Saturday, May 23, 2009

Nice weekend.. heavy rain looms Monday for southern RRV/ND/MN

High pressure over southern MB is finally bringing a beautiful weekend over the area with sunny skies.. light winds and seasonable temperatures of 18c today and 21c Sunday. A great weekend to finally get that overdue landscaping started!

Attention then turns to a potentially heavy rainfall event that will be unfolding over North Dakota and northern Minnesota Sunday night into Monday that may affect southeast MB as well. A slow moving low pressure system with plenty of moisture feeding into the system will generate an area of slow moving showers and embedded thunderstorms Sunday night through Monday night over northeast ND, northern MN, possibly spreading into SE Manitoba mainly south and east of Winnipeg. Computer models are indicating that 50 to 75 mm is possible through this period, with the latest Canadian GLB model suggesting the Sprague area could be seeing 100 to 150 mm of rain Monday into Monday night! It is still too early to give precise details on location and amounts of rain with this upcoming system, but the potential exists for heavy rainfall over eastern North Dakota, northern MN, and the southern Red River basin through SE Manitoba Sunday night into Monday night. Stay tuned..

39 comments:

  1. Onset of moisture return is delayed from what models were advertizing a few days ago... we will have to contend with cool high pressure for one more nite.

    LLJ and right entrance of upper jet streak lining up a bit better with QPF on GFS. LLJ cranks up on Sunday evening and nose swings from central N Dakota into NW Minnesota by dawn Monday. It remains fairly stationary during the day Monday and runs parallel with warm front/inverted trough. Theta e ridge also remains relatively anchored, so there is potential for cells to build back and train along stalled front.

    Two questions remain...

    1)where exactly will the front stall? GEM is further north with the low (Idaho vs Wyoming on GFS), and QPF (but still south of Winnipeg)

    2)is QPF overdone? ...limited instability and weaker dynamics etc. On the other hand, Mother Nature always seems to have some tricks up her sleeve.

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  2. So looking at the weather forecasts for Sunday morning it shows Winnipeg getting heavy rain through Monday and into Tuesday. Dis the system shift further north than originally expected? How far North in the Red River is it going? Is this rain the result of two different systems or is it all one system?

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  3. Next Friday and Saturday look good for Severe Thunderstorms. Areas of play are Southern Manitoba, Northern North Dakota into Northern Minnesota. Great Shear Profiles, decent moisture, and nice temps, and a possible warm front (Friday) should set the stage for Severe Wx...Saturday might be a cold front or trough that triggers the inclement wx.

    This bears watching. This is from the 12z GFS, so it'll likely change as the days near...but I thought I'd offer a glimmer of hope to severe weather enthusiasts...maybe Vortex 2 will leave their domain to chase the Northern stuff!


    Oh...and something moves through for Wednesday too...a cold front looks to be the weapon of choice...we'll see what happens with this in terms of weather of the severe type! Thermodynamics aren't great...but we don't need much for funnels to spin up...look at this past Friday...lake breezes are magical!

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  4. Daryl..

    Depends on which model you look at.. American models continue to depict heaviest rain axis along and south of the US border, while Canadian models are pushing the heaviest axis further north over southern MB along the TransCanada corridor. We'll have to see how this system evolves today into tonight to get a better handle on where the upper low exactly is developing, and how the low level jets are setting up. Suffice to say Winnipeg and the RRV are within the threat area of getting heavy rain Monday..

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  5. Special weather statement issued for all the heavy rain expected in Southern Manitoba!

    Is there any chance of any thunderstorms with this system giving locally higher amounts???

    Remember with the last heavy rain event.... You can easily have a 10-20 mm difference of rainfall WITHIN the City of Winnipeg!
    39 mm at the airport
    52 mm at the forks!

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  6. I think there will be embedded thunderstorms which are driving these large rainfall numbers. Not everyone will see 40-70 mm of rain, but there will be narrow swath with such values.. and yes, there could be locally higher amounts. Still a tough call as to where this heavy rainfall axis will set up.. a shift of 60-100 miles could mean the difference between getting 60 mm or just a sprinkling.

