AREAS AFFECTED...CNTRL/ERN/SRN WI...FAR NERN IA...PARTS OF FAR NRN
IL...FAR SRN PART OF THE UPPER PENINSULA OF MI
CONCERNING...BLIZZARD
VALID 201728Z - 202330Z
SUMMARY...BLIZZARD CONDITIONS WILL OVERSPREAD THE AREA THIS
AFTERNOON.
DISCUSSION...FRONTOGENESIS WITHIN THE DEFORMATION ZONE OF THE LARGE
EXTRATROPICAL CYCLONE OVER THE SWRN GREAT LAKES REGION IS BEING
LOCALLY ENHANCED INVOF A SECONDARY VORT MAX NEARING THE W END OF
LAKE MICHIGAN N OF CHICAGO PER WATER VAPOR LOOPS. MODERATE TO
LOCALLY HEAVY SNOW IS ONGOING ACROSS PARTS OF CNTRL/SRN WI...AND
SNOWFALL INTENSITY WILL INCREASE AS A 985-MB SFC LOW N OF PEORIA IL
DEEPENS AND TRACKS TOWARD CHICAGO. SNOWFALL RATES OF 1-1.5 IN/HR
WILL BECOME LIKELY BY 1830-1900Z...HIGHEST SE OF A LINE FROM AROUND
GREEN BAY WI TO FAR NERN IA. CONVECTIVELY ENHANCED SNOW RATES MAY
OCCUR IN ASSOCIATION WITH NARROW ELEVATED CAPE LAYERS PER FORECAST
SOUNDINGS...WHICH MAY SUPPORT AN ISOLATED LIGHTNING STRIKE OR TWO.
NNELY TO NWLY WINDS WILL CONTINUE TO STRENGTHEN OWING TO THE
TIGHTENING SFC PRESSURE GRADIENT OVER THE WRN/NRN QUADRANTS OF THE
SFC LOW...WITH SPEEDS OF 25-35 MPH AND GUSTS REACHING 40-50 MPH
BECOMING COMMON BY 20Z. THE STRONGEST WINDS MAY...AT TIMES...LAG
SLIGHTLY TO THE W OF THE HIGHEST SNOWFALL RATES. HOWEVER...EVEN
LIGHT SNOW AND FRESHLY FALLEN SNOW WILL COMBINE WITH THE STRONG
WINDS TO CREATE BLIZZARD CONDITIONS WITH VISIBILITIES BELOW
ONE-QUARTER MILE.
..COHEN.. 12/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MQT...GRB...LOT...MKX...DVN...ARX...
LAT...LON 43049136 43299129 44129082 45188947 45558791 45468697
44948695 44118757 42778851 42478929 42409016 42439070
42599108 43049136
