Weather Events

Warm Front Shields are associated with multi-layered cloud features, with abundant low and mid level clouds in the warm sector. Moderate to heavy precipitation can be found well ahead of the surface front, but after the passage of the front in the warm sector, slight to moderate precipitation is still possible.

Parameter Description
Precipitation
  • Slight, moderate or heavy precipitation ahead of the surface front.
  • In winter, ahead of the surface front, snow, freezing rain and drizzle is possible
  • After the front passage, rain and drizzle (light snow in winter)
Temperature
  • Rises slowly after the passage of the front.
Wind (incl. gusts)
  • Veering of the wind at the front passage.
  • Sometimes in the warm sector, wind increases and becomes more gusty
Other relevant information
  • Precipitation areas move faster than the surface front (embedded in Warm Conveyor Belt)
  • Sometimes moderate to severe icing occurs ahead of the surface front
  • In wintertime, the warm sector often contains mist and a risk of fog exists there
  • In the warm sector, low-level turbulence is possible
  • In the summer thunder is possible, most likely on the warm side of the front.

For a demonstration of the typically associated weather events, the case of 5 March 2020 at 12 UTC is used as a representative sample.

beforeafter

Legend:
5 March 2020 at 12UTC: IR + synoptic measurements (above) + probability of moderate rain (Precipitting clouds PC - NWCSAF).
Note: for a larger SYNOP image click this link.

The biggest part of the WF shield over France and Western Germany shows wide-spread precipitation. To the east, over Eastern Germany and Austria there is no precipitation reported. In both the measurements and the precipitation probabilities from the NWCSAF, the enhancement of precipitation at the windward side of the Alps is obvious.

beforeafter

beforeafter

5 March 2020 at 12 UTC
1st row: Cloud Type (CT NWCSAF) (above) + Cloud Top Height (CTTH - NWCSAF) (below); 2nd row: Convective Rainfall Rate (CRR NWCSAF) (above) + Radar intensities from Opera radar system (below).

For identifying values for Cloud type (CT), Cloud type height (CTTH), precipitating clouds (PC), and Opera radar for any pixel in the images look into the legends. (link).