CONVECTIVE FORECAST
VALID Tue 29 Nov 06:00 - Wed 30 Nov 06:00 2005 (UTC)
ISSUED: 29 Nov 09:59 (UTC)
FORECASTER: VAN DER VELDE

SYNOPSIS

Long zone of low pressure stretches down from Scandinavia to southern Europe below a 500 hPa trough with a PVA max walking into the northern Mediterranean. A SFC trough will remain stationary over the eastern North Sea, and a polar low will develop and reach central Norway tonight.

DISCUSSION

...central Norway...
Current satellite image shows enhanced convection without much of a structure on the northern Atlantic. GFS and NMM models forecast a full circulation as this area slides into central Norway, suggesting it may have become a polar low. Considerable SREH and low-level shear may induce rotating updrafts and support tornadoes/waterspouts. At least heavy snowshowers are the main issue.

...eastern North Sea...
Stationary zone with weak shear, low level convergence and steep low-level lapse rates and buoyancy make for a setting usually conducive to producing some waterspouts.
The same may go for the southeastern Baltic Sea, but wind field is stronger and buoyancy more sketchy there.

...Mediterranean Sea...
Due to very steep low-level lapse rates and strong buoyancy, also shown by e.g. 00Z Mallorca sounding, waterspouts should not be ruled out, especially where lower levels are moister and there is significant convergence of BL winds, i.e. the area around Corsica and the west coast of Italy. Upper winds create fair deep-layer shear, around 20 m/s 0-6 km, and 00Z soundings have also shown good low-level veering of winds, which may aid in developing tornadoes/spouts.

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