Nevadas

5 de Enero de 1997

It was the great snowfall of the end of the millennium, an early gift from the wise men.
As almost everyone will know, it rarely snows in Chulilla. For this to happen, a number of conditions must be met:
1. There must be a mass of cold air in the medium-high layers of the atmosphere, with approximate temperatures of -5º to about 1500m high (about 850 mb of atmospheric pressure).
2.We must have a slight entry of winds of maritime origin. In our area the northeast is more favorable.
  Analyzing these situations we have to say that for the first to occur, a mass of continental air generated in Eastern Europe needs to move westward, affecting us at least a little. These air masses cannot be produced in small regions such as the Iberian Peninsula, they need large continental regions in which the earth can cool quite quickly (compared to water). Taking a look at the world map we can see that only the northern part of the American continent and the Eurasian continent can generate such cold air mass. In our case, things are even more complicated because they are located in the surroundings of a warm sea. This causes that if the incidence of the east wind is notorious, the temperatures will rise and with this the risk of snowfall will decrease at least at low levels.
Analyzing the case at hand, that is, the snowfall of January 5, 1997, we see that by reviewing the 850 mb map, which indicates the level from which the snow begins to set, the snow level was more or less at 400 m. Simply reading the newspaper the next day, we found that there were isolated snowfalls below that level. This can be easily explained, the wind, although of maritime component, was negligible, which contributed to produce a horizontal thermal stratification, which, in a valley sufficiently closed like ours (the Turia valley) if it snowed in the high part, little by little the cold air was descending altitude taking advantage of its greater weight and snowing in the lower levels of the valley. That explains how it could snow in the garden about 250 m and yet it did not curdle in Casinos at 350 m.

You can see the image of the Meteosat corresponding to that day here.