Thunderstorms possible tonight.. cooler weather for start of September..

August will be ending on a warm and muggy note, with morning clouds giving way to some afternoon sun along with humid conditions. A storm system developing over Montana will trigger a few thunderstorms over eastern SK and western MB later today into this evening, some possibly severe with damaging winds and large hail, along with a risk of isolated tornadoes. The system will sweep a cold front across southern MB tonight with showers and thunderstorms possible across the Red River valley through the Interlake regions. Cooler weather is on tap for the first few days of September behind this system.

Another 30C day on tap today.. showers possible Sunday

30C temperatures will be returning to southern Manitoba today as southerly winds develop ahead of a trough of low pressure pushing across southern SK. For Winnipeg, today's high of 30-32C will be the 19th time this summer the city has hit the 30c mark.. the most 30c days in a summer since 2006 when we had 22 days of 30C or more. On average, Winnipeg sees 11 days of 30C weather between June and August but the past few summers have generally fallen short of that mark. In fact, this summer's 30C total will match the total number of 30C days for the past 3 summers combined! The following table lists the number of 30C days in Winnipeg (at YWG airport) since 2006.

30C days in Winnipeg - June through August

2011 ...... 19 (as of Aug 25th)
2010 ...... 11
2009 ....... 3
2008 ....... 5
2007 ....... 10
2006 ....... 22

Slightly cooler but sunny conditions are forecast for Friday and Saturday before some unsettled weather moves in for Sunday with showers and scattered thunderstorms possible over the Red River valley. Let's hope it materializes. Other than a 20 minute downpour of 21 mm during last Thursday's thunderstorm, rain events have been few and far between these past two months.

City sizzles through hottest day in 16 years..

It was a torrid Tuesday over southern Manitoba as a southwest flow of hot dry air sent temperatures into the mid to upper thirties over the Red River valley. In Winnipeg, the mercury soared to a record breaking 37.2C by 2:30 pm, beating the previous high for Aug 23rd of 36.7C set in 1952. Not only was this the hottest day of the summer, it was also Winnipeg's hottest temperature since June 17 1995 when the city hit 37.8C. The record heat today was accompanied by very dry conditions (see YWG 22Z sounding), with dewpoints dropping to the 10C mark by mid afternoon giving humidity values of only 20%. At my Rob's Obs station in Charleswood, a maximum temperature of 38.0C was reached at 2:49 pm today, the hottest temperature at my site since it was started in 2001. (see my station's temperature trace above)

Luckily the record heat will be short lived. A cold front was pushing through southern Manitoba Tuesday evening dropping temperatures into the 20s accompanied by gusty northwest winds. This front will usher in a cooler airmass for Wednesday with temperatures some 10 degrees cooler than today.

30C weather set to return to southern MB.. record heat possible Tuesday..

If the past few days had you thinking that the summer of 2011 was over.. think again. Mid summer heat is set to return to southern Manitoba Monday and Tuesday with temperatures climbing well into the thirties. In fact, Tuesday could see some record highs across the Red River valley as temperatures soar into the 35-38C range. Winnipeg's record high Tuesday (23rd) is 36.7C from 1952, and it's possible we may come close to that mark. Conditions are favourable for very warm air to surface Tuesday as the Red River valley gets a southwest flow tapping a hot and dry airmass moving across the Prairies. Typically these are the set-ups that usually give Winnipeg and the Red River Valley its hottest temperatures. Winnipeg's hottest temperature so far this summer was a 34.4C reading on July 19th.. so Tuesday has the potential to be the hottest day of the summer. After a brief cooldown Wednesday, 30C weather is possible later in the week. More beach weather ahead as the fabulous summer of 2011 continues!

Severe thunderstorms roll through Winnipeg/ northern RRV

After dodging thunderstorms much of the summer, a line of severe thunderstorms pushed across Winnipeg Thursday evening, bringing heavy rain, intense lightning, strong winds and marble to toonie size hail to parts of the city. The line of thunderstorms developed northwest of the city Thursday evening and pushed across the city between 8:50 and 9:30 pm preceded by an impressive shelf cloud ahead of the storm (see photos). The storms brought some welcome rain of 15-25 mm across much of the city including 21 mm at YWG airport.. the heaviest rainfall of the summer, and the first daily rainfall over 5 mm at the airport since June 22nd. The line of storms was triggered by a cold front pushing across southern MB, which will usher in cooler weather for the weekend. Winnipeg hit 31C Thursday.. the 16th occurrence of 30C plus temperatures this summer.

Photos above courtesy of Winnipeg Free Press (top) and Weather Network (lower 3) See additional photos from CTV Winnipeg.

