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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