Friday, May 31, 2013

..Soggy end to May over southern Manitoba..

A slow moving storm system over the Dakotas brought another round of heavy rainfall to southern Mnaitoba over the past two days, less than 2 weeks after  a similar rainfall event brought drenching rains to the same area over the Victoria Day weekend. General rainfall amounts of 30 to 60 mm were widespread mainly along and south of the TransCanada highway  with locally heavier amounts  of 80 to 125 mm along the western Red River valley. 

At my site in Charleswood, I recorded a storm rainfall total of 43 mm, while 50 to 70 mm was reported over the south end of the city. La Salle reported 54 mm.  Unofficial reports of 80 to 125 mm were received for areas along the western Red River valley from the Austin and MacGregor areas to west of Miami to the US border. Overland flooding was once again reported in the Morden area due to heavy rains along the Pembina escarpment. This area was flooded over the Victoria day weekend as well with local amounts of 100 to 200 mm of rain during the 3 day rainfall event.   

Rainfall storm totals to 1 am Saturday since the rain began Thursday morning..   
  
ENVIRONMENT CANADA STATIONS  
  
DEERWOOD .................. 81 MM  
MORDEN .................... 69 MM  
PORTAGE LA PRAIRIE ........ 63 MM  
CARMAN .................... 52 MM  
EMERSON ................... 42 MM  
WINNIPEG FORKS ............ 40 MM  
WINNIPEG AIRPORT .......... 38 MM  
PINAWA .................... 37 MM  
GRETNA .................... 36 MM  
GIMLI ..................... 35 MM  
CARBERRY .................. 29 MM  
MELITA .................... 24 MM  
PILOT MOUND ............... 22 MM  
BRANDON ................... 19 MM  
SPRAGUE ................... 13 MM  
MCCREARY .................. 11 MM  
DAUPHIN ...................  6 MM  
  
MANITOBA AGRICULTURE SITES (MAFRI)  
  
TREHERNE .................. 68 MM  
PORTAGE LA PRAIRIE EAST ... 67 MM  
RESTON .................... 56 MM  
CARMAN .................... 55 MM  
STARBUCK .................. 54 MM  
WINKLER ................... 53 MM  
MORRIS .................... 49 MM  
ST ADOLPHE ................ 42 MM  
MANITOU ................... 42 MM  
LETELLIER ................. 41 MM  
DELORAINE ................. 41 MM  
GLADSTONE ................. 39 MM  
ST PIERRE ................. 37 MM  
ELM CREEK ................. 37 MM  
ALTONA .................... 36 MM  
SELKIRK ................... 30 MM  
STEINBACH ................. 26 MM

Sunday, May 26, 2013

Unsettled week ahead..

The weather pattern will be getting more unsettled over southern MB this week as an upper ridge of high pressure starts building over eastern North America, while a long wave upper trof sets up over the west. This will set up a storm track across the northern Plains and southern Prairies this week, with periodic weather systems bringing occasional rounds of showers and possible thunderstorms.  The first wave of precipitation is expected this afternoon into tonight over southern MB as a band of showers over North Dakota spreads northeast. Another impulse over the Dakotas will threaten more showers and possibly thunderstorms over southern MB later Monday through Monday night into early Tuesday with locally heavy rain possible. Drier weather is expected midweek before a more potent system developing over the Dakotas brings more showers and thunderstorms later in the week. Overall, not the greatest week if you're looking for a prolonged stretch of sunny warm weather!  But then, this is not unusual for this time of year. On average, June is the wettest month of the year over southern MB, as increasingly warmer and more humid air to our south tries to spread north, and interacts with weather system crossing the Prairies.     

Wednesday, May 22, 2013

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.

Friday, May 17, 2013

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) 

Sunday, May 12, 2013

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)      



Tuesday, May 07, 2013

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.

Thursday, May 02, 2013

A nice improving trend through the weekend into next week..

After a wintery-like start to the month, things will be improving nicely over southern MB over the next few days with mainly sunny skies and warming temperatures through the weekend into the beginning of next week.  Temperatures will climb to the 10C mark Friday, still about 7C below normal, but feeling a lot nicer with sunny skies and light winds. The weekend looks beautiful with sunny skies, light winds and temperatures climbing to seasonal values of 17C by Sunday. Even warmer weather is expected early next week with temperatures climbing into the low 20s for the first time this spring.. a much anticipated warming trend for winter-weary Manitobans.  

April 2013 coldest since 1907.. 3rd coldest on record in Winnipeg 

Temperature graph
Winnipeg - April 2013
showing persistent
cold during the month
April 2013 was the coldest April in over a century in southern Manitoba. The average monthly temperature at Winnipeg airport was a March-like -2.1C, over 6C below normal, and tying April 1907 as the 3rd coldest April in Winnipeg since records began in 1872.  Every day but three were below normal, with a staggering 46 day streak of below normal temperatures from March 10th to April 25th.  The month featured the latest date ever for Winnipeg to hit the +5C mark (April 24th), and the second latest date to hit +10C (April 26th)  Snow cover in Winnipeg, which began back on Nov 10th, did not completely melt until April 26th.. one of the latest snow melts in city history. Luckily, precipitation was fairly normal for the month, and together with a long gradual melt allowed for a reduced flood threat over the Red River valley,   


Top 5 coldest Aprils in Winnipeg (since 1872)

1. 1893 ........  -2.9C
2. 1874 ........  -2.7C
3. 2013 ........  -2.1C
    1907 ........  -2.1C  (tied)
5. 1950 ........  -1.6C
    1996 ........  -1.6C  (tied)