Slow moving upper air low pressure forecast to spin up over Midwest this weekend and linger into first days of next with with cool, frequently cloudy weather and instability showers
Disturbance moving toward the Chicago area
A northeast-bound disturbance, whose cloud shield can be seen on satellite imagery making a move toward the Chicago area from downstate Illinois and Indiana is to usher clouds into the area Thursday overnight. Its northernmost showers are modeled to spread northward reaching Chicago toward morning and into the early and possibly mid-afternoon hours Friday.
A POWERFUL 165 MPH JET STREAM SPEED MAX IS DIVING SOUTHWARD OUT OF BRITISH COLUMBIA IN WESTERN CANADA AND TO CARVE OUT A STUBBORN UPPER AIR LOW
The reservoir of cold, unstable air aloft accompanying it sets the stage for a long advertised new multi-day round of clouds and instability showers beginning Saturday and lingering into Tuesday. By extinguishing the late April sun, temps here will take a hit with daytime highs, which could reach the low 60s Saturday, dropping to 51 Sunday, 47 Monday and 53 Tuesday.
Breaks in the overcast the from Wednesday forward permit warming—but modeling suggest more substantial warming is a good bet in the week which follows next. The early read is ABOVE NORMAL TEMPS are to take up residence here beginning a week from Monday or Tuesday with daytime highs likely to reach the 70s then.
VIEW SLIDESHOW OF DEVELOPMENT
May Temperatures in Chicago
AS POINTED OUT YESTERDAY, a survey of May temp records here shows May to be a month still capable of cool periods–but with a MUCH GREATER POTENTIAL FOR WARM SPELLS. Chances for 80-degree temps surge to 99%, to 90% for one or more 85-degree temps and even a 49% chance for the year’s first 90-degree temps.