May 24 -Convective storms across the divide

NIPIKA

Convective storms all around, except for the valley​

We arrived with cumulus clouds overhead. It was evident that we had a bit of precipitation overnight given some muddy sections driving into the site on km 14 of Palliser road.  Selina confirmed this by looking at the geonor data, which showed amounts of ~1.4 mm around 0600 am MDT.

The whole day was spent watching a variety of cloud types, including Cumulonimbus, nimbostratus, cirrus and towering cumulus, 

Little precipitation was observed at Nipika, with very light precipitation beginning around 1720 UTC and occurring intermittently till around 2010 UTC. Precipitation rates never increased above an intensity of 1. We did observe precipitation on the slopes of the Mitchell Range (East) and with more over the Stanford Range (West).

Throughout most of the afternoon clear blue skies were observed overtop of our site within the valley. This blue sky gap in the clouds fluctuated in width between the two mountain ranges. Many times we thought the cells would make their way towards us, but alas, they would appear to dissipate and virga was observed before the cells reached us. For the most part, winds would fluctuate between westerly and northerly. Though winds were often calm within the valley, there were also some gusty moments likely from outflows of the storms.

Tomorrow there will be a race in the area which will bring  around 200-300 people to the Nipika area. We had a public visitor who had stopped by during a training session. It was delightful to know that he was a fellow earth scientist, who had completed his MSc in glacier hydrology at the University of Calgary - what a small world!

- Juris Almonte

Field Participants: Selina Mitchell, Charlie Hébert-Pinard & Juris Almonte

FORTRESS

Convective storms, no snow 

Yesterday André & I went back to Alberta, after many days spent at Nipika. 2 hours only after our arrival at BGI, we were ready to take our first nightshift, as a convective storm was supposed to bring precipitation over Fortress that night, and possibly the 2 following days.
On our way to Fortress, we made a carsonde, but we didn't find any transition zone. There was no more rain when we arrived on site.
We started taking observations at 05.00 UTC. During the night we observed a light rainfall starting around 06.00 UTC, and increasing to become moderate around 08.30 UTC, before finally ending around 09.20 UTC.
With nothing else visible on the radar, we decided to stop taking observations at 10.00 UTC and got back to BGI to catch up with some sleep, tired but also a bit frustrated. After missing the snow for so long while we were at Nipika, we were pretty excited about the possibility of finally getting some snow, but we can't report anything else than rain at most moderate during that night.

- Cécile

The radar showing the convective cells that hit us during that night

Hilary and I left BGI on Friday morning at around 1400UTC, observing light rain on our way to Fortress Mountain. Seeing along the way that a few mountain tops were foggy, we did a Car-sonde on our way up the mountain and, at 1433UTC, caught the beginning of a transition at the altitude of 1693m where we observed a small amount of solid/mixed particles among the rain. Mixed precipitation was occurring from that point to the top with increasing amount relative to rain. We started taking observations at 1450 while Fortress top was receiving a mixture of rain, graupel and iced particles. Being at the top until 2300UTC, we witnessed three episodes of precipitation, respectively from our arrival (1440) to 1640, from 1900 to 2020 and finally from 2130 to our departure (2240UTC). This 1st one was characterized with rain mixed with graupel and unrimed partially iced particles mainly at a light-to-moderate intensity. On the 2nd episode, we observed light rain followed by moderate to intense mixture of rain and pellets (iced and liquid core). The 3rd one consisted of lighter rain only, reaching moderate intensity. Negligible to light northerly winds were noticed during the day, often weaker during precipitation. Between those events, we had nice weather characterized by sunny with partially to completely overcast sky. Since we couldn’t take macrophotos, we tried to figure out an efficient way to take close-up pictures with the Olympus camera. Results were good, as we’ve been able to capture small details on fabric and on snowpack. Edges of the pictures were still blurred which suggest that we need a little more practice.

- Aurélie

​André & I went back to Fortress to replace Hilary & Aurélie. We noticed a really heavy rainfall while we were driving to Fortress, but it stopped when we arrived on top of the mountain, and Hilary & Aurélie confirmed that they didn't get any of it.
We started taking observations at 22.50 UTC. After a whole night spent hoping for some snow without any result, we still believed that we could have a chance to get some during the day, as the girls got some just before we arrived. But to our great despair, not only didn't we get any snow, but neither did we get any rain. We kept taking observations for some time, as the radar was showing some important convective cells close to us, but those cells remained very stationary and were diminishing. Moreover the most recent update of GEM 2.5 didn't plan any precipitation for the rest of the day, so we decided to go back to BGI and check the radar from there, just to make sure we wouldn't miss anything. For now (0500 UTC), we still haven't see any major change. We will get up early tomorrow morning, to check what the radar looks like, and get prepared to go on the field, as the storm was originally supposed to be the strongest during that day.

- Cécile Carton

Field participants: André Bertoncini, Cécile Carton, Hilary Smith & Aurélie Desroches-Lapointe

Nipika

Fortress