Thursday, July 31, 2014

Warm west - cool east

Waterspouts are possible over the Great Lakes again today.
It is another chilly morning here on L'Ile Perrot with the temperature sitting at 15C (59F) after an overnight low of 13C (55F) around 6am this morning. We have some sunshine around as well as some mist and fog. As I have said all week, it feels more like a September morning than late July. Sadly my favorite month of the year is over, and it will end on a cool note with highs forecast near 21C (70F). A rather vigorous upper air disturbance will provide enough lift for scattered showers and thunderstorms today as it drifts from Ontario into New England. Some of the storms may have small hail and heavy rain. On Wednesday several decent storms affected the Ottawa Valley with over 23mm of rain for the nations capital. We may see similar amounts today, but not for everyone, they will be scattered in nature. Showers will taper off this evening followed by a partly sunny Friday and a little warmer, up to 25C (77F). The threat for some thunderstorms will still exist Friday afternoon for Montreal. The weekend at this time looks sunny and warm. Let hope it holds.

The cool weather this morning stretches all the way down to the Gulf of Mexico with record lows at Pensacola, Florida of 64F and Mobile, Alabama at 63F, one degree off their coldest July morning on record. The cool air aloft has produced numerous showers and thunderstorms over the Great Lakes, several that produced waterspouts on Wednesday. The threat is there again today especially over Lake Erie. Waterspouts are similar to tornadoes but generally weaker. They can certainly upset smaller watercraft.

Meanwhile it is warm in the west with temperatures once again soaring into the middle 30's. Bow Island, Alberta hit 35.2C (96F) on Wednesday while Calgary was 32C (90F). Calgary also had a rare heat burst in the early morning hours of Wednesday. Heat bursts occur from collapsing thunderstorms. Around 1am, a gusty southwest winds hit 85km/h at the airport with a dry dewpoint of 1C (humidity was less than 15%). Meanwhile the mercury shot up to 29C (85F), almost desert like.

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