Hokuriku: From the 21st to the 22nd, there will be village snow, so be careful of heavy snow even in flat areas. Heavy snow due to JPCZ as well.
December 20, 2023 18:12
From the 21st (Thursday) to the 23rd (Saturday), a winter-like atmospheric pressure pattern will strengthen, and the strongest cold air so far this season will move southward. Especially on the 21st (Thursday) due to the influence of JPCZ moving southward over the Hokuriku region, and on the 22nd (Friday) due to the influence of local fronts (Hokuriku front, coastal front) occurring on the coast of Hokuriku apart from JPCZ. , there is a risk of heavy snowfall. Even in flat areas, you need to be wary of heavy snow or short-lived strong snow. On the 23rd (Saturday), the snow will change to mountain snow, and the peak of snowfall in the plains is expected to pass.
JPCZ heading towards Hokuriku; heavy snow similar to village snow possible on Friday 22nd
On the 21st (Thursday), winter-like atmospheric pressure patterns will become stronger. It will snow as far as the coast of the Hokuriku region, with cold air reaching -9 degrees Celsius at an altitude of around 1,500 meters, which will cover the entire Hokuriku region at night. In addition, clouds that have developed along with the JPCZ (Japan Sea Polar Air Mass Convergence Zone) will move southward over the Hokuriku region. It is necessary to be cautious of increasing snowfall, including in flat areas, especially when passing JPCZ.
On the 22nd (Friday), JPCZ will move south to near Wakasa Bay. On the other hand, in the Hokuriku region, winds will enter areas with locally weak winds, and winds will collide (converge) along the coast, resulting in the formation of local fronts. This is called the coastal front or the Hokuriku front, and is part of the “Sato-snow-type” pattern that causes heavy snowfall mainly in the flatlands of the Hokuriku region.
Throughout the 22nd (Friday), the areas around Niigata City, the coast of Joetsu to the northern eastern coast of Toyama Prefecture, the western part of Toyama Prefecture to the coast of Ishikawa Prefecture, including the area around Kanazawa City, and the flatlands of northern Reihoku, Fukui Prefecture, including Fukui City, etc. , there is a risk of heavy snowfall even in populated areas. There is a risk that snowfall will increase rapidly in a short period of time, so please be careful about disrupting transportation and stranding vehicles.
On the 23rd (Saturday), the pressure distribution will change to a mountain snow pattern, and the winter pattern will gradually ease, so the peak of snowfall in the plains is expected to pass.
Heavy snow warning period and snowfall amount in each region
On the morning of the 21st (Thursday), snowfall will begin to increase in Shigetsu, Niigata. After that, snowfall will become heavier in many places as the JPCZ moves south, and in the evening snowfall will become heavier in the flatlands of Toyama and Ishikawa prefectures, and by late evening it will also increase in the flatlands of Fukui prefecture.
On the 22nd (Friday), we need to be careful of heavy snow in the flat areas. From the night of the 22nd, the snow will gradually change to a mountain snow type, with heavy snowfall expected along the mountains.
On Saturday the 23rd, snowfall in the plains is expected to pass its peak and snow will fall mainly along the mountains.
The expected amount of snowfall is expected to increase, including in flat areas, and there is a risk of heavy snow even in flat areas, especially from 6:00 PM on the 21st to 6:00 PM on the 22nd.
Characteristics of Satoyuki type weather map
There are various characteristics that can be called a winter type atmospheric pressure distribution, but there are two main types of winter types: mountain snow type and sato snow type.
The mountain snow pattern is a pattern in which the amount of snowfall increases mainly in mountainous areas, and is a textbook winter pattern with vertical isobars, northwest winds, and streaks of clouds coming in from the Sea of Japan. In this case, in flat areas, snow and rain will fall and stop, which means that the amount of snowfall will be less.
On the other hand, the Satoyuki type is a pattern in which heavy snowfall occurs in flat areas, and is characterized by the isobars on weather maps concave in a bag-like shape over the Sea of Japan, with strong cold air in the upper atmosphere. JPCZ and small cyclones are often hidden in concave areas of isobars. Another characteristic is that the intervals between the isobars are loose, and the winds are weak, making it easier for convergence to occur in coastal areas. In addition, the isobar lines around Hokuriku lie diagonally, so winds often blow from the west or southwest when it snows in the countryside.
The figure is a weather map of the Sato-type heavy snow that occurred from January 12th to 13th, 2018. At this time, it converged in the JPCZ and coastal areas, and the snow exceeded 80 cm in Niigata and Takaoka Fushiki (Toyama Prefecture). It snowed heavily, with 62 centimeters of snow falling in Kanazawa.
This time, the cold air is not as strong as it was this time, so we don’t expect the amount of snow to increase to this extent, but this will be the first real snowfall of the season, so we need to be very careful.
If you have to go out by car, take proper precautions.
This time, there is a risk of warning-level heavy snowfall even in flat areas, and various road-related organizations are urging people to refrain from going out by car for non-essential reasons and the possibility of road closures. However, if you have to go out for work reasons or other reasons, you need to check the latest weather and traffic information, act with caution, and take proper equipment.
First, to avoid getting your car stuck, carry tire chains even if you have changed to winter tires. Also have a shovel and tow rope ready.
Sometimes you can get stuck. You may be forced to wait for a long time, so in addition to emergency food, it is a good idea to prepare cold weather measures such as blankets and body warmers, as well as flashlights in case you are stranded at night.
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2023-12-20 09:12:54
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