Looking Ahead to the September 27-30 Snowstorm

A significant, and potentially historic early fall snow storm could occur in parts of southern Alberta and northwest Montana this weekend, with the heaviest totals focused on the Waterton/Glacier region, owing chiefly to persistent upslope flow. Numerous daily snowfall records are expected to fall, with some record cold overnight lows immediately following the system being possible as well.

Impacts:

The storm is expected to have numerous impacts to travel, especially along and east of the Rocky Mountains, impacting the HWY 1 and 2 corridors west and south of Calgary, as well as along Highways 22 and 3 in southwestern Alberta. While the snow may not initially stick to road surfaces, temperatures will fall below freezing this weekend, and the snow will begin to rapidly accumulate – especially during overnight periods. Moreover, blowing and drifting snow may develop in places on Sunday and early Monday, reducing visibility to near zero. Travel is not advised in these conditions, especially given the fact that many folks don’t quite have their winter tires on yet. Standard snow plough safety will be required, including giving them lots of space and not passing them unless safe to do so. If travel is essential, pack along safety supplies including food, water, a cell phone, a source of light, blankets, and ensure the gas tank is full.

A hard freeze has yet to occur in the area set to receive heavy snowfall accumulations, so fall foliage has yet to peak in some areas. While it will not be as green as in the September 8-10, 2014 Calgary event, some damage to trees is likely, especially given the moderately strong winds that could develop during the day on Sunday. This could also have the undesired effect of tree limbs falling and endangering life and property below, as well as an attendant risk of power outages.

Impacts to agriculture are also expected, as the fall harvest is still underway and slightly behind in some areas of southern Alberta.

Meteorology:

The main weather maker responsible for this event will be an upper low that stalls during the weekend over the northwest US, tapping into both cold, Arctic air from the north, as well as a healthy source of moisture wrapping in from the east. The positioning of the low will place the area of concern beneath its northeast quadrant, where a number of lifting mechanisms will join forces and provide sustained lift supportive of the development of heavy snowfall. In fact, the setup is reminiscent of warm season heavy rainfall events that have been associated with flooding in southwest Alberta in the past. 

EPS ensembles indicating extremely large accumulations of snow in Waterton/Glacier. 

SREF ensemble mean has nearly 3 feet of snow near Browning, Montana by late Sunday evening.

As for the nitty-gritty details, DCVA and warm advection will occur in tandem across portions of the southwestern prairies and far northern High Plains, amid an environment of strengthening lower and mid-tropospheric easterly flow that will translate to sustained orographic ascent along the Rockies. As the low south of the border becomes more organized, moist, low level easterly flow comprising the cold conveyor belt will pile into the terrain, bringing heavy snow and strengthening east-northeasterly surface winds that will begin late Friday, and peak on Sunday and into early Monday. 

Strong, low level easterly flow ramps up on Sunday.

The storm will have ample access to moisture for record-breaking snow totals. 

Vertical temperature profiles will support snow-water ratios increasing to 10:1 or more by early Saturday along the front range, as a deep, DGZ develops aloft, with ample ascent through the profile to support continued development of heavy snow. Model QPF totals are impressive and in good agreement that substantially heavy snow could occur in a localized area along the front range near Waterton/Glacier, with lesser but still significant amounts over the plains to the east – especially as the system departs the Rockies and an area of heavy snow tracks near the international border to the northwest of the surface low. Snowfall totals will vary greatly along the northern fringe of this track, which is one of the factors in the uncertainty of snow totals in the Calgary area. 

A deep dendritic growth zone, as well as deep, easterly flow are indicated on this sounding for Sunday afternoon in extreme SW Alberta, resulting in strong ascent (among other forcing mechanisms) that leads to heavy snow development. Blizzard conditions will be possible across the main area of concern during the latter half of Sunday in particular.

As skies clear out following the passage of the system, strong radiational cooling over the fresh snowpack could lead to a few record low temperatures being set in parts of Alberta and Montana. Indeed, it will suddenly feel as though we have entered a time warp to late November, as persistent troughing across the region will delay the melt and keep things cool into the first part of October! 

That's a Wrap - 2019 Storm Season Highlights!

