27 May 2010

27th May 2010 - Thursday

High: 10.7
Low: 0.4
Days we didn't see any sun: (39)
Days swept snow from drive (0)
Days shovelled snow from drive (14)

It was a very wet and cloudy start and looked as though it had been raining heavily overnight. It started to rain again at around 8am and was farily heavy. It was only +6 and cool and wet.

We currently have the following weather warning in place:

Rainfall warning for
Okotoks, High River & Claresholm

A spring storm will track across Southern Alberta today and Friday bringing large amounts of precipitation to parts of the province. 30 to 40 millimeters of rain has already fallen in areas south of Calgary early this morning with another 30 to 50 millimeters expected today in those same regions.

Further northwest over higher elevations in the foothills and mountains precipitation is largely falling as snow. The snow will spread to valley bottoms in these regions overnight as colder air is drawn into the system from the north. Accumulations should reach 10 cm in these areas by Friday morning with local amounts over higher elevations approaching 25 cm.

Precipitation should ease throughout the day Friday as the system moves eastward.

At around noon the snow turned to sleet and in just over an hour the snow was piling up on the cars. The temperature had dropped to +1 by noon. It snowed for the rest of the afternoon.
The Rain Warning was replaced with a Snowfall warning:

10 to 20 centimetres of snow overnight into Friday morning. A disturbance moving into Northern Montana continues to spread significant amounts of moisture across Southern Alberta. At the same time moderate northeasterly flow in the low levels is gradually injecting cooler air into the system. As a result rainfall will change to snow in most areas early this evening if it hasn't already done so. Snowfall amounts as high as 20 cm are possible especially in the foothills and over higher terrain. Due to warm ground temperatures much of the snow will initially melt however most areas can still expect to see 10 cm of snow on the ground by Friday morning.

Further east in the Brooks and Lethbridge regions rainfall will become mixed with snow overnight however significant snowfall accumulations are not expected in these areas and a rainfall warning is still in effect.

Precipitation should ease throughout the day Friday as the system moves eastward.

Meanwhile, thunderstorms that have developed in Montana are moving northward into the Cypress Hills region. Some of these storms are exhibiting the potential to produce large hail and locally heavy rainfall.

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