Storm Forecast
Valid: Sat 19 May 2007 06:00 to Sun 20 May 2007 06:00 UTC
Issued: Sat 19 May 2007 06:10
Forecaster: DAHL

SYNOPSIS

Quasi-stationary large-scale upper trough located over the N Atlantic/NW Europe on Saturday 06Z will amplify as vort max is rounding its base during the period. Strong SFC low is maintained by a perturbation at its EWD periphery, which is - like the accompanying SFC low - expected to lift to N Scandinavia by Sunday morning, while undergoing slight weakening. Weak, slowly eastward moving upper low off the Moroccan W Atlantic coast will eventually merge with the large-scale trough. These features maintain warm advection across the southwestern and central parts of Europe. Also, an intense and quasi-stationary upper cut-off low is present over the Aegean region, which is continuing to promote warm advection across much of E and SE Europe, aided by weak and comparatively small SFC lows that accompany the various peripheral vort maxima.

DISCUSSION

... E Aegean ... W Turkey ...

Though it appears that most of the instability has been mixed out during the past days, environment should remain favorable for deep convection. Some severe potential should exist over the E Aegean Sea and W Turkey where 25 to 30 m/s deep shear and 10 m/s 0-1 km shear will likely be present. Given rather low LCL/LFC heights and minimal capping, this should be supportive of a few tornadic supercells. Also, large hail and severe wind gusts may occur.

... Iberian Peninsula ... France ...

Scattered TSTMS will likely form over Portugal/Spain, France, and possibly also over SW Germany during peak-heating hours along and ahead of the SFC cold front. Large-scale support in terms of both, vertical shear and forcing for upward motion is expected to remain fairly weak, and organized severe threat should be accordingly low. Models simulate weak frontal waves over Spain, France, and SRN Germany which should be focus for convective evolution. An isolated severe TSTM or two may develop if storms happen to favorably intercept outflow boundaries of previous/neighboring convection or other mesoscale fatures. Threat is too low for a categorical risk, however.