More than 30cm of snowfall in 12 hours in Nagano Prefecture; first snowfall in Kyushu observed in Saga

2024/12/14 13:41

Snow continues to fall mainly on the Sea of Japan side, and a heavy snow warning has been issued in Nagano Prefecture.



Looking at the amount of snowfall in the 12 hours up to noon today, Saturday the 14th, Otari Village in Nagano Prefecture recorded 37 cm of snowfall, Shinano Town recorded 30 cm, and Hakuba Village recorded 25 cm of snowfall, with some areas recording more than 30 cm of snowfall in the past 12 hours.

The snow has spread to northern Kanto and western Japan.



As of noon today, it was announced that the first snow was observed in four locations: Mito, Kofu, Tottori, and Saga. This is the first snowfall in Kyushu this season, and in Mito and Kofu, the first snowfall was observed much earlier than last year.



As for the snow forecast for the future, snow will continue intermittently in similar locations, mainly on the Sea of Japan side. There will be blizzards in Hokkaido toward the night, and there is a risk of localized snowfall intensifying along the mountains of Tohoku and Hokuriku.

Please be aware of falling snow, frozen roads, fallen trees due to snow, and power outages. In case of a road closure or getting stuck on a snowy road, please prepare warm clothes, hand warmers, blankets, and other items to keep you warm in your car. It is also a good idea to have a mobile battery, emergency food, and drinking water on hand.

Today's weather: Winter pressure pattern strengthens; watch out for heavy snow and rain on the Japan Sea side

2024/12/14 07:04

Today, the 14th (Sunday), a low pressure system developing east of Japan is expected to move eastward, and winter pressure patterns are expected to strengthen around Japan.



Snow and rain will fall on the Sea of Japan side from northern Japan to Sanin.
The snow will intensify and become heavy in the mountains, so be careful of increased snowfall and worsening road conditions. Snow is also expected to accumulate in the mountains of western Japan. Please be careful when driving.

From Hokuriku to Sanin, intermittent rain clouds are expected to flow in due to the JPCZ (Japan Sea Polar Air Mass Convergence Zone) occurring in the Sea of Japan. Please be careful as the atmospheric conditions will become unstable and there is a risk of lightning, gusts of wind, and tornadoes.

Although most areas on the Pacific coast will be sunny, rain clouds will flow in from the Sea of Japan, and there is a possibility of sudden rain in the Kinki region, so it is a good idea to bring rain gear such as a folding umbrella.

The temperature will be cold, typical of this time of year, nationwide.
Please take proper measures to protect yourself from the cold when going out.

Tomorrow's (Saturday) 14th forecast: Winter pressure pattern strengthens, causing severe cold nationwide

2024/12/13 18:30

Tomorrow, the 14th (Sat), the winter pressure pattern is expected to strengthen. A strong cold wind with temperatures below -6 C at about 1,500m above sea level, which is a guideline for snowfall even on flat land, will move south from northern Kanto to Hokuriku. In addition, cold winds of the same strength are expected to flow into parts of the Chugoku region, southern Kyushu, and Shikoku.



Looking at the predicted minimum temperature tomorrow morning, the 14th, Sapporo is expected to be -5 C. In Asahikawa and Kushiro, it is expected to be -10 C, so it looks like it will be very cold.
In Tohoku and Hokuriku, many places will be around 1 C.
Many places from Western Japan to Eastern Japan will be around 5 C, and it will be colder than normal or slightly below normal.



Looking at the expected maximum temperatures, many places will have temperatures similar to those in early to mid-January due to the strong cold air caused by the winter pressure pattern.
In Hokkaido, many areas where it snows will have a maximum temperature below 0 C, making it a true winter day.
In Kanto and Tokai, temperatures are likely to be normal, but tomorrow, the 14th, the wind will strengthen from the north to the west, so it will feel colder.
In Western Japan, the cold will be lower than normal due to the influence of cold air.

It will be very cold nationwide, so please take care of your health. When going out, it is a good idea to choose a thick outerwear such as a down jacket.

What is JPCZ When it snows heavily, it becomes a heavy snowfall. Will JPCZ occur this weekend

2024/12/13 17:02

What is the "JPCZ" (Japan Sea Polar Air Mass Convergence Zone) that you hear about in weather forecasts when there is heavy snow

#What is the JPCZ
The JPCZ is a convergence zone where seasonal winds that have bypassed the Changbai Mountains collide in the Sea of Japan in winter.
When northerly and western winds collide, an updraft occurs, and bands of clouds form.
In particular, when there is a strong winter-type atmospheric pressure pattern or when cold air from above flows in, the seawater temperature of the Sea of Japan is relatively high, so a large amount of water vapor is supplied and snow clouds develop near the JPCZ.
In areas on the Sea of Japan side of Honshu, where developed snow clouds flow in one after another, heavy snow can occur locally.
Snow accumulates not only along the mountains on the Sea of Japan side, where heavy snow is likely to occur, but also on flat land, and snow clouds can flow on the Pacific side.



