Identify and interpret broad scale, synoptic and mesoscale systems

Arctic Fronts form in the Arctic region, and move southwards in southerly flows. When they reach Northern Europe, they have usually travelled over an open sea, and convective cloudiness has developed. The appearance of an Arctic Cold Fronts is then, essentially, that of a shallow Cold Front. Arctic Cold Fronts are usually so far north that Meteosat images alone are inadequate to recognize them. The final check is best made using a loop of AVHRR images with the help of numerical model parameter fields.

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The extra tropical transition (ETT) of Hurricanes over the Atlantic is something that happens about 5 times a year and can severely disrupt the weather forecast. In this CAL the important features of ETT are addressed and physical theories are presented. After each chapter several exercises allow you to test the theory.

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In this module, the two major mid-latitude cyclone models, the Norwegian cyclone model and the Shapiro-Keyser cyclone model, will be explained in detail. The intention of the module is to point out the main differences in the life cycles of cyclones of the Norwegian type and the Shapiro-Keyser (S-K) type. Special focus will be placed on the synoptic preconditions that lead to the formation of cyclones.
Finally, sting jets, which often appear in the context of Shapiro-Keyser cyclones, will be briefly introduced.

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This training module treats the developement of cyclones at the downwind side of a mountain range with a special focus on the Alps. The module deals with the physical facts that lead to the creation of a lee cyclone, from its very beginning as a low-level vortex in the vicinity of a mountain range until its final stage as a mesoscale cyclone. The module tries to give an answer, why some of the lee vortices never develop into a full-grown cyclone and instead remain a local wind phenomenon or at best a low-level vortex that soon dissipates when leaving the downwind area by looking at the triggers that form cyclones. Local winds like the Bora and the Mistral are often linked to Lee Cyclogenesis in the Gulf of Genua. They will be treated at the end of the module.

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According to their degree of organization, thunderstorms can conceptually be divided into single cells, multicells and supercells. Organized storms, in particular supercells, are responsible for the large majority of severe convective weather like large hail and damaging wind gusts. They are favored by high latent instability and/or strong vertical wind shear and exhibit characteristic behavior in radar and satellite data. For nowcasting purposes and timely weather warnings, it is therefore crucial to recognize organized and severe thunderstorms in remote sensing data. This presentation focuses on key properties of this distinction and illustrates some characteristic examples.

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Lecture slides...

Due to the Azores geographical location, this archipelago is occasionally affected by strong Extratropical cyclones and Tropical cyclones. Extratropical cyclones are more frequent in winter and are often associated with strong winds, heavy precipitation and heavy waves which can be damaging and contribute to social and economic distress. Tropical cyclones, on the other hand occur mostly in September and October and in the past have caused loss of lives and property damage. Forecasting this type of systems is very challenging, mostly because a small variation in path can cause large difference in the impacts. This talk presents some tropical and extratropical cyclones that affected the Azores and also the challenges that forecasters face in this situations.

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Lecture slides

The Mediterranean tropical-like cyclones are intense sub-synoptic maritime lows with strong winds, axisymmetric warm-core structure and tropical cyclone features, such as a cloud-free eye and spiral deep convection. They are frequently referred to as medicanes (MEDIterranean hurriCANES) due to their resemblance to tropical cyclones. Despite their low frequency (of about 1.1-1.6 systems per year), medicanes constitute a serious natural hazard to life, property and the environment of the coastal regions of the Mediterranean basin and the Black Sea. Their accurate prediction is a challenge for the numerical weather prediction models. This presentation includes some past cases of medicanes, the description of their structure and characteristics, criteria that are used to define them, the development mechanisms, climatology, consequences and finally a detailed case study of medicane Qendresa (November 2014).

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Lecture slides

The EUMETSAT-operated Copernicus Sentinel-3A satellite has been providing near-real time data to the marine community since mid-2016, and will be soon be joined in operations by its sister, Sentinel-3B. This presentation will give an overview of the available Sentinel-3 marine products, with a primary focus on data streams associated by the altimeter (SRAL) and sea surface temperature radiometer (SLSTR). Examples of the relevant applications will be presented, along with a discussion of how users can best access data and monitor its quality.

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Lecture slides

Winds over sea are essential for marine forecasting and used in nowcasting and numerical weather prediction (NWP) to aid in off-shore activities (energy sector, transport, fisheries and recreation), particularly to secure safety of life and property. Winds over sea are observed by satellites and available from NWP model forecasts. Most satellite winds over sea are provided by scatterometers; they provide swath fields of both wind speed and wind direction from polar satellites. Currently, winds from EUMETSAT’s MetOp-A, MetOpB and the Indian ScatSat-1 are operationally available and provide good coverage around 9:00 and 21:00 local solar time (LST). Very soon they will be complemented by a few more. The lecture focuses on what scatterometer winds really represent, how good they are and what aspects need attention when applying these winds in your routine operations alongside with NWP model winds.

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Lecture slides

Satellite image interpretation of shallow clouds and related weather phenomena is a very important task for nowcasting because NWP-models and statistical methods exhibit still deficiencies in simulating these phenomena in a proper way. Especially over oceans but also over land observation networks are often too coarse meshed for nowcasting.
The theory and the most suitable satellite products will be explained first. In combination with other data (e.g., observations, radio soundings, radar products) examples will be discussed for the following application areas:

1. Diagnosing shallow clouds in respect to water content and related weather, e.g., drizzle of different intensities;
2. Identifying fog and low stratus and how to estimate the fog/stratus layer’s thickness. The likelihood of dissolving and connected weather phenomena (e.g., freezing drizzle) will be covered, too.

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Lecture slides

Convection can be found everywhere on the planet. However in meteorological way of thinking in mid-latitudes there is convection in different airmasses and also at the boundary of these airmasses. Convection at the boundaries belongs to the sub-features of frontal systems and we won’t deal with convection in the frontal systems.
In this lecture a few examples of unstable air Conceptual models will be shown, for instance: Cumulonimbi, Enhancement of convection by PV, Spanish Plume, etc. The typical environment is one part and the organization modes is the second part of the lecture.

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There are a number of structures and processes happening after a cold front has passed an area, e.g. enhanced cumuli, commas, instant occlusions, etc. Commas, for example are meso-scale structures developing within cold air, often behind frontal cloud bands. They occur mainly during the cold season and are a common feature for Northern and Western Europe - nevertheless commas can also be found in the south. As commas can cause severe weather this conceptual model is of high interest for forecasters. In this lecture life cycles of commas will be shown, what do commas form from, what can they form into, how they are connected to other mentioned phenomena and how they appear in satellite imagery - seen by MSG and polar orbiting satellites.

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Lecture slides