When they woke up on May 4th, Hadleigh and Selina were already prepared for a long day and probably a night of storms, thanks to the forecasts. As soon as they heard that Fortress was starting to be hit by snow, they jumped in the truck to get there as soon as possible, arriving at the Nipika station at around 1630 UTC.
However it was a quiet day at Nipika, and until Hilary and I (Cécile) joined them in the field around 2330 UTC, nothing special happened, except for a sun dog and some short showers.
As it was our first day in Nipika, Hadleigh and Selina showed us around the site. After sitting for a while beneath a cloudy sky, and enduring some short showers, we then got prepared for the night, taking turns to make observations. From time to time we noticed dark eastern clouds spreading to the continental divide.
While Hadleigh and I were taking observations, we started to notice weak rain which got stronger until the end of our shift at 0700 UTC.
Hilary and Selina's shift was accompanied by mixed precipitation that included frequent showers containing both graupel and rain. When dawn broke the next day, a whitened landscape greeted us, with the snow line hovering only about 200 metres above our site. Cold and weary after a night beneath frigid precipitation, we swept our encampment away into the truck and headed off into the dawn at 1200 UTC.
Morning at Fortress Andre & I arrived on site at 16:30 UTC to make sure we would not miss the beginning of the storm. The timing was good, we set everything up right on time and start taking observations when the snow began around 17:00 UTC. It started with very few small hydrometeors falling quickly and it was pretty windy up there. It continued on and off for 3 hours. We had mostly graupel of different sizes (from 0.5 to 4 mm), but also heavily rimed dendrites and irregulars. The wind was coming from North and was also on and off. The visibility stayed pretty good, especially on South view where it was almost sunny, but there was some low gray clouds approaching on the North side.
At 20:00 UTC, things got more interesting, the snowfall and wind speed gained intensity. The temperature, which was around zero at the beginning, decrease so the hydrometeors stop melting and we observed some nice stellar dendrites and a lot of needles! At 4:00 UTC, Juris & Mathieu arrived on site to take the next shift. - Charlie Morning from Juris' perspective This morning we did a changeover of people at Storm Mountain Lodge; Hilary and Cecile are now at Nipika and Mathieu and I back at Fortress. Mathieu and I were quick to get a bit of rest before our night shift at Fortress Mountain. While at BGI we noticed light to moderate snowfall throughout the whole day at BGI. Mathieu watched the MRR data and was happy to report that it was capturing the convective action aloft.
Mathieu takes the first shift We arrived at fortress trailer at 0040 UTC and discussed the details of the storm with Charlie and Andre. Soon we started taking measurements while the storm was quite intense. The intensity diminished and reintensified by 0330 UTC (9:30 pm local time). Juris replaced me for the observations at 0410 UTC. By 0400 UTC, 10 cm had already accumulated since the beginning of the storm.
0410 UTC - 0600 UTC Over my two hour shift, precipitation varied from light to moderate-heavy precipitation. Winds were predominantly from the N, or NE. There was some lightly rimed particles at the beginning. During collection of snowflakes on pad, some particles were heavily rimed, while others had almost no riming. Precipitation types included stellars, various dendrites and needles. By 0600 15 cm of snow was recorded on the plywood sheet.
0600 UTC - 1200 UTC From 0600 to 0700 UTC precipitation remained moderate to heavy with snow aggregates, some around 1.5 cm and by 0710 UTC the storm intensity remained low, with light winds. By 1125 UTC snow had stopped.Mathieu and Juris conducted a snow depth survey down Fortress Mountain starting at 0600 UTC. Just like last weekend’s storm it was evident that orographic enhancement played a role in the precipitation amounts up the Fortress road. We started at 2004 m where there was 23 cm with a SWE of 15.5 mm and at the bottom of the road, outside of the gate we had observed a snow depth of 5 cm with a SWE of 1 mm.
Field Participants: André Bertoncini, Charlie Hebert-Pinard, Mathieu Lachapelle & Juris Almonte