#When the JPCZ stagnates, it causes heavy snow. People are stranded in heavy snow.
The JPCZ changes position little by little depending on where the wind hits it. However, when it stagnates, snow clouds that have developed in the same place continue to flow in, causing a lot of snow to fall in a short period of time, resulting in "heavy snow."

In January 2021, the JPCZ stagnated near Wakasa Bay, causing heavy snow to fall.
About 1,600 vehicles were stranded on the Hokuriku Expressway in Fukui Prefecture.



#JPCZ may occur tonight through the weekend
The JPCZ will become apparent in the central Sea of Japan tonight, Friday the 13th, and will head toward the Hokuriku region.
Tomorrow, northerly winds will prevail and gradually move south toward northern Kinki and Sanin.
The JPCZ is not expected to stagnate in the same place, but this weekend the winter pressure pattern will gradually strengthen, and strong cold air for this time of year will flow in, so please prepare for heavy snow, especially on the Sea of Japan side.

The weather in the Tokai to Kanto-Koshin region, which has been clear for winter, is about to deteriorate. Snow is accumulating in some areas due to a low pressure system along the southern coast.

2024/12/13 14:22

Today, the 13th (Friday), the winter pressure pattern is weakening.
When the winter pressure pattern is weakening, the low pressure moving east along the southern coast of Honshu is called a south coast low pressure.
A south coast low pressure system can bring snow to the Pacific side of Honshu, where snow does not usually fall.

Today, the 13th (Friday), the weather from Tokai to Kanto, which has been sunny in winter, will gradually deteriorate due to the influence of a south coast low pressure system, and in Tokai and Koshin, there will be places where snow will accumulate, mainly along the mountains.



In Tokai, some places will start to rain as early as the evening.
In Kanto, rain is expected to fall at night, mainly along the coast.

In addition, snow will fall in some areas in the central and eastern mountainous areas of Shizuoka Prefecture and the Fuji Five Lakes area of Yamanashi Prefecture from the evening to the night of today, Friday the 13th.
In some areas, it is expected that up to 1 cm of snow will fall, and some areas will accumulate snow.
Please be careful of traffic disruptions and frozen roads due to snow.

Snow clouds drift across the Pacific coast of western Japan this weekend, urging people to put on winter tires

2024/12/13 12:53

Snow is expected to fall in some areas of western Japan from Saturday the 14th to Sunday the 15th.

Around the weekend from Saturday the 14th to Sunday the 15th, cold air that is expected to cause snow even on flat land below -6 C at an altitude of around 1,500m will move south to the Sea of Japan side of western Japan. This is a strong cold front for this time of year.



In Kinki, snow will fall mainly in mountainous areas in the morning of tomorrow, Saturday the 14th, and some areas will accumulate snow. After that, snow is expected to fall again around Sunday the 15th, mainly in mountainous areas, and the amount of snow is expected to increase.
Snow clouds will also flow into the Pacific side of Kinki.
In Wakayama Prefecture, snow is likely to accumulate in some areas even in the Kihoku plains.

In Chugoku and Shikoku, snow will accumulate mainly in mountainous areas, and there will be areas where snow is mixed in even on the plains.

In Kyushu, snow will accumulate in some areas, mainly in mountainous areas, from the early hours of tomorrow, the 14th (Saturday) to the morning of the day after tomorrow, the 15th (Sunday).
Snow is expected to accumulate not only in the northern but also in the southern mountainous areas.
In the northern plains, there will be areas where rain will mix with snow, and some areas will see their first snowfall.



Please be careful of traffic disruptions due to snow accumulation and frozen roads in Western Japan as well.
Please use winter tires when crossing mountain passes.
If you are planning to travel to areas where snowfall is expected over the weekend, please check the latest weather and traffic information and plan your trip with plenty of time.

Snowfall in the mountainous areas of western Japan, where the JPCZ is aimed, is like a "snowy linear precipitation band."

2024/12/13 12:11

Tonight on Friday the 13th, a convergence line where northerly and westerly winds collide, the Japan Sea Polar Convergence Zone (JPCZ), is expected to form in the Sea of Japan.

Around the JPCZ, the atmospheric conditions will become unstable, and rain and snow clouds may develop, causing thunderstorms and intensifying rain and snow.


