Another Showery Day; Nicer Weather On The Horizon!

One more day of showers is in store for Winnipeg as another upper low tracks across the province before conditions finally begin to improve as the long-wave upper trough that has been quasi-stationary over the Prairies shifts off to the east and upper ridging begins building in.

6hr. QPF for Thursday afternoon from the GEM-REG

6-hour accumulated rainfall for Thursday afternoon from the GEM-REG. Showers with a slight chance of a thundershower are expected through much of Southern Manitoba today.

Another low will track across Southern Manitoba today, bringing with it more cloud and a chance of showers. This system brought widespread thundershowers to Alberta & Saskatchewan yesterday with multiple sightings of funnel clouds as well. Activity will be more subdued over Manitoba today as the system won’t have quite as much energy to work with as yesterday; in general the clouds should break up over the RRV a little this afternoon with scattered showers developing over SW Manitoba and pushing eastwards through the afternoon. Rain will likely be hit and miss as the disorganized mass pushes eastwards. Showers will move into the Winnipeg area by mid-afternoon and will push out/diminish in the early evening as daytime heating diminishes. There’s a slight chance for a thundershower or two, but that chance is marginal at best.

As the low moves off into NW Ontario tomorrow evening, it will mark the transition to a markedly different weather pattern. Through the day on Thursday, upper ridging will begin to build it’s way into the Prairies. We’ll finally see the sun again on Thursday as temperatures climb into the low 20’s across the RRV. There’s a slight chance of some showers/thunderstorms over SW Manitoba and the RRV as a shortwave slides down through the area. After that, it’s all sunshine as the upper ridge continues building into our area. Temperatures should push into the mid-20’s for the weekend with plenty of sunshine. Finally, some time to dry out!

Unsettled Weather to Continue

This week will continue to be unsettled weather-wise. It appears that we will see the chance for rain virtually every day for the next several days.

A trough of low pressure over the Prairies

A trough of low pressure over the Prairies (the jet stream is in blue)

A trough of low pressure sitting over the Prairie provinces will be responsible for our unsettled weather over the coming days. This trough is created due to the fact that the jet stream will be to our south, allowing cooler air from the north to spill down into lower latitudes. As weather systems track along the jet stream they will create chances for rain in Southern Manitoba. It appears that rain is a possibility on every day from Monday through Thursday. At this time it looks as though rainfall amounts on Monday and Tuesday will be fairly light, if it rains in your location at all, but the precipitation forecast for later in the week is less clear.

Due to the cloudy and potentially wet conditions expected on Monday and Tuesday, temperatures won’t be very warm. Highs on Monday will generally be in the high teens over Southern Manitoba, except for border regions and parts of south-eastern Manitoba where temperatures should be closer to twenty degrees. Tuesday is likewise expected to remain cool, with highs in the mid to upper teens expected. Temperatures on Wednesday will be governed by when and if it rains, but it doesn’t look like it will be warmer than twenty for midweek (if it indeed gets that warm at all).

Too much uncertainty exists in the forecast at this point to talk about the weather much beyond Wednesday. However, at this time it doesn’t appear that we will be going back into a prolonged spell of nice weather in the short-term.

Elsewhere in Weather News: June 16th, 2012

Large Waterspout Makes Landfall in Venice

A large waterspout made landfall on the islands of Venice on Tuesday, June 12th. The tornado caused considerable damage on the islands but missed the picturesque city centre of Venice altogether. As the waterspout made landfall on Venice’s lagoon, it traveled towards the island of Saint’Erasmo and Certosa where there were numerous reports of trees being shredded and uprooted, roofs being torn off and the city’s well-known gondolas being thrashed around. Two significant structures that were reported as being damaged include a soccer stadium and a naval academy where a tree fell, trapping 15 students inside the building. Winds were estimated to be howling at a rate of about 145km/h inside the twister at the time it made landfall, classifying it as an EF-1 tornado under the Enhanced Fujita Scale. One man was injured and the damages are estimated to be near a couple of millions of dollars.

Venice waterspout

Picture of the waterspout/tornado as it makes landfall. (Source: Cristian Cavallarin)

Damage path

Damage on one of Venice’s islands. (Source: EPA)

Waterspouts in the region are usually associated with small spin-ups and pulse storms over a large body of water, which typically dissipate when making landfall. However, this waterspout in particular had not dissipated as it moved over the islands due to its unusual strength and cone-like shape – signifying strong rotation present. According to a satellite picture taken at the time, it appears a shortwave provided the necessary ingredients to spawn the tornado and lengthen the duration of the storms.

Satellite picture

Satellite picture on the morning of June 12th, 2012. Approximate location of Venice, Italy represented by the green dot on the map. (Source: EarthSky/CIMSS)

Even though tornadoes are not as common in Europe as they are in North America, Italy has seen its fair share of deadly tornadoes this past century. A couple of notable tornadoes are:

-The Montello tornado in 1930 – possibly the strongest tornado ever to touch down in Europe, it brought gusts of over 500km/h and completely levelled brick buildings.
-The Venice tornado outbreak of 1970 – which included a notable tornado that went through Venice causing deaths and destruction throughout the city.

View of the tornado from downtown Venice. (Source: The Telegraph)

Storms were reported to have cleared out of Venice’s region near the end of this week. The weekend forecast in that area calls for light showers on Saturday and all-out sun on Sunday.

A couple other notable events that have happened in other parts of the world since last weekend include: a hurricane spinning up in the Eastern Pacific heading towards Mexico’s western coast; and significant flooding in Pensacola, Florida where over 540mm (more than a year’s worth of precipitation in Winnipeg, Manitoba) fell in 24 hours!

Stormier Weather Set To Return

Southern Manitoba will be under an increasing risk of thunderstorms as the week progresses. Heat and humidity will slowly build back into the region as a deep upper trough begins to build over the Rocky Mountains before tracking eastwards across the Prairies later in the week.

GEM-REG 6-hour Precipitation for Thursday Afternoon

6-hour accumulated precipitation through Wednesday afternoon from the GEM-REG model.

We’ll see warmer temperatures today as warmer air pushes in behind a warm front that passed through overnight. Daytime highs should be near the 25°C mark through most of the RRV. By this afternoon a weak frontal wave will be positioned near the international border with a trough extending NW to a low pressure system tracking into Western Manitoba. Showers and thunderstorms will develop over SW Manitoba early this afternoon and slowly develop northeastwards into the Red River Valley. It will mainly be regions through the northern Red River Valley that face the risk for showers or thunderstorms (Portage la Prairie, Winnipeg, Selkirk; as seen in the image above). The showers and thunderstorms will lift northwards into the Interlake overnight while overnight lows drop to the mid-teens over most of Southern Manitoba.

12 hour accumulated precipitation through Thursday

12 hour accumulated precipitation through Thursday from the GFS model.

Opinions differ for Thursday, however it’s generally expected that a north-south band of showers with a chance of an embedded thunderstorm will develop over the Red River Valley or the Whiteshell in the afternoon. This line will slowly move eastwards and intensify into a band of thunderstorms. Again, there’s still quite a bit of uncertainty to where this line will develop, and the potential exists for fairly large (close to 1”) rainfall accumulations. We’ll be keeping close track of this system’s development.

Friday looks to be a fairly nice day with comfortable humdity and daytime highs in the mid-20’s. A large MCS is forecast to develop on Friday night in North Dakota, bringing the chance for a stormy and rainy Saturday. We’ll take a closer look at that system later this week.