Fall-like weather will move into Manitoba this week as moderate westerly winds behind a cold front that moved through yesterday usher out any notion of humidity and bring cool nights back to the region.
Today will be a mild day with a high near 21°C in the Red River Valley, but beneath sunny skies will be a moderate westerly winds of 40 gusting to 60 km/h. Expect to see a few less leaves on some of the trees when the day is done.
Strong westerly winds (shown by purples and pinks) will develop over southern Manitoba today.
Winds will taper off this evening as the temperature heads to a low near 9°C under clear skies.
Tuesday will be another mainly sunny day courtesy a ridge of high pressure moving into the region. Winds may pick up to 20-30 km/h in the morning, but will then taper off in the afternoon as the main ridge axis moves into the Red River Valley. Temperatures will climb once again to a high near 21°C.
Temperatures will head to a low near 10°C on Tuesday night with increasing cloudiness as a low pressure system begins to organize south of the border.
Wednesday will bring mixed to mostly cloudy skies to Winnipeg & the Red River Valley. There will be a chance for some light rain near the International border as this weather system grazes along the 49th parallel, but little accumulation is expected at this point. Winds will be out of the north at 15-25 km/h and temperatures will climb to a cooler high of 17 or 18°C.
Expect skies to clear on Wednesday night as temperatures head to a low near 8°C.
Long Range
A fairly strong low pressure system is forecast to develop in the second half of the week, but general consensus at the moment is that it will remain the United States’ problem, leaving us to wrap up the second half of the work week with partly cloudy skies and seasonal highs in the mid-teens. As we head into the weekend, the chance for rain will re-emerge as the weather turns a little more unsettled. At this point, it doesn’t appear that any widespread or major rainfalls are expected.
Winnipeg’s seasonal daytime high is currently 17°C while the seasonal overnight low is 5°C.
Summer-like warmth is on the way back to Winnipeg and the Red River Valley for the second half of the week as a deep southerly feed draws heat northwards out of the United States.
Today will be another pleasant day with seasonal conditions across the Red River Valley as the ridge of high pressure that brought pleasant days to the region continues its gradual trek across the province. Winds will continue light with daytime highs around 24°C and comfortable humidity. Tonight will see a seasonable 10°C for the overnight low.
A warm front will be pushing eastwards across Manitoba on Thursday.
Thursday will mark the return of hotter weather as a deep southerly flow develops ahead of a strengthening low pressure system in Alberta. Morning will bring a few clouds as a warm front pushes eastwards across the valley, bringing with it a chance for some showers or perhaps even a thundershower. After the warm front pushes through in the morning, winds will pick up out of the southeast through the remainder of the day to around 30 km/h by late afternoon. Those breezy southerly winds will draw warmer air northwards, pushing Thursday’s daytime high up to near the 28°C mark under partly cloudy skies in the afternoon.
Thursday night will be significantly milder than the past few nights as the warmer air in the region combines with breezy winds that persist through the night to keep the overnight low from dipping much below the 17 or 18°C mark. Skies will be mixed overnight, but no precipitation is expected at this point.
A strong pressure gradient in place over Southern Manitoba will bring windy conditions on Friday.
Friday will be a mild and windy day. Southerly winds of 40 gusting to 60 km/h will be in place over the valley for much of the day under partly cloudy to mixed skies as temperatures climb once again to around the 28°C mark. Friday night will be another mild one with an overnight low near 19 or 20°C with breezy southerlies continuing.
Weekend Outlook
This weekend will bring another mild, although likely unsettled, day on Saturday with a surge of humidity ahead of a cold front bringing the chance for some thunderstorm activity. Sunday looks cooler and drier with highs in the low 20’s and mixed skies.
This week will start out with another risk of severe thunderstorms across southern Manitoba. On the bright side, conditions prior to the storms will be warm.
A low pressure system moving into southern Manitoba will bring a risk of severe storms to the region
This Week
Today will be a warm and increasingly humid day across southern Manitoba. High temperatures will generally be in the upper twenties, although some locations may reach the 30C mark. The increased humidity will push humidex values into the mid-upper thirties. The approach of a strong low pressure system will result in a stiff southerly wind developing across southern Manitoba. Wind speeds in the Red River Valley will be 40 km/h gusting to 60 km/h by late afternoon. Other portions of southern Manitoba will also be windy, but with speeds perhaps a bit lower than those in the RRV. This same low pressure system will bring a risk of severe storms to most of southern Manitoba as a cold front slices into this warm, humid air mass. All hazards will be possible with storms that develop, with the primary risks being large hail and damaging wind gusts. Tornadoes will be possible with any storms that remain isolated, although the tornadic risk is somewhat lower than last Wednesday.
AWM Day 1 Convective Outlook for August 8, 2016
Models hint at an organized convective system perhaps developing out of the afternoon/evening storms. Should such a scenario play out, the Red River Valley and southeastern Manitoba may be at risk for more widespread damaging winds from the evening into the overnight period.