Thunderstorms developing through Interlake.. severe thunderstorm watch in effect into this evening

A cold front over western Manitoba late this afternoon is triggering a line of thunderstorms mainly northwest of the Red River valley through the western Interlake areas late today, with some potentially severe storms developing. (see 5:50 pm radar image left) A severe thunderstorm watch has been posted for much of southern Manitoba including Winnipeg and the Red River valley for the potential for severe thunderstorms into this evening as the cold front approaches. It looks like the bulk of storms will pass to the north of Winnipeg through the Interlake region, but the potential is there for isolated storms to develop further south. This front will usher in a cooler airmass for the next few days with highs only in the low 20s through the weekend. Warmer weather is expected to return to southern MB early next week.

Strong westerly winds to buffet Manitoba lakes this afternoon into Wednesday morning

A cold front pushing across southern Manitoba today will usher in a westerly flow of drier and cooler air this afternoon into tonight. West winds gusting to 60 or 70 km/h are likely this afternoon into this evening across the Red River valley as drier air pushes in from the west (see real time wind readings from Winnipeg airport). Strong wind warnings have been posted over the Lake Manitoba and southern Lake Winnipeg marine areas for sustained westerly to northwest winds of 30 knots later today into tonight, with west to northwest gales of 40-45 knots forecast over the north basin of Lake Winnipeg by tonight. These strong winds will cause already high lake levels to rise another 0.5 to 1 metre on the east and south side of the lakes, with waves of 1-2 metres on top of that. See real time lake levels for Manitoba (click here for Victoria Beach or Lk Wpg north basin), and here for latest Manitoba marine observations.

Showers and thunderstorms overnight into Tuesday..

Here we go again.. another weather system will be pushing into southern Manitoba tonight into Tuesday spreading showers and thunderstorms into the region. The big question is.. will Winnipeg finally see some significant rainfall out of this or will precipitation skirt the city as it's done the past 6 weeks or so? At Winnipeg airport, only 20 mm of rain has fallen since June 23rd, with no daily rainfall greater than 5 mm in that time. (note that some areas of the city have had more rain) The last thunderstorm to hit the airport was back on July 4th. So it's been a long stretch of dodging convective weather systems over the northern RRV. Will this next round be the same story? For tonight, thunderstorms are expected to develop over North Dakota and southwest Manitoba, some potentially severe, which are forecast to spread into the RRV overnight into Tuesday. Some of the rain could be heavy with local amounts of 20-40 mm possible in thunderstorms. The unsettled weather is expected to push east of the RRV later Tuesday with breezy and cooler conditions Tuesday night into Wednesday. Hit or miss for Winnipeg? Let us know in Rob's Obs latest poll!

Another chance of showers/thunderstorms mainly south of Winnipeg tonight.. nice weekend shaping up with more dry warm weather into early next week..

A weak system tracking through the Dakotas will bring another chance of showers and thunderstorms later today into tonight mainly near and south of the international border. Scattered thunderstorms are possible over the Red River valley, but the more organized activity is expected mainly south of the border, as has been the case most of the summer. Sunny and warm weather is expected over southern Manitoba for the weekend into early next week, with temperature climbing to the 30C mark once again by Sunday. Great weather for beach lovers, but not for farmers in the northern RRV who are desperately looking for some significant rainfall.

Severe thunderstorms over southwest Manitoba Sunday evening.. showers/storms bypass Winnipeg/northern RRV yet again..

Some stunning images sent to the Weather Network of locally severe thunderstorms that affected southwest Manitoba last evening. The left image shows a shelf cloud passing over Oak Lake, MB which produced strong wind gusts, heavy downpours, and quarter size hail. The right image is a beautiful shot from Virden of mammatus clouds being underlit by a setting sun. Mammatus cloud sometimes accompany tornadic storms, and this cell did indeed produce a brief tornado just east of Virden Saturday evening. The strongest storms generally moved from the Transcanada highway near the SK border down towards the southern RRV last night, once again bypassing Winnipeg and the northern RRV. About 5-15 mm of rain was recorded in storms last night over the southern Red River valley.

These storms come from the same system that pounded southern Saskatchewan Saturday with some exceptionally heavy rain and hail north and east of Regina. Hail up to a foot deep fell on Highway 6 north of Regina Saturday afternoon (image left) which disrupted travel in the area. 50-70 mm of rain flooded areas just east of Regina along with hail and local funnel clouds.

