500mb heights/winds on Friday night depicting the Omega Block over Eastern North America.
Southern Manitoba has been under the grip of below-normal temperatures yet again over the past couple days, but a shift in the storm track will allow warmer air to build into the region. A large omega block, pictured above demonstrating it’s namesake (the wind flowing around the blocking pattern looks like the greek letter omega: Ω), will inhibit eastwards motion of the large-scale pattern, so the big question is: when exactly is it going to warm up? Fortunately, it’s not going to take too long.
Large-Scale Pattern Shift
Typically when blocking patterns set up, weather remains rather stagnant for a lengthy period of time: the rain stays in more or less the same place (it’s forecast to rain for most of the next 6-7 days in eastern portions of Iowa) and the sunshine remains over similar places. In extreme cases, features such as Omega Blocks can result in catastrophic flooding or droughts as similar conditions persist for weeks on end.
Fortunately, that won’t be our story. The blocking pattern is slowly decaying, but the real driver for our change in temperature will be the future of the upper trough currently over Manitoba/Northwestern Ontario. It’s simple existence is quite an anomalous feature and has only been able to maintain it’s existence by a continual reinforcement of Arctic air. Over the next few days, though, the northern storm track is going to become more active as disturbances begin to ripple through the NWT and Nunavut. These features will strengthen the upper-level winds north of 60° and cut off the reinforcing cold air.
Without this cold air injection and with the sun continually climbing higher in the sky, the cold air in our upper trough will quickly be modified out. As the northern storm track becomes more active, the flow aloft across the Northern Prairies will become more zonal as well, which will help bring warmer air into the region, although an upper ridge is forecast to build in over the Southern Prairies, keeping our winds fairly light aloft. So what does all this mean?
Friday
11°C /
0°CSunny
Saturday14°C /
3°CSunny
Sundy18°C /
8°CSunny
What will be happening over the next few days, effectively, is the “bottling up” of winter once again, locking it north of a strong jet stream running through the Northern Praires/Southern Arctic. Warmer air will slowly build back into the region with temperatures returning to normal or just above normal by the end of the weekend. In addition to the warming temperatures, we’ll see nothing but sun sun sun!
Next Week
The trend looks to continue through next week, with temperatures climbing into the low 20’s and more sunshine prevailing. The next chance for any sort of precipitation looks not to be until maybe the end of the week. A warm, dry week will be good news for the flood situation in Southern Manitoba.