Moisture: Surface dewpoints of 17-21 C are expected across southern Manitoba, with 850 mb dewpoints of 12-15 C by early evening. Moisture is expected to be well mixed within the boundary layer, giving a 100-mb mean mixing ratio of approximately 12-13 g/kg.
Instability: The aforementioned well-mixed boundary layer will sit beneath mid-level lapse rates of approximately 7 C/km. Steep low-level lapse rates will be present owing to the well-mixed, and relatively deep boundary layer. Resulting MLCAPE values will be near 2000-2500 J/kg across south-central Manitoba by early evening. Early evening instability will generally be poor in the Red River Valley and points east, with MLCAPE of 1000 J/kg or less. However, by the late evening period (03Z onward), MLCAPE/MUCAPE will increase to near 2000 J/kg in the region.
Wind Shear: A 50 kt 500-mb jet streak pushing into SW Manitoba will be preceded by approximately 40 kt of westerly flow over southern Manitoba. Except near the surface warm front, surface winds will generally be southerly, and as a result will not enhance the effective bulk wind difference (EBWD) in a notable way. The result will be EBWD values of 30-40 kt across southern Manitoba, with locally higher values near the surface warm front. More interestingly, a strong southerly low-level jet of 30-40 kt is expected over south-central Manitoba by late afternoon. This will result in 0-1 km wind shear of 15-25 kt. Effective storm relative helicity values will also be strong, at 250-400 m2/s2 during the evening. Low-level shear and helicity are also expected to benefit from the decoupling of the boundary layer by mid-late evening, as the LLJ increases to 45 kt by 0300 UTC.
Trigger: The primary trigger for deep convection Monday evening will be a cold front moving in from eastern Saskatchewan and a warm front extending eastward from a low pressure system near the MB/SK border. Forcing for ascent will be quite strong, especially over western Manitoba, where a potent shortwave trough will help knock down heights by the afternoon. The combination of the low-level mesoscale ascent with the surface fronts and mid-level ascent from the incoming shortwave should easily be able to trigger storms by late afternoon across western Manitoba.
Discussion: Severe thunderstorms are likely to develop across western Manitoba/central Interlake beginning Monday afternoon. Initial storms will likely be a mix of supercells and multicell clusters, owing to the strong forcing. Any initial cells that are able to maintain relatively unpolluted surface-based inflow will present a tornado risk, owing to the strong low-level shear/helicity and steep low-level lapse rates. All initial severe cells will be capable of large hail and damaging wind gusts. As the evening progresses, some models hint at upscale growth/cold pool mergers leading to the development of a bowing system over the southern interlake, or adjacent regions. Should such a system develop and have a significant line-trailing cold pool, it would tend to move ESE/SE, potentially impacting Winnipeg, the Red River Valley, and southeastern Manitoba. A system will a less pronounced cold pool may take a most easterly track, primarily avoiding the Red River Valley. Latest models suggest a well-organized, cold-pool driven MCS is the less likely outcome. The overall risk is slight for all of southern Manitoba. A future moderate risk is possible should a forward-propagating system become more likely.
The cold front which triggered today’s storms will pass through the Red River Valley early Tuesday, likely bringing with it some showers and/or weak thunderstorms. After the front clears the region, skies will begin to clear, allowing temperatures to climb into the low twenties by afternoon. Winds will be northerly at 20-30 km/h behind the front.
Wednesday’s forecast remains fairly uncertain at this point. Models hint at the potential for rain across much of southern Manitoba, though the amount and duration of this rain is quite uncertain. Some models bring significant rain to the region, while others bring only light showers. It appears regions along the international border may be at the highest risk for significant accumulations, though that could change as new data becomes available. Outside the rain, skies will be mainly cloudy with temperatures near 20C. Winds will be easterly at 20-30 km/h.
Long Range
The long range forecast shows little change in our pattern over the next couple weeks. Expect to see 1 or 2 weather systems rolling through our region every week, with stormy conditions associated with the passage of each system. Between systems we can expect generally pleasant conditions, with temperatures near to above-seasonal values.
A low pressure system tracking eastwards through Saskatchewan will bring a potent severe thunderstorm threat to Southern Manitoba today. The development of severe thunderstorms capable of producing damaging hail and winds, torrential downpours, and tornadoes is expected this afternoon over portions of southwestern Manitoba. These thunderstorms will then track eastwards across the Red River Valley & the southeastern corner of the province through the evening hours.
Hot and humid weather will return to Winnipeg today as temperatures soar to the 30°C mark while dewpoint temperatures climb towards the 20°C mark in the Red River Valley courtesy a gusty southeasterly wind of 30-40 km/h that will develop midday. This hot and humid weather will serve as the pressure cooker for severe thunderstorm development as a low pressure system tracks into the province this afternoon.