    By the way, beautiful day out there today.. first time I can say it feels like summer. Sunny, warm, light winds.. this is what spring should be like!

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  8. I sure hope we don't get 40 to 70mm of rain. That will continue to set-back an already miserable Spring. If I had to grudgingly make a rainfall prediction, it would be for 30 to 50mm. In General amounts might not vary much from the last heavy rainfall event, except that the rain will remain farther south and avoid areas like Gimli.

    P.S. The average high temperature so far this May is 12.9C in Steinbach...OUCH. The average high is 19.1C!!

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  9. Looking at the radar this morning ....it looks like today is going to be a WASHOUT!

    Very heavy rain will be hitting Winnipeg just in time for rush hour!

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  10. Yes the rain pretty well started up right as scheduled at 6:30am Hopefully we get a couple of weeks of dry weather after this one.

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  11. Well...unfortunately the models have completely flipped for the 29th...30th has some potential...but it does not lookthat great attm.

    I'm sure the models will flip back and forth...either way...the jet stream is in this area. We just need a healthy return flow out of the S or SW then we're in business...especially with westerly upper-level winds.

    It looks like there is potential in SE ND today. If they can heat up, I think there might be some severe wx down there. Heavy rain over CYWG right now so moisture is around. Now let's see what happens in the warm sector where there is more sun.

    Darn 12z run...in the mean time...I'm still thinking there'll be a decent set-up this wknd in the Northern Plains!

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  12. Rob!
    How much rain did you get in the rain gauge???

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  13. At 2:10 PM the rain has stopped in Winnipeg and there is nothing on radar. I wonder if it's over or if it's just a recess? I hope this extra rain won't contribute to an excess water event.

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  14. It's looking that the bulk of the rain stayed a little south of Winnipeg. Appears it is over unless something else develops.

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  15. Generally 15-30 mm along and south of the trans Canada as of 2 pm.
    Moderate cells still training over the Emerson to Sprague region and will be interesting to see rainfall totals from there.

    Despite strong radar returns overnite and in early morning, low levels took a long time to saturate due to dry east flow.

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  16. General amounts of 20 to 40 mm over the southern RRV and SE MB.. with Sprague up to 48 mm as of 9 pm (and still raining) Radar shows heaviest swath was from Emerson area through Sandilands Forest to Lake of the Woods where 40-60 mm may have fallen.

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  17. NWS Grand Forks reporting rainfall totals of 2.5 to 3.5 inches (60-90 mm) just south of the border from south of Langdon to Pembina. Flood warning issued for Pembina county for small stream and overland flooding. I imagine this will keep the Red River levels up a little while longer..

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  18. Did someone say an Excess water event..What a difference a few weeks makes An inconvenience not a disaster These names cover the entire US RRV Fromm the Southern headwaters near Whapeton/Breckinridge to the Sheyenne, Red lake River, Sabin,Rosseau,Snake,Rivers etc and Devils Lake. A few more Excess Water events like this and Devils Lake will be part of the RRV for the second or third time in 4000 years The Last time was the (minor?) flood of 1826 nlol


    NOAA

    SOME OF THE RAINFALL TOTALS THAT OCCURRED OVER THE AREA
    STARTING LATE SUNDAY NIGHT (MAY 24TH) THROUGH LATE MONDAY NIGHT (MAY
    25TH). ......AREAL FLOOD WARNINGS HAVE BEEN ISSUED FOR PEMBINA...
    KITTSON AND ROSEAU COUNTIES. A RIVER FLOOD WARNING WAS ALSO ISSUED
    FOR THE TWO RIVERS RIVER AT HALLOCK. THE RAINFALL ALSO MADE AN
    IMPACT ON DEVILS LAKE...WHICH SHOWED A FAIRLY RAPID RISE OF ABOUT
    TWO TENTHS OF A FOOT.



