Tuesday, June 26, 2007

A break from severe weather!

It's been a very active few days over southern MB, with some of the most severe weather we've seen in years. It started off with a couple of strong nightime thunderstorms that rolled through Winnipeg last Sunday and Tuesday nights giving heavy rain and strong winds. Then Friday and Saturday saw two major tornado events, one that produced an F4 tornado in Elie that caused severe damage, and then at least 3 tornadoes over southwest MB Saturday night, two rated at least F3, one with a damage path almost 2 km wide. Friday night through Sunday night also produced severe thunderstorms across southern MB each night.. with severe winds causing major damage in the Whiteshell Saturday night, and large hail and heavy rain in other places (including over 100 mm near the Peace Gardens Saturday night!) Winnipeg was hit with two severe storms Saturday night.. one that brought 107 km/h wind gusts in the evening that caused tree damage in parts of the city, and one that produced twoonie to hardball size hail in the north end overnight. The stormy weather made a final appearance last night with heavy rains south and east of Winnipeg.

The stormy week has brought my monthly rainfall total in Charleswood up to 118 mm, almost 30 mm above average for June. In northern and eastern areas of the city, monthly rainfall totals are over 150 mm. What a difference compared to last year. To put it in perspective, consider that I've recorded more rain in June this year than I recorded all of last May, June, July and August combined last year (total 114 mm)

The good news is that we won't be getting any more severe storms or heavy rain for awhile.. at least the rest of this week. Drier and cooler air has spread in from the west, which will stabilize things and give us a much needed period of dry weather. After a cool day tomorrow with a chance of some light showers, sunny and warmer weather will move in for Thursday through Saturday. The next chance for showers or thunderstorms will be by Sunday as a low pressure trough moves in from the west. Until then, enjoy the nice quiet weather!

Sunday, June 24, 2007

MB Tornado footage

Here are a couple of video clips showing tornadoes from southern MB the past two evenings. The first clip is the F4 Elie tornado of June 22nd from start to finish. The second clip shows a huge tornado over southwest MB last evening that touched down near Pipestone and travelled southeast, south of Hartney and north of Boissevain and Killarney. This thing was an absolute monster that luckily stayed mainly over open fields. West of Hartney, the damage path was 1.8 km wide! If it had struck a community, we would have had a second straight F4 on our hands (maybe even an F5) which would have caused a lot of damage, and probably a lot of fatalities. Scary stuff..

Elie tornado from start to finish - June 22, 2007

Monster tornado near Pipestone, MB - June 23, 2007

Saturday, June 23, 2007

Elie tornado rated as F5.. more tornadoes tonight

EC's storm investigation team has assessed that the Elie tornado (shown in image here) was an F5 strength on the Fujita tornado intensity scale. The rating was based on the fact that some homes were completely swept off their foundation, a classic signature of F4 or F5 tornadoes. This makes it Manitoba's strongest tornado on record, and the first F5 tornado officially recorded in Canada.

And the violent weather isn't over.. severe thunderstorms have again erupted over southwest Manitoba this evening, with an intense supercell north of Pipestone producing a confirmed tornado on the ground as of 7 pm. (no indication of damage yet)

Friday, June 22, 2007

Tornado hits just west of Winnipeg in Elie.. damage reported

June 22.... A tornado hit just west of Winnipeg around 6:30 pm Friday evening in Elie, MB on the TransCanada between Winnipeg and Portage. Significant damage was reported including damage to several buildings as well as a tractor trailer being thrown into a field off Hwy 1. No reports so far of deaths or injuries. The slow moving tornado was on the ground for at least 30 minutes and was extensively photographed by numerous eyewitnesses along the TransCanada along with some video footage. These dramatic photos of the Elie tornado were taken by Wayne Hanna (left image) and Justin Hobson (right image). For additional photos and full story, see today's Winnipeg Free Press.

Tuesday, June 19, 2007

Strong thunderstorm rolls through Winnipeg.. again..

Nice little thunderstorm squall just went through Winnipeg between 10 and 10:30 pm this evening giving quite a light show, torrential rain and strong wind gusts. Winds gusted to 32 knots (60 km/h) at the airport, but doppler radar (right image) indicated wind gusts up to 50 kt (90 km/h) possible just southwest of the city (such as Oak Bluff and Sanford areas) I recorded 7 mm of rain in about 10 minutes, with a peak rainfall intensity of 110.7 mm/hr at 10:15 pm. Just what we didn't need.. more rain!

