Scientifically, why is snowfall in the city of Zarqa considered rare?

Weather of Arabia - The Kingdom was affected last weekend by a fourth-degree air depression associated with a polar air mass, and snow fell and accumulated in its wake, praise be to God, in several parts of the north and center of the Kingdom and to a lesser extent in the southern regions. Some of the heights of Irbid and Zarqa witnessed snow showers for a short period at dawn on Thursday, but neither region witnessed any accumulations and this came according to expectations, and the city of Zarqa enjoys high privacy for snowfall and its accumulation, for several reasons, after God’s will:

The city of Zarqa is in the middle elevations category

As it is known, most of the areas of Zarqa city are located at a height between 570-660 meters, and therefore the snowfall and its accumulation on these areas requires a deepening of the very cold air mass in all layers of the atmosphere, and therefore the availability of very low temperatures (with values not available much) with depressions Atmospheric conditions allow snow to fall and accumulate on these areas.

Zarqa city lies under the rain shadow area.. what does that mean?

The Rain Shadow phenomenon occurs when the mountain ranges intercept the humid winds coming from the west, and in our case this is the mountains north of Amman (such as Jubeiha, Shafa Badran and Abu Nseir). Opposite the mountains (Zarqa city), the clouds fade away due to the falling winds, so Zarqa city falls under the influence of the so-called rain shadow phenomenon. The areas affected by the rain shadow phenomenon suffer from low humidity and high temperatures; Because of the downward winds on it.

Storm Jana on February 19, 2015 is considered the last storm that brought snowfalls to various regions of the governorate, and that was for the first time since 1993 AD, in an event described as historic, as the snow at that time covered large parts of the Kingdom, except for the Jordan Valley, the Dead Sea and the Gulf of Aqaba, following the rush of a mass of Polar air across the Siberian lands and reached the Turkish lands, then continued to move towards the south and reached the eastern basin of the Mediterranean Sea, and worked to form a strong and violent depression.