Storm Forecast
Valid: Fri 30 Jan 2009 06:00 to Sat 31 Jan 2009 06:00 UTC
Issued: Thu 29 Jan 2009 17:39
Forecaster: TUSCHY

SYNOPSIS

A short-lived omega-like configuration dictates the weather over Europe. The most progressive feature is a sharp upper trough over SW Europe although a weakening trend is anticipated during the forecast. WAA just downstream enables weak ridging over W-Europe, already losing strength during the night hours. A stout high pressure area over N-Europe builds southwards and slowly becomes the steering mechanism for N/NE and central Europe. A dome of cold air keeps conditions stable over NE Europe, while cold mid-levels above the warm Mediterranean assist in unsettled conditions. An intense depression NW of Ireland continues to move northwards with a strong pressure gradient still present over Ireland,UK and Scotland during the day. Strong/severe wind gusts are possible but those are not associated with strong/persistent convection.

DISCUSSION

... Around Crete ...

Northerly surface flow advects a dry/cold airmass over the Aegean Sea and Crete. Some mixing of lower levels keep LL mixing ratios high enough for some marginal instability release beneath cold mid-levels. Cold ELs hint on deep convection, but very thin CAPE profilers are expected, so marginal updraft strength keeps expected longevity of thunderstorms quite short. Also moderate LL CAPE release is possible, but there are no signals of convergence zones at lowest levels, so despite a low-end waterspout risk, no severe weather is forecast. Thunderstorm risk diminishes from west to east during the day and flairs up once again around W-/S-Greece during the night hours.

... Portugal ...

Weakening upper trough draws near from the west with some thunderstorms forecast during the evening/night hours. The main focus for initiation is along the W/SW coast of Portugal, but later-on also over the Strait of Gibraltar. Stronger storms could contain marginal/isolated large hail, but otherwise nothing severe is forecast. An isolated thunderstorm can't be ruled out over Portugal and even extreme W-Spain, but the coverage of thunderstorms remains very low, so the general thunderstorm area was not expanded towards the east.

During the end of the forcast, instability increases over the Balearic Islands and if the upper trough speeds up somewhat, a few storms could evolve. Most members of GFS and the majority of the models agree in the slower solution and hence no area was drawn.

... SW of Irleland ...

A strong cold-core low approaches from the SW at 00Z onwards and deep convection likely goes along with this feature. Expect main activity still outside of our area of responsibility and hence no thunderstorm area was included.