Sunday, April 13, 2014

Record cold possible this week before warming trend for Easter holiday weekend..

Well below normal temperatures will once again flood into southern Manitoba over the next few days in the wake of yesterday's storm system that brought snow, ice pellets and patchy rain or drizzle across the area. Temperatures are expected to remain below freezing through Thursday before milder weather moves in by the end of the week. Temperatures for the first half of the week will be more typical for early March than mid April, with highs around -5C and lows near -15C, well below normal for this time of year (normal highs are now +10C, normal lows -2C)  In fact, some record low maximum and minimum temperatures will be challenged this week in Winnipeg, especially Tuesday and Wednesday.

Record temperatures for Winnipeg this week.

DATE.........    REC LOW MIN ........... REC LOW MAX ..... Forecast low/high this week

Mon Apr 14 ....  -16.7C  (1893) .......   -7.8C (1880)  ............  -14/-6
Tue Apr 15 .....  -16.7C  (1893) ........  -6.7C  (1875) ............   -17/-6
Wed Apr 16 ....   -16.7C  (1875)  ......  -4.4C  (1910) ............  -13/-5
Thu Apr 17 .....   -13.3C  (1953) ........  -3.3C (1953)  ............  -12/-2

Normals for the period: High +10C, Low -2C.
  
Note that Winnipeg has never recorded a temperature colder than -15C after April 16th so temperatures this week represent some of the coldest weather on record for so late in the year here. The good news is that there are signs of a significant warmup by the Easter holiday weekend, with temperatures climbing to double digit values again. We can only hope the latest cold spell this week is winter's last hurrah after what has been a much too long stay this year. Over the past 11 weeks, Winnipeg has seen only 10 days above normal. The graph below shows daily temperature departures for Winnipeg over the past 90 days, which clearly shows an overly persistent pattern of well below normal temperatures since late January (in fact, since the beginning of December)  We're well overdue for a pattern change..

Daily temperature departures for Winnipeg over
the past 90 days. Mother Nature needs a major reboot

27 comments:

  1. I won't shed any tears if we don't end up breaking any records, in this latest cold snap.

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  2. Hi Rob, could you explain the graph and what "temperature departure" measures?

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    1. Certainly. That graph shows how much each day in Winnipeg has been above or below normal over the past 90 days (i.e. daily departure from normal) A red bar denotes an above normal day, and the blue bars are below normal. As you can see, there's been a woeful lack of above normal days over the past 3 months, and even those few days above normal have not been as extreme as the below normal spells, which sometimes have daily temperature departures of 15-20C below normal.

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    2. Rob Is that a trend we call AA Arctic or Polar Amplification. This trend has apparently shown up on some interesting graphs at particularly

      http://skepticalscience.com/What-causes-Arctic-amplification.html

      If it is, the warmer summers along the fiftyith latitude will be welcome.
      You can reach the URL on my name

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    3. Nothing less than a warm summer, fall, winter and spring will make up for the weather we've had here over the past year..

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  3. Hi Rob,

    Had quite a few flurries in the Southeastern Manitoba region today that were not in the forecast at all earlier in the day--a few times the visibility was down to about 1 mile.

    With a big high that was moving in and originally appearing to clear things out, what was the setup that caused them?

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    1. Saw the clouds and precip from hwy 75 looking southeast at noon on way to Emerson. Looked like virga. And no not in a distracted driver sort of way.
      Don

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    2. Anonymous, those flurries were from a narrow band of convection that set up from Winnipeg into SE MB in the NW flow. Showed up quite nicely on visible satellite imagery. The band of flurries appeared to form NW of Winnipeg and became enhanced over the darker urban area of the city into the snow free areas of SE MB. Very cold air aloft with warmer surface temps led to these bands of convection.. similar to summer time showers.

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  4. Rob, awhile back you made note of how this April is not as bad as last year....with us hitting 10C well before last season. Still this April is nothing to write home about so far.

    The snow is still going to stick around for almost as long, and this latest cold snap is brutal for this time of the year.

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    1. Yeah, we've had tastes of mild weather earlier than last year, but overall, both these Aprils have been horrible. I remember taking my kids to the playground by this time of year with beautiful warm sunshine and not a hint of snow on the ground. I can only hope these two Aprils have been out-of-norm anomalies and we can get back to more normal springs in the years ahead..

