The perfect snowfall even on the plains right at Christmas?

For several days we anticipatedfor the first time the probable arrival around December 25-26 in northern Italy of another Greenland polar air core with some possible surprises. And in fact today, December 17, some of today’s top nighttime models let us glimpse Fr.on December 25 the arrival of the polar air and then on December 26 the surprise … of a possible snowfall even in the plains of northern Italy

Why would it be the perfect snowfall?

Because it takes two ingredients for the snow to reach the plains:

• Arrival of air cold enough to bring the freezing level below 600-700 m. This situation in current circumstances should occur precisely on December 25 after a transfer of polar air from the upper Balkans to the Po valley. Today’s nighttime models predict that by the end of December 25 the zero degree level should drop to less than 200m on December 26 in many areas of the Po Valley.

• Within the next 24 hours, that is, before the cold air that flowed into the Po Valley on December 25 dissolves, warm and rainy southerly winds must arrive, which are forced to flow over the cushion of Cold air. Well, coincidentally, at the end of December 25, a low pressure vortex will be generated, generated in the lee of the Alps in the Ligurian Sea (“cyclogenesis in the Ligurian Sea”- Cover Image) that would push the warm south winds over the cushion of cold air that flowed into the Po Valley with consequent snowfall even on the plains.

KEEP IN MIND

• Forecasting a snowfall on the plain is the most difficult forecast for a meteorologist because, while a modest error of 100-200 meters is not perceived in the snow level in the mountains, a similar error on the plain (equal to a 0.5 ° C error in temperature forecast) often change from a “yes snow” situation to a “no snow” situation or vice versa.
• In addition, this forecast is made well in advance (8 days) and therefore has a probability of success of around 65% (more snow yes than snow no) because in the meantime the models could change some details (for example, the .. temperature degree)

• So if the snow is denied in the next few days I beg you not to make the usual complaint “But as you said the snow would come and now you will all stay”