Thursday, September 14, 2017

Welcome rain finally on the way for southern MB..

It's been awhile, but it finally looks like southern MB will have its first decent rainfall in weeks beginning tomorrow and continuing into early Saturday.  Models are indicating a general 20-35 mm of rain for most areas in southern MB Friday into Saturday morning, with locally heavier amounts of 50 mm thanks to embedded thunderstorms firing up over ND later Friday into Friday evening (spreading into southern MB mainly closer to the US border)

As for Winnipeg.. models are all over the place in terms of amounts here, but generally it looks like 25-40 mm of rain is possible from Friday afternoon into Saturday morning, with the bulk of rain falling Friday night when it could be heavy at times. Some models show heavier amounts due to embedded convection moving in Friday evening (GDPS shows over 70 mm for us!) Here are the various model outputs of rainfall for Winnipeg through midday Saturday.. (12Z or 18Z run)

RDPS... 32 mm
GDPS... 72 mm
NAM.... 43 mm
GFS.... 23 mm
ECMWF.. 26 mm
SREF... 18 mm
GEPS... 41 mm 

Multi-model average is 36 mm. Taking out the highest and lowest values gives a mean of 33 mm. Whatever the case, it'll be the most significant rainfall we've had here in weeks! In Winnipeg, only 2 mm of rain has fallen so far this month, coming off its 13 driest August when only 14 mm fell the entire month. Since July 23rd, Winnipeg airport has received only 21 mm of rain, a mere 18% of the normal 119 mm that should have fallen over that time. We are certainly overdue for a good soaking!     

50 comments:

  1. Rob! How much rain did winnipeg airport record?

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  2. Matthew I believe rob and Julian posted a list this morning on twitter that said the airport rec'd 7.9mm very little. Julian jjc in St Vital received 12.7 in south St Vital about half an inch and around the city was between these .

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    1. Yes, rainfall came up short in Winnipeg.. much less than models were predicting. Airport only came in with 8 mm and the Forks had 9 mm. I recorded 10 mm with up to 13 mm over south St Vital. Still, it was the most rain we've had here in weeks. And we may see a bit more later today into tonight.

      Much greater amounts fell over SE MB over the past 24 hrs with up to 30 mm in the Hadashville area and 42 mm in Sprague.

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    2. Well that sucks. I wanted that 30-40mm. This isn't enough to help ease the drought situation. Why did we get so much less than was predicted?

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    3. Heaviest area of rain was mainly over North Dakota into SE MB.. greater instability and moisture down there. Winnipeg was further north of the heaviest rain shield. Models generally overestimated amounts further north, although they did correctly show the heaviest area of rain occurring south of Winnipeg.

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    4. Thanks rob.

      Do you know what the maximum temperature was today? I don't think it even reached 10C did it?

      Any ideas on when we could expect our first frost?

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    5. No significant frost threat over us for the upcoming week with temperatures near or above normal much of the week.

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    6. It's looking like our first frost may not come until October, which interestingly would be the third time in the last 4 years that happened. I keep forgetting normals now are like 17C and lows are 5C. This September will likely finish in the top 30 warmest, which is no surprise.

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  3. I noticed there is a decent severe thunderstorm setup Tuesday with an approaching strong cold front according to the U.S. storm prediction center, though they have backed off on the northern extent of the slight risk a bit today (still into southeast North Dakota though). Manitoba would still appear to have a marginal risk.

    Is an appreciable severe storm event plausible in the second half of September with this setup and amount of daytime heating/moisture (or lack thereof), if not in Manitoba, then in the Dakotas?

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    1. I would be surprised to see severe thunderstorms this late in the season but I guess it's possible. It's been a complete rip off year for storms though.

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  4. This upcoming weekend looks downright interesting. If that upper level pattern holds, we could be in for some wild weather according to the GDPS!

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    1. Wild weather in what way? Rain storm?

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    2. Jet stream aligned straight from the south pulling in all kinds of moisture from the southern US plains which would mean some pretty unsettled weather.

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    3. Like thunderstorms or more rain? What about temperatures?

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  5. Well that was a major letdown. Good setup to get one last kick at some decent tstorms and Winnipeg barely gets any rain. Storms to the west gave locally torrential rainfall with 70-100 mm in the Baldur and Cartwright areas and over 50 mm in one hour as close as Elm Creek. Line fizzled by the time it got to Winnipeg by late evening, with only 2-3 mm of rain here. Not even a flash of lightning. We had a severe thunderstorm watch out for over 12 hours and couldn't even get a lightning strike here. Sad.

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    1. I agree rob it was a real rip off. What a horrible year for thunderstorms. I'm pretty sure that will be the last severe set up of the year. It's rare to get severe storms later than now.

