Unfortunately for the water-logged fields of the southern Red River Valley and the many ruined plans of office workers just looking for a couple nice days to spend outside, more unsettled weather will be moving through the Red River Valley this weekend with another round of showers or thunderstorms rolling in on Saturday night into Sunday.
Today will start off with the remaining convection from overnight pushing off to the east of the Red River Valley, with the sun then coming out in the morning and quickly pushing our temperatures up into the high-20’s. Winnipeg will likely be within a few degrees of the daytime high of 29°C by lunch. The rain overnight helped bump up our dewpoints, so until drier air begins moving in from the west this afternoon it will feel quite humid outside with temperatures of 26-29°C feeling more like 33-36°C. Temperatures will cool off tonight thanks to the lower dewpoint values moving in to a low temperature near 12°C.
Saturday will bring mixed skies and cooler temperatures as north to northeasterly winds shunt off the warmer air in place today. There isn’t too much to mention at this point for Saturday, so enjoy it! Temperatures will dip to around 13°C on Saturday night with increasing cloud.
The NAM shows an area of rain tracking across the Red River Valley on Sunday morning.
Sunday will likely bring another bought of convective rainfall to the region. A shortwave riding over the Northern Plains will lift northeastwards into southern Manitoba on Sunday, spreading an area of rain ahead of it. There will be a risk of a thunderstorm associated with it, but at that point the risk looks small. Current indications are that the rain will start in the morning, be fairly intense, and end by midday with a widespread 10-15mm, however speed and timing may change between now and then. Temperatures will be cool with a high in the mid-teens and a low near 10°C. Winds will be moderate out of the southeast at 30-40km/h.
Heading into next week, it looks like things will finally settle a bit and we may get a stretch of warm, dry weather with daytime highs in the upper 20’s, overnight lows in the mid-teens or warmer, and little expected by way of widespread precipitation or significant storm threats.
Winnipeg’s seasonal daytime high is currently 23°C while the seasonal overnight low is 10°C.
More rain is on the way to Southern Manitoba this week thanks to the development of a significant low pressure system through Saskatchewan & North Dakota, but we should squeeze in one more day of nice weather before it arrives.
This Week
Today will be the last decent day before another unsettled pattern builds in as temperatures reach the mid twenties under mainly sunny skies. We’ll be located north of a sharp warm front, causing our winds to be gusty out of the north-east through the day. Cloud cover will likely begin to roll in late in the afternoon or evening, signalling the end of the nice weather. Overnight rain and thunderstorms from North Dakota will lift into southern Manitoba, ushering in more unsettled weather for the next couple days. Overnight rainfall amounts will be difficult to pin down, but 5-15 mm seems probable in most areas, with locally higher amounts in the more intense cells.
Today will be warm and breezy as we sit north of a warm front
Tuesday will see rain ending in the morning, before drier conditions move in for midday. It appears possible that more showers and thunderstorms will develop in the afternoon, especially if there are some breaks in the cloud to allow for daytime heating. Additional rainfall will be sporadic with isolated patches of moderate amounts in showers and thunderstorms. Winds in the Red River Valley are expected to be southerly near 20 km/h.
A cold front will pass through southern Manitoba by Wednesday morning, allowing cooler air to filter down from the north. High temperatures will only be in the mid teens under mainly cloudy skies. Additional showers are likely through the day on Wednesday, but large accumulations are not expected. Winds will be gusty from the north-west at 30 km/h gusting to 50 km/h.
Long Range
It appears that we will return to a warmer pattern by the end of the week. However, models also hint at numerous chances for storms in an unsettled northwesterly flow 5-10 days from now. Temperatures will likely be near or slightly above seasonal during this time period, although some cool downs will likely be interspersed within the warmer periods.
The end of week in Winnipeg will be wet as a complex series of disturbances bring several waves of precipitation to the region. Storm-total rainfall amounts of 25-75mm are possible with this system, however the amount any one place receives will be highly dependent on the exact location these features line up, which at this point, is quite uncertain.
Rainfall
A few showers or thunderstorms are possible tonight as a mid-level warm front pushes northwards through North Dakota, aided by a 45kt low-level jet. The chance for rain over the Red River Valley will be mainly before 3AM, with the bulk of any shower activity moving northwards into the Interlake.
Friday will be a wet day over most of Southern Manitoba as a broad area of rain spreads across the Province along the northern edge of a low pressure system tracking through North Dakota into the Red River Valley and areas east. The main area of precipitation will blossom tonight in eastern Montana and then spread east-northeastwards into southwestern Manitoba near midnight, through the Interlake overnight, and then into the Red River Valley proper early Friday morning.
