Area concerning heavy snow this morning
Storm Prediction Center - Current Mesoscale Discussions
NWS STORM PREDICTION CENTER NORMAN OK
0632 AM CST SAT NOV 21 2015
AREAS AFFECTED...NRN IL...CHICAGOLAND...FAR E-CNTRL IA
CONCERNING...HEAVY SNOW
VALID 211232Z - 211630Z
SUMMARY...MODERATE TO OCCASIONALLY HEAVY SNOWFALL WITH SNOWFALL
RATES OVER 1 INCH PER HOUR IS EXPECTED TO PERSIST THROUGH THE
MORNING. SOME LOCALLY HEAVY SNOWFALL IS POSSIBLE ACROSS THE CHICAGO
METRO AREA IF POTENTIAL LAKE ENHANCEMENT IS REALIZED.
DISCUSSION...MODERATE SNOW HAS PERSISTED OVER THE PAST SEVERAL HOURS
ACROSS FAR E-CNTRL IA...NRN IL...AND SRN WI. SEVERAL SITES ALONG THE
IL/IA BORDER REPORTING HAVE INTERMITTENTLY REPORTED HEAVY SNOW.
REFLECTIVITY HAS ALSO SHOW A MODEST INCREASE IN THIS REGION. THESE
OBSERVATIONS INCREASE THE CONFIDENCE THAT OCCASIONALLY HEAVY SNOW
WILL LIKELY OCCUR AS THE SYSTEM CONTINUES TO MATURE -- WITH THE 850
AND 700 MB LOW CENTERS BECOMING MORE VERTICALLY-STACKED -- AND
BECOME MORE NEGATIVELY-TITLED. THIS AREA IS ALSO LOCATED IN THE
FAVORABLE LEFT-FRONT QUADRANT OF THE APPROACHING JET STREAK. IN
ADDITION TO THE EXPECTED INCREASE IN LARGE-SCALE LIFT...SOME
LAKE-ENHANCEMENT IS POSSIBLE AS THE TRAJECTORIES CONTINUE TO BECOME
MORE FAVORABLE OVER SOUTHERN LAKE MICHIGAN. WHILE THE BETTER LAKE
ENHANCEMENT IS EXPECTED THIS AFTERNOON...MESOSCALE BAND MAY LOCALLY
ENHANCE SNOWFALL RATES OVER PORTIONS OF CHICAGOLAND THIS MORNING.