Conditions will slowly warm this week as the weekend’s potent weather system departs our region. Temperatures should return to seasonal values by midweek.
Monday
Today will remain on the cool side, with high temperatures in the upper teens. Winds will remain gusty as well, as we continue to deal with the stiff north-west flow behind the weekend’s low pressure system. Skies will finally become sunny however, which is a welcome change from the grey and rainy conditions of the weekend.
Tuesday
Tuesday will see temperatures warm further, with highs reaching the low twenties. Skies will remain mainly sunny and winds will be light making for a nice day.
Wednesday
Wednesday should see temperatures climb back toward seasonal, or even above-seasonal values. High temperatures will be in the mid to upper twenties as we return to a mild southerly flow. Skies may be somewhat variable due to the passage of an upper-level disturbance.
The hurricane and typhoon seasons (Atlantic and Pacific basin, respectively) both ramped up this past week as three significant storms spun up with another one expected to strengthen.
Different model tracks for Danny – some models want to curve it northwards faster than others. (Source: Tropical Tidbits)
The first, hurricane Danny, formed a few days ago west of Cape Verde Islands, in the Atlantic basin. The conditions in the past days were good for steady intensification, until about Friday midday when the hurricane encountered dry air and began ingesting it. Before then however, a recon plane flew into Danny and registered winds that suggested the storm was already a major hurricane, of category three on Friday morning. This is the first major hurricane of the Atlantic this year and the earliest since 2009. As Danny is still far from the US mainland it is impossible to say which states it will affect, if any at all. Before then however, it is expected to move through the northern Antilles, but only as a tropical storm due to the fact that it will continue to gradually weaken due to high shear/dry air present east of the Antilles.
Two typhoons are also currently spinning simultaneously in the western Pacific, one off the western coast of Thailand (Goni), and one further west (Atsani). These were both once very powerful typhoons, of category four and five (super typhoon), respectively. They have since gradually weakened to category two equivalent storms however. Neither of them are expected to make direct landfall, but Goni has already had adverse effects on the northern Philippines and Thailand, bringing heavy rain and fairly strong winds as it brushed the islands. What is special about these two very powerful storms (category four and higher) was that they were churning in the western Pacific simultaneously, a feat that is fairly uncommon.
Beautiful satellite image taken on the 20th that captures both Goni and Atsani in the western Pacific. (Source: NASA)
Finally, the last storm of concern is tropical depression Kilo, located southeast of the Hawaiian Islands. As of Friday night Kilo was only a weak storm with sustained winds of 60km/h. However, Kilo is expected to continue curving northwestwards towards the Hawaiian Islands and strengthen. National Hurricane Centre is forecasting that it will strengthen to a category two hurricane and could come very close to making landfall on the island of Kauai. There’s still some uncertainty of its exact track this far out but it appears that this will be a major event for at least the western Hawaiian Islands.
A wild rollercoaster of weather conditions begins today as a fairly potent weather system develops today, rocketing temperatures close to the 30°C mark before things take a turn for the worse as a stormy transition sends daytime highs struggling into the low teens by the end of the weekend.
Friday: Another Beautiful Summer Day, Stormy End?
Today will be a gorgeous day as warm air surging northwards ahead of a developing low pressure system in the Northern Plains of the United States. Temperatures will climb into the upper 20’s this afternoon under fairly sunny skies. Some cloud cover will start working into the region in the afternoon alongside a slight chance of showers as a weak mid-level disturbance rolls through. In the evening, a low-level jet (LLJ) begins to intensify as the low pressure system deepens and brings more lift into the region, spreading more cloud into the region.
The RDPS is showing a warm front at 850mb just north of Winnipeg near midnight tonight. The LLJ is represented by the blue arrows and will be the trigger for thunderstorm activity tonight.
A round of thunderstorms is possible tonight along the nose of the LLJ. The risk is somewhat conditional, dependent exactly how how much moisture is advected northwards within the LLJ. Assuming enough moisture is present to realize the instability, we head to MIST:
Moisture: This will be the most uncertain aspect of tonight’s thunderstorm potential. Dewpoints at 850mb are forecast to be around 10°C, which should be enough to realize the elevated instability, however it’s a farily narrow ribbon, and if amounts are lacking a bit, convective initiation will struggle.
Instability: Fairly strong instability aloft will be present. Models suggest mid-level (700 – 500mb) lapse rates of 7–8°C/km this evening, which would be considered quite strong. If the expected moisture builds into the region, MUCAPE values of around 1000 J/kg should be realized.