The rain will taper off through the afternoon over the southwestern portion of the province, and in the late afternoon and evening through the Red River Valley. By the time this area of rain tapers off, general amounts will be 10-30mm over southwestern Manitoba and between 5-20mm over much of the Red River Valley & Interlake.[1]
For the southwestern portion of the province, this will mark the end of the main event. Further east here in Winnipeg and the Red River Valley, things become more complicated. After a brief break on Friday evening, rainfall will re-develop on Friday night along a deformation zone[2] ahead of another disturbance pushing northwards out of the central Plains of the United states. The deformation zone will lie along a line approximately NNE-SSE through the Red River Valley & this will result in a fairly persistent band of rain that abruptly tapers off to the west of this feature.
Here’s one shot in the dark at rainfall totals for Friday (from the 00Z April 15, 2016 NAM run).
Saturday will bring cloudy skies and more rain to the region. For much of the day, rainfall will be confined to the east of the deformation zone, however by late in the day, a low pressure system will push through SE Manitoba, pushing rainfall further west into the Red River Valley before everything moves off to the east on Saturday evening. For areas along and to the east of the deformation zone, rainfall totals on Saturday will likely end up in the 15-30mm range, while areas west of the deformation zone in the Red River Valley end up with 5-15mm.
Forecast Rainfall Totals by Area — April 15/16, 2016
Location
Rainfall Total (mm)
Friday
Saturday
Total
SW Manitoba
15-35
Trace-5
15-40
Red River Valley
15-25
Trace-35
15-60
SE Manitoba
10-20
15-40
25-60
Interlake
15-25
Trace-10
15-35
There is high confidence in elevated precipitable water values (relative to April), which confirms the potential of heavier rainfall in some locations on Saturday.
Throughout the duration of this event, it’s expected that all the precipitation will fall as rain, except for the higher terrain of the Riding Mountains & Turtle Mountain, where it may be mixed with periods of snow or freezing rain.
Unfortunately, at this point it’s practically impossible to refine rainfall amounts to anything more precise than these broad categories. As such, I’ve refrained from producing a rainfall forecast graphic as it’s simply too difficult to represent this spread in possible outcomes in a visual manner. We’ll try to provide updates as these systems continue to develop and mature.
The Rest of the Weather
Temperatures will be mild Friday with a daytime high near 12°C, however as the first impulse moves off to our east, cooler air will begin slumping southwards into the Red River Valley as northerly winds increase to 30-40km/h in the evening. Temperatures will dip to around 2°C on Friday night.
Saturday will be considerably cooler with a high temperature near 5-6°C in Winnipeg. The gusty northerlies will continue throughout the day. The wind will begin tapering off overnight as temperatures once again head to a low near 0°C.
Update: Sunday Switches to More of the Same
While originally we forecast that Sunday would bring clearing skies and warm temperatures, however dreams of sunshine will have to wait as this very complicated weather system’s evolution over the past couple days has changed the forecast towards a cooler and wetter variety.
This morning, much of the Red River Valley is still seeing some remnant showers or drizzle from the disturbance that moved through last night. This light precipitation will ease a little bit through the morning, but another disturbance moving into the region midday will spread more rain into Southern Manitoba. Currently entering North Dakota, another area of rain will push north-northeast and then shear out along a southwest-to-northeast oriented deformation zone, allowing rain to push into the southern Red River Valley. Most models indicate that much of the rain that develops will fall through Steinbach and areas eastwards, while areas west and north see little to nothing. Looking at this morning’s satellite imagery, however, and it appears that the deformation zone that will delineate today’s precipitation is a touch further north and west of most model placements.
This simulated RADAR image from the HRRR model valid Sunday afternoon shows rainfall over the Red River Valley.
Some of the high-resolution short-range models such as the RAP and the HRRR are catching onto this fact and, as pictured above, are beginning to shunt the precipitation further to the northwest. So rather than clearing skies, we’ll likely see some shower/rain activity redevelop this afternoon for Winnipeg, the Red River Valley and points eastwards. Amounts will be quite a bit less than the past couple days, with just 2-5 mm for most places and local accumulations in the 5-10 mm range. Any rain activity will taper off overnight.
Other than the rain, it will be cool with a daytime high near 5°C and chilly winds out of north at about 20 km/h. Temperatures will dip close to freezing tonight and we should see clearing and warmer weather begin to work back into the region on Monday.
