Category: Forecasts

Storm Chase Log – July 9th to 10th

Matthieu Leave a comment

As Brad forecasted on his Friday post, severe storms were expected on Saturday across southwest Manitoba as a result of an upper level ridge that rounded the southern Canadian Prairies began breaking down. Scott and I decided on Friday night to head out from Winnipeg for a chase around noon on Saturday in expectation of the severe storms.

July 9th

We decided, as our general target area, to head south of Brandon and refine the area as the early afternoon wore on because elevated convection was ongoing in the region. As we headed down highway 2, conditions looked promising for surface based storms as there wasn’t much cloud cover near border regions.

Initially we kept an eye on bubbling cumulus near Melita as we blasted west, however as we approached the so thought “elevated storms” near Souris it was evident that the storm had become surface based. Clear skies and warm temperatures south of the storm allowed the storm to ingest surface parcels as it dived southeastward. As we initially got close to the storm, we saw that the storm had a ground scraping shelf cloud – some of the best storm structure observed in southern Manitoba this year was observed west of Ninette. We continued to follow the storm in a southeasterly fashion and rotating wall clouds formed on a few occasions near Minto and Dunrea. It was also evident that the storm was producing damaging hail as the core had a greenish tinge of color.

Ground-scraping shelf cloud as we initially approached the storm north of Ninette.
Ground-scraping shelf cloud as we initially approached the storm north of Ninette.

Ongoing storms south of the border near Devils Lake spat out rain-cooled air and the supercell storm eventually began dying off near Cartright. Regardless, we continued to follow it south of the border until it eventually gusted out by late afternoon. We then looked at the weather models and saw that the next day could once again produce strong storms, this time in western North Dakota so we headed to Minot for the night.

A few rotating wall clouds were observed as the supercell dove southeasterly, northwest of Killarney.
A few rotating wall clouds were observed as the supercell dove southeasterly, northwest of Killarney.

July 10th

On the morning of the 10th we did our analysis and looked at short term convective models only to find that there was much disagreement as to what would happen during the afternoon. Most models did convect strong storms in the Dickinson area so we headed in that direction, from Minot. Unfortunately we forgot to check for construction delays before leaving and picked a highway that had construction for over 30 km. After a scenic route through the badlands of western North Dakota, we approached our target area. Simultaneously, storms began to form to our southwest near Baker, Montana – great timing!

We passed through Killdeer, North Dakota and headed to Dickinson to orient ourselves south of the storm. By then the storm was a full-fledged supercell. Once again it was evident that the storm was chucking very large hail. Green skies were present and the radar depicted reflectivities of over 70 dBz, we had to make sure not to get caught in the core of the storm. We first took a peek at the storm just northwest of Dickinson – this is when the storm looked best. A rotating wall cloud was observed and the storm appeared to be close to producing a tornado. Only about a half-hour or so after the wall cloud was initially observed however, the rear flank downdraft (RFD) of the storm had a mighty surge, near Killdeer. The RFD undercut the updraft portion of the storm and formed a shelf cloud – it was then evident that the storm had little tornado threat so we abandoned it. It did however have a significant wind and hail threat – Killdeer took the brunt of the storm and significant damage was observed to cars and houses.

Picture taken right after the hailstorm in Killdeer shows the extensive damage that wind-driven baseball sized hail causes. Windshields of cars were blown out as well as windows and siding destroyed in Killdeer. (Source: Ohio Storm Chasers//Aaron Rigsby)
Picture taken right after the hailstorm in Killdeer shows the extensive damage that wind-driven baseball sized hail causes. Windshields of cars were blown out as well as windows and siding destroyed in Killdeer. (Source: Ohio Storm Chasers//Aaron Rigsby)

We then bailed south to a secondary cell that had formed in extreme southwest ND. Lift along the front was too strong for any significant tornado potential and storm became linear. A bow echo was taking shape. We were, however, treated to an exceptional light show on the way back to Bismarck and 90km/h winds with torrential rains as were experienced as we cored the bow echo.

A bow echo raced across central ND as storms consolidated into a line by late evening.
A bow echo raced across central ND as storms consolidated into a line by late evening.

(Un)fortunately the tornado potential did not pan out for our two day chase trip, but overall some great storm structure and lightning was observed!

Fall-Like Wednesday Leads to Drier, Warmer Weather

Brad Leave a comment

Southern Manitoba will be under the influence of a major low pressure system for one more day, bringing gusty winds and more rain shower activity, before drier conditions begin moving in through the remainder of the week.

Winnipeg & the Red River Valley will continue to be under the influence of a major low pressure system currently located over eastern Manitoba for one more day. Today will see cloudy skies and on and off showers through the day across the region, although they will likely be more numerous through the morning hours. Winds will be quite breezy out of the west to northwest at 30-40 km/h with gusts up to around the 60 km/h mark, and it may even feel more like late-summer thanks to a below-seasonal high temperature of just 18°C.

The rain shower activity will taper off through the late afternoon into the evening hours, leaving mainly cloudy skies in Winnipeg as temperatures head to an overnight low near 13°C. The winds will continue breezy at around 30 km/h.

Around 5mm of rain can be expected from showers across much of Southern Manitoba today.
Around 5mm of rain can be expected from showers across much of Southern Manitoba today.

Thursday will bring mainly cloudy skies, although a bit of sun may be possible late in the day. Winds will be lighter than Wednesday at around 30 km/h out of the northwest. Daytime highs will be a bit warmer throughout the Red River Valley at around 20 or 21°C. A lingering trough may result in a few afternoon showers near the U.S. border and extending back into southwestern Manitoba.