To date, 2019 was by far my most active. I put on about 40000km between 35 chase days in Canada, and 8 in the US. I logged 12 tornadoes, and got intimate with tennis ball hail near Vulcan. There were some memorable chases, with my favourite one being in Saskatchewan on my birthday (June 27) with friends.

A good chase in Saskatchewan is MONEY, as storms are big, skies are huge, and there are plentiful foreground elements of antiquity for photography. Never turn one down if you get the chance - especially in the south and southwest!

We provided lots of live coverage of storms this season, and documented the aftermath of 3 tornadoes and one straight-line wind event.

Check out these clips if you want to see video of the best stuff:
Highlight Reel and Personal Reflections
2019 Alberta Storm Season Recap

There are numerous considerations that go into determining the value of a given chase, including the rarity of what is seen, storm aesthetics, the amount of time spent taking in those moments, and those you share it with, to name a few. Here are my top 10 chases of 2019, with only one photo from each event selected to represent the day!

#10: Spruce View, AB - July 31. This cyclic supercell had some promising moments, with strong low level rotation in its best cycle. This beefy meso was also one of the better ones of the numerous I saw this summer along the foothills. I'm surprised this one didn't produce a tornado. A weak spinup did occur later in the evening, even though I couldn't see the ground circulation from my location. 

#9: Rainier, AB - July 7. This day over-performed. I began along the Porcupines west of Nanton and tracked it due east, encountering tennis ball hail and a large tornado west of Lomond. One of the best things about this storm was that it tracked through my favourite chase terrain in Alberta - Vulcan County. Open skies, rolling terrain, pristine cropland, and a lack of power poles along many grid roads. 

#8: Dogpound, AB - June 18. Similar to July 21, 2015, but better. All the barber poles you could eat rolled off the foothills NW of Calgary that evening, lined up one after the other. I documented 5 supercells that day, beginning near Eden Valley in the afternoon, and ending near Didsbury. 

#7: Crossfield, AB - July 14. This was a special day, because not only did the storm pop right in our target, but we watched it form from the initial cumuli to the moment it produced a tornado, and beyond. It was really nice sharing that moment with friends. I share this photo because this was really cool to behold - a narrow swath through maturing barley and wheat looked amazing from the air, revealing the snaky tornado track toward our viewing location to the southeast. 

#6: McCook, NE - May 17. We targeted this storm for days, so it was satisfying to see it go. One of the most photogenic tornadoes I've witnessed. 

#5: Carmangay, AB - July 18. I'm glad I told my buddy Glen to go check out the boundary in southern Alberta, as I had a mandatory dance rehearsal for our big Salsa performance at Festival in Calgary, causing me to be late to the party by about an hour. Of course, I was miffed. However, while documenting the aftermath of the tornado, we were able to rescue a kitten from under some sketchy debris and reunite it with a little boy who thought it was a goner. That, and the successful dance performance later made the day more than worth it. 

#4: Alder Flats, AB - July 23. There are a few days each season that really ring the wow meter, and this was one of them. To date, I have never quite seen anything else quite like this. You can almost get a sense of the vacuum-like motion in the storm here even in the still photo - a scene that was impeccably timed and lit by the setting sun. Even though the clouds visually appear to be screaming, it was dead silent aside from the concerned cattle that were bellowing out in the field.

#3: Follett, TX to Laverne, OK - May 23. We thought we had missed the boat on this day, as a large wedge occurred near Canadian on an earlier cycle that was seen by a few chasers to our west. However, it made sense to get ahead of it to see if it would go again, and that it did. Before dark, it became a prolific, long-track tornado producer that dropped more tornadoes of all shapes and sizes than we could accurately count. 

#2: Altus, OK - May 8. This was a "day after the day" chase, with low-topped storms firing in crisp, dry mid and upper levels. At sunset, this made for wonderful scenes - especially after we stumbled upon the Navajo Mountains of southwest Oklahoma. It took Jo and I a long time to pick our jaws up off the fields after seeing this structure. 

#1: Val Marie, SK - June 27. No, not a tornado. We made the decision stick ahead of this linear MCS as it charged east across far southern Saskatchewan at a blistering pace, and boy did it pay. A thick, stratified shelf that looked like it was chiseled out of marble atop marvellous foreground...what more could you ask for?

What were your top chases this year?