SPC MD 29

MD 0029 CONCERNING WINTER MIXED PRECIPITATION FOR WESTERN OR AND SOUTHWEST WA

Mesoscale Discussion 0029
NWS Storm Prediction Center Norman OK
1120 AM CST Sat Jan 07 2017

Areas affected...Western OR and southwest WA

Concerning...Winter mixed precipitation 

Valid 071720Z - 072315Z

SUMMARY...Light to moderate freezing rain will persist across the
southern Willamette Valley this afternoon with sleet and freezing
rain expected to spread/develop north into portions of southwest WA
later this afternoon.

DISCUSSION...Precipitation is gradually spreading north across OR
ahead of a notable short-wave trough that is quickly approaching the
coast.  Latest water vapor imagery suggests a vort max is located
roughly 100mi west of 4mk and ascent ahead of this feature should
encourage precip to eventually moisten the boundary layer farther
north.  Forecast soundings suggest freezing rain will linger across
the southern valley, and near the coast, well into the evening hours
while sleet will initially be the primary type across the northern
Willamette Valley near the WA/OR border.  Changeover to freezing
rain should occur in the Portland vicinity between 01-03z.

..Darrow.. 01/07/2017

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

ATTN...WFO...PQR...

LAT...LON   43982338 45712329 45722391 46372387 46262266 45462210
            44932260 44012284 43982338 

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