Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 170037
SWOMCD
SPC MCD 170036
MIZ000-170630-

Mesoscale Discussion 0063
NWS Storm Prediction Center Norman OK
0636 PM CST Mon Jan 16 2017

Areas affected...Central and northern Lower Michigan

Concerning...Freezing rain

Valid 170036Z - 170630Z

SUMMARY...Precipitation rates are expected to slowly increase this
evening as temperatures mostly remain below freezing. An initial mix
of precipitation is expected to transition to mostly freezing rain
by late tonight, with rates up to 0.05 inches per hour possible.

DISCUSSION...At 0030Z, a shield of precipitation is slowly advancing
northward across Lower Michigan in advance of an upper trough and
associated low pressure system moving out of the central Plains.
Substantial dry air in the lower half of the troposphere, evident on
the 00Z APX sounding, has limited precipitation rates thus far, but
continued moistening will eventually lead to some increase in
precipitation rates this evening as ascent continues within the
warm-conveyor belt.

An initial mix of precipitation types is expected early this
evening, especially with northward extent, given a relatively weak
warm nose and potential for some evaporative cooling of the column
before saturation is achieved. Continued warm advection should
result in a strengthening warm nose and erosion of the subfreezing
layer near the surface, resulting in a transition to primarily
freezing rain by later this evening. Surface temperatures will be
somewhat marginal, especially across the southern part of the MCD
area, and a slow northward progression of the surface freezing line
will occur as weak but persistent warm advection continues, with an
eventual transition from freezing rain to rain possible from south
to north during the overnight hours.

..Dean.. 01/17/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DTX...APX...GRR...

LAT...LON   43298610 43498644 44038644 44488615 44748606 45068565
            45028517 45008466 44758396 44478346 43958308 43588291
            43278323 43098373 43048427 43058512 43298610



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