Sunday, May 12, 2013

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)      

1 comment:

  1. Thanks for the synopsis. I was curious about the sudden wind, but too lazy to investigate.

    Amazing video too. Looks very much like an a'a lava flow.