    LOCATION RAINFALL AMOUNT

    NEKOMA (CAVALIER 3.50in
    CONCRETE Pmbina 3.50
    BADGER 3.39
    LAKE BRONSON STATE PARK 3.25
    CAVALIER 2.91
    EDINBURG 2.75
    MILTON 2.75
    WARROAD 2.71
    CHURCHS FERRY 2.54
    ST. THOMAS 2.46
    ROSEAU 2.46
    RED LAKE FALLS 2.40
    GREENBUSH 2.38
    PEMBINA 2.37
    CAVALIER (PEMBINA CO) 2.34
    EDMORE 2.33
    HUMBOLDT 2.30
    BAKER 2.11
    FOREST RIVER 2.02
    HALLOCK 1.98
    LANGDON NDSU 1.87
    CANDO 1.71

    GRAFTON 1.66
    STEPHEN 1.57
    WYNDMERE 1.52
    MICHIGAN 1.44
    CRARY 1.42
    MAVIE 1.37
    ELDRED 1.32
    SABIN 1.32
    WAHPETON 1.25
    HILLSBORO 1.22
    ROSEAU 1.20
    MCHENRY 1.19
    LONG LOST LAKE 1.12
    NEW YORK MILLS (OTTER TAIL CO) 1.12
    MAYVILLE 0.97

    LIDGERWOOD 0.95
    BRECKENRIDGE 0.95
    GRAND FORKS NWS 0.92
    DALTON (OTTER TAIL 0.91
    MAYVILLE 0.86
    WARREN 0.83

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  19. Rob!
    Environment Canada is calling for
    27 C on Saturday!!
    Do you see that being possible or is that just WISH-CASTING????

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  20. Daniel.. I think you got your answer! High for Saturday now dropped to 18C! The GLB model, which drives EC’s automated extended forecast for Day 3 to 5, has slowed down a system over SK that was pushing warmer air into southern MB for Saturday. Model now shows a ridge over us Saturday with cooler temperatures.. but it still looks nice with sunny skies and temps near 20C.

    This shows the problem with automating an extended forecast based on one model. It can easily flip from one run to the next, resulting in rather large swings in the forecast. A blend of model forecasts using the ensemble approach will result in more conservative but less variable forecasts from one run to the next, and will generally trend in the right direction with subsequent runs. Note that ensemble forecasts for Winnipeg yesterday were showing highs around 18C rather than GLB’s optimistic 27C.

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  21. Rob.
    I wonder if this summer is going to be like last year's ???
    Every time it looks like there is going to be some "HOT" weather...it just somehow never makes it here!

    Don't get me wrong.. the weather is finally looking nice and warm.

    Just now we are finally hitting "NORMAL"
    temperatures but....nothing warmer than normal!

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  22. Does anyone know where I can get historical Mean Daily Dew Point data for the last 30 years. I suspect theres a correlation to the previous question.

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  23. The extended outlook on the GFS looks terribly bleak with well below normal values until perhaps the following weekend (10-12 days away).

    Persistent arctic vortex/cold pool aloft will continue to plague Manitoba. Cold 850 hPa air will begin oozing back in tomorrow. By Saturday, 850 hPa temps are AOB 0 C. With surface high pressure dropping down on the back side of the cold pool... either Friday or Saturday (or both) may see a hard freeze depending on exact timing of the ridge. Not sure if SCRIBE guidance is out to lunch or GEM is not as aggressive with cold air, but 6 C looks way too optimistic for both nites. Rob?

    Warmer air and moisture briefly return on Sunday giving us our next chance of precip... yet again however, the bulk of the warmth, moisture and instability stay south of the border.

    No sooner has that disturbance passed, cold pool once again builds over Manitoba. GFS finally shows this arctic vortex weakening and moving over eastern Canada within 10 to 12 days. The models have been toying (or better put struggling) with the idea of a western upper ridge becoming dominant and sending some heat are way... I will believe it when I see it.

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  24. strange pop up shower over the NE part of Winnipeg right now....fairly heavy but short downpour. Checking the radar showed a small shower over NE Winnipeg but it popped up out of thin air....anyone have any reasoning?

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  25. The showers last nite likely formed due to warm air advection on a LLJ ahead of a disturbance. Moisture transport was limited however, shallow moisture from local evaporation (southerly flow off of waterlogged southern RRV).

