Storm Forecast
Valid: Fri 12 Jan 2007 06:00 to Sat 13 Jan 2007 06:00 UTC
Issued: Thu 11 Jan 2007 23:21
Forecaster: DAHL

SYNOPSIS

Very fast, meandering upper westerly flow is stretching across the Atlantic and central portions of Europe, with an imbedded trough digging across E Europe into the Aegean region on Friday, where it will induce weak cyclogenesis until early Saturday morning. A stable perturbation, accompanied by an intense SFC low, will rapidly move across the N British Isles, the North Sea, and central Scandinavia during the period.

DISCUSSION

... North Sea ... extreme SW Norway ...

It appears that some convective potential will exist with the intense short-wave trough moving across the North Sea and central Scandinavia during the second half of the period. GFS comes up with some CAPE in association with this system, though the mesoscale distribution of the instability relative to the surface fronts are somewhat uncertain, as it the structure of the front. However, confidence is rather high that shallow convection may form along and W of the SFC cold front. This convection is likely to augment the severe back-ground flow, also, strong shear may favor shallow tornadic mesocyclones, though the primary threat should be tied to severe convective wind gusts. Indications are that convection will not make it far inland across the Norwegian Mountains, though the evolution of the precipitation/convection along the cold front remains quite uncertain at the moment, and an update may be necessary on Friday.

... NE Germany ... Poland ...

Model guidance suggests that convection forming in the wake of the precious SFC low, which lifts towards NE Europe on Friday - whereby in will undergo substantial weakening - will remain quite shallow. Deepest convection, and highest chances for isolated lightning and convectively augmented wind gusts may exist in the first few hours of the period from NE Germany into N and central Poland. Low-level and deep-layer shear profiles will remain more than adequate for severe convection, and there seems to be a slim chance of a few shallow mesocyclones. However, instability signals are too weak for a categorical outlook at the moment. But the situation may require an upgrade if convection happens to become deeper than currently anticipated.

... Balkan States ...

Chances of significant convection along the cold front which will move across E portions of Europe on Friday (which is trailing from the SFC low moving into NE Europe) seem to be rather low, though GFS maintains a weakly potentially unstable stratification, which is likely tied to dry mid/upper level air overspreading the SFC front. Will not introduce a TSTM area for this activity as chances for anything significant to develop should be too small.