Forecasting a Messy Mix of Rain, Snow, and Wind Slamming Hakuba. Is Hokkaido Next?

​It was quite a rollercoaster yesterday (2/22/17) in the Hakuba Region and is getting very messy now that the clock has struck midnight. In fact the reporting station in Hakuba, which is situated at roughly the same elevation as many of the bases (700m above sea level), has reported a very wet almost slushy 5cm of new snow in the past hour, with more expected overnight. The rollercoaster ride began this morning with a chilly morning low of -13.3C before rocketing up by an incredible 17.9 degrees by early afternoon, when at 1pm the high temperature reached 4.6C. To put this into perspective for those who use the imperial system, it equates to a morning low of 8F and an afternoon high of 40F (32 degree increase). While the rollercoaster ride of temperatures was sure to cause some issues with snow conditions at low and middle elevations the real story just started developing in the late evening hours of the 22nd as a low pressure system has rapidly strengthened bringing very heavy precipitation. This should be good news for the slopes, right? In this case in might not be, I am quite concerned about the quality of snow and the possibility of a rain/snow mix which might degrade the current snow pack. 


Mountain forecasting is notoriously difficult, but this is even more challenging. The currently available data which I feed into our in-house models is, to put it bluntly, worthless. However, using the reliable available data I feel very confident in stating that by late tonight (2/23/17) substantial precipitation will fall across the Hakuba Region. 25 to 50mm of liquid precipitation is expected for almost every location, with some locations likely approaching 75mm. Looking at the current radar there are exceptionally impressive returns for this time of the year with locations 150-200km to the SW of Hakuba reporting observations of 5 to 12mm in the past hour, even further to the SE the hills outside of Kochi have reported 20mm in the past hour. If this intense moisture can make its way into the mountains around Hakuba and temperatures remain cold enough to support snow, there could be very impressive totals albeit of very wet quality. With all of that being said I see a decent snow event for elevations above 1200m with totals of 15 to 30cm, but it will be very wet. I must mention that with the strong winds, wet snow, warm temperatures, and rain the avalanche risk has increased. 


Most of you reading this are probably planning to hit one of the many slopes on the beautiful island of Hokkaido, so enough of the suspense let’s talk snow. The situation in Hokkaido looks amazing! This storm will not be a record breaker by any means, but unlike Hakuba the temperatures across Hokkaido will be cold enough to support snow and on average you should be able to enjoy some new dry or dry/heavy quality snow. The strength of this system is impressive and assuming it becomes a “double barrel low” as I am predicting the entire island will receive snow.


At the moment the SE coast and resorts such as Rusutsu and Tomamu will receive the majority of their snow starting late this morning/early this afternoon and continuing overnight into the early morning hours of Friday (2/24/2017) as one of the lows tracks along the SE coast of Hokkaido. Niseko is in an interesting situation as it is starring down both “barrels” of this system, with impacts expected from both low pressure systems and also the potential for ocean effect snow. At the moment I would expect snow to become heaviest this afternoon and into tomorrow, with a possible break in the snow this evening/overnight. Kiroro and Furano will be the last to arrive to the party, but they will be the big winners from this event. While he majority of the snow in these locations will hold off until after dark this evening when it does arrive in earnest extremely strong winds will drop visibilities to near zero. The threat of moderate to heavy snow will persist well into Friday as ocean effect bands kick in. 

With how messy the situation is for Hakuba and has the potential to be for Hokkaido I will delay issuing an official forecast until the new data comes in. Please check back for an updated official graphical forecast around 730am (2/23/17) followed by snowfall graphics from our in-house weather model! 


​Paul