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  5. Rob, have a quick question for you, I know it's still a few days out, heading out on the highways for the Easter Weekend (Dauphin Area) & notice that they are now showing some mixed precip in the forecasts for Sat. It is with the warmer air pushing in for the weekend & does it look to be fairly light? Thanks

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    1. Anonymous.. Yes, unfortunately it looks like models have delayed the weekend warmup with a system tracking across southern Manitoba Saturday bringing the potential for another snowfall (because we just haven't had enough this winter, or spring). Models are still wavering on intensity and amounts, with the Canadian GDPS model being the most aggressive right now showing possible 10 cm across srn MB. Other models have less precip, with more a of a mixed wet snow/rain event. Hopefully, that's the case. Whatever the case, it's a system to keep an eye on..

      The good news is that Saturday's system won't have a lot of cold air behind it like last weekend's storm, so we should quickly warm up next week with a rapid snow melt. Mother Nature has a serious debt of good weather to pay for southern MB.

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  6. No record low for YWG this morning. "Only" got down to -13.2C at the airport last night as we had a weak E-SE flow off the city that kept the airport slightly warmer than surrounding areas. My station got down to -15.8C, while it was -20C or lower north and east of the city. Had there been a light NW flow, I'm sure the airport would have set a record overnight.

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  7. Rob, do you think Sunday's forecast of 12C and Monday's forecast of 15C is too optimistic?

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  8. Rob, what is the month May typically like following a cold winter and cold April?

    Thanks, Anon

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    1. Anon..

      I crunched the numbers for Mays following top 20 cold Marches and Aprils, and bascially got the same results. Of the top 20 coldest Marches or Aprils, about 55% were followed by a cooler than normal May (over 0.5C below normal), 30-35% were above normal (over +0.5C above normal), and 10-15% were near normal (within +/- 0.5C of normal)

      The average May temperature following those top 20 cold springs was around 10.5C. Normal May temperature is 11.6C based on 1981-2010 normals. So based on past history, you would expect May to finish at least 1C cooler than normal, not as abnormally cold as March and April were (although admittedly, some were quite cool, including May 1979 at +7.3C). The stats also show a greater chance of May finishing above normal compared to either March or April which were almost slam dunks to be below normal based on historical trends. So the bottom line is that May still has a greater likelihood of finishing below normal, but there is some optimism for a change to above normal conditions at some point. Let's go with that.. :)

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  9. Thanks for the info, Rob. Let's hope a change is near. I think we deserve it and more.

    Your blog is awesome. Keep up the good work, Rob!!!

    Thanks, Anon

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    1. Thanks for the comments. I have this crazy fantasy that Mother Nature totally relents in May, and we have the sunniest, hottest, driest May on record with a record number of 30C days. Won't happen.. but a guy can dream..

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  10. Rob never mind 30C at this point i'll take a nice stretch of seasonal temps with sunshine for now with the way things have gone the last 6 months or so. I am keeping the fingers crossed that the current long range holds for next week & the following.

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  11. A low of -15C forecast for Winnipeg for tomorrow morning. If we hit that, not only will it be a record low for April 17th, it would also mark the latest date on record that the city has hit -15C or lower. Current mark is April 16th at -16.7C (1875). Quite the dubious honour considering our records go back to 1872.. and include the little ice age period of the late 1800s.

    After that, things are looking up. Saturday's system looking more and more like a rain event for the city, although it may start off as some wet snow in the overnight period early Saturday. Accumulating snow more likely with this system to our north and west (Interlake through western Parklands) where it will be colder, as well as effects of higher elevation.

    And then, looks like a prolonged period of above freezing temperatures, both day and night, that will finally rid us of this remaining snowpack and perhaps transition us towards a more persistent springlike pattern.

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    1. General snowfall amounts of 15-25 cm over higher hills around Swan River with about 10 cm in the Riding Mtn park through central and northern Interlake areas.

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  12. Rob, what are your thoughts on the exact timing of precip moving in for this system? Forecasts show Friday evening/Overnite for Western MB & overnite into early Sat Morning for the city.

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    1. Looks like precip will be moving into SW MB Friday evening spreading into Winnipeg/RRV after midnight Friday night. Will likely come in as rain for the RRV possibly mixed with wet snow/ice pellets overnight before tapering off by midday Saturday. Accumulating snow possible further north of us through Interlake into western Parklands.. (Dauphin, Swan River, Arborg, etc)

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  13. It looks like a very potent system may give us some significant rain on Wednesday next week. Definately a system to keep an eye on over the next few days.

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    1. Yes, looks like a prolonged wet period possible Wednesday through Friday. Then turning colder again on the backside by late week.. No big sustained warmup evident just yet..

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  14. Rob, is your site officially snow free now??

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    1. Yes it is. I was calling a trace of snow on the ground by the 19th, and zero as of the 21st. So we lost our snow cover about a week earlier than last year (Apr 27th at my location)

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