Lake effect rains hit Winnipeg

Interesting band of rain last night off Lake Manitoba brought a narrow but fairly intense band of lake effect rainfall along the Hwy 6 corridor into Winnipeg overnight. The image attached is from Woodlands radar about 1130 pm last night showing the band coming off the east shore of Lake Manitoba right into Winnipeg. About 10 mm of rain was recorded here in Winnipeg from the band while most areas outside this band saw little or no rain.

Lake effect preciptation occurs when you have cool air sweeping over warmer lake waters creating narrow bands of convective cloud that can give you very localized but intense precipitation. The greater the contrast between the cool air and the warm lake waters, the greater the instability, and the more significant precipitation you can get. Normally, this occurs in the fall when you have cold fall airmasses moving over the still warm lake waters giving you areas of lake effect rain or snow if it's cold enough. It's unusual to get lake effect this time of year as the air aloft is usually too warm. However last night we had a fairly intense storm system drag some very cool air aloft over southern MB, with temperatures down to 3-4C at 850 mb. This air was taken over 18C lake waters to give enough instability to trigger lake effect precipitation. (You need at least 13C difference between 850 mb and lake water temperatures to initiate lake effect. You also need little directional wind shear in the low levels to focus the instability in narrower but more intense bands) The winds in the low levels were aligned from the northwest at about 300-310 degrees which brought the band off Lake Manitoba right into Winnipeg. If the winds had a more northerly component (like 330 degrees) the band would have oriented further west (see lake effect event of Oct 11 2006 for an example of this)

So if you thought last night had a fall-like feel to it.. you were right.. complete with lake effect! Let's hope we don't see another one of these events until the fall .. it's time for some warm dry weather!

Monday, June 18, 2007

Overnight thunderstorms

Nice thunderstorm rolled through Winnipeg overnight.. with the heaviest activity between 1 and 2 am with some very heavy rain and vivid lightning. At my site in Charleswood, I picked up 21 mm of rain, most of that between 1:15 and 1:45 am, with a peak rainfall intensity of 101.6 mm/hr at 1:18 pm. Other rainfall amounts from around the city included..

U of M ....... 17 mm
St Vital ..... 15 mm
Whyte Ridge... 11 mm
Fort Whyte ... 23 mm
Ft Richmond... 25 mm
Westwood ..... 22 mm
U of W ....... 25 mm
Transcona .... 33 mm
Starbuck ..... 27 mm
Dugald ....... 14 mm
Oakbank ...... 16 mm
Stony Mtn .... 25 mm
Stonewall .... 11 mm
Bird's Hill .. 14 mm

Note: The above reports are from private weather stations and are considered unofficial. Officially, Winnipeg airport recorded 25 mm from the storms.

Sunday, June 17, 2007

Weather Update - Manitoba Marathon

An area of showers and thunderstorms developed over North Dakota last night and is advancing northward into southern Manitoba this morning. As of 5 am the leading edge of the rain shield was just crossing the border from Melita to Emerson heading north. At its current rate.. the rain should be moving into the Winnipeg area by 8 or 9 am or so. The good news is that the area of rain appears to be weakening as it heads north so the rain may be light by the time it reaches Winnipeg. However there is still the possibility of some heavier showers at times along some embedded thunderstorms.. so be prepared for the possibility of lightning this morning. Once the rain moves in..it looks like it will last for a few hours before a break later this afternoon.

7 am weather update.. Ideal conditions to start the race this morning with cloudy skies, light east winds, and temperatures of 16C. In addition latest radar shows the area of rain south of Winnipeg is weakening so the rain may hold off for much of the race, leaving just cloudy skies and comfortably cool temperatures.

Friday, June 15, 2007

Showers moving in for Manitoba marathon..

It looks like the Manitoba marathon will be encountering some wet conditions for Sunday. An area of low pressure over the Dakotas will spawn some showers and thunderstorms south of the border Saturday night which will advance northward into southern MB by Sunday morning. Timing of the showers moving into Winnipeg is still uncertain.. but it appears that the race should start off dry for the 7 am start with comfortable temperatures around 15-18C, and light southeast winds. Clouds will thicken through the morning with showers arriving by mid to late morning. Some of the rain could be heavy at times as well with the possibility of a thunderstorm. Temperatures will level off around 20C or even fall in the afternoon as the rains pick up. So if you're running on Sunday, prepare for a wet finish, unless you're really fast! Good luck to all the runners..

Tuesday, June 12, 2007

Severe thunderstorms likely across southern MB today..

