Thursday, September 01, 2016

Summery start to September to give way to cooler wetter conditions over Labour Day weekend

September is off to a beautiful start over southern Manitoba with sunshine, balmy breezes and summerlike temperatures in the upper 20s (and even low 30s over western MB)  Friday will see another warm summerlike day, although winds will be quite gusty, especially in the Red River valley (including Winnipeg) where southerly winds gusting to 60 -70 km/h are expected by afternoon. Not the best bike riding weather if you're heading south!  Friday night, a weak front will push through southern Manitoba with a small chance of thunderstorms, leading to partly sunny skies Saturday and temperatures in the mid 20s. Clouds are expected to increase Saturday afternoon with a few showers likely by evening as a cold front pushes through. Sunday looks cooler and unsettled at this point as a low pressure system over the Dakotas rides up along the cold front and spreads an area of steady rain over much of southern Manitoba by the afternoon into the evening. This could be quite a soaking rainfall for many areas, with rainfall amounts of 20-40 mm possible Sunday afternoon into Monday morning. Rainfall should ease off Monday morning leaving cloudy and cool conditions Labour day Monday.  The rest of the week looks generally cooler than normal with temperatures in the upper teens.. a taste of fall as the kids head back to school! 

12 comments:

  1. Enjoy today.. looks like our last day over 25C for awhile, likely the rest of the week into next week as well. Hopefully we still have some 25C weather in the second half of September/early October to enjoy. But summer is pretty much over after today.. :(

    As for today, cold front pushes across RRV later today into this evening, which will likely trigger a band of thunderstorms, some possibly severe. The same front produced some strong thunderstorms over SE SK yesterday that gave some toonie size hail just east of Regina. Could see some heavy rainfall as well especially where storms train along the front.

    Then we get ready for super soaker Sunday as a low pressure wave moves into the Dakotas spreading a large area of rain across the RRV and SE MB. Latest guidance shows a good 25-50 mm possible by Monday morning, with local amounts of 60-70 mm possible. Cool fall like weather the rest of the week with another rain system possible by Thursday.

    So yeah, enjoy today.. ;)

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  2. Cells starting to pop around the Carman area as of 530 pm.. with general motion to the northeast towards Winnipeg. Could be seeing some showers or thunderstorms passing through here over the next few hours. Potential is there for heavy rainfall with training cells..

    Models still all over the place with how much rain Winnipeg will see tomorrow into Sunday night. RDPS gives us 13 mm while NAM gives us 58 mm. For now, best bet is to go with ensemble guidance which shows about 25 mm for Winnipeg (both SREF and GEPS) Sunday afternoon into Monday morning, but realizing total could be half or double that amount given how storm tracks, and how convection sets up. More confidence is seeing higher numbers south and east of Winnipeg.

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    1. Turns out RDPS was pretty good for Winnipeg with 14 mm at the airport Sunday, and general amounts of 10-20 mm across the city. Amounts ramped up quickly south and east of the city with 57 mm in Steinbach, 64 mm in Letellier, and 75 mm in the Gretna-Altona area.

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  3. Heavy rain band setting up a bit further southeast tonite, as front (and fall-like air mass behind it) progress very slowly.

    Most of the convection so far firing along the cool side of the boundary. Lines up well with convergence along the back edge of a strong LLJ coming up from the Plains, and band of 850 hPa frontogenesis. Looks as though far southern RRV and SE Manitoba may get brushed by more activity.

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  4. Rob The weather or at least the precipitation across the RRV and Western Canada has resembled nothing so much as 2010. And in fact the the Artic ice melt is similar to the 2010 2011 record low levels. Now Scott Sutherland is calling for similar to 2011 weather patterns due to to the slowing down of the Lanina transition and the North pacific Blob of Warm water.
    Do you foresee us having another 2010-2011 winter and spring? That would probably mean we may see very little of the River Walk in the next 11 months.

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    1. Don:

      Interesting correlations you make with 2010. As you mention, we are making a transition to a neutral ENSO phase this winter, which means our climate pattern this winter will be influenced by other climatic oscillations, which are tough to predict this far out. I hadn't heard about the warm blob in the north Pacific but that would suck for us, as it would tend to maintain upper ridges along the west coast, and induce downstream troughing over us (colder than normal) Looking at 2010-11 winter, winter arrived around mid November with quite a lot of snow in the second half of the month, followed by a generally near normal winter (temps and snowfall) Following spring was cool. Riverwalk was underwater all summer (2011) mainly due to record high levels on the Assiniboine. Hopefully we don't see a repeat. I really wish we could get into a drier long term pattern but it doesn't seem to be working out that way over the past decade or so.

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  5. Thanks for your info . I surmise by your answer, the AO and NAO will be drivers ths winter . I wish we could predict them much further out.

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    1. Yes.. the PNA will also be an influence if that warm pool in the Pacific persists. Trying to predict any of these oscillations is difficult at the best of times, never mind how they may interact with each other this winter. Bottom line.. a lot less predictablility on the upcoming winter than last year. About the only thing I can say with reasonable confidence is that it likely won't be as mild as last year.. but whether that means an average or below average winter, too early to say.

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  6. What happened to all the rain we were suppose to get? Wasn't EC forecasting like 20 mm and did we even get 1 mm?

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    1. Yeah, that rain band really wimped out over Winnipeg and to our east. Bulk of rain fell south and southwest of Winnipeg with 5-10 mm just south of the city, 10-20 mm in the Morden-Emerson area and up to 60 mm in the Boissevain-Killarney area.

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  7. Really hoping we get in on some of this action this weekend. Tired of all the rain fizzeling out by the time it gets either north of highway 1 or east of highway 75. Once again southern and SW Manitoba getting blessed with some rain meanwhile I've only had 60mm at my place since August 1st.

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  8. We have a little more than you and Rob . Pays to be on the hwy 75 and south of portage ave.
    When I lived in Charleswood we noticed the rain was always greatest near the Assinniboine . ASk those who were around in 04, 05 about the torrential rains. We thought of renaming Breezy Bend golf Course to Lake Breezy. Ask the people in and around Elie about the almost 9 inches of rain in one summer storm in the 80s. Ask the residents of St francis X Just north of hwy 1 on the assinniboine about the tornado they had around 1977 that lifted and an hour or so later flattenned a 10 mile stretch of forest nearly half a mile wide south of St malo. Seems counter intuitive.

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