This June has felt more like Spring than Summer so far, but that may be changing this week.
A surface high will be positioned over Southern Manitoba early this week.
Monday and Tuesday
Monday Mainly Sunny 23°C / 12°C
Tuesday Mix of sun and cloud. Chance of showers, risk of a thundershower 25°C / 14°C
Conditions today and tomorrow will be dominated by a surface ridge of high pressure. This high will keep wind speeds relatively light. It should also suppress the risk of showers for the most part, however by Tuesday there may be enough instability for a pop-up shower or thundershower. Temperatures will be in the low twenties today and in the mid twenties on Tuesday.
Wednesday
Wednesday Mainly Sunny. Slight risk of a thunderstorm 27°C / 16°C
Wednesday should be one of the warmer days this week, with high temperatures in the mid to upper twenties. A south-east flow will bring more moisture into the region, so you may notice that Wednesday is a bit more humid than Monday and Tuesday. This additional moisture will once again cause the atmosphere to destabilize, so there is a slight risk of a non-severe thunderstorm in Southern Manitoba.
Late Week
The late week period looks interesting. Models bring a significant stream of moisture up into Southern Manitoba for Thursday and Friday. This along with an incoming jet stream may allow for some strong thunderstorms. However, it is still too early to go into great detail about the storm potential. We’ll be sure to post much more about this in the comments if the risk looks legitimate.
Residents of Colorado Springs and surrounding areas have been on high alert this past week because of wildfires in the area that are burning out of control. Currently, there are three large fires burning in Colorado. The largest wildfire of the trio is known as the Black Forest Fire. This fire covers about 60 square kilometers and has destroyed about 400 homes already, as of Friday evening. Unfortunately, two people have also perished from this fire. On Friday thunderstorms moved over the area but although they brought much needed rain, they also had undesired effects such as cloud to ground lightning strikes that potentially sparked up new fires. The Black Forest Fire is around 30 percent contained as of Friday evening so firefighters still have quite a bit of work to do this weekend.
The reason for such extreme wildfire events this spring in Colorado can be associated with drought. The severe drought that was seen throughout the US Plains last year and into this spring has shifted slightly further west. Although areas of the Plains have been mostly relieved of drought from thunderstorm activity this spring, Colorado has continued to experience severe to exceptional drought. The town of Colorado Springs is located under extreme drought which translates into little moisture available for vegetation and in consequence, wildfires are easily sparked.
Plume of smoke from the Black Forest Fire threatens homes in the foreground. (Source:Reuters)
Temperatures are expected to remain quite warm with highs in the upper twenties and even low thirties in the area this weekend, not helping the fire risk. There is also a chance of storms. The longer range doesn’t look promising for drenching rains either as a ridge is expected to redevelop in the southern US Plains mid next week.
After several fairly nice days in a row, unsettled weather will make it’s return to southern Manitoba as a very powerful upper low moves into the Prairies. The unsettled weather will push through in three distinct phases over the next 3 days, varying from just a few showers to the potential for severe thunderstorms. Without further ado, lets get to it.
Today
We’ll see a very mixed day today as multiple weather features make their way over southern Manitoba. We’ll see a decent chance of some showers this morning as some elevated convection moves through the Red River Valley along the nose of an upper-level jet. We’ll then see a mix of sun and cloud through most of the rest of the day as we climb to a temperature around 24°C. The next bout of unsettled weather will move in this afternoon over SW Manitoba and in the late afternoon/evening for the Red River Valley as two distinct features move into the Red River Valley.
Through the afternoon the 850mb low-level jet (LLJ) will be working it’s way eastwards across Southern Manitoba and, while 700mb temperatures are forecast to sit around 6 or 7°C – a little high to get much convection – the LLJ has had a history of being able to get some heavy showers or weak thunderstorms going despite the marginal instability. This first feature will not likely produce any severe weather.
The second feature moving across southern Manitoba will be a surface trough extending from a low pressure centre in central Saskatchewan southeastwards through southern Manitoba. This trough has the potential to produce severe weather in Southern Manitoba, but the threat has to be considered fairly conditional due to two uncertainties:
Uncertainty in cloud coverage could result in cooler daytime highs than expected; the warmer it gets today the more likely storms will develop.
The warm temperatures at 700mb may be enough to prevent convection from developing; the trough will have fairly strong convergence associated with it, and there may be enough broad, synoptic-scale lift to overcome the warm air aloft.
My gut feeling is that we will see storms develop this afternoon; this trough has had a history of producing thunderstorms the past 3 days in a row. Going with this idea, it’s likely storms will initiate somewhere in SW Manitoba in the mid-to-late afternoon and slowly progress eastwards. The main threats with the storms will be:
Heavy Rain: Precipitable water (PWAT) values are expected to sit around 35–40mm this afternoon thanks to quite a deep layer of moisture moving across the province with this system. That’s a lot of water for these storms to work with. The trough line won’t be moving too quickly and, especially near the western escarpment of the RRV, conditions will be somewhat conducive to the development of quasi-stationary storms. Slow or non-existent storm motion could result in rapid accumulations of 2+” of rain in isolated storms.
