Archive for the ‘Europe forecasts’ Category

Global patterns and an outlook for month of April!

**NOTE: This post has been made on the very last days of March, so keep in mind some maps are not refreshed to the last data, but overall outlook remains the same**

ENSO is now well neutral. It will stay like this for a while, most likely with a slow upward trend to en El Nino. But as this is April outlook, we will will be looking only at April values of ENSO.

Current state:

The CFS version 2 forecast, keeps it neutral somewhere until June.

SOI is also an important feature here. It is also in neutral values at the moment, with a downward trend expected. At least through April/May, it should stay neutral, with a faster drop probably in May, preceding an El Nino development, as suggested by CFS and ECMWF ENSO Anomaly forecasts.

When both of these global features are normal, the Madden-Julian oscillation has the strongest impact on the pattern. Strong MJO activity is often observed around 6-12 months prior to an El Nino cycle. Besides the neutral ENSO, this helps to explain an obvious pattern teleconnection in north hemisphere, when comparing MJO phase composites with the actual patterns in March. Detailed March pattern analysis will be added as soon as reanalysis maps become available.

MJO Forecasts take it into phases 7,8 and 1.

The phase 7 will soon end, so since phases 8 and 1 seem to be a bit longer lasting, we will focus more on that.

This is phase 8 composite. The main features here are ridging over USA, with blocking over Greenland into Canada, ridging extending into Alaska, troughs over East coast, quite deep lowering over northern part of Europe, with ridging further south. Also keep an eye on the Asian features.

This is CFSv2 500hpa anomaly, weekly forecasts. Phase 8 should be quite strong and lasting somewhat like the first week in the forecast. To be honest, looks like a good match, with some differences over USA West coast and Asia, due to the forecast starting at April 1st and phase 8 starting around April 3rd.

Phase 1 will probably be quite fast and weaker, so not much similarities expected, except for Pacific.

Composite for the phase 1.

The forecast (please refer to the CFS weekly forecast above) is still somewhat reflecting the strong phase 8, with Pacific in a Phase 1 state, since it is the closest to MJO.

It is still a slight mystery where MJO will turn after phase 1, but monthly forecasts are suggesting its absence around middle to late April, with a possible return into phases 4-5 in May. But thats whole month in advance and trends will be monitored prior to the next outlook.

With ENSO in neutral, SOI in neutral, and MJO absent, it is seemingly possible that the trend of the first half of the month will continue.

Lets look at a few CFS forecasts.

This is global 700mb anomaly. Europe lower heights, Greenland and Alaska and W CONUS blocking, and USA East coast troughing, have MJO phase 8 written all over it…

Looking at week 3 and 4 CFS forecast, is not really reasonable, since it is very unreliable, but we will look for the main features just to see what it is suggesting, compared to what is expected of MJO. Both weeks are quite interesting. First, the EU lower geopotentials seems to continue, and the Canada ridging moves further north, replaced by negative departures. Both weeks, especially week 4, have some features that slightly suggest MJO really moving towards phase 5. But allot of this is still open for late April.

A look at Europe. After a persistent “death ridge” in March, a pattern reversal looks to be unfolding. Weakened blocking will move out, over Atlantic, starting to support more of a zonal oriented flow. Overall lower monthly geopotential heights over a continent, mean troughs persistence, with weak or absent ridging in between.

With more troughs and less ridging, its normal to expect anomalous rainfall. Looking at CFS, it clearly confirms it.

Looking at SEEVCC model, which is actually “based on dynamical downscaling of ECMWF seasonal forecast, using a regional atmosphere-ocean coupled model”. It too has the same idea of anomalous rainfall, especially in Central Europe. Now, compared to the CFS, there are some differences, especially over the Balkan region and SE Europe. This is likely due to a different model systems, higher terrain resolution, and also because the SEEVCC model was calculated in March 1st, while CFS is latest. But the idea generally stays the same.

