Saturday, 1 September 2012

August; the 14th Consecutive Warmer Than Normal Month

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     August will be remembered as a relatively quiet month for thunderstorms, as well as for its hot afternoons and cool comfortable nights. Daytime highs were well above normal, while overnight lows were actually below normal. Precipitation was well below normal at the airport with only *44.0* mm of rainfall making it the *48th driest August*. However, other parts of the city got much higher amounts, mainly due to some locally heavy thunderstorms August 3 which dumped copious amounts of rain to southern and central parts of the city. 61.6 mm of rainfall fell at my place in south St Vital for the month as a result.

      The month started angrily with two significant thunderstorm events on August 1 and August 3. These would end up being the only major thunderstorms of the month however.

August 1: To some, this was a repeat performance of July 29.
     Severe thunderstorms formed over western Manitoba and the Interlake early afternoon and organised themselves throughout the day as they moved southeastwards. They became linear by the time they reached the RRV in the early evening. Locally, they dumped copious amounts of hail and rainfall, and produced incredible winds. The Grand Beach-Grand Marais area was hardest hit. Golf ball sized hail pounded the region for several minutes, and winds gusted over 140 km/h!! Many trees were uprooted and power was knocked out to some. In addition, flooding occurred near Riverton where 90 mm of rain fell. Winnipeg was not as hard hit as winds gusted over 70 km/h, and rain was short-lived. Some branches weakened by the July 29 storm came down with the winds. Here is a summary of the event by EC.

August 3-4: Two rounds of storms affected Winnipeg late afternoon and evening Aug 3. The second round was the worst. Large and very dark clouds moved over the city dumping copious amounts of rainfall to southern and central areas. Winds also became gusty at times locally, blowing the torrential downpours horizontally. Strangely, only a few parts of the city reported these gusty winds. Over 30 mm of rain fell in St Vital while just 4 mm fell at the airport.
     More torrential rains fell the next morning on August 4, dumping an aditional 10 to 15 mm.

August 24: A moderately-interesting thunderstorm event for parts of southern Manitoba. Lightning was frequent around Winnipeg late in the evening. The storm produced brief torrential downpours in south and east parts of the city with 2-4 mm reported there.

     After a warm and stormy start, things were much cooler mid-month as daytime highs were in the low to mid twenties and overnight lows in the mid to high single digits. To many, it was probably a welcomed break from the heat. In fact, up to the 22nd temperatures were actually averaging below normal for the month. We had even seen our first lake-effect rainfall event of the season on Aug 15-16.

     Things returned to mid-summer heat late month as we experienced 6 days of 30°C+ weather. August 29 was a highlight as very hot temperatures moved in from south of the border. Temperatures were in the mid to high thirties throughout southern Manitoba, resulting in many records being broken. Dauphin was the hot spot at 37.9°C. Winnipeg reached 35.4°C; not breaking a record, but tying for hottest day of the year. To make things worse, it was humid on top of the heat for the RRV as humidex values were in the low forties. As of Sept 1, we have now had 21 days of 30°C+ heat in Winnipeg this year.

     The higher rainfall amounts this month in southern Manitoba along with cooler weather mid-month aided farmers. It is predicted to be a bumper-crop year, at the same time that prices are quite high due to drought in the US and eastern Canada. It could be a very good year for Manitoba farmers.

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