Nice dry weather for the rest of the week..

After a soggy holiday weekend that dumped 15-50 mm of rain over Winnipeg, and up to 200 mm over the Pembina escarpment west of Morden,  the weather pattern will be a lot drier this week as a ridge of high pressure builds in over the eastern Prairies. This ridge will bring mainly sunny skies and near normal temperatures for the rest of the week, along with low humidity and diminishing winds.. perfect conditions for drying out left over moisture from the weekend. The next chance for rain will be Saturday as a weakening band of showers from Saskatchewan pushes across southern MB. At this point, it looks weak, and the current forecast of "periods of rain" for Saturday looks overly pessimistic.

May 18-20 weekend rainfall totals..  

Winnipeg
north end....... 15 mm
Airport ......... 18 mm
Forks ............ 24 mm
Charleswood ... 27 mm
Norwood ........ 31 mm
South Winnipeg ... 30-50 mm

Thornhill .............  205 mm
Darlingford .......... 200 mm
Miami 10SW ...... 125 mm
Morden 6SW ...... 120 mm
Deerwood ........... 100 mm
Morden ...............  90 mm
Somerset .............  80 mm
Winkler ...............  77 mm
Manitou ............... 76 mm
Sprague ............... 73 mm
Carman ................ 68 mm
Emerson .............. 55 mm
Morris.................. 54 mm

Note the heaviest amounts over the western Red River valley along the Pembina escarpment. A persistent northeast upslope flow through the weekend contributed to the locally higher amounts in that area, leading to overland flooding. Note that similar amounts were reported along the escarpment in neighbouring North Dakota with reports of up to 225 mm near Walhalla. This has forced the evacuation of the town of Cavalier, ND due to concerns about a nearby dam failing.

Unsettled weekend.. locally heavy rain possible at times.. but rain-free periods as well

3 day precipitation outlook (Fri - Mon)
from HPC, amounts in inches
showing heaveist rain of 75+ mm
south of the US border

A complex weather pattern will be setting up over the Northern US plains this weekend,  which will be impacting the weather over southern MB for the May long weekend.  A series of disturbances will be triggering showers and scattered thunderstorms over North Dakota and northern Minnesota over the the next few days, some of which may bring areas of heavy rain to southern MB.  Models however are having a tough time coming to a consensus as to when and where most of the precipitation will be falling over southern MB. It appears there will be an initial band of showers and thunderstorms developing tonight over North Dakota and spreading into southern MB overnight into Saturday, with the potential for locally heavy rain in showers or scattered thunderstorms.  On Sunday, a stronger system developing over South Dakota will move into northwest Minnesota, triggering more widespread showers and thunderstorms south of the border. This area of precipitation is expected to push over southeast MB Sunday night into Monday, although models having varying opinions on how far northwest this second wave of showers will spread. Some models are indicating that most of the heaviest precipitation will stay over extreme southeast MB and miss Winnipeg and the RRV. Other models are indicating that showers will push into Winnipeg and the southern Interlake by holiday Monday. Thus, the forecast for the latter half of the holiday weekend is still in doubt. Bottom line: not the best holiday weekend, but not a total washout either. Note however, that the potential for locally heavy rain (50 mm or more) is possible this weekend for parts of southern MB including the Red River valley.  (Consult  HPC precipitation forecasts for updated trends on expected precipitation patterns this weekend) 

Warmer week ahead..

After a rather cool weekend, warmer weather is on tap for southern Manitoba this week, as temperatures climb back into the 20s. Strong southerly winds gusting to 60 or 70 km/h Monday morning in Winnipeg and the Red River valley will signal the start of the warmup, with temperatures climbing into the low to mid 20s in the afternoon as winds shift into the west.  On Tuesday morning, a disturbance crossing southern Manitoba will bring an area of showers across the Red River valley, with the slight chance of an isolated thunderstorm in spots. This unsettled weather will move through by late Tuesday with generally dry and seasonable  weather for the balance of the week, with daily highs in the low 20s.  Unsettled weather is likely to return by Friday, with models indicating the potential for a stronger system affecting southern Manitoba by Sunday or Monday with heavy rain possible. The warmer weather along with some moisture and higher dewpoints will hopefully help accelerate leaf budding this week, which is still behind normal due to the prolonged winter and delayed spring this year.   

Powerful wind gusts drive ice floes on Dauphin Lake onshore damaging cottages, homes..