      Our attention now turns to a cool down coming up this weekend. It looks like highs will be descending towards the lower teens by late month. Is fall arriving for good? I sure hope so. I suspect Thursday could be our last 20C of the year given the forecast.

      Note this September is in place for the 7th warmest overall right now. What are the long range indications for temperatures into October rob?

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    2. According to CPC, first half of October has slightly better than even odds of seeing warmer than normal temps over western Canada and the Prairies. They hint that the western ridge will re-establish itself after being mainly over eastern NA for the latter half of September.

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    3. Hi rob. What exactly does this mean? That ridge that baked the west in incredible summer heat didn't have much effect here, we had a cooler than normal summer. So does this mean it won't effect us this time?

      I continually am hearing talks of a major pattern change in late October that would bring permanent snowcover by Halloween. Is this possible? According to AccuWeather we could be in for a brutal last half of October and a very cold November. What are your thoughts on this?


      La Niña developing this winter would also give us the chance of a much colder winter and spring.

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    4. I don't have a lot of faith in long term predictions.. so all I can say is a change to a consistently colder pattern by Halloween is certainly possible, but right now, there's not enough overwhelming evidence to say that will happen. Latest CPC outlook for October favours generally above normal temperatures for the Prairies and western Canada. History over the past decade suggests our falls are getting milder with later starts to winter.. which would reduce the odds of getting permanent snowcover by Halloween. Not that it couldn't happen.. it's just that the odds are less likely now. Even a La Nina doesn't necessarily mean a cold and snowy winter for us.. it increases the odds, but other climatic patterns can negate the effect of La Nina. A positive phase of the Arctic Oscillation for example could keep Arctic air from pushing south, giving us a very mild winter. This happened during the La Nina winter of 2011-12, one of the mildest winters ever recorded in southern MB (see my blog post about that winter at: http://robsobsblog.blogspot.ca/2014/02/2014-vs-2012-tale-of-2-winters.html)

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    5. That's interesting Rob. Snowcover by Halloween have happened in the past, although not for a long time now. Please not another mild winter, the last 2 have been incredibly warm and I'm ready for a cold classic winter. I would be really surprised if we got another very warm fall and winter for the third straight year..... it just doesn't seem normal. Falls 2015 and 2016 as well as winter 15/16 and 16/17 were all some of the warmest on record.

      I remember 2011/12. That was the year with that freaky march heat wave. I also remember 2013/14, and I would love to have a brutal winter like that one again.

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    7. Rob do you think springs are coming earlier now too? We had a couple of very early springs this decade, 2010/12/15/16 all had snowcover gone by mid March. Is this a trend or just a random occurrence? Then on the other hand we had 2013 and 2014 in which snowcovers didn't disappear until the 3rd and 4th week of April both years. I remember snow still in our backyard at the start of May 2013!

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  6. Continued SW flow aloft will push through a couple more waves and chances for rain. Tonight a front will come through - and with LLJ cranking up - chance for elevated storms to our SE overnite.

    By tomorrow, front will return northwards as stronger wave tracks NE. Warm sector may brush areas as far north as Fargo (with dewpoints >= 20 C and record heat for the Twin Cities). Sharp baroclinic zone will set-up with models like 3km NAM showing bulk of precipitation occurring in the cold sectors of the disturbance. This is associated with the deformation zone of the system, attendant frontogenesis, and impressive elevated instability (MUCAPE of 1500-2000 J/Kg). Best chance for rain and thunder will be later tomorrow afternoon and evening.

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    1. I'm just ready for Old Man Winter already. Enough of this heat. Unfortunately it looks like September is going to finish in the top 30 warmest. After nice cooler summer it unfortunately looks like another long period of above normal temperatures is on the way. It boggles my mind how we can have a third consecutive record warm fall.

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  7. Finally! Now that was a wicked storm we had tonight! Rob how much rain did you get?

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  8. Rob slightly off topic but your links on your Precip page to USA palmer reports have been coming up " cannot reach server" for several months if not over a year now.

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    1. OK thanks Don.. I'll update the links.

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  9. Before everyone has a 🙀you can reach there through here (i meant drought) http://www.cpc.ncep.noaa.gov/products/monitoring_and_data/drought.shtml

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  10. I have a question that is way off topic and i apologize in advance. You can delete if you prefer.
    We all talk about the weather a lot but we dont actively write about what we can do in about it. I would like to see at least links on this site to things like AGW and programs to reduce our footprint. E.g. The Ontario Govt has a program which provides a substantial incentive to puechase All electric vehicles . In effect a $14,000 rebate for cars which now cost as low as $35,000 US for a Tesla. and other vehicles. Such as nissan Leaf.
    Link http://www.mto.gov.on.ca/english/vehicles/electric/electric-vehicle-incentive-program.shtml

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  11. Attention turns to next system moving up.. models show rain arriving near midnite, and print out 15-20 mm for Winnipeg and 25+ mm for southern RRV and SE Manitoba by late tomorrow. Past system tracked a bit further NW than projected so hopefully Winnipeg can get better into the deformation zone precipitation band.

