Azor anticyclone dominating weather in Europe

Most of Europe is currently under the influence of a major Azor anticyclone which does not allow any trough to pass through central and southern Europe. It does not look like the pattern will change in the next 7-10 days, but GFS was offering some hope yesterday when it forecast a nice trough with serious setup potential. We will see how that develops. Meanwhile the SSTs in the Mediterranean sea are currently somewhat stagnant but will rise during this pattern of warm weather.

A lot of CAPE will be available for the storms is next days across most of Europe but given the basically non-existent shear there is no severe weather threat at least 7-10 days ahead. Azor anticyclone is just too strong currently. There could be some nice lightning displays though.

Severe weather weekly forecast for central Europe 25.4. - 1.5. 2011

Week 5 : April 25th - May 1st

High pressure system still mostly dominates Europe. Scattered thunderstorms are forecast across most of central and eastern Europe for Monday. Marginal cape is available in those areas with the largest CAPE (around 500-600 J/kg) in N-Italy, Slovenia and Hungary. Weak DLS will prevent severe weather with the exception of a small jet-stream above Slovakia, Austria and Poland where 20 m/s is present and could produce some large hail and/or strong wind. Strong convergence is present along the Dinaric mountains in Slovenia and eastern Alps region in Austria towards Hungary. This is where the convection will likely fire first.

With the maximum temperatures around 20°C later this week, severe weather will be diminished, but the potential returns in the beginning of May, when GFS is drawing some interesting setups.

Severe weather weekly forecast for CTRL-Europe 18.4. - 24.4. 2011

Week 4 : April 18th - April 24th

Huge anticyclonic system is currently in place and will dominate the weather in central Europe in the next 1-2 weeks. There will some scattered instability (not larger than 500-600 J/kg) but due to non-existent wind shear no severe weather will happen. Very stable weather is expected, in fact, looking at the picture lower, I have not yet seen this kind of agreeing between different GFS ensemble runs. Usually, they are all over the place. This time, even 14 days ahead, all ensembles are relatively closely together. Plan a picnic because no storm chasing is going to happen this week (and probably the next one). Well, it's April, what do you expect?

Sea temperature in the Mediterranean sea are still rather low and haven't warmed up significantly in the last weeks, still in the 15°C range.

Severe weather weekly forecast for CTRL-Europe 11.4. - 17.4. 2011

Week 3 : April 11th - April 18th

Another front will pass central Europe on Tuesday afternoon/evening. The bad news is the front will come rather late in the evening across the Alps. There should be enough CAPE for moderate convection. Best CAPE is forecast around Bologna-Venice region where GFS is drawing around 600 J/kg, but marginal CAPE will be present all the way from W-Italy to E-Hungary. Decent deep-layer shear will be present (>15 m/s), but with the lack of any low-level jet, storms will tend to merge into lines on the front. The best conditions for rotating storms are south of Venice where some veering winds and consequently moderate SREH3 are present. With some organization, large hail is possible. Pre-frontal afternoon initiation is questionable given the lack of serious convergence, but there will be only little CIN (up to 50 J/kg) so diurnal heating could speed things up.

Another interesting area will be in NE-Slovenia and W-Hungary. Strong backing winds will be present but with little CAPE. Storms on the front will quickly get elevated and any severe threat will be diminished rather soon.

After the front will pass, the air will stabilize and we do not expect any severe weather threats soon.

Severe weather weekly forecast for CTRL-Europe 4.4. - 10.4. 2011

Week 2: April 4th - April 10th

A cold front from the N-NW will affect the weather in the beginning of the week passing through N-Italy, Slovenia and Hungary on Monday afternoon, from 15Z onward. There will be a small CAPE buildup meaning only marginal instability. Only moderate shear is forecast so little organization will be possible. Widespread weak convection with some lightning should be observed on the front with rain.

We should experience another weak front on Friday. Max temperatures will be around 25°C with limited convective potential. Air will be mostly stable over the course of the week. Higher convective potential is possible next weekend, GFS is currently forecasting 600 J/kg CAPE but it is still too far away to make and conclusions. This instability is non-frontal based just on higher moisture content so GFS is likely to change his mind in the next run.

Severe weather weekly forecast for central Europe - 28.3. to 4.4. 2011

From April on I'll be doing weekly forecasts for convective weather for central Europe. I will be analysing synoptic scale weather, severe convective situations and storm chasing opportunities for the upcoming week. Detailed analysis for especially interesting situations will be written in separate blog posts. Let's start.

Week 1: March 28th - April 3rd

Nothing particularly interesting in terms of severe weather is going to happen in the following week. Weak cold front will affect the weather in the beginning of the week but it is quickly going to bounce off with Tmax ranging from 15 to 20 °C in the next days all the way to the end of the week, when they will be topping 20°C. Dewpoints will remain low due to low moisture (around 7g/kg) barely topping 12°C. CAPE buildup will therefore be limited to a couple of hundred J/kg in higher moisture areas.
Sea temperatures are still low, but with warmer weather that will change soon. Northern Adriatic sea has about 10-11°C while Mediteranian sea has about 14°C.

Top 3 images of 2010

Still suffering from severe supercell deprivation syndrome (SDS) and it's getting worse. Still winter but I guess april isn't too far away. Storm season in Europe usually doesn't start until late april, early may, when the first storms start to fire (we don't have the Gulf ... :( ). We can get first severe storms as late as June, when the storm season in the USA is already in full swing!

So here I'm offering my top 3 photos of 2010.

Supercell and lightning from Medvedje Brdo, Slovenia.

Front passing and morning shelf cloud from Medvedje Brdo, Slovenia.

HP supercell with shelf cloud near Portogruaro, Italy

Honorable mention:

Rotating mesocyclone, large hailer near Trebnje, Slovenia.

August 24th 2010 - Supercell near Udine

A short report from a supercell near Udine last year. Wasn't much of a storm but it cooled the boundary layer all over FVG so no more storms that day. :(


(Author: Nejc Ucman & R. Pucer)

September 17-19th 2010 - Flooding in SE-Slovenia

An amazing weekend with record rainfall (up to 650 mm in 3 days). Historic flooding all over Slovenia. All of the rivers were basically flooding.

August 8th 2010 - Supercell with lightning in central Slovenia

From Medvedje Brdo.

August 13th 2010 - Cold front passing in Medvedje Brdo, W-Slovenia

The front arrived in the morning. Wasn't expecting much, but got surprised! A morning shelf cloud and what a spectacular one!

August 5th 2010 - Possible supercell near Novo Mesto

Got run over at home with a nice cell in the line. I liked the moist east wind on the ground before the storm. Veering was pretty good in combination with the jet from the south. A nice wall cloud. Could not really tell if the thing was rotating because it was too far away. Pretty dynamic. Higher CAPE would definitely help.