A hot and humid airmass combined with a slow moving cold front to our west will likely trigger another round of severe thunderstorms over southern MB this afternoon into this evening. A cold frontal trough this morning extends from Arborg through Portage La Prairie to west of Pilot Mound, and this feature will likely focus severe thunderstorm development later today mainly west of the Red River valley, pushing into the Red River valley this evening. Looking at the soundings this morning, the potential is there for massive thunderstorms of 60000 feet with energy values of 3000 j/kg or more! Yesterday, the same trough line produced numerous severe thunderstorms over southeastern SK with quarter to golf ball size hail, and damaging wind gusts to 100 km/h or more. These severe weather threats will likely be repeated today, except this time over southwestern MB. Discrete supercell thunderstorms may also give isolated tornadoes. Exceptionally heavy downpours will also accompany the storms thanks to a very humid airmass in place east of the frontal trough with dewpoints in the 20-22C range. These can lead to locally flooding rainfall rates of 50-100 mm/hr possible. Put it all together, and you have the ingredients for a very active afternoon and evening over southern MB today!

Thursday, June 07, 2007

Wet and windy day in southeast MB..

A nice oil painting look to this morning's webcam shot of downtown Winnipeg thanks to gusty winds and a light drizzle falling. Looks like another wet day in store for Winnipeg and southeastern MB today as an unseasonably strong low pressure system over the Dakotas moves northeast. 20 to 30 mm of rain is possible today especially south and east of Winnipeg.. an area already soaked by heavy rains at the end of May. It will also be cool and very windy.. with northerly winds gusting to 70 or 80 km/h at times through the Red River valley. Not a pleasant day! At least things are looking drier and warmer for the weekend..

Wednesday, June 06, 2007

More rain on the way.. heavy at times..

Looks like another shot of rain is headed for Southern MB.. and rainfall will likely be heavy at times overnight through Thursday with amounts of 25-50 mm possible across southern MB including Winnipeg. A major storm system is developing over the northern Plains states, which will likely bring a severe weather outbreak through the northern and central plains , especially from South Dakota into Kansas where tornadoes, damaging winds and large hail are likely. For us in Southern MB, we'll likely miss out on severe weather, but we'll see lots of rain. An inital band of rain will move in this afternoon giving 5 to 10 mm by evening. Things will get more interesting tonight as thunderstorms from the plains system push northward from the Dakotas into southern MB spreading heavy rain across the Red River valley overnight through Thursday. Most places will likely see at least 25 mm of rain by Thursday evening, with some places likely getting 50 mm or more. It will also turn windy Thursday with strong northerly winds gusting to 70 km/h and temperatures only around 10 degrees or so. What a lovely June day Thursday will be! The good news is that we should clear out Thursday night with drier and warmer weather forecast through the upcoming weekend.

Saturday, June 02, 2007

May 2007 Highlights

..Warm start then cooler and very wet..

Weather conditions started off warm in May over Winnipeg after April’s warm temperatures and below normal rainfall. In fact, the dryness was quickly becoming a concern to area farmers and forestry officials with increasing incidents of grass fires and forest fires. A much need rainfall of 20-30 mm fell on the 4th-6th which helped to quickly green up area vegetation. Temperatures continued to warm up reaching a peak of 31C on the 9th.. a record high for the date. By mid month however, the weather became more variable and unsettled, with very wet conditions in the last 10 days of the month. Frequent showers and locally heavy thunderstorms brought heavy rains to parts of southern Manitoba, especially just south and east of Winnipeg. Officially, 75 mm of rain fell at Winnipeg airport for the month, about 20 mm above average for May. However rainfall was much heavier to the south and east, with 93 mm at the Forks weather station downtown, 120 mm in St Vital and 126 mm in Dugald. Even heavier rains fell across the southern Red River valley and Whiteshell areas with monthly rainfall totals of 165 mm in Morden, 135 mm in Morris, 130 mm in Pinawa, and a whopping 206 mm in Kenora.. thanks in large part to a tremendous one day rainfall of 106 mm on May 29th that caused some road washouts in Pointe Du Bois. By the end of May, farmers had had enough of a good thing.. and were eager for a stretch of warm dry weather once again to continue with planting and spraying operations.

All in all.. a very wet end to a changeable month.

Friday, June 01, 2007

Thunderstorms bring heavy rains just south of Winnipeg

A band of thunderstorms developed south of the city Friday evening and remained nearly stationary in an east to west band generally staying along and south of the Perimeter highway. While the city saw little or no rain, Oak Bluff reported at least 25 mm of rain while Sanford had 30-40 mm between 6 and 9 pm. The rain dropped off sharply north of Wilkes Ave with just a trace amount in Charleswood. That's what you call "local" downpours! Notice the distinct "outflow" boundary on the radar image (thin blue arched lines) produced by cool air flowing out of the thunderstorm activity to the south. Radar image is from 7:50 pm Friday evening.