The "linear precipitation band" that brings heavy rain in summer also occurs when developed rain clouds line up in a line, but the JPCZ brings heavy snow when a line of snow clouds that developed in the Sea of Japan in winter flows into it.

It can be said to be a "linear snow precipitation band" in winter.



Looking at the forecast for rain, snow and wind tonight,
The JPCZ (red dotted line), where northerly and westerly winds collide, is expected to head toward Hokuriku.

As a result, snow and rain may intensify tonight in Hokuriku and around Gifu Prefecture.

Please be aware of lightning strikes, tornadoes and other violent gusts of wind, and sudden heavy rain, as thunder may also occur.



Northern winds will prevail through tomorrow, the 14th (Sat), and the JPCZ is expected to gradually move toward Kinki and Sanin.

Furthermore, strong cold air will move south through the 15th (Sun), and snow will accumulate in some areas, mainly in northern Kyushu, Sanin, and the mountainous areas of northern Kinki.

Even in areas on the Pacific coast that are not usually used to snow, it is likely that snow will fall in some places, so transportation and other facilities need to be prepared for snowfall.



The JPCZ is expected to shift north and south through the first half of next week, and snow is expected to continue around Sanin and Hokuriku.

Depending on the wind direction and the timing of the strong cold air flow,
the areas where the snow will intensify will also shift north and south,
so please continue to pay close attention to the latest snow information.

The Geminid meteor shower is at its best. What's the weather like tonight through tomorrow morning

2024/12/13 08:45

The Geminids, one of the three major meteor showers, will be at its best from the night of today, Friday the 13th, to the morning of tomorrow, Saturday the 14th. This year, the full moon is on Sunday the 15th, and the moonlight will be almost all night, so the conditions for observation are not good. However, since the Geminids are a meteor shower in which many shooting stars can be seen, up to 40 meteors can be seen per hour in places with good observation conditions.



Tonight, a low pressure system will move along the Sea of Japan side and the Pacific Ocean side. Clouds are likely to spread on the Sea of Japan side, and many places will experience rain or snow, making observation difficult. Okinawa will also be affected by the cold air, and the weather will be cloudy and rainy, making observation difficult.



As the date changes, a low pressure system will move over the Tokai Sea by the morning of the 14th (Sat), and the clouds in Tokai and Kanto will gradually clear, and the clear areas will spread. Even if observations are difficult tonight, there will likely be a chance to see the Geminid meteor shower by tomorrow morning. The Pacific side of Hokkaido is clear and sunny, and the observation conditions are likely to be the best nationwide.

This year, the peak of the meteor shower activity is expected to be around 10 a.m. tomorrow, the 14th (Sat), and the best time to see it will be from the night of the 13th (Fri) to the early morning of the 14th (Sat).

Friday 13th: Two low pressure systems formed, causing rain on the Pacific coast

2024/12/13 06:02

Today, the 13th (Friday), a low pressure system has formed off the coast of San'in and is moving eastward. The low pressure system will move towards Hokuriku by night. Meanwhile, a new low pressure system is expected to form off the coast of Shikoku on the Pacific side, and is expected to move towards the Izu Islands.

Snow will fall intermittently on Hokkaido and the Sea of Japan side of Tohoku. In Hokuriku, rain will fall mainly on flat land, and some areas will be accompanied by thunder. In San'in, rain clouds will cover the area from the afternoon, and some areas will experience thunderstorms. Clouds are likely to spread during the day today on the Pacific side, where sunny weather has continued until now, and temporary rain is expected in the afternoon, mainly in the coastal areas on the Pacific side of eastern Japan.



The expected maximum temperature is -1c in Sapporo, 5c in Akita, and many places in northern Japan will be below 5c. In Hokkaido, the Sea of Japan side and the Sea of Okhotsk side will experience mid-winter highs below 0 C. In Tokyo and Nagoya, it will be 10 C, and in Osaka, it will be 13 C. There will be little sunshine in eastern and western Japan, and it will be cold like winter in many places. Influenza is spreading and the air is dry on many days, so please be careful to take care of your health.

Winter air arrives. The 7th will be the first true winter day of the season in the Kanto region. Weather and temperature summary (December 1st to December 7th, 2024)

2024/12/13 00:23

This is a summary of the weather and temperature from December 1st to December 7th, 2024.

