Cooler Saturday.. then a sunny and warmer week ahead. 2012 on pace to be one of Winnipeg's warmest years on record..

A northerly flow of somewhat cooler air is expected over southern Manitoba Saturday along with some clouds and the chance of a brief morning shower. Temperatures which rebounded nicely Friday into the mid 20s, will drop back into the low 20s Saturday and into the single digits again Saturday night.  Sunday should see sunny skies giving way to fair weather clouds by midday, along with highs in the low to mid 20s. After that, the upcoming week looks promising with plenty of sunshine, and temperatures warming back into the upper 20s to possibly even 30C again by midweek.. a nice stretch of weather for those not quite ready to give up on summer just yet. Unsettled weather is possible by the end of the week.

The warmer weather will help prevent, or at least delay, August from becoming our first month in over a year that has averaged below normal.  The last month that averaged below normal in Winnipeg was May 2011 (June 2011 was almost exactly normal).  Since then, Winnipeg has gone 13 straight months above normal resulting in the warmest 12 month period on record in the city since records began in 1872 (12 month mean of +6.0C between Aug 2011-Jul 2012)  Over that time we have set some impressive milestones including..

July 2011 ... driest July on record (10.0 mm)
Aug 2011 ... hottest day since 1995 (37.2C on Aug 23rd)
Oct 2011 ...  hottest October day on record (31.1C on Oct 5th)
Dec 2011 ... rare brown Christmas over southern RRV
Jan 2012 ... 3rd warmest January on record
Feb 2012 ... 4th warmest winter on record
Mar 2012 ... Warmest March on record
Jul 2012 ... 5th hottest July on record

Aug 2011 - Jul 2012   Warmest 12 month period on record (+6.0C) 

Winnipeg annual temperature anomalies 1872-2012

Not surprisingly, 2012 is also on pace to be one of Winnipeg's warmest years on record.  As of the end of July 2012, the year to date average in Winnipeg was +4.0C, tied with 1987 as the warmest annual average through the end of July.  1987 is Winnipeg's warmest calendar year on record at 5.4C. The normal annual average over the 20th century in Winnipeg has been +2.5C.  This graph, courtesy of  A Weather Moment, nicely displays the annual averages for Winnipeg since 1872 in terms of temperature anomalies from normal. The chart clearly shows how 2012 (dark red) is on pace to be one of the city's warmest years on record (the top 5 years being 1987, 1931, 1878, 1998 and most recently 2006)  barring any shifts to significantly colder weather between now and December. However, with Arctic sea ice approaching a record minimum, and an El Nino likely in place for this winter, the odds of significantly colder weather in the next few months appear to be slim at this point.            

Cooler weather this week..

Cooler than normal weather is expected this week over Southern Manitoba as an upper trough intensifies over the eastern Prairies by midweek ushering in a northwest flow of cooler air.  Generally fair and pleasant weather is expected Monday into Tuesday with highs in the 22-24C range. By Tuesday night into Wednesday, a low pressure system is expected to cross southern Manitoba bringing showers and scattered thunderstorms, possibly with some locally heavy rain, followed by a push of cooler air through the end of the week. High temperatures Wednesday through Friday are only expected to be in the upper teens to near 20C under partly cloudy conditions. Warmer weather is expected on the weekend with a return to normal temperatures in the mid 20s.  Normal highs for this time of year are about 25C over southern Manitoba.  

July 2012 hottest month in US history.. extends warmest 12 month period on record

July 2012 has finished as the hottest month in the contiguous US since national records started in 1895, according to recent figures from the National Climatic Data Center. The national monthly average of 77.6F in July 2012 was 0.2F warmer than the previous hottest month of July 1936, set during the great Dust Bowl era.  The month was dominated by hot and dry conditions over most of the US, with the heat mainly centered over the Great Plains through the midwest and Ohio Valley into the mid Atlantic seaboard.  Seven states recorded their 2nd warmest July on record on a statewide average.

The record hot month extended the persistent warmth that began last summer, with the last 12 months now standing as the warmest 12 month period in the US since 1895. The average US national temperature over the last 12 months has been 56.1F (13C), or about 3.3F above normal. Previous to this year, the warmest 12 month period was Nov 1999 to Oct 2000 which averaged 2.7F above normal at 55.5F. The record warmth has also been occurring north of the border as well. Winnipeg has recorded 13 consecutive months above normal dating back to July 2011, and the last 12 months (August 2011-July 2012) have been the warmest 12 month period on record since records began in Winnipeg in 1872. Prior to this year, the warmest 12 month period in the city was from Nov 1877 to Oct 1878, thanks to the record warm El Nino winter of 1877-1878 (still the warmest winter on record in Winnipeg)  

Graph of national US temperature
anomalies since 1895.   Note how much
warmer 2012 has been to date, warmer
than any other similar period since 1895.

In addition, the year to date average of 56.4F so far in 2012 is the warmest Jan-July period ever recorded in the US, easily beating the previous warmest Jan-July period of 1998 (at 54.5F) The graph left shows how dramatically warmer this year has been to date, especially with the warm winter and spring that has made this year warmer than any other corresponding period in US history (since 1895 anyways)  In Winnipeg, our year to date average through the end of July 2012 is 4.0C, tying 1987 for the warmest year through July. (1987 stands as Winnipeg's warmest calendar year with an average of 5.4C.)  For more details on the exceptional warmth of July 2012 and the past year, see blog entries from Dr Jeff Masters and climate historian Chris Burt.              

Pleasant week ahead..

Generally dry and warm weather is expected through the upcoming week with little in the way of weather systems affecting Winnipeg and the Red River valley. Models are indicating a weak system tracking from southern Saskatchewan into North Dakota Tuesday night into Wednesday that may bring some scattered showers and thunderstorms over southwest MB, but the bulk of precipitation with that system is expected to remain south of the border. Other than that, it looks like mainly sunny and seasonably warm weather this week with temperatures in the mid to upper 20s, along with comfortable humidity levels and generally light winds.  Enjoy!

Wet start to the holiday weekend.. showers and thunderstorms developing today with locally heavy rain possible

A pair of low pressure systems, one over southwest MB this morning and another in the Dakotas, will slowly push eastward today, triggering showers and a few thunderstorms this afternoon into this evening over southern MB.  Depending on how much sunshine we get today, some of these thunderstorms may be strong to possibly severe, with large hail and heavy rain possible.  This system will slowly push into NW Ontario overnight into Saturday, with cooler and showery weather over southern Manitoba behind the system. In all, about 15-25 mm of rain is possible today into Saturday over southern MB including Winnipeg and the RRV, with locally heavier amounts of 25-50 mm possible with stronger or more persistent thunderstorms. Sunnier and warmer weather is expected for the latter half of the holiday weekend.

RAINFALL SUMMARY - Rainfall amounts Aug 3-4, 2012
 

Location            amount

Gimli               42.3 mm
Fisher Branch       37.2 mm
Steinbach           35.5 mm
Birtle              32.9 mm
Swan valley         32.8 mm
Portage la Prairie  32.0 mm
Starbuck            30.6 mm
Brandon             30.2 mm

Winnipeg locations

East st. Paul       50.0 mm
St. Vital           46.0 mm
The forks           35.4 mm
Whyte ridge         32.8 mm
Charleswood         30.5 mm
Airport             26.5 mm