Nowcasting Symposium 2009

The International Symposium on Nowcasting and Very Short Range Forecasting (WSN09) will be held at the Tellus Conference Centre in Whistler, British Columbia, from 30 August to 4 September 2009.

This meeting is organized by the World Weather Research Programme (WWRP) of the World Meteorological Organization (WMO) and will be hosted by Environment Canada. The previous Symposium (WSN05) was held in Toulouse, France.

For further information seehttp://www.nowcasting2009.ca/ (this web site is also a great source of training material).

Radar images for Central Europe

Enjoy this link: Radar images in EC

Radar Errors and Limitations

(more details on JetStream - great generous site for the public!!!)

Radar is a detector that has its limitations, first of it is the ... fact that the Earth is curve while the beam propagates with a smaller curvature, so, the beam is bending upward with the distance. Further the echoes are on the screen, the higher is the sample! (you can use the graphic above to have an idea about this variation).

But this has a great advantage in... the wind field. It enables us to see the wind shear (how wind changes with height) in a single glance (some details here:

http://ww2010.atmos.uiuc.edu/(Gh)/guides/rs/rad/ptrn/ptrn1.rxml).

And this is the real advantage of Doppler radar in front of other detectors because the wind shear actually controls the severity of a convective development.

Radar is all a trade, or better say that learns you how to change the weakeness into a strength.

Carpathian Convergence Line

This time was seen only by the satellite, the clouds developed were not stromg enough to be detected by radar (in summer this situation can bring severe storms).

Foehn on radar and satellite

The slopes exposed to the circulation (northern slopes of the Carpathians) received rain while the southern slopes, in the lee, experienced a diminish of cloudiness and reflectivity.
The Northern part of Oltenia has a mild climate due to this effect. Well, Favonius, Roman king, gave the name to this warm wind.

Convective inhibition

Early in the morning, a band of low clouds prevent the insolation of the land beneath. Later in the day (the image on top), this region remained stable to convection while around it the air became unstable.

A perfect example of ingredients at work!

Satellite can give a great view about the ingredients needed for convection: instability, moisture, some lifting In the image there is an airmass of stratus clouds, with some inhibition (CIN) for convection. But there is a spot where some convergence at the surface (lifting) helped to overcome this CIN, a nice cell developed, and the outflow, symetric, produced some stable clear air around. Ian Bell found this great image in the internet.

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