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Holiday Weekend Turns Unsettled

May 20, 2016May 22, 2016 Brad Leave a comment

Summer warmth will continue in Winnipeg for the weekend as southerly winds continue to pull moisture northwards from the United States. By the latter half of the weekend, conditions will become noticeably more humid as a low pressure system begins moving into the region, bringing with it the first organized thunderstorm threat of 2016.

Today will be a beautiful day for Winnipeg & the Red River Valley with mainly sunny skies over the region as temperatures climb to a high near 26°C. Winds will be out of the south at around 20 km/h. There could be an isolated pop-up shower this afternoon through the RRV, but the chance for that will be quite small and not nearly as much shower activity is expected as was seen yesterday through the Red River Valley. Temperatures will fall to a low near 14°C tonight under clear skies.

RDPS Forecast Surface Temperature valid 00Z Sunday May 22, 2016 — It will be another warm day on Saturday with high temperatures in the upper-20’s over Southern Manitoba.

Saturday will be another beautiful day with a high temperature once again near 26 or 27°C under sunny skies. It will be a little breezier than Friday with winds strengthening to around 30 km/h. Expect a low near 16°C on Saturday night with winds out of the south near 20 km/h.

Things will begin to change on Sunday as a low pressure system approaches from the west and some of the more humid air from the US begins working into Manitoba. The day will start off sunny with winds out of the south strengthening to 30-40 km/h. It will begin to feel more humid as the day progresses as dewpoint temperatures climb into the mid-teens. It will be warm, too, with a daytime high near 28°C.

NAM SBCAPE, SFC/850/500 X-Over valid 00Z Monday May 23, 2016 — Forecast instability (SBCAPE) and wind crossover on Sunday evening.

Through the afternoon, the threat for thunderstorms will develop across southwestern Manitoba and spread eastwards into the Red River Valley for the evening. Instability will peak over SW Manitoba in the afternoon with SBCAPE¹ values approaching 2500 J/kg and then tapering off to the 1500-2000 J/kg range as the axis of instability moves into the Red River Valley. Fairly unidirectional wind profiles combined with 30-40 kt of surface to 500mb bulk shear will favour the development of a line of thunderstorms moving northeastwards. The thunderstorms will likely be moderate-to-strong but at this point the threat for severe thunderstorms seems relatively low in the Red River Valley. West of the Red River Valley there is a slight chance for severe thunderstorms, particularly early on in the event before the thunderstorms develop into a line. The primary threat over southwestern Manitoba with any severe thunderstorms that may form will be large hail. We'll continue to keep an eye on things as they develop and refine the storm forecast if needed.

Unsettled Start to Next Week

Holiday Monday will be lead off an unsettled start to next week. Daytime highs will fall back to the low 20's with showers or thundershowers likely to start off Monday and then general unsettledness continuing through the first few days of next week. Conditions will improve through the second half of the week with warmer temperatures returning to the region.

Winnipeg’s seasonal daytime high is currently 21°C while the seasonal overnight low is 6°C.

Surface-based convective available potential energy ↩

A Stretch of Beautiful Summer Weather

May 18, 2016May 18, 2016 Brad

Winnipeg will see plenty of sun and warmth as the first deep southerly flow of the year develops this week, advecting warm and increasingly humid air northwards from the Great Plains of the United States into Manitoba.

The coming days will be bring beautiful summer weather with plenty of sunshine and temperatures soaring into the mid-20's. This afternoon will also bring breezy southerly winds to around 30-40km/h. We'll see just a few clouds today as a weak disturbance moving into Manitoba from the western Prairies slowly falls apart.

RDPS Temperature Forecast valid Thursday Afternoon — The RDPS shows warm summer-like temepratures across the Prairies on Thursday.

Thursday and Friday will both be sunnier days with winds out of the south at 20-30km/h. Thursday will be the windier of the two with gusts in the 40-50km/h range possible, while Friday will see winds more steady and a bit lighter. For both days, the high will be near 26 or 27°C.

Nights will be much milder than we've seen lately with overnight lows in the 12-15°C range.

Of note, and a significant change from what we've seen so far this year, is that this prolonged period of southerly winds will finally bring some more humid air into the region as moisture from the Great Plains of the United States. By the end of Friday, dewpoints will have climbed from near 0°C into the upper single digits. While we won't notice a significant difference in how it feels, it will certainly alleviate some of the moisture stress for plants which could help improve the fire danger in the region.

Long Range: 2016's First Humid Days?

For the weekend, the weather will continue distinctly summery with high temperatures climbing into the upper 20's. Along with the continued warmth, those southerly winds will continue to push moisture northwards and begin pushing dewpoint values towards something that may actually begin to feel humid. By the end of Saturday, it is forecast that the dewpoint will climb to around 12-13°C which is a fairly typical summer value for the region. On Sunday, however, a surge of humidity is expected to push into Manitoba, bringing dewpoint values into the 15-17°C range, which will begin to feel a bit humid when combined with a high near 29°C.

GFS Surface Dewpoint Forecast valid Sunday Evening — The GFS shows clearly this weekend’s stream of humidity from the Gulf of Mexico northwards through the Great Plains into Southern Manitoba.