Skies will continue to clear Thursday night as temperatures dip to around 12°C.

Friday will be a pleasant day with light winds, plenty of sun and a high near 23°C.

Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.

Thunderstorms & Showers to Start The Week

Brad Leave a comment

A severe thunderstorm threat returns to Southern Manitoba today as very warm and humid conditions persist in the region for one final day before a cold front pushes cooler and drier air into the region. The passage of the cold front will not be an end to the unsettled weather, though, as a couple more days of showers or thunderstorms will occur with a large upper-level low passing over the region.

Today brings a notable severe weather threat to southern Manitoba with a slight risk of severe thunderstorms developing over southwestern Manitoba and a moderate risk in the Red River Valley eastwards through the SE corner of the province.1 The thunderstorms will develop mid-day and push eastwards with the cold front through the remainder of the afternoon. It is most likely that the thunderstorms develop over southwest Manitoba first, and then push towards into the Red River Valley this evening. Stay aware of any watches or warnings issued by Environment Canada.

The HRRR develops a line of thunderstorms along the cold front and pushes it into the Red River Valley this evening.
The HRRR develops a line of thunderstorms along the cold front and pushes it into the Red River Valley this evening.

Otherwise, this mornings cloud cover will break up a bit to produce mixed skies and the relatively small amount of sunshine will push the daytime highs to around 26°C. With very humid air in place, it will be a fairly uncomfortable day, feeling more like the low- to mid-thirties. After the thunderstorms move through this evening, we’ll head to a low near 16°C with breezy southerly winds.

Tomorrow will likely bring some sun first thing in the morning, but more clouds will move in with a good chance of more shower or thunderstorm activity in the afternoon. At this point severe thunderstorms aren’t expected, but we’ll keep an eye on things to see if anything changes. Winds will be pick up to be gusty out of the north near 40km/h. Expect a high near 23°C and a low near 14°C with a continued chance for showers overnight.

Wednesday will be a cool and cloudy day with a good chance of more rain. The daytime high will only be around 20°C and winds will continue gusty out of the northwest, although not quite as strong as Tuesday. The shower activity will taper off in the evening as temperatures head to a low near 14°C.

The latter half of the week is looking like a return to seasonal temperatures and a chance of actually drying out a little bit.

Winnipeg’s seasonal daytime high is currently 26°C while the seasonal overnight low is 13°C.

  1. Apologies for the lack of an outlook image; time constraints have prevented me from making one. ↩

Increasingly Muggy Weather on the Way for the Winnipeg Folk Festival

Brad 4 Comments

Unsettled weather is on its way back to the province as a trough of low pressure develops over the western Prairies and draws humid air northwards out of the United States. For people heading out to Bird's Hill for the Folk Fest, this means increasingly muggy weather through the weekend with the potential for thunderstorms both Saturday & Sunday.

Today will be a fairly pleasant day. The system that brought up to 20 mm of rain to the Red River Valley yesterday1 will be moving off the east and any remaining cloud from it should clear out through the morning leaving just a few clouds around for the afternoon. Temperatures will climb to a high near 25°C. Expect just a few clouds overnight and a low near 14°C.

Saturday

Saturday will see more humid air beginning to work into the region. Morning sun will be replaced by clouds as the day goes on while the temperature climbs to a high near 26°C. There will be a slight chance of thunderstorms in the evening, but the main threat will occur through the overnight period. There will be a very small chance of severe thunderstorms.

Update: Severe Thunderstorms Hit SW Manitoba on Saturday July 9, 2016

Severe thunderstorms developed over SW Manitoba on Saturday and focused into one primary strong supercell thunderstorm that organized near Virden, MB and then moved southeastwards through Minto & Ninette before continuing on across the US border. It produced a variety of severe weather, with numerous reports of heavy rain, large hail and severe winds:

A summary of the severe weather over southwestern Saskatchewan on July 9, 2016
A summary of the severe weather over southwestern Saskatchewan on July 9, 2016

Sunday

Sunday will see the humidity move into the region full force with dewpoint values climbing up into the low 20's. This will make the high near 27°C feel very warm, however conditions will be a bit more bearable due to the fair amount of cloud cover expected through the day. Any times the sun does poke out, though, will likely see things begin feeling very warm very quickly.

A organized line of thunderstorms sweeping across Southern Manitoba is possible Sunday night.
A organized line of thunderstorms sweeping across Southern Manitoba is possible Sunday night.

Rain-wise, we may see some remnant showers or thunderstorms in the morning from any activity on Saturday night, and then things should diminish for much of the day. By Sunday evening & overnight, the thunderstorm threat once again returns. Sunday night will see a slight to moderate threat of severe thunderstorms across the Red River Valley. Large MUCAPE values overnight coupled with 30-50 kt of bulk shear ahead of an incoming shortwave will support the development of organized thunderstorm activity across a wide area of Southern Manitoba. The primary threats will be large hail and strong winds, with rapid rainfall accumulations also a concern.2

It will be a very mild night with a low near 21°C.

Long Range

The start of next week continues warm and humid with a thunderstorm threat late in the day into the overnight period. Heading through Tuesday into mid-week, the main upper low associated with the weekend's weather pattern moves into the region, bringing relief from the humidity and cooler temperatures alongside more cloud and chances for showers.

  1. While Winnipeg saw nothing but a few light showers late in the evening, the rain managed to push as far north as St. Adolphe, which saw 2mm. ↩
  2. Although the thunderstorms will likely have very intense rainfall, they will be moving relatively quickly, making accumulations not as prominent a threat as the hail or wind potential. ↩