17:28 Mon Nov 25, 2019
The Snow Storm that Overproduced
Under predicting snow is pretty rare thing to do up here, especially with the winds that we see, blow over will usually prevent us from getting the full sample of snowfall in a 6 hour period. Yesterday, we had a strengthening costal low that moved into the Gulf of Maine with heavy precipitation wrapping around the back side of the low. We were stuck between a low in Canada and the coastal low, keeping the winds fairly light for our standard which allowed more snow to fall on the can and also stack better rather than being compacted by the wind. The storm also ended up being slightly further west then originally predicted so we ended up being under the heavier band of precipitation. There was a sharp cut off on the back edge of the precipitation and we expected to be more on the lighter side but luckily we got impacted by the heaviest band. Being up here it is always fun to get worse then expected!
If you lived south of the White Mountains, you most likely missed out on much of the snow since with the more westerly track, the warm front made it further inland. This caused the precipitation to chance over to sleet, freezing rain and even rain. Being much closer to the front and being at elevation helped out with lift over the White Mountains with snowfall rates being much higher than expected and the precipitation lasted for several hours longer. The rain snow line on Mt. Washington looked to have gotten up to about 4500 feet based on our vertical temperature profile and which ones got above freezing. Luckily towards the end of the day, the atmosphere cooled below freezing all the way to the base with a foot of snow at Wildcat and 10 inches of snow at Pinkham notch.
During the height of the storm, some of the observers and interns went outside to explore around the summit and find the deepest snow that we could find. By about 9 pm, there were several drifts, especially up near the summit cone and off the edge of the building where the snow got to be 3 to 4 feet deep. Much of the summit had knee deep snow so it is possible that we got more snow then the 11 inches measured. Winds unfortunately picked up overnight with a lot of the snow blowing off of the summit cone and probably into the ravines and down near tree line.
The good news is that it will finally be snow cat season for us and we will not have to take the truck and van anymore with chains on them. We may have to use them again if the snow at the base melts then we would take the truck and van at least part way up but the middle and upper sections of the road now have enough snow. We had a few of the snow cat drivers out earlier today and they successfully made it all the way to the summit with the snow cat. This should also make for e quicker trip up and down the mountain on Wednesday with the road work already done. It is not looking like we will get more snow for the rest of the shift so we will be good to go!
Adam Gill, Weather Observer/IT Specialist