175
FXUS66 KMFR 270919
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
119 AM PST FRI NOV 27 2009
DISCUSSION
COLD FRONT NOW NOW APPROACHING THE CASCADES WILL
MOVE ACROSS THE REMAINDER OF OUR AREA THIS MORNING. COOL AIR
SHOWERS FOLLOW THE FRONT THIS AFTERNOON ENDING TONIGHT AS THE
UPPER LEVEL TROUGH MOVES EAST OF OUR AREA. UPPER RIDGE WILL BUILD
OVER THE PACIFIC NORTHWEST OVER THE WEEKEND. HOWEVER...AS THIS
TAKES PLACE A WARM FRONT WILL MOVE OVER THE TOP OF THE BUILDING
RIDGE PROVIDING SOME LIGHT PRECIPITATION TO NORTHERN OREGON WITH A
SLIGHT CHANCE OF PRECIP SATURDAY ACROSS THE VERY NORTHERN PART OF
OUR AREA.
THE NEXT SYSTEM TO AFFECT OUR REGION WILL BE A WEAK COLD FRONT
THAT WILL MOVE INLAND MAINLY NORTH OF OUR AREA LATER MONDAY AND
MONDAY NIGHT. THERE IS SOME UNCERTAINTY CONCERNING THE WEATHER
FOLLOWING THIS SYSTEM. THE LATEST GFS FORECAST WAS AN EXTREME
OUTLIER WITH ALMOST NO CHANCE OF VERIFYING SO I HAVE DISCOUNTED IT
ALTOGETHER. THE ENSEMBLE MEAN, CANADIAN AND ECMWF INDICATE THAT
THE RIDGE WILL REBUILD TUESDAY AND WEDNESDAY WITH SOME INCREASING
TROUGHINESS AND CHANCE FOR LIGHT PRECIP TOWARDS THURSDAY NIGHT AND
FRIDAY. GIVEN THE UNCERTAINTY OF THE FORECAST AND THE OVERALL
RIDGE PATTERN NEXT WEEK...I HAVE OPTED TO CONTINUE THE WESTSIDE VALLEY
FOG AND LOW CLOUDS/FAIR HIGHER ELEVATIONS AND EASTSIDE FORECAST
WITH LITTLE OR NO CHANCE OF MEASUREABLE PRECIPITATION.
BECAUSE OF THE DOMINANCE OF THE RIDGE AFTER FRIDAY...THE SURFACE THERMAL
TROUGH WILL DEVELOP ALONG THE SOUTH OREGON COAST GIVING RISE TO
HIGHER END SMALL CRAFT WINDS AND SOME HAZARDOUS SEAS IN OUR
COASTAL WATERS. THESE CONDITIONS WILL BE PERSISTENT DURING THE
COMING WEEK.
AVIATION
AREAS OF MVFR CONDITIONS IN SHOWERS THROUGH THE
MORNING PERIOD IS EXPECTED ALONG WITH MOUNTAIN OBSCURATION. AS THE
UPPER TROUGH EXITS OUR AREA THIS AFTERNOON EXPECT VFR CONDITIONS
EVERYWHERE IN SCATTERED TO BROKEN CUMULUS CLOUDINESS.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 10 AM
THIS MORNING TO 10 PM PST THIS EVENING FOR PZZ356.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST SATURDAY
FOR PZZ350-PZZ356-PZZ370.
SMALL CRAFT ADVISORY FOR WINDS FROM 7 AM THIS MORNING TO NOON
PST TODAY FOR PZZ350.
SMALL CRAFT ADVISORY FOR WINDS UNTIL NOON PST TODAY FOR PZZ370.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST SUNDAY FOR PZZ376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY
FOR PZZ376.
DDG
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