Wind driven ice floes swallow up cottages in
Ochre Beach, MB - May 10 2013

Powerful northerly winds gusting up to 80 km/h over western Manitoba pushed ice on Dauphin Lake onto the south shore of the lake late Friday, damaging or destroying over 2 dozen waterfront homes and cottages in Ochre Beach, MB.   The ice was pushed up 20-30 feet, crushing cottages in its relentless path onshore. Luckily, no one was injured during the late day event, which witnesses report took only 15 minutes to occur, some describing it as an "ice tsunami". See CBC news story  as well as Winnipeg Free Press story on "ice shove" phenomena with more great photos.   

What happened?

Foxwarren radar just before 6 pm
showing showers with strong
outflow winds approaching
Ochre Beach

Friday May 10th was a fairly windy day over western Manitoba with gusty northerly winds of 40 to 60 km/h behind a cold front that had pushed through earlier in the day. By afternoon, an area of convective showers had developed over central Manitoba and was pushing down over western MB from the northwest. At around 6 pm, radar was detecting an area of showers spreading over the north part of Dauphin Lake heading south towards Ochre Beach. At the time, Dauphin airport was reporting a temperature of 10C with a dewpoint of -4C, indicating dry air in the low levels. At 6:16 pm as the showers were starting to pass through, winds at Dauphin airport suddenly starting gusting to 75 km/h (41 knots) with a peak gust of 80 km/h (43 knots) at 6:22 pm (2322Z)  (see observations below)  These winds were indicative of strong "downburst winds" caused by convective showers tapping strong winds aloft (80-90 km/h) and spreading them down to the surface (note also strong pressure rises reported at the time, characteristic of strong winds pushing down).  It is likely during this time that the lake ice was driven onshore by the fairly brief but powerful wind gusts. Note that the lake ice was fractured and crystallized owing to the lateness of the season, which made it easier for strong winds to push the ice floes onshore.

Dauphin Airport AWOS observations -  18-00Z May 10 2013 

CYDN 101800Z AUTO 36021G29KT 9SM FEW036 10/00 A3007 RMK MAX WND 35023KT AT 1750Z SLP192
CYDN 101900Z AUTO 35023G34KT 9SM CLR 12/M04 A3008 RMK MAX WND 35028KT AT 1853Z SLP193
CYDN 102000Z AUTO 01020G33KT 9SM CLR 12/M05 A3009 RMK MAX WND 36028KT AT 1938Z SLP199
CYDN 102100Z AUTO 01023G32KT 9SM FEW075 13/M06 A3010 RMK MAX WND 01027KT AT 2023Z SLP201
 CYDN 102200Z AUTO 33016G23KT 9SM FEW080 BKN098 12/M06 A3011 RMK MAX WND 36025KT AT 2101Z SLP203
CYDN 102300Z AUTO 02017G23KT 9SM SCT070 BKN087 BKN110 10/M04 A3013 RMK MAX WND 35022KT AT 2214Z SLP211
CYDN 102316Z AUTO 35032G41KT 9SM BKN060 BKN074 OVC088 08/M00 A3015 RMK MAX WND 35032KT AT 2316Z PRESRR SLP221
CYDN 102322Z AUTO 35031G43KT 9SM -RA FEW033 SCT050 BKN065 OVC080 06/02 A3017 RMK MAX WND 35036KT AT 2317Z PRESRR SLP228
CYDN 102359Z AUTO 36013G19KT 9SM SCT025 BKN060 OVC081 05/02 A3019 RMK MAX WND 35036KT AT 2317Z PRESRR SLP234CYDN 110000Z AUTO 36014G19KT 9SM SCT025 BKN065 OVC075 05/02 A3019 RMK MAX WND 35036KT AT 2317Z PRESRR SLP235

Lake ice comes onshore off Mille Lacs Lake in northern Minnesota - May 11 2013

Amazingly, the exact same phenomena occurred the very next day, May 11th, on a lake in northern Minnesota, Mille Lacs Lake, east of Brainerd, with strong winds pushing lake ice onshore causing damage to a lakeside home there.  (see video below)      

Cooler weather on the way..

After 2 days of summerlike temperatures in the mid 20s, things will be cooling off noticeably Wednesday as a cold front pushes through southern Manitoba, with brisk northerly winds ushering in temperatures some 10-15C cooler than the past couple of days.  The cold front will be pushing through Winnipeg after midnight tonight, with northerly winds increasing to 30 gusting 50 km/h behind the front. Temperatures Wednesday will be struggling to get much above 10C, which will feel even cooler with the wind, with below normal temperatures lingering into Thursday. Friday will see a bit of moderation as we get back into a southerly flow of milder air, however another cold front will be pushing through Friday evening ushering in even cooler air for the start of the weekend.  Warmer weather with temperatures back in the 20s is expected by Monday over southern Manitoba.