Hadleigh, Selina, André & I (Cécile) arrived at Nipika at 10:46 PM (MDT). After a quick check-up of the instruments, which were functioning well, we organized ourselves in regard of the long night of observations we were about to live.
André and Hadleigh took the first shift until 0900 UTC. They didn't see anything other than a small drizzle and at most a light rainfall which didn't last more than a few minutes. But when Selina and I took over the observations, we noticed around 0940 UTC rainfall that lasted for about one hour, and got stronger, until reaching its maximum around 1000 UTC. It had bigger droplets and a medium falling speed, which is probably a first since we started taking observations at this site 3 weeks ago.
After that episode and for the rest of the night, drizzle and light to very light rainfall were back again. The wind was almost nonexistant during our shift, and we reached a minimum temperature of 7°C, which was actually pretty bearable for a whole night outdoors.
We left Nipika at 1720 UTC to take some rest, knowing that we would have to go back on site tonight for another night shift, to catch the 15 mm of total rain forecasted by the model GEM for the next 24 hours. After a whole night spent to get only 1 mm of rain or so, hopefully the weather will finally give us the dose of storm we are waiting for.
Field Participants: Hadleigh Thompson, Selina Mitchell, André Bertoncini & Cécile Carton
Juris and I (Hilary) left BGI for Fortress shortly after 0400 UTC on May 16. We noticed some radiation fog near the ground on the way over and temperatures were above 0C. We arrived at the Fortress gate around 0435 UTC. We thought there was a possibility that precipitation could be mixed at the top, so we conducted a carsonde on the road up. Precipitation was liquid throughout the drive and we were disappointed that it was not an interesting car sonde. However, just before the parking area at the top of Fortress we noticed mixed precipitation! We took note of the altitude and time, then parked the car and finished the sonde.
We started taking observations at 0500 UTC. Precipitation began as mixed and very light, then became solid as the night progressed. Winds were light and pretty heavy fog rolled into the area for about half an hour around 0510 UTC. Precipitation was mostly liquid until 0930 UTC when it became solid, which consisted of mainly rimed dendrites and aggregates. From 1110 UTC precipitation consisted of small particles, but were noticeably 3D in structure, with some riming. For example, a radiating assemblage of plates was observed at 1150 UTC, although not photographed.
The importance of orography was also noted when winds were generally observed from the NNW, while the flow as it appeared on Strathmore radar was very different, showing a predominantly southerly flow.
We (Hilary & Juris) left Fortress Mountain around 1220 UTC and conducted another carsonde heading down as Aurélie and Charlie mentioned they observed a transition from rain to snow heading up the road to replace us. At the top we had solid precipitation at 2076 m with temperatures near 0-1°C, mixed precipitation at an elevation of 1922 m with a temperature of 0.5°C. Mixed precipitation became rain at 1823 m with temperatures at ~1.6°C
-Hilary & Juris
Aurélie and I (Charlie) arrived on site at 1200 UTC for the second half of the event. It was already light to moderate snow at the top and a rain to snow transition has been observed on the way up the mountain. Between 1500 and 1630 UTC, we observed some transitions of different precipitation types, starting with capped columns, followed by unrimed dendrites, then aggregates, then rimed particles and needles, ending with graupels and a large amount of needles. Even with those important hydrometeor type changes, the weather conditions stayed pretty consistent during all of our part of this event. The wind was negligible, temperature was a bit over zero, the visibility was moderate to poor and the snow fall intensity was always light to moderate.
We notice that the Strathmore Radar was indicating no precipitation at Fortress at 1620 UTC and even after that time, it seemed like nothing was coming, new cells were appearing at the border. Although we did not observe any interruption of precipitation from 1200 UTC to our departure at 1930 UTC.
Field Participants: Charlie Hébert-Pinard, Aurélie Desroches Lapointe, Juris Almonte & Hilary Smith