 In the last two weeks, Japan has been inundated with rainfall totaling over 70 inches in areas over the extreme southwestern part of the country. This has been cited as one of worst flooding disasters to ever occur there. The flooding rains have lead to numerous landslides as well as rivers overflowing their banks which has caused immense damage to cities and villages. The death toll has risen to 200 and continues to rise by the day, with another 54 people that remain unaccounted for. The Hiroshima and Okayama Prefecture areas took the brunt of the storms, with rainfall rates exceeding three inches per hour at times. Japan’s Shikoku Island was also hit hard. The Associated Press reported that 10.4 inches of rain accumulated in its Kochi Prefecture in just three hours, with more than 70 inches of rain totaling at the end of the storm system. The World Meteorological Organization reports that the total precipitation at many of the observation sites reached two to upwards of four times the annual mean which also happens to be the monthly precipitation for the month of July in southwestern Japan.
Japan is no stranger to natural disasters, with the catastrophic tsunami in 2011 that caused the meltdown at the Fukushima Daiichi Nuclear Power Plant. The scenes of the flooded landscapes with rooftops just barely visible this past week eerily resembles the aftermath of the 2011 tsunami. In the case of this storm, the torrential rainfall can be blamed on a combination of events occurring. Tropical moisture was pulled north, colliding with the remnants of Typhoon Prapiroon as well as colliding with a front stalled over Japan. While uncommon to occur, the atmospheric conditions were just right in this case, creating multiple storms behind the parent thunderstorms. This process had the storms lining up and inundating the same region over and over, causing the massive landslides and flooding to occur instantaneously. While natural disasters are bound to happen throughout the world even without climate change existing, the continuous acknowledgment as well as educating others on this matter will really make a difference on tackling these problems in the world. For more about flooding and other applied meteorology topics, please click here! ©2018 Weather Forecaster Michael Ames
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If you’re like me and enjoyed the past few days of low humidity with plentiful sunshine in the northern Mid-Atlantic, you will not like this 2-week outlook. The Climate Prediction Center has issued their 6-10 (below) and 8-14 day precipitation probability outlook through the end of July into the beginning of August. It’s anything but sunshine and low humidity, but let’s dive into the setup and why the forecast calls for above normal precipitation along the East Coast.  The shortwave that is diving into the Ohio Valley shown below which was the lifting mechanism for the severe weather outbreak across Kentucky this afternoon and evening (July 20th) will be one of the keys to this upcoming wet forecast along the East Coast. This animation from GOES-16 Water Vapor shows this interaction between the shortwave moving into the Ohio Valley igniting the severe storms in Kentucky/Indiana, (satellite animation credited to College of DuPage).  Looking at the 500 mb pattern this weekend (July 21-22) an almost wintertime storm pattern develops. There is a substantial cut-off low pressure across the Ohio Valley, the same system that produced the severe weather mentioned above. The two ridges, one to the west across the High Plains region as well as the Bermuda high stretching and strengthening into portions of eastern Canada, keep will keep this pattern locked in.  The position of the cut-off low sits around the Ohio Valley will allow for a low pressure to develop and rotate around the counterclockwise circulation and up the East Coast. Shown below is an animation from the GFS depicting the coastal low’s location and intensity with the precipitation overlaid, courtesy of Tropical Tidbits. Notice the upper level low’s influence on the track of the coastal low in this animation.  As the shortwave drifts to the south while the high pressure continues to stay strong to the east, a stationary front develops and sits over the area Monday morning through mid-week (WPC photo below #1). Also notice the increase in moisture distinguished by the dew points surging back into the 70+ degree mark as Gulf of Mexico and Atlantic moisture is driven up the coast into early next week (photo below #2). With all the moisture in the area, CAPE values near 1000 J/kg in some places, the stationary front as the lifting mechanism along with upper level support from a jet streak to the north and northwest (jet stream photo below #3), periods of rain and thunderstorms will develop throughout much of next week. 
Just to give a perspective on how much rainfall is possible, WPC paints a healthy amount of rain, up to 5 inches in areas from the interior Northeast down through portions of the Mid-Atlantic.  A wet and soggy weekend into next week is on tap for many along the East Coast especially from the Mid-Atlantic to the Northeast. Always be sure to look out for flooding and know the safety and precautions that come with it (click here to review flooding safety protocols from the NWS).
Stay tuned to GWCC and click here to view other potential flooding events! ©2018 Meteorologist Joe DeLizio |
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