    Last nite we were in warm sector... had the warm core moved in earlier, yesterday afternoon would have seen highs at least into the mid twenties. Cold front came thru around 3 am and significant cold advection sets in today. We may struggle to get to the forecast high of 17 C.

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  26. Rob!
    Environment Canada insists that this is going to be a hot summer!

    I hope they are right!
    I mean the weather pattern is going to have to do a complete 180 for that to happen!

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  27. Who knows what will happen with this summer, but this weekend still looks bad...

    Tomorrow actually looks like a mild day with some warm advection and good mixing with westerly flow. Things go downhill from there however, with very strong cold advection over nite Friday and late May version of arctic high building down.

    Models hang on to some cloud Saturday morning... this is critical, if high is able to cause at least some clearing, lows could quickly spike down to near zero(especially YWG). Saturday looks quite cool with 850 hPa temps around 2-3 C and possible patchy low clouds. Core of cold pool will be over NW Ontatio (850 hPa temps below zero!).

    Moisture return and warm advection on Sunday morning could lead to elevated showers, but moisture and instability remain somewhat in question. Strong cold advection recommences by afternoon and falling temps are possible. In fact GFS shows another chilly high moving in giving another frost potential Monday morning.

    After this point GFS has all kinds of difficulty resolving a complex split flow pattern that may emerge.
    Main idea is to modify and shift arctic vortex over eastern Hudson Bay. However, it also wants generate a cold pool over Alberta north of a large cut off low over California (very strange looking pattern). Latest run wants to merge the two and give us a SW flow .. interesting but far too early to put any stock into this solution.

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  28. May has been far below normal...and the numbers back it up:

    Average temp: +11.9C
    Actual average temp (2009): +7.9C
    Departure: -4.0C

    Average High: +19.1C
    Actual average high (2009): +13.6C
    Departure: -5.5C

    Incredibly cold for May and even more frightening is that the models show no warm-up going into June (they actually show things getting colder).

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  29. Chris - St.Vital7:14 AM, May 29, 2009

    There WILL be snow in June. You heard it here first. Maybe not snow, but definitely frost. EC saying top end early next week will be 13 or 14C.

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  30. Well ...frost warning issued for tonight!!

    lows as low a -5 in some parts of southern Manitoba!

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  31. Winds are crazy strong here in St. Andrews right now. I would guess some gusts were up to 90km/h.

    Andrew

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  32. Yeah, I suspected the automated guidance was way too warm. Glad to see the meteorologists adjusted down the forecast. The down side is an awful lack of forecast continuity. Forecast this morning was still for +5 C for the low. As Rob has suggested many times... if EC insists on using automated extended forecasts, they could at least adopt a blended or ensemble approach for better continuity.

    Btw... some surface based convection trying to form along arctic front dropping south. Very low dewpoints and moisture will lead to sparse coverage. However, lapse rates are steep providing instability. Looks like a cell trying to form over the downtown core right now.

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  33. Wow .. very strong gust front tearing thru central Winnipeg right now.. kicking up strong dust clouds.

    This is a classic example of high based, dry convection typical of arid climates like the US southwest.

    The low relative humidities causes a very high LCL(lifted condensation level) and significant evaporative cooling. This leads to very strong downdrafts and gusty winds mixing down to the surface. Often times precip never reaches (virga) as in this case.

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  34. Now that's what I call a cold front!
    We got the very strong winds here on the west side of the city also.

    You could feel the temperature drop almost right away with the passage of the cold front!

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  35. Rob, I'm gonna get some peak gusts, so stay with me!

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  36. Winds gusted to 40 knots (74 km/h) at the airport at 6:15 pm, with the temperature dropping 6 degrees from the 22C at 6 pm. Lots of blowing dust around. As Daniel noted, classic example of high-based dry microburst.

    Winds starting to drop off now, but there still may be enough of a breeze overnight to prevent a widespread freeze. The northerly component of the wind coming off the downtown core will likely spare southern Winnipeg from a frost tonight.

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