Monday, July 23, 2007

Heat Wave - Day 2

After a sizzling Sunday, it's a meltdown Monday as the hot and humid airmass persists over southern MB. As of 11 am, humidex values had already surpassed the 40 degree mark over many localities thanks to some very high dewpoints today.. including an unbelievable 28C dewpoint reading at Carman. (I suspect this value is erroneously high, as the dewpoint at Carman always seems to be a couple of degrees too moist compared to neighbouring sites.) Nonetheless, dewpoints across southern MB are in the 22-25c range today which will make today's 35C temperatures feel oppressive. Take it easy out there.

By the way, I replaced the barometric graph plot on my main page with a dewpoint/heat index plot to better gauge how sticky it is over the next few days.


  1. I was suspicious of the Carman DP reading as well. Amusingly, the National Weather Service forecast for the Hallock/Lancaster area is for a high of 89F today. Hmmmm let's was 90 at noon. I went for mid 90s, and I'm pretty sure that's what we will get. Maybe a bit hotter tomorrow. Looking forward to the break later in the week.

  2. Got to 33.6C (92F) at Winnipeg airport today.. with a peak humidex of 43. Eight record highs were set across Manitoba today, mainly in the north with Island Lake hitting 34.6C, the provincial hot spot.

    It was even hotter out west, with temperatures hitting up to 40C in Val Marie, SK. Numerous record highs set out west, thanks to a drier airmass that allowed full heating of the surface. Medicine Hat, AB has recorded 13 straight days above 30C, with at least 7 of those above 35C. Fish are dying in the lakes and rivers out there because of the heat.

    Here in southern MB, it was the humidex that was the main story today with afternoon readings of 42-45C. Carman hit a peak humidex of 49C, but that was based on a suspiciously high dewpoint of 28C at the time.

  3. Got to 34C (93F) at the Hallock airport today. The highest dew point was 26C (79F). That combination (resulting in a peak humidex reading of 47) and little wind made for a dreadfully uncomfortable day, making me glad I do not work outdoors. More of the same tomorrow...slightly warmer but with a little bit of a breeze. Slight chance of a thunderstorm overnight...better chance Wed. night into early Thursday. Models now putting lows at 13C for Friday morning. What a nice change.

  4. A couple of very warm nights coming up.. especially tomorrow (Tuesday) night. After another 33-35C day on Tuesday, we'll have a southerly breeze Tuesday night with 850 mb temperatures climbing to 27C during the night. Current forecast calls for a low of 25C (77F) which seems reasonable.. there's even a possibility we'll stay above 80F all night if the winds can stay up. It's going to be a rough couple of nights sleeping for those without A/C.

  5. Wow. I think the hottest night in Winnipeg history was on 7/12/36 when the low was 28.3C after the all-time high of 42.2 was reached the day before. One of the models is showing a low of 25.3 down here tomorrow night...may have to raise my forecast from 24 to 25 if the models come into more agreement on the next run.

  6. The high dewpoints in Carman are interesting...note that Pilot Mound also reached a dewpoint of 27 C on Monday. The area at the base of the Pembina Escarpment is a warm micro climate and has lighter alluvial soils than in the red river valley. Farmers can get out earlier in the season and consequently a fair amount of corn and potatoes are grown.

    Corn likely transpires a very large amount of water into the air..I would imagine a lot more than canola or wheat...but I am just guessing...Dewpoints in corn growing regions of southern Minnesota can also reach around 27 C.

    On a different note... southern Manitoba will be on the nose of low level jet tonite...right now it is feeding some storms south of Brandon...but the storms have to overcome very warm air aloft. If a t-storm complex does get going...there will be a lot of debris cloud to contend with tomorrow. The outflow from any convection could shove the front further east than anticipated.


  7. Dan,

    you could be right on that one...maybe the outflow from what became a large mass of storms that went through NE North Dakota and NW Minnesota (the northern extent of which passed just to our south in Lancaster) did push that front a little further east. Our dew points have been a bit lower so far today, and that will help temperatures climb. Still shooting for 36 here in the NW corner of MN.