There’s not a month of the year more likely to produce cool easterly lake breezes near Lake Michigan than May. Easterly winds have historically occurred on 45% of May days—and Tuesday will be no exception. In fact, Tuesday’s easterly flow will mark the 6th consecutive day onshore winds have been a part of the Chicago weather scene.
The lake winds have, in recent days, been stronger than those predicted Tuesday and Wednesday, and therefore in a position to deliver their lake-cooling to more of the metro area than will be the case the next few days.
An impressive “cut-off” low, responsible for drenching sections of downstate Illinois and Missouri with more than 4″ of rain over the weekend, has contributed to the strength of the Chicago area’s easterly flow in recent days. But, its influence over Chicago’s weather, is fading. That’s why Tuesday’s east to northeast winds will be lighter and, therefore, able to send lake-cooled air little more than several miles inland—unlike Monday when they propelled lake-cooled air as much as 15 miles inland.
Afternoon temperatures may hold to the low and mid 60s Tuesday on area beaches—a little warmer than the widespread 50s observed there Monday. Inland areas, on the other hand, are to see readings flirting with 80-degrees Tuesday and into the low 80s Wednesday from DuPage county westward to the Fox Valley.
Warmth in coming days to boost 2013′s lagging 70-degree count
May’s opening 6 days have averaged 6.7-degrees cooler than the same period a year ago. The lower temps have impacted the area’s 70+degree count as well.
Monday’s 71-degree high at O’Hare and Midway brought to just 6 the total number of 70s on the books in 2013. That’s just over half the normal 11 days of 70s by this date and only a fraction of last year’s nineteen 70s up to May 7.
Rains, some thundery, may total one-half inch—locally more—later this week
A few isolated showers may build in the afternoon warmth Tuesday to the south and east of Chicago. But it’s late Wednesday night through Thursday night which have the best chance of producing rain this week.
An average across a suite of computer model rain projections puts potential late week rainfall here around 0.70″—though the range in predictions from which that average was derived, runs from as little as 0.38 inches to as much as 1.17 inches. That spread may more accurately reflect the range in potential late-week rainfall which is likely to affect the area.
Sharp weekend cooling could produce Mothers Day temps at early April levels Sunday
A sharp temperature pullback from the 70s predicted in coming days takes place this Mother’s Day weekend. The cooling is likely to begin Friday. Daytime highs near 60 Saturday will trend lower with the arrival of strong northerly winds Saturday afternoon and night.
Peak readings Sunday (Mother’s Day itself) may rise no higher than the 50s.
Season’s widest Lower 48 warming to-date indicated by models next week
It’s next week that forecast trends suggest may bring the widest warming of 2013 yet seen across the Lower 48. Chicago temperatures amid gusty SW winds Monday may resurge to within striking distance of 70-degrees while the large area of 80s predicted in the Plains and western Midwest as the next week gets underway on Monday, may offer a clue to what’s ahead for Chicago.