MESOSCALE DISCUSSION 0012
   NWS STORM PREDICTION CENTER NORMAN OK
   0744 AM CST TUE JAN 06 2004
   
   AREAS AFFECTED...NWRN OR THROUGH SWRN WA
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 061344Z - 061745Z
   
   SNOW SHOULD GRADUALLY TRANSITION TO FREEZING RAIN FROM SW TO NE
   ACROSS NWRN OR AND SWRN WA THROUGH THE MORNING. PERIODS OF MODERATE
   TO HEAVY SNOW WILL LIKELY PERSIST OVER THE CASCADE RANGE.
   
   THIS MORNING PRECIPITATION CONTINUES TO SPREAD INLAND ALONG WARM
   CONVEYOR BELT DOWNSTREAM FROM UPPER TROUGH OVER THE ERN PACIFIC. AS
   OF 13Z THE PRECIPITATION REMAINED MOSTLY IN THE FORM OF SNOW OVER
   MUCH OF THE AREA. HOWEVER...SNOW WAS BEGINNING TO CHANGE TO FREEZING
   RAIN FROM NEAR EUGENE NWWD THROUGH COASTAL OR. AS THE STRONG 50+ KT
   SSWLY LOW LEVEL JET CONTINUES SHIFTING EWD NEXT SEVERAL HOURS...A
   LAYER OF ABOVE FREEZING AIR WILL ADVECT OVER TOP OF THE VERY COLD
   AND DENSE AIR NEAR THE SURFACE...RESULTING IN SNOW TRANSITIONING TO
   FREEZING RAIN. THE FREEZING RAIN MAY PERSIST INTO THE AFTERNOON IN
   THE WILLAMETTE VALLEY FROM SALEM NEWD THROUGH PORTLAND AND PORTIONS
   OF SWRN WA WHERE THE LOW LEVEL COLD AIR WILL BE SLOWER TO ERODE.
   FARTHER EAST...SNOW SHOULD CONTINUE TO INCREASE ALONG THE CASCADE
   RANGE AS THE LOW LEVEL FLOW VEERS AND STRENGTHENS...ENHANCING
   OROGRAPHIC LIFT.
   
   ..DIAL.. 01/06/2004
   
   
   ATTN...WFO...PDT...SEW...PQR...
   
   43892281 44242363 46262350 46922281 46932148 45682140
   44362174