Sunday 10 June 2018

Day 15 - South Dakota

SUN 10 JUN 2018

Today’s play involved a cold front arriving from the northwest, intersected by a dryline moving east from Wyoming into South Dakota.
Hand drawn surface analysis at 15z (09:00 MDT). Isobars black, isodrosotherms green
SPC Forecast
SPC Tornado Probability Forecast
After a bite to eat in Spearfish (SD), we nudged a little ways north to Bell Fourche Reservoir, where we sat next to the water watching cumulus attempting to build along the cold front and dryline. Eventually the convection became more robust and off we went after a impressive looking thunderstorm south of Buffalo (SD).  As we approached, the storm became tornado-warned - road options were less than ideal, and trying to keep up with the storm, given the lack of roads, was proving tricky.
Looking north from Belle Fourche (SD) at the developing thunderstorms
Radar and our GPS location (blue circle). Red polygon tornado warning
We saw a thin rope funnel extend two thirds of the way to the ground - but to my knowledge no full tornado was ever reported with this storm. We then got cut off by a new thunderstorm developing overhead, and were then stuck in heavy rain and hail for quite some time as we tried to get out of the storm and get round its southern flank (and ultimately ahead of it).  Eventually we did, and headed east to Faith (SD) to watch the line of thunderstorms approaching, with a spectacular gust front - one of the best I’ve ever seen, especially given the stark contrast of colour between electric blue in the ‘whales mouth’, which was flashing constantly with lightning, and the orange of the setting sun behind. Part of this line of thunderstorms became briefly tornado-warned once again, but alas looked visually unlikely to produce anything (and it didn’t).

Shelf approaching Faith (SD), looking west
Gust front approaching from the west
Behind the gust front - often referred to as the 'whales mouth'
Radar and our GPS location (blue circle). Red polygon tornado warning
We eventually left the storms and headed to a hotel in Fort Pierre (SD) for the night - an interesting city in the sense that Fort Pierre is located on the western banks of the Missouri river and is therefore in the Mountain Time Zone (MDT), while the city of Pierre on the other side of the river is located in Central Time Zone. However, everyone in Fort Pierre apparently goes by Central Time (which is 1 hour ahead) except the bars - because it means they can stay open an hour longer relative to the ‘working day’!
GPS tracker

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