|Mesoscale Discussion 11|
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Mesoscale Discussion 0011
NWS Storm Prediction Center Norman OK
0200 PM CST Sun Jan 07 2018
Areas affected...portions of central and northern IL...northwest
Indiana...far eastern IA...northeast MO
Valid 072000Z - 080000Z
SUMMARY...Freezing rain rates around 0.05 inch per 3 hours are
expected this afternoon/early evening. (Corrected MD graphic area).
DISCUSSION...Radar mosaic shows a light precipitation shield from
north-central IL southwestward into the Lower MO Valley early this
afternoon. Kirksville, MO reported around 0.04 inch of freezing
rain during the 17z-18z period with other stations across the
MO/IL/IA tri-state reporting lighter rates. The precipitation is
located within a warm conveyer atop an initially dry/cold boundary
layer. As as shortwave trough over the central/southern Great
Plains moves towards the Ozarks/Northwest Gulf Coastal regions, the
zone of stronger ascent will move into IL from the west as the low
levels saturate. Forecast soundings show an above-freezing layer
centered around the 900-850 mb layer. There is some disagreement
amongst short-term models as to the surface temperature remaining at
or below freezing. However, considerable wet-bulb cooling will
favor freezing rain as the primary precipitation type as
temperatures gradually warm through the upper 20s to near freezing.
The pre-conditioned cold temperatures may facilitate greater ice
accumulation than otherwise would occur as temperatures warm and
become more marginal (around 32 degrees F).
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 40058881 39869052 40179179 40859173 41859062 41988768
41518694 41068698 40718724 40058881
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