Thursday, May 31, 2018

City swamped with heavy rainfall - up to 75 mm reported in River Heights

A slow moving band of showers and embedded thunderstorms moved across the city of Winnipeg late Wednesday afternoon, resulting in a deluge of rain over much of the city. The heaviest rain moved in from the southwest around 4 pm, and proceeded to slowly track across the downtown core over the next 2-3 hours. By the time the rain tapered off in the early evening, amounts of 25 to 75 mm were reported across the city, the heaviest in the Tuxedo-River Heights area.  The heavy rain caused flash flooding of Winnipeg streets, with Pembina Highway temporarily closed due to flooding under the Jubilee overpass. By contrast, very little rain fell over southeast sections of the city with 5 mm or less over south St Vital into the Sage Creek area.

Rainfall map for city of Winnipeg based on unofficial Weather Underground
reporting sites up to 7:15 pm May 30 2018. Values in inches, contours in mm 

Official rainfall amounts for the event included:

Winnipeg Forks:  46.1 mm
Winnipeg airport: 26.3 mm 

Unofficial amounts included:

River Heights: 74 mm
Tuxedo: 69 mm
U of Winnipeg: 52 mm
Linden Woods: 25-40 mm
Charleswood: 28 mm (my site)
Whyte Ridge: 27 mm

The rainfall has made up for a very dry start to spring with virtually no rain through April into the first half of May.  As of today, May precipitation now sits at 54 mm for Winnipeg airport and 70 mm at the Forks. Average monthly precipitation in Winnipeg for May is around 60 mm.

Rainfall map from Weatherlogics using over 300 rainfall reports

Wednesday, May 09, 2018

Very dry weather continues.. Winnipeg closing in on top 5 dry spells of all time

The dry weather of the past 2 months continues into May, with no measurable precipitation recorded so far in the month. In fact, as of May 9th, Winnipeg has gone 27 consecutive days without any measurable precipitation. The last day with measurable precipitation in Winnipeg was on April 12th when 1.2 mm of melted snow was recorded at the airport. (measurable precipitation is defined as a day with 0.2 mm or more of melted precipitation (rain or snow)  With no significant precipitation expected through May 15th, this current dry spell may enter the record books as one of the top 5 longest dry spells in Winnipeg since records began in 1872. The chart above shows the top 5 longest dry spells in the city, the longest being 47 days without measurable precipitation in the fall of 1976. The longest dry spell in the spring (which is a more serious time for dry weather) was in 1980 when Winnipeg went 40 straight days without measurable precipitation.  How long this current dry spell will last is difficult to say at this point.. but increasingly it looks like it may become historic before it's finally over. The dry weather has caused major headaches for city firefighters who have had to battle numerous grass fires in the past few days in and around the city.     

UPDATE:  Well, the dry spell ended at YWG airport but there's a bit of a controversy over exactly when the streak ended.  Officially, the first measurable precip at YWG airport in May was on May 17th when 0.8 mm of rain fell. That would have put the dry spell at 34 days, tied with 1882 as the 4th longest dry spell on record.   However, it appears the official precipitation gauge at the airport (XWG CS station) was possibly under-reporting rainfall from the 15th through the 19th. A co-located rain gauge at XWG picked up 0.2 mm of rain on the 15th, as did many private stations in Winnipeg with some light rainshowers that day. If that's the case, the dry spell would have ended on the 15th for a streak of 32 days, which would be the 6th longest dry spell on record. Which is correct? I'm going with the latter (32 day streak) with 0.2 mm of rain on the 15th, not much, but just enough to break the precip-free streak.