AREAS AFFECTED...NWRN INDIANA...NRN/CNTRL/W-CNTRL IL...PARTS OF
E-CNTRL/SERN/S-CNTRL MO
CONCERNING...WINTER MIXED PRECIPITATION
VALID 130017Z - 130615Z
SUMMARY...WINTER MIXED PRECIPITATION WILL INCREASE IN COVERAGE AND
INTENSITY THIS EVENING. THIS WILL INCLUDE THE THREAT FOR FREEZING
RAIN WITH RATES OF 0.05 TO 0.10 IN/HR...WITH LOCALLY HIGHER RATES
ALSO POSSIBLE. FREEZING RAIN WILL BECOME INCREASINGLY LIKELY IN THE
CHICAGO AND ST. LOUIS AREAS AFTER 04Z.
DISCUSSION...A LARGE SHIELD OF CONVECTIVE-DEBRIS-RELATED
PRECIPITATION WITHIN A WARM CONVEYOR BELT WILL CONTINUE TO
OVERSPREAD THE AREA THIS EVENING. THIS ACTIVITY SHOULD PERSIST THE
OVERNIGHT HOURS AS ELEVATED WARM ADVECTION OCCURS THROUGH THE
NIGHT...WITH A TENDENCY FOR HIGHER PRECIPITATION RATES TO SHIFT NEWD
IN TANDEM WITH THE STRONGER ASCENT.
AS SUBFREEZING SFC-LAYER TEMPERATURES UNDERCUT THE ELEVATED WARM
ADVECTION...THE LEADING EDGE OF WINTER MIXED PRECIPITATION WILL
ADVANCE ESEWD ACROSS THE REGION. IMMEDIATELY BEHIND THIS LEADING
EDGE...A 40-70-MILE WIDE CORRIDOR OF POTENTIAL FREEZING RAIN WILL BE
ASSOCIATED WITH LIQUID-EQUIVALENT RATES OF 0.05-0.10 IN/HR. LOCALLY
HIGHER RATES MAY OCCUR OWING TO A MODEST CONVECTIVE ENHANCEMENT
ASSOCIATED WITH NARROW ELEVATED CAPE PROFILES. THE FREEZING-RAIN
CORRIDOR WILL LIKELY MOVE INTO NWRN INDIANA BY 07Z.
SENSIBLE HEAT FLUXES ASSOCIATED WITH PREVIOUSLY FALLEN LIQUID MAY
INITIALLY DELAY THE ONSET OF ICING ON MANY SURFACES...ASIDE FROM
ELEVATED/METAL SURFACES. REGARDLESS...OBSERVATIONS UPSTREAM ACROSS
CNTRL MO INTO NERN OK INDICATE PERSISTENT FREEZING RAIN
OCCURRING...AND SFC ICING WILL BE LIKELY.
TO THE WNW OF THE FREEZING-RAIN CORRIDOR...DEEPER COLD AIR WILL
LIMIT/PRECLUDE MELTING OF DESCENDING HYDROMETERS AND SUPPORT SLEET
AND LIGHT TO OCCASIONALLY MODERATE SNOW. REMAINING PRECIPITATION
WILL PROGRESSIVELY TRANSITION TO SLEET/SNOW FROM WNW TO ESE DURING
THE OVERNIGHT HOURS...ESPECIALLY ACROSS NRN IL. PRECIPITATION RATES
ARE EXPECTED TO DECREASE AREA-WIDE BY 09Z AS STRONGER FORCING FOR
ASCENT SHIFTS NE OF THE AREA.
PLEASE REFERENCE MCD 16 FOR ADDITIONAL DETAILS REGARDING ONGOING
WINTER MIXED PRECIPITATION ACROSS NERN OK...SERN KS...CNTRL MO...AND
W-CNTRL IL.
..COHEN.. 01/13/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...LOT...ILX...LSX...DVN...SGF...
LAT...LON 42428783 41838762 41628732 41668710 41638697 41398697
41168716 40538755 39478833 38798905 37649004 36759171
36519342 36659386 36919364 37599270 38429166 39459025
40098976 40779025 41449012 41868981 42368904 42428783
