Bountiful St. Patrick's Day sunshine isn't to be the last in coming days. There's more great weather on deck---though there are also signs Chicago's weekend weather could become dicey with rain and even the threat of wet snow. Storms must be monitored closely this time of year. Their varied temperatures can take rain to snow despite a period of warmth. This storm's impact on the Chicago area is still days away and will depend on a variety of factors including its future track.
Snow is to be the last thing on people's minds Wednesday. Temperatures surged past 60-degrees Tuesday-- topping out at 61 at O'Hare and as warm as 69 at Elgin, 68 Itasca and 67 in Oswego and 66 at Blue Island. These readings are 18 or more degrees above normal---and Wednesday looks even warmer. The 65 predicted at O'Hare Wednesday afternoon would immediately become 2010's warmest to date and would arrive nearly a year to the day of last year's first 70-degree reading---a 74-degree high which occurred on today's date in 2009.
But it's Thursday which stands a good chance of becoming the warmest of the current mild spell. That's when the city's official high is predicted to move to within striking distance of 70-degrees. Large scale subsidence of air beneath the incoming nose of a powerful jet stream is to combine forces with Thursday's generous sunshine and strong west winds capable of overcome lake cooling to produce the first 70-degree reading of 2010 nearly 4 months after the Chicago area's last 70 on Nov. 8.
Warm weather isn't surprising this time of year nor is it mis-timed. In the past decade, March 22 has been the average first date for a 70 here---and March 24 has been the average over the past half century of readings at O'Hare.
Tuesday becomes one of only 10 days in the past 140 years with relative humidities in the teens
Remarkably low relative humidities (RH) across the metro area played a role in producing Tuesday's warm highs. Dry air heats expeditiously. A plunge in RH readings observed just after noon Tuesday coincided with rapid warming. The appearance of low humidities occurred as winds helped mix exceptionally dry air, which had hovered just above the surface since Monday, down to ground-level.
Chicago recorded 90 percent of its possible sunshine Tuesday bringing the March average to 43 percent---52 is considered "normal" here in March.
Windy Seattle storm could head toward the Midwest
The storm system which may impact the Midwest this swept hit Seattle and Pacific Northwest with 60+ mph winds Tuesday, forcing bridge closures and producing power outages. It produced wind gusts of up to 69 mph at Tatoosh Island WA and 46 mph gusts in Seattle proper. At least 6,000 were reported without power in the region.
Despite the unseasonably mild weather predicted in Chicago over coming days, the weekend storm is to bring rain to the area which could mix with or change to wet snow Sunday. March in Chicago has never closed without at least a trace (0.1 inch or less) of snow.
Snow is to be the last thing on people's minds Wednesday. Temperatures surged past 60-degrees Tuesday-- topping out at 61 at O'Hare and as warm as 69 at Elgin, 68 Itasca and 67 in Oswego and 66 at Blue Island. These readings are 18 or more degrees above normal---and Wednesday looks even warmer. The 65 predicted at O'Hare Wednesday afternoon would immediately become 2010's warmest to date and would arrive nearly a year to the day of last year's first 70-degree reading---a 74-degree high which occurred on today's date in 2009.
But it's Thursday which stands a good chance of becoming the warmest of the current mild spell. That's when the city's official high is predicted to move to within striking distance of 70-degrees. Large scale subsidence of air beneath the incoming nose of a powerful jet stream is to combine forces with Thursday's generous sunshine and strong west winds capable of overcome lake cooling to produce the first 70-degree reading of 2010 nearly 4 months after the Chicago area's last 70 on Nov. 8.
Warm weather isn't surprising this time of year nor is it mis-timed. In the past decade, March 22 has been the average first date for a 70 here---and March 24 has been the average over the past half century of readings at O'Hare.
Tuesday becomes one of only 10 days in the past 140 years with relative humidities in the teens
Remarkably low relative humidities (RH) across the metro area played a role in producing Tuesday's warm highs. Dry air heats expeditiously. A plunge in RH readings observed just after noon Tuesday coincided with rapid warming. The appearance of low humidities occurred as winds helped mix exceptionally dry air, which had hovered just above the surface since Monday, down to ground-level.
Chicago recorded 90 percent of its possible sunshine Tuesday bringing the March average to 43 percent---52 is considered "normal" here in March.
Windy Seattle storm could head toward the Midwest
The storm system which may impact the Midwest this swept hit Seattle and Pacific Northwest with 60+ mph winds Tuesday, forcing bridge closures and producing power outages. It produced wind gusts of up to 69 mph at Tatoosh Island WA and 46 mph gusts in Seattle proper. At least 6,000 were reported without power in the region.
Despite the unseasonably mild weather predicted in Chicago over coming days, the weekend storm is to bring rain to the area which could mix with or change to wet snow Sunday. March in Chicago has never closed without at least a trace (0.1 inch or less) of snow.
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