Shear: The overall shear looks great, with widespread bulk shear values of 40–50kt expected over the Red River Valley this evening. The high bulk shear values are produced through a combination of strong velocity shear through the vertical coupled with large, looping hodographs indicative of favourable directional shear.
Trigger: Isentropic ascent of the LLJ as it overruns a warm front draped west-to-east along the international border coupled with falling heights ahead of the incoming upper-level low should provide a strong enough trigger to initiate convective activity.
All this combined means that there’s a fairly good chance of some thunderstorm activity through the Red River Valley this evening. It likely won’t be severe; I think the higher threat for severe storms activity will be more in southwestern Manitoba where things will initiate earlier and rooted closer to the warm front. That said, it certainly can’t be ruled out that there may be a rouge severe thunderstorm cell through the evening into the first half of the overnight period. Expect a low temperature near 17°C.
Mixed Bag On Saturday
There remains some uncertainty as to how Saturday will play out, but it seems quite probable that we’ll see some shower or thunderstorm activity through the day. There may be a few sunny breaks, but it should be cloudier than not through much of the day. If any rain manages to hold off until later in day, marginally severe thunderstorms could be possible in the Red River Valley, however it would be dependent on how much heating occurs (read: how sunny it manages to be). Even with decent heating shear looks marginal which will provide a barrier to significant thunderstorm development.
This comes with a caveat, however, as the forecast will be dependant on the timing of the cold frontal passage. With current best indications, there will be a slight risk of severe thunderstorms to the east of the Red River Valley on Saturday afternoon, however if the front slows down a little, that threat could shift westwards into the Red River Valley. We’ll take a closer look at it in an update tonight or tomorrow morning.
That said, temperatures will top out around 25°C with fairly light winds.
Saturday night will see the Red River Valley on the back side of the low and behind the cold front; colder air will begin pushing in alongside strengthening northerly winds. Expect a low near 13°C.
Miserable Sunday
Sunday will be a miserable day by any standard. Very cold air over the region—850mb temperatures are forecast to be a chilly 0–2°C—will keep our daytime highs to just the low teens. Very strong northerly winds will be in place over the region; sustained winds will likely reach 50–60km/h with gusts reaching as high as 80km/h or so. On top of all that, wrap-around precipitation will work it’s way across the Red River Valley, bringing more rain and/or showers to the region.
The NAM is forecasting 850mb temperatures of 0-2°C and very strong northerly winds over the Red River Vallye on Sunday. Miserable.
To top it off, with lake temperatures near 21°C and 850mb temperatures forecast to be near 0°C, lake-effect or lake-enhanced rain/drizzle is probable in the lee of the lakes, persisting possibly into Monday morning.
The low temperature on Sunday night will be around 6 or 7°C.
Hopeful in the Long Range
The good news is that the long-range forecast looks good. Rather quickly behind the passage of this low, a broad upper-level ridge is forecast to begin building back into the Prairies. This will bring significantly warmer weather back to the region. Considering it’s still August and we’re talking about daytime highs in the low teens, a quick bounce back into the mid- to upper–20’s for daytime highs will be much appreciated.
Benign weather will continue over the Red River Valley for the next few days as a weak ridge of high pressure remains entrenched over the region until Friday. Heading into the weekend, however, it looks like rain may be possible as a low pressure system moves into the region through the day.
There isn’t a whole lot to say regarding the coming days, so I’ll keep this post fairly brief! The weather for today and tomorrow will be largely dictated by a weak ridge of high pressure over the region that’s more a result of larger low pressure systems to our west and east than being particularly potent in and of itself.
Today will see temperatures climb to around 23°C with breezy winds building out of the north to 30–40km/h thanks to a low pressure system passing to our east. The day will start overcast with some mid- to high-level cloud that will gradually clear out through the day. Winds will taper off this evening as low temperatures head to around 9°C.
Thursday will be mainly sunny day with light winds and a high near 25°C. Expect a low near 13°C on Thursday night.
The GDPS is showing a low pressure system moving through Southern Manitboa on Friday night capable of bringing some rain to the Red River Valley.
Friday will see increasing cloudiness, particularly in the afternoon as a low pressure system begins working into the region. Temperatures will climb to around 25°C. Friday night will likely bring some rain, although specifics are still quite fuzzy. Temperatures will dip back down to around 13°C again.
Mixed Weekend
This weekend looks mixed at this point, with slightly cooler, cloudier weather on Saturday with a chance of showers and sunnier conditions on Sunday. There’s quite a bit of uncertainty with Friday night/Saturday’s low pressure system, so it’s a bit early to make much in the way of concrete forecasts. High temperatures will likely be in the low 20’s with a chance of warmer weather returning for the beginning of next week.
