
Issued: Sat 03 Mar 2018 09:15
A level 1 was issued across S-Spain/Portugal and NW-Morocco mainly for excessive rain and a low end tornado and large hail risk.
A level 1 was issued for S-CNTRL France mainly for heavy rain.
A level 1 was issued for parts of Turkey maily for isolated large hail and a low-end tornado risk.
The frontal zone is far displaced to the south and impacts the Mediterranean and surrounding regions. Numerous disturbances accompanied by more or less active fronts swing east and bring unsettled conditions to this area.
Further north, cold and dry conditions persit and keep the thunderstorm chances in ceck (excluding isolated offshore convection).
... Mediterranean ...
S-Iberian Peninsula and NW-Morocco:
Probably the most active region will be far S-Spain/Portugal to NW-Morocco. An atmospheric river still points towards this region with ongoing influx of subtropical air. Most active time-frame will be until 15Z as a sharp upper trough with cold mid-level temperatures shifts east. Strong lift and an unstable airmass create favorable conditions for scattered thunderstorms. The main hazard will be excessive rain with repeatedly onshore moving storms. DLS of 15 m/s is borderline for organized storms, but combined with enhanced LL shear along the coasts, an isolated tornado and large hail risk (with cold mid-levels and low WBZ levels) also exist. Beyond 15Z the thunderstorms risk decreases as mid-levels warm, but an isolated risk continues until 06Z with an localized heavy rainfall threat.
The isolated large hail and tornado risk expands north towards S-Portugal and S-/CNTRL-Spain between 09-15 UTC as the upper trough affects the area. We therefore enlarged the level area to the north. Further east, mixing lower BL moisture with diminishing CAPE.
Lowering surface pressure east of Spain causes an overnight heavy rainfall threat for the level 1 area. 35kt SE-erly flow advects a moist airmass to the north and despite limited CAPE, a few thunderstorms are possible with a N-S aligned and gradually eastward moving cluster. Progressive nature of this event lowers the rainfall risk, so overall amounts should stay in a level 1 category.
A mid-level wave races east but features rather mild mid-levels with weak DLS. Still overlap of NE-ward fanning EML and a marine airmass result in low to moderate CAPE with scattered thunderstorms. Nothing severe is forecast with main activity probably found along the crest of the wave over S-Italy in form of a prolonged period of rain/snow.
A low-amplitude mid-level wave traverses east and is accompanied by a diffuse LL depression. Moderate CAPE with strong DLS support a few more organized storms with isolated large hail, gusty winds and a low-end tornado risk along the coasts. The threat diminishes from W to E during the day.
Elsewhere, isolated but mostly sub-severe thunderstorms are forecast in the lightning areas. Isolated severe can't be excluded but this risk is mainly dictated by the mesoscale.
... NW-France to far S-UK ...
Another mid-level impulse lifts to the ENE with cold-mid-levels atop a marine air mass. Low CAPE and weak shear preclude organized DMC activity but still graupel and gusty winds can't be ruled out with stronger updrafts.