Strong Straight-line Winds/Tornadoes: 0–6km bulk shear values will sit around 40kt this afternoon with favourable veering profiles. There’s certainly enough directional shear for storms to develop into supercells, however there may be a lack of backing in the lowest levels to produce enough low-level shear for tornadoes to become a threat. For that reason, I think the most likely wind-related threat would be the potential for strong straight-line winds. This threat would be secondary to the heavy rainfall threat.
Fortunately, with limited CAPE, a high freezing level and significantly weaker winds in the upper atmosphere than on Monday, hail will not likely pose much of a threat today. The showers and thunderstorms should develop this afternoon over SW Manitoba, push through the Red River Valley this evening and lift northwards into the Interlake, flattening out into an area of rain overnight. We’ll see clearing skies overnight here in Winnipeg as we drop to a low of around 14°C.
Saturday & Sunday
Through the weekend we’ll see the passage of the upper low as it moves from central Saskatchewan into NW Ontario. It will begin to move into the region on Saturday and allow things to broadly destabilize in the afternoon which will produce scattered showers and thundershowers. No severe weather is expected. We’ll see a high near 23°C on Saturday and then dip to a low of 12°C overnight with some cloudy periods. On Sunday, we’ll see more cloud than sun and a high near 21°C with scattered showers throughout southern Manitoba. Skies will clear out on Sunday night as we dip to near 10°C.
Next Week
It looks nice for the start of next week with sunshine returning and temperatures climbing back into the mid-to-upper 20’s. At this time it looks like another system will move through late next week bringing another chance of showers and thunderstorms.
Beautiful weather will continue across southern Manitoba through the next few days as a ridge of high pressure works it’s way across the Province. Things will turn stormier heading into the weekend as a potent upper trough pushes inland from the Pacific.
Today & Tomorrow
Wednesday 25°C / 12°C A few clouds in the afternoon.
Thursday 25°C / 12°C Description
Over the next couple days mainly sunny skies will dominate as a surface ridge slowly works it’s way across the province. Unlike the past couple days where we’ve enjoyed sunny skies here in the Red River Valley while areas further north in the Interlake and Central Manitoba were stuck underneath extensive cloud cover & showers, pretty much the entirety of Manitoba will be seeing plenty of sun and temperatures in the mid–20’s. Today we’ll climb to around 24°C and probably climb a degree or two higher for Thursday. Overnight lows will be comfortably seasonal, dipping down to around 12°C.
Things will begin taking a turn on Friday, though, as a strong southerly flow develops which will begin to push heat and moisture northwards through the High Plains and into the Southern Prairies. While it looks like the end of the week will have quite a bit of thunderstorm activity in Saskatchewan, things aren’t quite as clear cut here. Let’s take a look at how things look to pan out for us right now.
Friday
Friday 23°C / 13°C Increasing cloud with risk of a thunderstorm. Chance of thunderstorms overnight.
A strong southerly flow will develop on Friday as the upper trough begins it’s way inland. Winds will increase to around 40km/h up and begin to bring moisture northwards. This will feed into a broad area of low pressure working it’s way across the Prairies. With the strong feed of moisture streaming northwards, we’ll likely see increasing cloudiness fairly early in the day which will limit our daytime high to a few degrees cooler than today or tomorrow. At this point, no severe storms are expected in the Red River Valley although a few scattered thunderstorms may manage to pop up, especially over the western RRV; for severe storms conditions look to be far more favourable further west in Eastern Saskatchewan or extreme SW Manitoba where the apex of the 850mb warm nose will reside with it’s associated low-level jet. Conditions there look favourable for the potential development of severe storms, although it may get messy very quickly with linear upscale growth shortly after initiation. Since the conditions there don’t directly pertain to the Red River Valley, I’ll leave a discussion of the severe weather potential for that region in the comments below.
Rainfall forecast for Friday night (Sat 00Z – Sat 12Z) from the GDPS.
The storms that fire Friday evening will continue through the night at least as a band of rain but more likely as an organized area of nocturnal thunderstorms. The low looks to lift northwards through the night before continuing eastwards, and the storms are expected to follow suit, moving ENE after initiation. At this point, it looks quite likely that Friday night will be a stormy night in the Interlake, however in the Red River Valley things are more uncertain. With much of the forcing lifting northwards, storms may have a difficult time surviving further south where lift will not necessarily be lacking, but not nearly as focused. Wherever the storms do go, the threat for severe storms will likely continue into the night. A strong 40+kt 850mb low-level jet will provide ample lift and moisture for the system and help maintain 1000+J/kg MUCAPEs through the night. The main threat with these storms would be large hail and the potential for strong straight-line winds.
We’ll keep a close eye on this system and have a more comprehensive look at it on Friday morning’s post. Until then, get out there and enjoy the beautiful weather!
