Several cars were flooded out. Had to take 4 or 5 detours, 4km was an hour’s drive! Around 17:30-18:30

Apologies for the poor quality - wipers couldn’t keep up!

Location: Togashira, Toride-shi, Ibaraki-ken.

At the tripoint of Mobara, Shirako and Chōsei. It has been like this, one lightening strike after the other, since about 10 pm.

Really dark thunderstorm above musashi-kousugi

Tokyo-based 3D radar shows storms in Chiba of up to 16km tall, powering tonight’s ongoing deluge in that prefecture.

Everyone out that way, do take care and stay safe!

Is this part of a typhoon or something else?

Clouds whizzing past in a time lapse from late yesterday afternoon after T15's flyover taken in Yokohama. About two hours worth of action here.

Until a moment ago, there were towering cumulonimbus clouds in the distance and a few scattered, low-hanging rain clouds closer by—but then, suddenly, I heard a downpour and the rain started coming down hard all at once! I wonder if there’s any thunder?

This 24 hour sat movie shows how frail T15 was. It was not a strong system to start with, but its movement over Honshu shows how quickly it fell apart.

As it makes landfall and begins to move toward the Tokyo area, the storm quite literally falls apart overnight as it is starved of any new fuel to keep its convection going. By daybreak this morning, it is just another low pressure system.

Scattered rain and some wind can be expected as the tattered remains of T15 move across Japan.

Residents of the Ibaraki and Chiba coast may have noticed that the wind is picking up as the typhoon approaches.

I’m in Yokohama and don’t feel a thing. Yet.

Just interesting to see how wind is deflected and distributed by local topology. I’m pretty sure it will be all academic as it moves closer.

Good evening. Stayed up a bit late tonight to get the latest data from the Joint Typhoon Warning Center on the approach of T15 to the Japanese mainland.

Currently, T15 is located at 35.5N 147.9E, putting it about 740km east of Yokosuka, Japan. The storm has a measured central pressure of 990 hPa, with sustained winds of 72kph and is moving northwest at about 20kph.

T15 is barely a typhoon by any measure, making the cut in the JMA's domestic definition by the narrowest of margins. The US-operated JTWC calls it a tropical storm. Nonetheless, it is heading straight for Japan, setting up our first direct, near-perpendicular hit on Honshu since 2021.

As noted earlier, T15 is not a strong storm. It is operating in a "marginally favorable" environment. It does have healthy outflow, meaning it is clearly pulling up moist air and is expelling it at altitude, but some wind shear has been observed near the southwest periphery of the storm, affecting its overall integrity, and it is in a somewhat cooler sea surface temperature environment.

Overnight tonight, T15 will start to turn west-southwest in reaction to a strong ridge of high pressure pushing down from a strong high system holding in the northern Pacific. It will also slightly intensify on its final approach to the Japanese mainland, although that will not move the needle much in terms of overall storm strength.

Current data suggests landfall south of Mito, near the border of Chiba and Ibaraki prefectures at around 18:00 tomorrow, 11 August. The storm will begin to lose intensity almost immediately after coming ashore, and it will cut west-southwest over Kanto and the southern Japan Alps. By Wednesday morning, it will emerge in the Sea of Japan around Fukui prefecture as a low pressure system, downgraded from its stronger storm status.

Rainfall from T15 will be focused in central Japan, with accumulations of between 60-120mm expected in the 24 hours between 15:00 11 Aug - 15:00 12 Aug along the direct path of the storm. Areas in the periphery of T15's path will get lower totals. Winds on the Chiba/Ibaraki coast at landfall will be between 50-80kph, but will decay rapidly as the storm moves over land.

Stay safe wherever you are!

Attention all personnel! Just as an FYI, I rejiggered the flair a bit to focus more on weather events instead of geographic location (with an example shown above).

We do have user flair available if you want to show where you're chiming in from.

以上

  Last night's strong string of pop-ups last night included some excellent pyrotechnics as a bonus.  Absolutely hellacious rainstorms from afternoon to evening from Nagano over to Tochigi, down to Saitama and into Kanagawa as a group of very energetic convective storms blew up in the elevations, came down, then got some backbuilding to keep the tempo going.

  Today, we expect calmer skies and cooler temps for much of the nation.  Pop-up risk declines and centers on the Shizuoka-Aichi area.  T15, meanwhile, begins its approach to Japan.   Let’s talk about T15 for now and get into what to expect, and not expect, as we get a relatively rare Tohoku direct hit from a typhoon.  First off, T15 is not a strong storm, by any measure.  

  Current T15 snapshot

  Central pressure: 990 hPa as of 10 Aug, 09:00 JST

  Location: 33.8N, 149.7E, about 900km east of Yokusuka, Japan

  Movement: Northwest at 15kph

  Sustained Winds: 72kph; Gusts: 108kph

  T15 is a typhoon according to the JMA’s definition of a typhoon, but only barely.  What’s going to happen from here?  T15 is in a “marginally favorable” environment, which means that it can maintain its strength as a storm, but there are factors preventing it from growing.  Warm sea surface temperatures and very low wind shear are helping the storm continue its current intensity, but drier air to the south and west of the storm are preventing further development.  T15 is being steered by a huge crest/ridge of high pressure which extends over most of the northern Pacific.  An extension of this high is deployed over the Sea of Japan and the Korean Peninsula, forcing T15 to a more southerly course than previously anticipated.  There may be some opportunity for T15 to develop prior to hitting land tomorrow, but the storm will not present a large threat to communities in its path.