Temperature wise, these two have a slightly different opinion. CFS has average to cooler temperatures over western to middle and northern Europe, where it is also forecasting the main trough activity. Now the reason behind the positive anomaly over to the east is, atleast in my opinion, mainly because of the deeper trough over western Europe, meaning that western to middle Europe is situated more over the back side and the core of the troughs, while more to the east, the SW-erly jet stream advecting warm temperatures into south-eastern Europe.

SEEVCC also has the idea of above average temperatures, not so east and more over Central Europe. Given that it was made on March 1st, the lastest run will show the main positive anomalies to be more to the east.

This is how CFS looked like with March 1st to 10th initial conditions. The positive anomaly was more to the west and northward.

 

Summary: Overall we are quite in agreement with what CFS and SEEVCC are offering. April should be quite normal temperature wise, with above average temperatures possible from central towards east Europe especially later in the month, and normal, maybe slightly below average over some parts of western Europe.

Precipitation anomalies seem to be mostly normal to slightly above average over most of Europe, especially over central Europe, but with complex terrain, precipitation anomalies can differ greatly on a small scale!

A quite dynamical April seem to be in store, like April should look like in Europe. This also the time of year, when winter is retreating towards north and warmth slowly progresses from the south. So the occasional clashes contribute to the overall dynamical patterns and the weather.

Prepared by:
Andrej Flis
Marko Korosec


Extreme drought over Slovenia continues, first supercell of 2012!

Drought conditions are worsening lately, as a bit of rain a couple of days ago did not help much. Some areas in W-CNTRL Slovenia did received around 15-25mm of rain, except the NW part which received 40mm+ locally. While the rest of the country, especially SSE parts receive only a few drops. There were actually some interesting intense showers in SW Slovenia, accompanied by small hail. Shear was actually pretty good that day and despite low CAPE, I managed to observe one supercell from Kozina do Senozece in the late afternoon, here are two shots from that day…

This weekend brought a few showers across the country, as a weak upper low is wobbling around the Alps, but no serious rainfalls were recorded anywhere. Not to mention the Bora winds since last night, which will even worsen the fire danger conditions.

Here is the latest Fire probs index map… a few areas are still and yet again above 200 which is incredible! Not to mention fire danger at the highest level 5! Soil moisture and conditions improved only in NW Slovenia where higher amount of rain was recorded, fire probs index droped to almost 0 after the event, now is again above 50 at level 3/5.

And looking over the long-range model maps, there is a hope for a pattern change in the beginning of April, but for not models are not too impressive with the amount of rain… not even with confidence in anything worth.

Conditions will surely be monitored further, stay tuned!


Extreme polar airmass spreading into central Europe next week!

Rapidly and completelly changing weather pattern across Europe is unfolding this weekend, with a large blocking over western Europe/Atlantic sea. It is blocking the zonal flow and providing more meridional flow across central Europe. This will result in changing weather into more winter alike. Despite almost no snow chance for southern Alpine region, except the NW Italy which received deep snow cover today, an unusually powerful polar trough will bring extreme cold across E-CNTRL Europe in the next 7-10 days! Such setup usually need a blocking Atlantic high as well as extensive Scandinavian/Russian ridge resulting in the massive advection of Siberrian cold airmass towards the central Europe.

Here is a map of the pattern later next week, showing a strong ridging over NE Europe and large cyclone over N-CNTRL Mediterranean, resulting in strong pressure/temperature gradient in between. As a result, a strong ENE-erly flow towards the Mediterranean brings extreme cold with 850mb temps between -15 and -20°C. Additionally, very strong to extreme Bora winds are expected, likely reaching gusts up to 200 km/h locally!

Indeed details are not yet well defined as regarding the precipitation over the next weekend, but its sure that cold airmass will be one of the most impressive in the last decades (30-40 years). Still some uncertainities exist, but for sure winter with very cold to near extreme temperatures returning into large large of Europe. This map shows the 850mb temperature anomaly, very impressive at least to say! It is completely the opposite picture from what we experienced in the last weeks.

Here is an ENS forecast for central Slovenia… pretty extreme anomaly!

Stay tuned for future updates on this impressive setup next week!