Storm Forecast
Valid: Fri 06 Apr 2007 06:00 to Sat 07 Apr 2007 06:00 UTC
Issued: Thu 05 Apr 2007 19:36
Forecaster: TUSCHY

SYNOPSIS

A late winter-time - like storm system will affect N-Norway and Sweden at least for the next 24 hours.This vortex will bring cold and unsettled weather conditions for most parts of N-Europe.
A constantly eastward building high pressure area over W-CNTRL Europe will bring stable and dry conditions tho those regions, while a weakening upper-level disturbance over SW Europe is the focus for some convective activity during the forecast period.

DISCUSSION

...N-Norway / Sweden...

A trough axis will reach the coastal regions of NW Norway during the later afternoon/ early evening hours from the NW.
Attendant PVA field is forecast to cross the area and this will occur during a time, where some support of upper-levels ( left exit region of strong 300hPa jet streak ) will be present.
Temperatures continue a rapid cool down at all levels with GFS indicating a wide area of negative temperature advection mainly during the morning / early afternoon hours.
The main focus for an isolated thunderstorm will arise around 18Z mainly in the highlighted area.
Wrap - around moisture of the main vortex will be involved in the eastward shifting trough axis. Hence, models indicate somewhat higher Theta-E values, surging southward along the coast of NW Norway.
Lapse rates stay steep at mid-levels and some low-end instability release looks reasonable at this time.
Primary threat will be mostly sub-severe hail due to a combination of 15-20m/s DLS, rising EL temperatures and steep lapse rates.

An isolated SFLOC report SE of the highlighted area can't be excluded ( mainly over the NW part of the Gulf of Bothnia), but expected coverage will be too marginal for issuing any higher probabilities.

...SE Spain...

A weakening upper-level system over Spain will stay nearly stationary during the forecast period with strong jet systems on its base. Those streaks, although weakening, will stay east of the Strait of Gibraltar... and so do the left exit regions.
An eastward shifting vort max and a prolonged period of upper-level divergence will support scattered thunderstorm development over SE Spain .
The main focus for storm evolution will be an east / northeastward shifting moisture boundary, which will cross most parts of S/SE Spain from the west during the daytime hours.
An area of repeating thunderstorm development / A cluster of storms can be expected to evolve east of the Strait of Gibraltar, moving towards the east / northeast.
DLS of 15-20m/s will support multicells with marginal hail and an isolated severe wind gust being the main threat.

Forecast soundings of this area indicate a well saturated atmosphere and expected type of thunderstorm evolution and strong lift will also pose an excessive rainfall and hence a flash flood threat mainly between Almeria and Valencia.