A battle of the seasons - flood risk lowering for Montreal

Despite water levels lowering on the Ottawa River this weekend, pumps will remain in place in Sainte-Anne-de-Bellevue and other municipalities until the threat is over. (Valley Weather)

The weather was anything but May-like on Saturday across southwestern Quebec, with a cold northwest wind, chilly temperatures and even some sleet and graupel falling from the sky. An upper air disturbance produced enough instability to generate a few lightning strikes early Saturday afternoon. Temperatures remained quite chilly throughout the weekend, with scattered frost reported. Highs were in the 9C to 12C range (49-54F), with low temperatures a few degrees either side of the freezing point.

Early Monday morning, we have milder air trying to work into the region, accompanied by some robust showers along a warm front. That front should clear the region by noon, allowing for a few breaks and gusty, warm southwest winds. Temperatures should warm into the upper teens and even a fews 20s around. The same can be expected for Tuesday, before a cold front sweeps across eastern Ontario and southern Quebec.

That front will produce a few showers and even a thunderstorm, before a soaking rain develops into Wednesday. Temperatures will fall back to the single digits for highs on Wednesday, as the seasons continue to battle across most of Canada.

The weather was cold enough for sleet to fall over the weekend in parts of southern Quebec. (Valley Weather)

Spring Flooding

The news is better concerning the ongoing spring flood potential. Pumps and dikes remain in place, but most roads have been reopened as water levels continue to drop along the Ottawa River and Lake of Two Mountains. Over 100mm (4 inches) of rain fell in April across the region, allowing for water levels to rise sharply late last month. Since May 1st, another 5-10mm has fallen, with 15-20mm possible this week. That being said, water levels remain stable in the Ontario portions of the river and are even lowering in some cases. The end result is that mitigation and observation efforts will remain as is for most municipalities in the greater Montreal area, but the forecast looks favourable at this time for a continued drop in in levels.

The gauge at Sainte-Anne-de-Bellevue remained in minor flood stage Monday morning, at 23,83 metres and slowly rising. However most other gauges on other portions of the Ottawa River upstream from Montreal are showing levels stable or even lowering.

Over the weekend the bridge to Île Mercier was reopened, as was Chemin de l'Anse à l'Orme late last week. Both had been clsoed since mid-April after being inundated by high water from Rivière des Prairies.