By Meteorologist Tom Skilling
An intensifying spring storm's gusty and still-strengthening northeast winds roll into town Thursday, more than 30 hours ahead of the system's rains. Potentially heavy downpours are to hold off in the city until late Friday but may well end up producing 1-inch totals by late Saturday across a few of this area's hardest hit locations. It would make it Chicago's heaviest rain tally in the 6 weeks since 1.11 inches of rain fell March 4.
The dimensions of the approaching storm are stunning, covering more than 4.2-million square miles. It measures 2,900 miles from north to south and nearly 1,500 miles from east to west, but is only one in a series of rain-generating systems expected to ride across the Midwest in the coming two weeks. Estimates averaged across the ten most recent runs of the National Weather Service's Global Forecast System (GFS) computer model suggest 2-week Chicago area rainfall could reach or exceed 4 inches ---a tally more than twice normal.
Wednesday's "warmth" won't be repeated here
The northeast winds riding into the city off Lake Michigan Thursday have origins within a vast reservoir of cool air to the north. It's a set-up which shaves 18-degrees off the day's predicted highs.
Wednesday, a day with much lighter east winds and a good deal of sunshine, generated a 68-degree high at O'Hare---the city's third warmest temperature of the year.
Warmest suburbs register mid 70s Wednesday
Inland locations fared even better Wednesday, registering highs of 75-degrees in Buffalo Grove, Itasca and Geneva, 74 Algonquin, Joliet and Elk Grove Village, 73 DeKalb and 71-degrees at Mt. Prospect, Frankfort and Mokena .
It was 80 this date a year ago; Thursday's predicted 50 is to be 30-degrees cooler
Temperatures on this date in 2010 soared to 80-degrees. April as a whole was running more than 5-degrees warmer. That means Thursday's 50-degree high (a number of areas closest to the lake are likely to have trouble moving out of the mid 40s) is to be at least 30-degrees colder than a year ago.
Winds to strengthen at a slow, steady pace, topping 40 mph at times by Friday
Wednesday's winds were light and its sunshine fairly prolific, both factors which contributed to the day's warmth. A far different meteorological set-up comes together Thursday and Friday. Clouds will be more extensive and a stronger wind regime is under development. It means gusts of 25 to 30 mph may sweep the area Thursday afternoon building at times to 40 mph late Thursday night and to 45 mph or higher at times Friday.
The winds will tap dry air for a time late tonight into Friday morning permitting clouds to break. It's a development which may allow Friday to open with mixed sun before thicker clouds take hold and the atmosphere saturates as powerful southeast winds just above the surface import impressive quantities of Gulf moisture expected to saturate the air and produce rain.
The flood of warm, moist air into the area Friday night may fuel occasionally thundery downpours likely to occur amid slowly rising overnight temperatures.
Tremendous vertical motions in powerful storms contribute to their powerful winds; sprawling Canadian high to the north another factor
Pressures are predicted to vary widely between a huge Canadian high to the north with a central pressure of 1039 mb. (30.68 inches) and a deepening low pressure over eastern Kansas with a pressure of 993 mb (29.32 inches). This and the vigorous ascension of air above the incoming storm's center will contribute to the strengthening winds predicted to sweep Chicago and much of the Midwest in coming days.
A new severe weather outbreak threatens the Plains and sections of the Midwest in coming days
The storm's warm sector appears likely to produce a severe weather outbreak Thursday and Friday from Kansas and Missouri eastward into downstate Illinois and Indiana.
An intensifying spring storm's gusty and still-strengthening northeast winds roll into town Thursday, more than 30 hours ahead of the system's rains. Potentially heavy downpours are to hold off in the city until late Friday but may well end up producing 1-inch totals by late Saturday across a few of this area's hardest hit locations. It would make it Chicago's heaviest rain tally in the 6 weeks since 1.11 inches of rain fell March 4.
The dimensions of the approaching storm are stunning, covering more than 4.2-million square miles. It measures 2,900 miles from north to south and nearly 1,500 miles from east to west, but is only one in a series of rain-generating systems expected to ride across the Midwest in the coming two weeks. Estimates averaged across the ten most recent runs of the National Weather Service's Global Forecast System (GFS) computer model suggest 2-week Chicago area rainfall could reach or exceed 4 inches ---a tally more than twice normal.Wednesday's "warmth" won't be repeated here
The northeast winds riding into the city off Lake Michigan Thursday have origins within a vast reservoir of cool air to the north. It's a set-up which shaves 18-degrees off the day's predicted highs.
Wednesday, a day with much lighter east winds and a good deal of sunshine, generated a 68-degree high at O'Hare---the city's third warmest temperature of the year.
Warmest suburbs register mid 70s Wednesday
Inland locations fared even better Wednesday, registering highs of 75-degrees in Buffalo Grove, Itasca and Geneva, 74 Algonquin, Joliet and Elk Grove Village, 73 DeKalb and 71-degrees at Mt. Prospect, Frankfort and Mokena .
It was 80 this date a year ago; Thursday's predicted 50 is to be 30-degrees cooler
Temperatures on this date in 2010 soared to 80-degrees. April as a whole was running more than 5-degrees warmer. That means Thursday's 50-degree high (a number of areas closest to the lake are likely to have trouble moving out of the mid 40s) is to be at least 30-degrees colder than a year ago.
Winds to strengthen at a slow, steady pace, topping 40 mph at times by Friday
Wednesday's winds were light and its sunshine fairly prolific, both factors which contributed to the day's warmth. A far different meteorological set-up comes together Thursday and Friday. Clouds will be more extensive and a stronger wind regime is under development. It means gusts of 25 to 30 mph may sweep the area Thursday afternoon building at times to 40 mph late Thursday night and to 45 mph or higher at times Friday.
The winds will tap dry air for a time late tonight into Friday morning permitting clouds to break. It's a development which may allow Friday to open with mixed sun before thicker clouds take hold and the atmosphere saturates as powerful southeast winds just above the surface import impressive quantities of Gulf moisture expected to saturate the air and produce rain.
The flood of warm, moist air into the area Friday night may fuel occasionally thundery downpours likely to occur amid slowly rising overnight temperatures.
Tremendous vertical motions in powerful storms contribute to their powerful winds; sprawling Canadian high to the north another factor
Pressures are predicted to vary widely between a huge Canadian high to the north with a central pressure of 1039 mb. (30.68 inches) and a deepening low pressure over eastern Kansas with a pressure of 993 mb (29.32 inches). This and the vigorous ascension of air above the incoming storm's center will contribute to the strengthening winds predicted to sweep Chicago and much of the Midwest in coming days.
A new severe weather outbreak threatens the Plains and sections of the Midwest in coming days
The storm's warm sector appears likely to produce a severe weather outbreak Thursday and Friday from Kansas and Missouri eastward into downstate Illinois and Indiana.
