Severe storms move through northern Alberta
Thursday, June 13, 2013, 7:13 AM -
Severe storms are moving through northern Alberta.
A series of tornado watches and warnings were issued in several parts of the region, including Fort Saskatchewan, Leduc and the City of Edmonton -- but they have since been dropped.
The watches were prompted as a large and slow moving dip in the jet stream, called an upper level trough moves across B.C. -- spelling unsettled weather across Alberta through the end of the week.
Wednesday has the greatest threat for thunderstorms across much of the province, with the best chance for severe thunderstorms around the Capital Region and across the southeast. Some thunderstorms are possible again on Thursday, but are most likely towards the Saskatchewan border and into Saskatchewan.
Unsettled weather will continue into Friday as a low pressure system will stall over western Saskatchewan and linger into the start of the weekend. This system will likely produce more significant rainfall for the Fort McMurray region.
Next week, the computer models are suggesting a more significant period of severe thunderstorms may occur in the Monday/Tuesday timeframe. This activity would also affect Saskatchewan and Manitoba.
We’ll be watching the weather pattern over the next few days to see how this plays out, but there is no question we are entering the meat of severe weather season across the Prairies, and a big event next week is certainly possible.
WHAT TO EXPECT
Ironically, sun is NOT good news if you want to avoid storms. Any sun will only serve to heat up the ground, which in turn heats up the air, which in turn starts to rise -- just like a cork held down and then released in water -- and produces thunderstorms.
The main threat from these storms Wednesday afternoon and evening will be hail and locally gusty winds with the potential to produce a tornado.
Storms will track from SW to NE, so anyone in the city should be keeping an eye to the SW for approaching storms, and be aware of what’s going on upstream in places like Drayton Valley. Storms will weaken later in the evening.
Wednesday, Medicine Hat/SE Alberta
Severe thunderstorm watches are in effect for adjacent areas of Saskatchewan and extreme SE Alberta.
Storms will fire Wednesday afternoon near the Montana border and track northeastwards toward the Medicine Hat area in the late afternoon hours.
Along Hwy 1 between YYC and the Hat, there could be some light sprinkles, but the real action should begin mid-late afternoon farther southeast.
These storms will be capable of producing large hail and locally damaging winds. Again, the tornado threat is not high, but an isolated tornado is always possible with severe thunderstorms.
The storm threat will push east into Saskatchewan through the evening hours.
Fort McMurray Flooding
The flooding in Fort Mac is the result of a continuous spell of wet weather, with heavy rain that fell late last week into this week. More significant rain is likely, especially later Thursday into Friday as a low pressure system develops along the Alberta/Saskatchewan border and parks itself for a couple of days.
The Wood Buffalo RCMP and other law enforcement officials are overseeing mandatory evacuations for Ptarmigan and Court Trailer Park in the waterways of Fort McMurray as flood concerns rise.
Exactly what this means for the flooding situation is unclear, as Alberta Environment monitoring gauges on the Hangingstone River (see below) have shown a drop in water levels in the last day.
However, if river levels don’t drop enough before the next round of rain, the flooding situation could be exacerbated.
With files from Cheryl Santa Maria