721  
FXUS66 KMFR 182200  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
200 PM PST FRI JAN 18 2019  
   
DISCUSSION
 
18/12Z NAM/GFS/EC IN.  
 
THE HEMISPHERIC VIEW SHOWS A WAVE NUMBER OF FOUR AROUND THE GLOBE.  
NORMALLY THIS IS A PROGRESSIVE PATTERN, AND INITIALLY IT WILL BE.  
HOWEVER, THE PATTERN WILL STALL IN THE EXTENDED PERIOD.  
 
IN THE NEAR TERM IT WILL BE VERY WET AND OCCASIONALLY WINDY WITH  
HIGH SNOW LEVELS. AN UPPER LEVEL RIDGE WILL BREAK TO THE EAST OF  
THE AREA TODAY. A SURFACE WARM FRONT WILL MOVE IN FROM THE  
SOUTHWEST, BRINGING PRECIPITATION TO MOST OF THE AREA LATER TODAY  
INTO TONIGHT. INITIAL RAIN RATES WILL BE LIGHT TO MODERATE.  
 
HOWEVER, THAT WILL CHANGE AS THE UPPER RIDGE MOVES OUT AND  
SOUTHWEST WINDS ALOFT INCREASE OVER THE AREA. THE TRAILING COLD  
FRONT WILL MOVE INTO THE AREA TONIGHT, BUT IT WILL STALL AS IT  
BECOMES PARALLEL TO THE STEERING FLOW. WEAK WAVES WILL FORM AND  
MOVE NORTHEAST ALONG THE FRONTAL BOUNDARY.  
 
THIS WILL MAKE FOR A LONG PERIOD OF SIGNIFICANT PRECIPITATION  
TONIGHT INTO SUNDAY, OCCASIONALLY ENHANCED AS THE FRONTAL WAVES  
MOVE THROUGH. THE HEAVIEST AMOUNTS WILL FALL OVER WESTERN  
SISKIYOU COUNTY AND EXTREME SOUTHWEST OREGON. PRECIPITATION TOTALS  
FROM THIS AFTERNOON THROUGH SUNDAY NIGHT WILL BE IMPRESSIVE. FROM  
THE CASCADES WEST, TOTALS WILL RANGE FROM ONE TO TWO INCHES IN  
THE ROGUE AND SHASTA VALLEYS TO NEARLY 10 INCHES IN THE COAST  
RANGE ABOVE BROOKINGS. A FLOOD WATCH IS IN EFFECT FOR PORTIONS OF  
THE WEST SIDE AS WELL AS THE COQUILLE RIVER AT COQUILLE. SEE  
PDXFFAMFR FOR DETAILS.  
 
WINDS WILL BE A FACTOR AS WELL THIS AFTERNOON INTO SATURDAY  
MORNING, AND MANY AREAS WILL SEE WIND ADVISORY LEVEL WINDS. THERE  
IS ALSO A HIGH WIND WARNING FOR THE COAST, MOSTLY FROM AROUND CAPE  
BLANCO SOUTH. SEE PDXNPWMFR FOR DETAILS.  
 
SNOW LEVELS ARE NOW RISING, AND WILL EXCEED 8000 FEET OVER MOST OF  
THE AREA TONIGHT, REMAINING THERE UNTIL THE FRONT MOVES INLAND.  
 
THE UPPER LEVEL TROUGH WILL APPROACH THE COAST SUNDAY, AND THIS  
WILL UNSTALL THE FRONT AND FORCE IT INLAND. THE HEAVY  
PRECIPITATION WILL DIMINISH, BUT POST-FRONTAL SHOWERS WILL PERSIST  
UNTIL THE UPPER TROUGH, AND THE WAVES DIVING DOWN THE BACKSIDE OF  
IT, CLEAR OUT TO THE EAST MONDAY EVENING. SNOW LEVELS WILL DROP  
DOWN TO 3000-4000 FEET SUNDAY NIGHT, BUT THE HEAVY PRECIPITATION  
WILL BE OVER BY THEN.  
 