With the humidity will also come unsettled weather. It's far to early to get into many specifics, but beginning on Sunday afternoon, the chance for thunderstorms will make an appearance across Southern Manitoba. Early indications are that there may be a slight chance for severe thunderstorms with a primary threat of severe hail. We'll be sure to keep an eye on things as they develop and provide a more in-depth outlook in our Friday post.

Winnipeg’s seasonal daytime high is currently 20°C while the seasonal overnight low is 6°C.

Flurries Start Off A Cool Weekend

May 13, 2016May 12, 2016 Brad

Today will start off with flurries moving through the Red River Valley, setting the stage for a snap of cool weather that will bring temperatures well below seasonal. While temperatures will rebound slowly through the weekend, it will hardly be beautiful spring weather.

Today will be a rude awakening for many, as cold temperatures combine with a weak disturbance rolling through the region to produce widespread light flurry activity through the Red River Valley. Some places might get lucky enough to see things change over to scattered showers briefly this afternoon, but for the most part, expect some light snow for much of the morning and into the afternoon. Fortunately, the snow won't really stick and no accumulation is expected.

In addition to the snow, the winds will continue to be strong out of the northwest at 40 gusting 60km/h with a daytime high that just barely gets to 5°C.¹ Temperatures will dip to near the -4°C mark tonight with clearing skies. Near the core of Winnipeg it's not as likely that there will be a hard freeze, but certainly near the outer edges of the city and into the rural areas a significant freeze is likely so you may want to take precautions if you've any sensitive plants outside already.

GDPS Forecast 850mb Temperature Anomaly — The 850mb temperature anomaly forecast shows a large core of below-seasonal (blue) temperatures over Manitoba today.

Saturday will finally bring out the sun in Winnipeg, but it will continue to be chilly with a daytime high of 9°C under mainly sunny skies. Winds will continue out of the northwest, but be slightly weaker at 20km/h or so. Expect a low near the freezing mark on Saturday night with partly cloudy skies and light winds.

Sunday will see another disturbance moving through the province in the northwest flow. More cloud will move into Winnipeg alongside slightly warmer temperatures; daytime highs are expected to climb into the mid-teens! A band of showers will likely move through in the afternoon, bringing a decent chance of precipitation to most areas in the Red River Valley. Winds will vary through the Red River Valley from light to around 30km/h. Expect a low on Sunday night near 3°C with partly cloudy skies.

Long Range: Climbing To Seasonal

Looking ahead to the start of next week, it appears that temperatures will make a continued climb back towards seasonal, however the with a stubborn upper trough refusing to leave the area, that could end up taking longer than expected. Conditions aren't expected to be too bad with a good mix of sun and cloud and highs in the mid- to upper-teens. There will be a slight chance of showers.

Winnipeg’s seasonal daytime high is currently 19°C while the seasonal overnight low is 5°C.

Nearly 15°C below normal for daytime highs right now in Winnipeg. ↩

Unsettled Transition to A Cool Weekend

May 11, 2016May 10, 2016 Brad

An upper-level low tracking across the province today will bring showers to the region and mark the beginning of a transition into cooler weather that will persist through the weekend.

Today will bring another batch of showers to Southern Manitoba as an upper-level low that has brought several days of much-needed rain to Saskatchewan pushes across Southern Manitoba. Much of today will be cloudy for Winnipeg & the Red River Valley until this evening when showers develop underneath the core of the upper low. Much of the precipitation expected today will fall through the evening & overnight, with anywhere from a trace to another 5-10mm possible across the area. There's an outside chance of a lightning strike or two, but no organized thunderstorm threat is expected.

Winds will strengthen out of the south-southeast at 20-30km/h today, with temperatures climbing to around 17°C. As the low passes by tonight, the winds will diminish and shift out of the northwest, making for a damp and chilly night with temperatures dipping to around 6°C.

The high-resolution NAM shows a further 10*mm* or so of rain tonight for Winnipeg.

Any remaining shower activity will taper off on Thursday morning with a slight chance of some more shower activity lingering through the day. Skies will remain mostly cloudy and the wind will pick up to a fairly moderate breeze out of the northwest at 30-40km/h. Temperatures will be cooler with a high near just 11°C. While the cloud will break up a little bit on Thursday night, Winnipeg will likely be stuck with mostly cloudy skies and northwesterly winds at 30km/h. It will be quite chilly with low temperatures bottoming out at 1-2°C.

The cold overnight low on Thursday night combined with a weak disturbance slumping southwards will mean that Winnipeg will see a chance of…flurries on Thursday night into Friday morning.

The clouds will gradually part on Friday and the sun should make an appearance for the afternoon. Temperatures will be well below normal, though, with a high of just 6-7°C and breezy northwesterly winds again at 30-40km/h. Friday night will bring partly cloudy skies, diminishing winds and a low temperature dipping below the freezing mark and bottoming out near -3°C.

850mb Temperature Anomaly valid 12Z May 14, 2016 — This plot of 850mb temperature anomalies for Saturday morning shows the below-normal temperatures that will be in place later this week.

The below-seasonal temperatures will persist through the weekend and into early next week before finally beginning to return to normal in the middle of the week.