STORM FORECAST
VALID Mon 27 Mar 06:00 - Tue 28 Mar 06:00 2006 (UTC)
ISSUED: 26 Mar 18:28 (UTC)
FORECASTER: TUSCHY

A threat level 1 is forecast across Northern Germany

SYNOPSIS

A broad upper-level trough is placed west of Europe, which will slowly start an eastward translation, affecting most parts of northwestern and central Europe during the next 24 hours...Attendant depression will cross Ireland/Scottland during the noon/early evening hours, moving further towards the northeast....Downstream of this system, a strong SW-erly flow will be established over western/central Europe,supporting the advection of a warm and humid airmass further towards the NE... In addition...this progressive pattern helps to shift the axis of a weakening ridge further towards the east/southeast towards the central Mediterranean.
Most parts of eastern Europe will see cool and stable conditions under the influence of another longwave trough.

DISCUSSION

...Northern Germany...
A well developed warm front is predicted to cross the region of interest during the early morning hours from the southwest towards the northeast...A humid and pretty warm airmass will cover most parts of Germany, including the level 1 area.

Only weak model signals for clearing in the postfrontal airmass rise the concern about its final quality... GFS indicates a slight chance for clearing during the noon and early afternoon hours over most parts of northern/central and southeastern Germany... Despite the uncertainness about the degree of insolation, expect broad area of low to moderate instability release( about 300 J/kg SBCAPE )to develop in the region of interest.

Shear will be quite strong ( low level shear of ~12m/s )and if the low-level wind will tend to back more than the models indicate, even stronger shear values can be expected...Time frame for storms to become severe, will be limited ( between 12 and ~17Z ),but a few storms should be capable of producing hail ( matching the criteria for severe hail ) and a few strong to severe wind gusts during the period ... Low LCLs and broad area of moderately enhanced helical flow would also pose a risk for a few tornadoes, mainly in regions, where backed wind field can be established.

Isolated storms should also develop further to the south along SE-ward moving cold front, but diminishing instability , placement in the right exit area of arriving upper-level jet and arrivial during the evening hours should limit coverage and strength of those TSTMs...However, weaker wind shear could be balanced by topographical modified low level flow...this combined with low LCLs would also pose a marginal hail risk and the possibility for a short tornado report.

During the night hours, enhanced TSTM development will cover a broad area from the Bay of Biscay-north/central France towards NW Germany, when mid-levels will start to cool down...Main limiting factor for widespread TSTM development will be marginal instability release ( mainly over NW France ), but broad area of enhanced low level shear and low LCLs favor an increased risk for one or two tornadoes and marginal hail...Main activity expected in the western and northern part of this broad TSTM area.

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