Showers and scattered thunderstorms possible tonight.. cooler weather moving in Monday

A cold front over southern Saskatchewan will push eastward across southern Manitoba tonight. This front will trigger some showers and thunderstorms over western Manitoba this evening.. some possibly severe.. before they move into the Red River valley overnight. Rainfall amounts are not likely to be heavy as the band of showers will be fairly short lived and fast moving, but local amounts of 5-10 mm with up to 20 mm in thunderstorms are possible. The line of showers will move east of the RRV overnight with cooler weather on tap Monday along with clouds, brisk NW winds and a chance of showers. Temperatures are only expected to be in the low 20s over the next couple of days. Drier and warmer weather is expected Wednesday before another chance of showers Thursday. Overall, it looks like temperatures will be averaging near to slightly below normal over southern Manitoba over the next week or so. (Ignore the eternally optimistic warm and sunny Day 6-7 forecast.. it has a warm and dry bias and fails to capture cooling trends properly)

Showers and thunderstorms with heavy rainfall south of the border tonight into Saturday.. flash flood watch in effect for North Dakota

A low pressure area will track across North Dakota tonight into Saturday, bringing widespread thunderstorms with some heavy rainfall likely generally near and south of the international border. Local rainfall amounts of 50-75 mm are possible in these areas overnight into Saturday, and flash flood watches are in effect for much of northern ND. There will be a sharp cutoff to the rain north of the border with little rain expected over the northern Red River valley including Winnipeg. This will be the latest in a series of convective weather systems that have brought thunderstorms and heavier rainfall over the southern RRV into North Dakota over the past few weeks. While the northern RRV struggles with very dry conditions since the end of June, it's been a different story south of the border where rainfall has averaged above normal in July in many areas.

Hot humid day on tap.. strong thunderstorms possible this afternoon/evening?

Hot and more humid conditions will spread over southern MB today ahead of a trough of low pressure through Saskatchewan. Afternoon temperatures will reach the low thirties with dewpoints climbing into the uncomfortable low 20s today. This will send humidex values close to the 40C mark this afternoon across the RRV, and thus a humidex advisory has been issued for the area including Winnipeg. The big question is what will happen later this afternoon into this evening as the frontal trough approaches from the west. This trough will encounter the hot and humid airmass over southern MB to trigger some scattered thunderstorms later today.. some of which may be severe with heavy rain, hail and strong winds possible. There is even a risk of isolated tornadoes with any discrete supercells that develop. At this point, the best chance for convective development will be over the RRV, and SE MB into ND.. but hopefully, some weaker storms fire up in the RRV to give us some much needed rainfall. Will we miss out again, or will we finally see some rain today? Stay tuned..

11:00 am update: A severe thunderstorm watch has been issued for all of southern Manitoba including Winnipeg for the potential for severe thunderstorms this afternoon into this evening.

Winnipeg sets mark for driest July on record..

The hot and dry weather of the past month has resulted in the driest July on record in Winnipeg since records began almost 140 years ago in 1872. Only 10.0 mm of rain was recorded at Winnipeg airport in July 2011, beating the previous driest July of 2006 at 10.5 mm. Normal July rainfall in Winnipeg is around 70 mm so rainfall this month was a meager 14% of normal. Rainfall was a little higher in other parts of the city in July including downtown (17.8 mm at the Forks) and northern sections (20-25 mm over North Kildonan/E St Paul areas) due to locally heavier showers and thunderstorms earlier in the month. But southern and western parts of the city have been the driest with only 8-10 mm recorded in July along the south perimeter.

The dry weather has been the result of a split in weather systems across the RRV this past month, with the jet stream bringing synoptic systems and significant rainfall across the central Prairies, while scattered thunderstorms further south have been tracking mainly south and west of the RRV through Saskatchewan into the Dakotas (see Prairie precip anomaly map above). The result has been a lack of precipitation events especially over the northern RRV, Steinbach and the Whiteshell areas. This is in sharp contrast to the start of the growing season that saw cool and wet conditions through May and early June across the region. The dry weather now has become a serious concern for farmers whose crops have not developed deep enough root systems to tap into more plentiful soil moisture deeper down in the earth.

The southern Red River valley was not quite as dry in July, being grazed by some thunderstorm complexes tracking through North Dakota. Areas from Morris to Emerson saw around 50 mm in July, while heavier amounts were recorded south of the border including Grand Forks at 67 mm, and Fargo at 133 mm.

Some July rainfall totals included..

Winnipeg airport..... 10.0 mm
Winnipeg Forks ...... 17.8 mm
Charleswood ........... 14.0 mm /Rob's Obs/
Brady landfill ........... 9 mm
Oak Bluff ................. 9 mm
St Vital .................. 14 mm
Whyte Ridge ............ 20 mm
N. Kildonan .............. 20 mm
E St Paul .................. 24 mm

Starbuck .................. 8 mm
Steinbach ................. 9 mm
Sanford .................... 10 mm
Portage ................... 14 mm
Pinawa .................... 16 mm
Selkirk ..................... 17 mm
St Pierre ................... 26 mm
Winkler .................... 35 mm
Carman ................... 38 mm
Morden ................... 44 mm
Morris ...................... 47 mm
Emerson ................... 55 mm
Grand Forks ............ 67 mm
Fargo ........................ 133 mm

Gimli ......................... 70 mm
Arborg ..................... 57 mm
Brandon .................. 65 mm
Dauphin .................. 153 mm
The Pas .................. 141 mm