Winnipeg’s seasonal daytime high is currently 10°C while the seasonal overnight low is -2°C.
Higher amounts that this are possible, but will likely be confined to small regions impacted more heavily by any convective elements that develop within the synoptic rain area. ↩
The deformation zone is a feature in the mid- and upper-atmosphere that firmly separates the warmer, more humid air associated with a low pressure system and the drier, colder air moving in behind it. ↩
While warmer will arrive in Southern Manitoba today with thanks to an abrupt switch to above normal temperatures, the bigger weather story on the horizon is the increasingly unsettled weather that will move into the region for the end of the week, culminating in what will most likely be the first major spring storm for Winnipeg & the Red River Valley.
Today will be the most pleasant day of the week as temperatures soar into the mid-teens with winds gradually increasing out of the southeast to around 30km/h for the afternoon. Skies will be fairly sunny, so all in all it will be a great day and boy, best to get out and enjoy it. Skies will begin clouding up tonight as the first of several systems approaches. Those breezy southeasterly winds will continue throughout the night. Into the second half of the night, some shower activity will begin spreading into the Red River Valley from western Manitoba.
Thursday will start off with some showers throughout the Red River Valley tapering off by mid-day. Temperatures will be quite mild with daytime highs climbing up to around the 17°C mark as a warm front pushes northwards out of the United States in response to a deep upper-level trough digging into the Plains from the Rocky Mountains.
A strong southerly flow aloft will develop on Thursday, surging Gulf moisture northwards.
With the warm front developing over the region through the afternoon, a chance of some isolated showers or drizzle will continue throughout Thursday afternoon. Heading into Thursday night, the main event will begin to take shape: a major storm that will impact all of Southern Manitoba.
As this large-scale trough mentioned above develops, a significant amount of Gulf moisture will surge northwards through the Plains of the United States and head into Southern Manitoba, sending PWAT[1] values soaring to nearly 20mm above seasonal values. As a low pressure system pushes out of Wyoming and heads northeastwards into the Dakotas on Thursday night, a large area of rain will blossom over Montana, North Dakota and SE Saskatchewan and spread eastwards into Manitoba through the day on Friday.
While all the models show heavy precipitation for Southern Manitoba, they differ in placement.
The amount of precipitation is a relatively known quantity; it looks like 40-75mm over the course of 2 days is likely along the main axis of precipitation with amounts dropping to around 15-25mm along the edges of the precipitation. The challenge comes in where exactly this band of precipitation will set up, which will be determined by the position of the warm front and how far northwards it can push. The vast majority of the precipitation will fall to the north and northwest of the warm front, while drier and warmer weather remains to the south and southeast of the front.
There’s a chance that some of the rain may change over to snow on the western fringes of this system, most likely in the Melita, Virden and Minnedosa/Riding Mountain region. Depending on exact temperatures and the timing of the transition, it could mean a significant snowfall if the switch-over happens and it happens early enough.
For Winnipeg, the general consensus for 2-day totals tends to be around 45mm by Saturday evening. The nature of getting to that number varies, with the GFS producing a fair amount of rain on Friday and Saturday while the GDPS holds almost all the precipitation back until Saturday. We’ll have simply wait and see how exactly the warm front sets up to have a better idea of where the precipitation is going to fly.
Summary
Mild weather returns to Manitoba through the second half of this week, however with it will come the development of the first major spring storm of the year. A few showers will move through on Thursday morning, however the main event will occur through Friday and Saturday when a sharp warm front will separate temperatures in the mid-single digits over western Manitoba from near-20°C temperatures over southeastern Manitoba. To the north and northwest of this warm front, a significant rainfall event is expected, driven by a surge of moisture from the Gulf of Mexico as a deep long-wave trough digs into the Plains of the United States.
GDPS Forecast PWAT Anomaly valid 06Z Saturday April 16, 2016
By the time all is said and done, between 40-75mm is likely to have fallen along the axis of heaviest precipitation by Saturday evening. Where exactly this line lies will depend on exactly how far northwards the warm front is able to push; the uncertainty associated with this means that we simply have to wait and see how things develop to refine Winnipeg’s forecast for timing & amounts of precipitation.
With such a big system on the doorstep and so much uncertainty, we’ll be working ahead and getting our Friday forecast out at some point on Thursday evening rather than on Friday morning so that you can get a better idea ahead of time on what to expect for the weekend!
Winnipeg’s seasonal daytime high is currently 10°C while the seasonal overnight low is -2°C.
Precipitable Water, a vertical integration of the amount of water vapour in a column of the atmosphere. ↩
