Extended Forecast
Valid: Wed 15 Jun 2022 06:00 to Thu 16 Jun 2022 06:00 UTC
Issued: Mon 13 Jun 2022 14:43
Forecaster: TUSCHY

A level 1 was issued for parts of S-CNTRL Europe mainly for large hail and severe wind gusts.

A level 1 was issued for parts of Portugal and NW Spain mainly for large hail and severe wind gusts.

SYNOPSIS

Zonal flow aloft covers most of Europe with a more prominent upper trough situated over NE Europe. Embedded in this flow regime, numerous low amplitude waves move E/SE over CNTRL into SE Europe.

SW Europe remains beneath a strong ridge with 500 height readings around the 90th percentile range, whereas 850 hPa temperatures once again hover along record readings (25-30C over CNTRL Spain, lowering to 20-22C over S France).
A gradually northward crawling cut-off just W of Portugal backs this ridge and both features remain in a steady state for this period.

A diffuse and only slowly structuring warm front runs from E-CNTRL France to the E towards the Alps.


DISCUSSION

...S France to Switzerland into N Italy ...

A LL confluent flow regime is present over S France with drier S-erlies from the Mediterranean meeting moist westerlies from SW into CNTRL France. Deeper BL moisture beneath rather steep mid-level lapse rates support MLCAPE aoa 2000 J/kg. However, stout cap should suppress DMC activity with a low-end risk in the immediate vicinity of the LL confluence zone. Not much frontogenesis is forecast along the synoptic-scale warm front, so CI is very uncertain / unlikely. Hence we excluded SW France from any level and lightning areas for now.

Most likely CI will be confined along the mountains with cold pool driven motion to the SE. 500-1000 J/kg MLCAPE with 15-20 m/s DLS and 10-15 m/s 0-3 km shear support a mix of multicells and isolated/temporal supercells with large hail and severe wind gusts the main risk. There is not much synoptic support for any longer lived system to evolve but a weakening MCS could still survive all the way to the Ligurian Sea. A strong gust front may bring a risk of severe wind gusts to offshore areas over the Ligurian Sea.

... CNTRL Italy ...

Converging sea breezes help to spark a few thunderstorms along the CNTRL Apennines. 500 to locally up to 1500 J/kg MLCAPE with deep/well mixed subcloud layers and very steep LL lapse rates indicate a risk for severe downbursts and some hail. DLS around 10 m/s however should keep any severe risk more isolated.

... Spain and Portugal ...

The combination of increasing synoptic-scale lift and intense diurnal heating assist in isolated to scattered CI along the W fringe of the hottest low/mid-tropospheric air mass. Forecast soundings in this region indicate mixing up to 4 km AGL with 0-3 km lapse rates in excess of 9-10 K/km and DCAPE values in the 1500-1800 J/kg range. Severe wind gusts from high based convection and hail would be the main hazard.

... Other lightning areas ...

Broad lightning areas were added for E/NE Europe but CAPE shear space remains too uncertain or unimpressive to add a confined level 1 area for now. Gusty winds and small hail accompany stronger storms.