#Summary of the weather for this period (December 1st to December 7th)
Average temperatures were normal or slightly higher in many places nationwide. From Kanto to the west, some places were more than 1 C higher than normal, with Tokyo and Maebashi being 1.8 C higher than normal, and Fukuoka being 1.2 C higher. As December began, reports of maple and ginkgo observations continued to come in from western to eastern Japan, but most were later than normal. Precipitation was higher than normal in many places from southwestern Hokkaido to Tohoku and the Sea of Japan side of Hokuriku, but extremely low on the Pacific side. In Akita, it was nearly 1.5 times the normal amount, but in some places on the Pacific side, such as Tokyo, it was not observed at all. Sunshine hours were below normal, mainly on the Sea of Japan side of Hokkaido and Hokuriku, and Niigata and Kanazawa had about half the normal amount of sunshine. On the other hand, the Pacific side was generally above average, with Tokyo reaching about 1.5 times the average.



#Characteristics of pressure distribution
On the 1st, a winter-type pressure distribution centered on northern Japan. Cold air below 0c remained at about 1,500m above northern Japan. On the 2nd, Japan was covered by a high pressure system centered off the coast of Sanriku. A low pressure system accompanied by a front moved northeast-northeast through Primorsky Krai. On the 3rd, a low pressure system accompanied by a front moved north near Sakhalin. A cold front extending from the low pressure system passed through northern Japan. At 9 p.m., a new low pressure system formed in the Sea of Japan and moved northeast-northeast. A front stagnated over the southern seas of Japan. On the 4th, a low pressure system in the Sea of Japan passed through Tohoku. After that, a winter-type pressure pattern was observed around Japan. A low pressure system formed on the front line over the southern seas of Japan, and moved eastward over the southern seas of Japan. On the 5th, a low pressure system moved eastward north of Hokkaido. A winter-type pressure pattern continued around Japan. On the 6th, a low pressure system passed through northern Japan from the Sea of Japan, passed off the coast of Sanriku, and moved northeastward. The winter-type pressure pattern strengthened around Japan by the 7th.

#Precipitation
On the 1st, snow fell in Hokkaido and northern Tohoku on the Sea of Japan side, and rain fell in southern Tohoku and Sanin. On the 2nd, the weather was sunny throughout the country during the day, but rain began to fall on the Sea of Japan side of northern Japan from the night. On the 3rd, rain fell from Hokuriku to Tohoku. Heavy rain of 20.5 mm per hour was observed in Yurihonjo City, Akita Prefecture, the largest ever recorded in December. On the 4th, the rain intensified in the Soya region of Hokkaido, and some places observed snowfall of more than 20 cm. On the 5th, snow and rain fell mainly on the Sea of Japan side from Hokkaido to Sanin. The 3-hour snowfall was 19cm in Kotanbetsu, Rumoi, Hokkaido. On the 6th, Hokkaido experienced a strong winter pressure pattern, and the west winds accompanied by snow were very strong on the Sea of Japan side, and blizzard warnings were issued in some areas. In Hokuriku, active rain clouds associated with the JPCZ caused rain to continue, and heavy rain warnings were issued in some areas. On the 7th, heavy rain warnings (landslides) continued in Niigata and Toyama prefectures, and in Noe, Itoigawa City, Niigata Prefecture, and Takada, Joetsu City, Niigata Prefecture, the 24-hour rainfall updated the highest value in December, resulting in record rainfall for December.

#Temperature
On the 1st, northern Japan and Hokuriku, which were affected by the cold air, felt cold with temperatures of 10.8 C in Niigata, 11 C in Sendai, and 5.5 C in Sapporo. On the 2nd, the maximum temperature exceeded 20 C in parts of Kyushu and Shikoku. The maximum temperature observed was 21.6 C in Miyazaki (similar to early November). On the 3rd, eastern Hokkaido recorded a record high temperature for December, with Nemuro City recording 13.6 C. This is the first record in 134 years since December 9, 1890. On the 4th, it was warm mainly in the Kanto region, while central Tokyo was at 17.8 C, the same temperature as early November. On the 5th, a temperature of -13.4 C was recorded in Nakashibetsu, Nemuro, Hokkaido. The cold intensified mainly inland areas from western to eastern Japan, with minimum temperatures of -0.4 C in Nagano, 4.4 C in Kyoto, and 3.7 C in Tottori. On the 6th, the maximum temperature in Tokyo was 16.7 C, the 10th consecutive day of 15 C or higher. On the 7th, the 24th solar term, "Daisetsu". Cold air flowed in, and the maximum temperature in central Tokyo was 12.4 C, the first time it had fallen below 15 C in 11 days. Sapporo City recorded -0.6 C, the first true winter day of the season. A temperature of -0.6 C was recorded in Tashiro, Tsumagoi Village, Agatsuma District, Gunma Prefecture. It was the Kanto region's first true winter day.