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  12. Rob! Are we looking at our first frost Thursday night into Friday morning?

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    1. It's possible there will be patchy frost tonight, but I don't think it will be widespread or severe. We certainly have ideal conditions for temps to drop tonight with clear skies and light winds as a big ridge of high pressure builds in tonight. But dewpoints aren't terribly dry, and ground is fairly moist still from recent rainfall. As a result, I think we'll see temperatures dropping to around +1C or so by Friday morning with patchy frost or more likely dew. I don't see a killing freeze occurring, in Winnipeg area anyways. Judging by long range outlook with mild and wetter conditions through early October, a killing freeze is still a while away yet.

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    2. Thanks rob. I really hope this fall isn't going to go in the direction of last years. I wonder if the airport will drop below freezing tonight though?

      It actually looks like the warm weather will only be for the first 2 days of October and then tapering to normal conditions that will last through mid month. What are your thoughts on this?

      Any idea on when we will finally switch to a more consistent fall like pattern?

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    3. I expect the weather pattern for the first half of October here will be similar to what we saw over the last half of September.. generally unsettled with above normal precip and near normal temps alternating between spells of above and below normal conditions. To me, that's fall like.. but if you're looking for colder conditions with frost or snow.. I don't see much for us through the second week of October. Better chance of cooler conditions over western MB into Saskatchewan as upper ridge builds over Ontario and cold trough persists over western Canada.

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    4. Airport has dropped to 4.9C as of 11 pm with a light NW wind, while most other sites in Winnipeg are still around +8 to +10C. Shows the cool bias at YWG airport with a light NW wind under clear skies. Airport will likely get down to the 0C mark by morning, but I think most places in the city will stay above freezing tonight. Still some ground frost possible, although heavy dew will likely spare much frost damage.

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    5. Hey Rob. I am hoping it goes below 0C tonight. That light NW wind always gets the airport colder. I actually wouldn't call it a " bias ". I think it's a good thing they take the measurements from the airport because it's the true temperature and not affected by the urban heat island

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    6. I call it a bias because the airport tends to be a bit colder in light NW flows than most surrounding sites. It almost looks like a localized effect at the airport, which doesn't make it very representative of temperatures within Winnipeg in these situations. In these cases, a more representative temperature for the city would be something between the Forks and the airport (like mine for example!)

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    7. Yes that makes sense Rob. Because the forks would be too warm because of the heat effect, but I think your right about how yours would be a good value. What was the low at your place?

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    8. Yeah, that between-hours low seems unrepresentative of even rural sites outside the city. Some of the traditionally colder sites to the east actually stayed above zero. Difficult to say with certainty because most of the Manitoba Ag sites stopped updating early Wednesday morning.. but I would be willing to bet scattered light frost with 1.5 m above zero were the norm in the open country outside the city.

      With a NW flow, cold drainage is likely following the Omand's creek basin. In the past, the recording site was farther south and away from that influence.

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    9. We had some light frost on our lawn this morning in the suburbs so it must have gotten to freezing

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    10. at the ground level, but not at where standard temperature gauges are situated (typically 1.5 m)

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    11. Yes but it must have froze at that level at the airport as the low was -1.2C.

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    12. ..and that value was likely unrepresentative of other open areas around the city

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  13. -0.3C is the lowest in the hourly readings, so winnipeg has officially posted the first frost of the 2017 fall season!

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  14. An official low of -1.2C at Winnipeg airport.. first freeze of the season there. Not quite as chilly elsewhere across the city with lows in the 0 to +5C range. A low of +4.5C downtown at the Forks while it got down to +0.9C at my site here in Charleswood. I noticed some frost on rooftops and cars, but not much on the grass.. which had more dew than frost. Likely helped by recent moisture.

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    1. Chilly morning that's for sure! -1.2C, not bad! We live not far from the airport and there was some grass frost here.

      Is it true that Saturday night could see a low of +15C? I heard it's going to be very warm

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  15. Showers will be pulling out of Winnipeg early this evening then mainly cloudy tonight. Another area of convection forecast to develop over Dakotas/Minnesota tonight pushing showers into RRV/SE MB Monday morning. Showers should pull out of Winnipeg by midday, with some afternoon sun and brisk SW winds developing. That should get bump our temperature up to 17-18C for the afternoon.

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    1. Rob. Is the first half of October now looking above normal?

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  16. September finished with a mean of 14.2 degrees making it the 23rd warmest September on record

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