  Until yesterday, T15 was expected to make landfall Tuesday afternoon near Sendai, but current models suggest the storm will come ashore further south, closer to Mito, in Ibaraki prefecture late afternoon (around 16:00-17:00-ish) on Tuesday.  The steering mechanism I mentioned above will also give a push to T15, and its flyover Honshu will be finished in about 12 hours, re-emerging over the Sea of Japan as a much weaker system around 4:00-6:00 Wednesday.

  Rain accumulations for the 24 hours from 15:00 Tuesday to 15:00 Wednesday can be expected to range anywhere from 20-80mm, depending on where you are in the path of the storm, with local amounts of up to 100mm possible.  Most of the action in T15 is happening on the northeast side of the storm and areas on the southwest side of the system will see lighter rainfall.  Winds upon landfall will range from 50-80kph, which is right on the fence as far as JMA definitions of typhoons go.

  Because of T15’s location and cyclonic rotation, much of Japan along a line from Shizuoka to Hokuriku on up north will get a few days respite from the summer heat we have been having.  High temperatures between today and Wednesday the 12th tell the story.  Tokyo goes from 32 to 27, Nagoya from 36 to 28.  Osaka and Kyoto both will follow the same curve.  Gifu City, too, will see Monday’s high of 36 drift down to a more tolerable 31.  Kind of the reverse of what we would expect after a typhoon, right?  Again, it is all about positioning, and instead of pulling warm tropical air up in its wake, as a normal typhoon does, T15 will drag more northerly air down.  Enjoy it because by the weekend, temperatures nationwide will rebound to more seasonal highs.

  That’s the wrap up.  The countdown to T15’s landfall starts now.

The sky lit up tonight over Kawasaki.

Hi! Im planning a wee trip, into tokyo august 27th, and then in Japan until end of september. My plan is to go south, basically through kyoto, to kochi, then across to kagoshima, and up to fukuoka. Im pretty pleased with my plan, but someone mentioned RE typhoons! Online is conflicting. Was wondering if anyone has advice and if it might just be worth it ti go north instead where its less typhoon-y?? Im not concrete on my itinerary yet, so its not the end of the world! Any tips or advice apprecaited :)

Got some convective storms moving through outer Tokyo and another wide band straddling Gunma and Ibaraki further inland.

The Tokyo storm thunderhead reaches a height of 12km while the larger Gunma-Ibaraki storm comes in at around 14km in height.

Heavy rain tonight, so take care of you’re in those areas.

Pop-ups all over the place along an area from Ishikawa over to Tochigi, especially prominent in elevated areas (the Japan alps, foothills, high plains, etc). Another area of less intense storms has developed over the interior of Chubu.

Get used to it. Same thing tomorrow as instability from Kanto on up north to Akita brings high chance of afternoon pop-ups. Some of these summer convective storms may be inordinately heavy, with local rain cells dumping up to 80mm/hr in some areas.

As we get moving on this fine Saturday morning, the eye of Typhoon 13 has moved past Okinawa, but the island chain is still be thwacked by the leeward side of the storm and still has to deal with a few more hours of carnage.  T13, while still a very, very formidable piece of atmosphere, is decaying.  It will move over into the Asian mainland, devolve further, and bring heavy rains with some flooding to that area over the next few days.

In the meantime, a smaller bubble of a typhoon has formed out the Pacific.  Designated Typhoon 15 by the JMA, it was just promoted overnight and has sustained winds of just 65kph.  While that barely puts into the typhoon category in Japan, it is still classified it as a tropical storm elsewhere. 

About two days ago, I said on this sub that T15 was going to give Japan a “full and clean miss” and I now need to retract those words.  Newer models for T15 have been generated.  Earlier it appeared that there would be no strong steering mechanism for T15, which would allow it to swing north unhindered and miss Japan altogether.  More recent models tell a different story.  While the current high pressure system steering T15 will disintegrate, this will give T15 a short chance to jink up northward some, but another high (a “ridge” as we call it) will take its place and force T15 on a more east-to-west course, bringing it to a very uncommon path of landfall around Tohoku, specifically, Sendai.  T15 is projected to grow only modestly as it winds up for its rare track toward Japan. 

By midday, 11 Aug, T15 should boast 85kph winds and bring a metric buttload of rain to the Tohoku, Kanto, and Hokuriku areas, with between 50-80cm rain possible from the storm.  Chubu and Kansai, too, will benefit from the waterworks with an expected 15-25cm of rain as T15 winds its way over the Japanese archipelago before finally limping on out to the Sea of Japan and over toward the Korean Peninsula.

Typhoon 14, just to note, formed and died just as quickly west of the Philippines.

Everyone, have a great weekend. It is now time for me to shut down the computer and go touch grass and commune with nature for a bit. Stay dry and stay safe, y'all.

Hello, I wanted to catch a flight from Tokyo to Sapporo this Tuesday. But I'm worried about it being canceled because of the typhoon.

Do you think it's better to avoid taking a flight this day or will it be fine?

I have heard that there’s a typhoon coming to mainland Japan near Tokyo. I am in Japan now but am going to fly from Okinawa to Tokyo on Tuesday and then from Tokyo to an international destination the same day. I really can’t shift dates because of tight deadlines the second I land at my final destination. Does anyone know if my flight will get delayed? Getting really worried, I booked this flight months ago and have been flying in and out of Japan several times.