Latest meso-scale discussion from SPC targets I-80 corridor south for heaviest snowfall

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Mesoscale Discussion 0049
   NWS Storm Prediction Center Norman OK
   0457 PM CST Mon Feb 05 2018

   Areas affected...Portions of far southeastern Iowa into northern

   Concerning...Heavy snow 

   Valid 052257Z - 060300Z

   SUMMARY...Moderate to occasionally heavy snow will continue across
   parts of northern Illinois into northern Indiana for a few more
   hours. Rates up to one inch per hour will be possible.

   DISCUSSION...Regional radar data highlight a progressive, but
   organized band of snowfall extending from southeastern Iowa into
   northwestern Indiana late this afternoon. Satellite and radar data
   suggest that isentropic ascent within the 700-500mb layer is
   fostering efficient ice-crystal production aloft, and forecast
   soundings indicate that modest aggregation processes may also be
   augmenting snowfall rates. These conclusions are consistent with
   radar cross-sections showing an increase in reflectivity and
   decrease in differential reflectivity in the direction towards
   ground (within the heaviest parts of the band). Additionally, while
   the dendritic growth layer is not particularly deep (somewhat
   limiting rates), adequate ascent above 700mb is favorable for
   dendritic/planar crystals, and modest enhancements in KDP are noted
   around 12-17K ft. This microphysical profile should continue to
   yield snowfall rates up to one inch per hour as the band advances
   east. However, rates should gradually diminish later this evening
   and with eastward extent, owing to a decrease in ascent within the
   -10 to -20 C layer.
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