SWOMCD
SPC MCD 170424
IAZ000-MOZ000-KSZ000-NEZ000-170930-
MESOSCALE DISCUSSION 0019
NWS STORM PREDICTION CENTER NORMAN OK
1024 PM CST MON JAN 16 2012
AREAS AFFECTED...PORTIONS KS...SERN NEB...NWRN TO EXTREME N-CENTRAL
MO...EXTREME SRN IA.
CONCERNING...FREEZING RAIN
VALID 170424Z - 170930Z
CORRIDOR OF FREEZING RAIN WITH RATES NEAR .10 INCH/HOUR IS POSSIBLE
FROM BETWEEN MHK-CNK ENEWD ACROSS STJ-FNB CORRIDOR THROUGH ABOUT
07Z...IN TWO SHOTS BETWEEN NOW AN ABOUT 09Z. DURING THAT TIME
FRAME...THREAT ALSO WILL SHIFT/EXPAND ENEWD TOWARD MO/IA BORDER
REGION FROM N OF IRK WWD ACROSS I-35. ISOLATED THUNDER ALSO IS
POSSIBLE...WITH LOCALIZED/SHORT-LIVED ENHANCEMENT OF PRECIP RATES TO
NEAR .25 INCH/HOUR IN THEIR CORES. ISOLATED SLEET AND SNOW ALSO ARE
POSSIBLE...HOWEVER PRIMARY WINTER-PRECIP HAZARD WILL BE ASSOCIATED
WITH FREEZING RAIN.
TWO MAIN PRECIP AREAS IN CLOSE SPATIAL PROXIMITY WILL OFFER
POTENTIAL FOR FREEZING RAIN...
1. PLUME OF CONVECTION IN ELEVATED/LOW-LEVEL WAA REGIME...MOVING
NEWD ACROSS NERN KS AS OF 04Z...MOSTLY BOUNDED BY I-70...SLN AND
FNB. THIS ACTIVITY WILL MOVE ENEWD ACROSS NWRN MO THROUGH 07Z.
2. ANOTHER PRECIP AREA MOVING ENEWD ACROSS HYS/RSL AS OF 04Z AND
EXTENDING NEWD TO NEAR HJH...INCREASING IN COVERAGE/INTENSITY AS IT
IMPINGES ON GREATER LOW-LEVEL MOISTURE WITH EWD EXTENT. THIS AREA
IS STARTING TO MERGE WITH LEADING PRECIP PLUME NW OF MHK.
04Z SFC FREEZING LINE WAS DRAWN FROM LUCAS COUNTY IA SWWD BETWEEN
FNB-STJ...JUST S MHK...TO BETWEEN EWK-HUT. FREEZING LINE WILL SHIFT
SWD TO NEAR OTM-STJ-EWK LINE THROUGH NEXT 2-3 HOURS...RELATED TO
COMBINATION OF POST-FRONTAL CAA AND WET-BULB COOLING AS PRECIP FALLS
INTO INITIALLY LARGE BOUNDARY-LAYER DEWPOINT DEPRESSIONS. TIME
SERIES OF FCST SOUNDINGS SUGGEST STEEPENING MIDLEVEL LAPSE RATES AS
MIDLEVEL DCVA JUXTAPOSES WITH NWRN RIM OF ELEVATED WAA
CONVEYOR...WHILE BASAL INFLOW LAYER NEAR 70-MB LEVEL MOISTENS
FURTHER. THIS PROCESS WILL YIELD ELEVATED MUCAPE AROUND 100-250
J/KG...SOME OF WHICH EXTENDS INTO FAVORABLE THERMAL LAYERS FOR LTG
GENERATION. PRECIP GENERATED IN CAPE LAYER WILL FALL THROUGH
RELATIVELY WARM ZONE AT BASE OF ELEVATED MIXED-LAYER AIR BETWEEN
700-850 MB...MAINLY IN SUPERCOOLED/LIQUID FORM BUT WITH SOME SLEET
POSSIBLE. CHANGEOVER TO SNOW MAY OCCUR FROM W-E AFTER ABOUT
08Z...AS COLUMNAR COOLING SHUNTS DENDRITIC GROWTH LAYER LOWER IN
ELEVATION AGL.
..EDWARDS.. 01/17/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...DMX...EAX...OAX...TOP...
LAT...LON 39409769 39979687 40549542 40879346 40589283 40039408
39179585 39029715 39409769
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