 
   
AVIATION...FOR THE 18/18Z TAFS
 
LOW LEVEL WIND SPEED SHEAR WILL BE  
THE MAIN CONCERN TODAY FOR NORTH BEND, ROSEBURG AND MEDFORD. WIND  
SHEAR COULD START OUT AT 1500 AT THE COAST AND MEDFORD LATER THIS  
MORNING, THEN 2000 FEET THIS AFTERNOON. IN THE UMPQUA BASIN,  
INCLUDING ROSEBURG, IT IS EXPECTED TO BE AT 1500 FEET LATER THIS  
MORNING.  
 
THE FREEZING LEVEL ON THE SOUNDING AT MEDFORD WAS 4,900 FEET, BUT  
IT'S EXPECTED TO RISE TO AROUND 7000 FEET LATER THIS MORNING AND  
8500 FEET THIS AFTERNOON.  
 
EAST OF THE CASCADES, WE'RE EXPECTING SNOW TO CONTINUE THIS MORNING,  
BUT A CHANGE OVER TO RAIN IS LIKELY WITHIN THE NEXT 3 HOURS. GIVEN  
THE WARMER ROAD TEMPERATURES AND THE FREEZING LEVEL AROUND 4900  
FEET, WE'RE NOT EXPECTING OVER 1 INCH OF SNOW IN KLAMATH FALLS.  
LIFR WILL PREVAIL UNTIL 1 PM OR SO AS SNOW CONTINUES TO FALL, BUT  
A MIX OF MVFR AND IFR ARE EXPECTED IN THE AFTERNOON.  
 
AS FOR CIGS AND VISIBILITIES TODAY, MVFR AND IFR WILL REMAIN  
DOMINANT IN THE VALLEYS AND ALONG THE COAST. ALL THE ADDED MOISTURE  
IN THE VALLEYS WILL LIKELY RESULT IN MORE IFR FOG FRIDAY NIGHT AND  
SATURDAY MORNING.  
 
-PETRUCELLI/SMITH  
 

 
   
MARINE...UPDATED 130 PM PST FRIDAY 18 JANUARY 2019
 
GALES WILL  
PERSIST IN THE WATERS THIS AFTERNOON THROUGH SATURDAY MORNING. THE  
STRONGEST WINDS WILL OCCUR 5 TO 15 NM AWAY FROM SHORE AND NORTH OF  
CAPE BLANCO. WAVES WILL ALSO REMAIN HAZARDOUS THROUGH THIS WEEKEND  
AS FRESH SWELL AND A HIGH AND STEEP WEST SWELL COMBINE TO CREATE  
HAZARDOUS SEAS. EVENTUALLY, HIGH PRESSURE WILL BUILD SUNDAY AND  
SEAS WILL BEGIN TO SETTLE AROUND THAT TIME. THEY MAY REMAIN  
HAZARDOUS TO SMALLER CRAFTS AT TIMES AS STORM SYSTEMS STILL REMAIN  
PRESENT WELL TO OUR WEST.  
 
SURF HEIGHTS HAVE DROPPED BELOW ADVISORY THRESHOLDS AND WILL  
CONTINUE TO FALL MOVING INTO SATURDAY.  
 
-SMITH  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM PST SATURDAY FOR  
ORZ030-031.  
HIGH WIND WARNING UNTIL 4 AM PST SATURDAY FOR ORZ021-022.  
FLOOD WATCH FROM 4 PM PST THIS AFTERNOON THROUGH LATE SATURDAY  
NIGHT FOR ORZ021-022-024.  
WIND ADVISORY UNTIL 4 AM PST SATURDAY FOR ORZ023-024.  
WIND ADVISORY UNTIL 4 AM PST SATURDAY FOR ORZ026.  
 
CA...FLOOD WATCH FROM 4 PM PST THIS AFTERNOON THROUGH LATE SATURDAY  
NIGHT FOR CAZ080.  
WIND ADVISORY UNTIL 10 AM PST SATURDAY FOR CAZ081.  
 
PACIFIC COASTAL WATERS...GALE WARNING UNTIL 4 AM PST SATURDAY FOR  
PZZ350-356-370-376.  
 

 
 
15/20/11  
 
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