|Morden resident cuts his lawn on Dec 4 2015|
as temperatures soar to 14.2C (from CBC)
|Max temperatures across southern MB - Dec 4 2015|
Warmest readings in snowfree and downslope areas
Relief map of Pembina valley (left) shows Pembina escarpment running just west of Morden, dividing higher terrain to the west and the lower flat plains of the Red River valley to the east. South to southwest downslope winds blowing off the higher terrain can result in warmer temperatures immediately to the east of the escarpment (like a mini-chinook) Image on the right is a visible satellite image taken Dec 4th at 2:45 pm showing snowcover over southern MB. There was a distinct line from Portage La Prairie through Carman to Emerson, separating snow-covered areas to the east and bare ground to the south and west. Temperatures were some 5-10C cooler over the snow-covered areas, with highs of +2-4C, including a windy +2.3C in Winnipeg (surface plots on image are in degrees F. Morden is shown as 57F (14C) at this time) The high resolution image below shows the snowcover in greater detail. Note the distinct snow line running through Carman to northeast of Emerson. Note also deeper snowpack (brighter white area) still evident west and northwest of Winnipeg.
|High resolution MODIS satellite image showing snowcover|
over Red River valley on Dec 4 2015
|Sfc map - 6 am Dec 4 2015|
|925 mb - 6 am Dec 4 2015|
Of note is how warm the air was just above the surface that day. Air temperatures up to +14C were observed over the Morden area at 925 mb, or about 700 metres above ground. This is exceptionally warm air for December, and was helped northward by a strong south-southwest wind of 50+ knots (90+ km/h) at this 925 mb level. These warm values would eventually cool off to +8C by mid afternoon, but it showed the potential for temperatures over 10C in snowfree areas that day. Morden got the greatest benefit of this warm air aloft, helped by sunshine, snowfree ground, and downslope winds. It should be noted that on this day, the downslope winds did not reach much further east of Morden, and in fact, nearby Winkler, just east of Morden, only got up to 9.5C that day as their winds were more southeast through the day tapping cooler air off the snowcovered Red River valley.
A look at Morden's hourly temperature chart for Dec 4th shows that temperatures rose from +5C at 9 am to +10C by 11am, and 12.7C by noon. It would climb to a maximum of 14.2C shortly after 2 pm, before downslope winds from a 200 degree direction shifted to the southeast (160 degrees) tapping cooler air over the snow-cooled Red River valley. Temperatures dropped quickly to 8C by 3 pm and +5C by 4 pm.
Road trip to Morden
|Snowcover becomes meager|
east of Carman
|Snowcover disappears south|
|Green fields north of Morden|
Dec 4 2015
As I turned south on Hwy 3 heading to Morden, the snowpack disappeared completely just south of Carman and from there on, there wasn't a hint of snow anywhere, with the landscape resembling something from October or April. The temperature rose to 10C by the Hwy 23 intersection and 11C by the turnoff to Morden.
|Hwy 3 to Morden - Dec 4 2015|
|Downtown Morden - Dec 4 2015|
|Car thermometer registers|
15C in Morden - Dec 4 2015
|Dec 4 2015 in Morden - or is it April?|