Through the morning hours, a few isolated thunderstorms are possible across the southwestern and south-central portions of the province, but they aren’t expected to be particularly notable. By early to mid-afternoon, the “main event” will start with thunderstorms developing along a north-south line west of the Red River Valley. Through the late afternoon into the evening, these thunderstorms will move eastwards across the Red River Valley and southeastern Manitoba.
These thunderstorms will be capable of producing large and damaging hail, dangerous straight-line winds exceeding 100 km/h, and torrential downpours capable of flash flooding. In the early hours of the system, over portions of southwestern Manitoba and possibly extending into the western Red River Valley, these thunderstorms will also be capable of producing a tornado.
Moisture: Dewpoints climbing into the 20-23°C range will combine with moderate vertical extent as an organized moisture feed advects into the province from the Dakotas.
Instability: Significant moisture coupled with moderate mid-level lapse rates to produce MLCAPE values 2000-3000 J/kg. MUCAPE values of 1500-2000 J/kg will continue overnight into northwestern Ontario.
Shear: Significant speed and directional shear will be in place over the province with textbook-quality looping hodographs present under 50-60 kt of 0-6km bulk shear will practically guarantee supercell development upon storm initiation and will be completely supportive of upscale growth into the overnight period.
Trigger: A frontal wave passing by the province and associated low pressure system and trough will provide ample lift and convergence to trigger thunderstorm development.
As storms develop, they will very quickly begin rotating and mature into supercell thunderstorms. These storms will very quickly develop hail and severe wind threats. Low lifting condensation levels coupled with the strongly veering hodographs and notable low-level CAPE also suggests a tornado threat for the first few hours of the storm life-cycle. This will most likely be constrained in an area from Brandon to Winnipeg along the Trans-Canada Highway and then south to the American border.
The severe thunderstorm threat will continue eastwards with the line through the evening into Ontario.
AWM Day 1 Convective Outlook for August 3, 2016
The thunderstorms will track eastwards through the evening hours, with Winnipeg most likely seeing the activity between 8PM and 1AM.
Winds will diminish tonight behind the thunderstorm activity as temperature dip to around 17°C.
Update: EC Event Summary
Environment Canada has issued a summary of the severe weather that occurred across #MBstorm yesterday. The highlights are two confirmed tornadoes, loonie to quarter sized hail, wind gusts up to 111 km/h, and 4″ of rain!
Weather summary for Manitoba
issued by Environment Canada
at 5:04 a.m. CDT Thursday 4 August 2016.
Discussion.
An intense low pressure system tracking across the Prairies brought
widespread severe weather to much of southern Manitoba on Wednesday.
Two tornadoes have been confirmed, and numerous reports of heavy
rain, damaging winds, and large hail were also received.
The following reports have been received by ECCC meteorologists
(event times are approximate):
A funnel cloud was reported 8 km north of Hartney at 5:00 pm CDT.
A brief tornado was reported near Margaret at 5:10 pm CDT. No damage
was reported with this tornado.
A larger, longer lived tornado was reported 10 km west of Baldur at
5:20 pm CDT. It tracked northwards towards Stockton where a large
shed was destroyed shortly after 5:30 pm CDT.
ECCC meteorologists continue to investigate these and other
unconfirmed tornadoes.
Hail reports:
Loonie sized hail at Brandon at 6:05 pm CDT.
Quarter sized hail at Shoal Lake at 9:20 pm CDT.
Loonie sized hail at Wasagaming at 10:10 pm CDT.
Peak wind gust reports:
111 km/h at Morden at 7:26 pm CDT.
93 km/h at Portage la Prairie at 7:10 pm CDT.
92 km/h at St. Adolphe at 9:05 pm CDT.
85 km/h at Gretna at 7:46 pm CDT.
74 km/h at Winnipeg Airport at 9:45 pm CDT.
Rainfall totals in millimetres:
Erickson 104
Neepawa 75
Glenboro 66
St. Adolphe 64
Holland 56
Ethelbert 53
Fisherton 53
Morden 53
Killarney 50
Souris 49
Cypress River 45
Elm Creek 43
Snowflake 43
Winnipeg The Forks 2.7
Winnipeg Airport 1.4
Environment and Climate Change Canada meteorologists are actively
seeking pictures or videos from Wednesday's severe weather events
and further damage they may have caused. Should you have any
information regarding these events or to report severe weather at
any time, please call 1-800-239-0484, email storm@ec.gc.ca, or tweet
#MBStorm.
Please note that this summary may contain preliminary or unofficial
information and does not constitute a complete or final report.
End/PASPC
The Rest of the Week
Thursday will be a cooler day with a high near just 21°C with gusty northwesterly winds at 30-40 km/h. There will be a slight chance of some showers as the wrap-around from this low moves across the province. The humidity will be flushed out of the province making for more comfortable conditions. Temperatures will dip to 13°C Thursday night with clearing skies and diminishing winds.
Friday will be a pleasant day with winds out of the northwest at 20-30 km/h, highs in the mid-20’s and mainly sunny skies.
Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.
