FXUS66 KMFR 261711
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
911 AM PST SAT DEC 26 2009

.DISCUSSION...THE 12Z SOUNDING LOOKS FAIRLY SIMILAR TO YESTERDAY
WITH A MASSIVE INVERSION AND DRY UPPER LEVELS...THOUGH THE UPPER 
WINDS HAVE INCREASED AND COME AROUND SOUTHEAST. MORE LIGHT SNOW
AROUND THE MEDFORD AIRPORT THIS MORNING AS FOG SEEDING EFFORTS
CONTINUE. FOG NOT SO BAD IN THE UMPQUA...WHERE ROSEBURG REPORTS 7
MILE VISIBILITY WITH A LOW CEILING. LOOKS LIKE WE'LL ALLOW THE
ADVISORY TO CONTINUE INTO LATE MORNING AS SCHEDULED. MOST AREAS
OVER THE MOUNTAINS AND WEST ABOVE 2000 FT WILL EXPERIENCE MILD
AFTERNOON TEMPERATURES AND BREEZY SOUTHEAST WINDS. FORECAST MODEL
SOUNDINGS LOOK DRASTICALLY OVERDONE IN THEIR IMPROVEMENT OF THE
STAGNANT BOUNDARY LAYER BY 00Z THIS AFTERNOON - DON'T SEE ENOUGH
DESTABILIZATION CAUSE FOR A GOOD SCOUR-OUT TODAY WEST OF THE
CASCADES. INCREASING SOUTHEAST WINDS SHOULD ALLOW FOR BETTER
VENTILATION MOST AREAS...SO THE AIR STAGNATION WILL LIKELY BE
ALLOWED TO EXPIRE.

RADAR FROM EUREKA IS SHOWING A BROKEN BAND OF 25-35 DBZ ECHOES
OFFSHORE IN ASSOCIATION WITH THE UPPER TROUGH MOVING IN. THE
PRECIP IS ADVANCING SLOWLY. LATEST NAM12 AND GFS SHOW THE PRECIP
ADVANCING TO A LINE FROM NORTH BEND TO MEDFORD TO MT. SHASTA BY 10
PM TONIGHT. AREAS IN THE LEE (THE NORTH SIDE UNDER A SOUTH WIND)
OF HIGHER TERRAIN WILL LIKELY BE SLIGHTED OF PRECIP WITH DOWNSLOPE
FLOW. THE CONCERN HAS BEEN FOR A POTENTIAL FOR FREEZING
PRECIPITATION IN THE WEST-SIDE VALLEYS OF JACKSON...JOSEPHINE...
AND SISKIYOU COUNTIES AS THE PRECIP COMES IN. HOWEVER THE
TEMPERATURES ARE ONLY A COUPLE DEGREES FROM FREEZING AT MID-
MORNING AND WE EXPECT A RISE OF SEVERAL DEGREES THROUGH AFTERNOON.
THEN...WITH AN INCREASING UPPER CLOUD DECK THROUGH LATE AFTERNOON
AND EVENING...THE EVENING COOLING SHOULD BE SLOW. THUS...WE THINK
THE FREEZING RAIN POTENTIAL IS LOW AT THIS TIME...AND THAT TEMPS
IN THE MENTIONED VALLEYS THIS EVENING AND OVERNIGHT WILL HOVER
SOMEWHERE IN THE LOWER 30S. WE MIGHT STILL HAVE A MENTION OF
PATCHY OR LOCAL LIGHT FREEZING RAIN TONIGHT.

IN THE NEAR-TERM, WE'LL NOT BE MAKING ANY CHANGES TO THE FORECAST
THIS MORNING. IN THE AFTERNOON PACKAGE WE'LL TRY TO PERFECT THE
PROBABILITIES FOR PRECIP TONIGHT WITH SNOW LEVELS AND LIGHT SNOW 
ACCUMULATIONS INTO SUNDAY. STAVISH

&&

.AVIATION...IFR IN LOW CLOUDS AND FOG WITH FREEZING FOG OVER THE
WESTERN VALLEYS OF SOUTHWEST OREGON WILL CONTINUE INTO AFTERNOON.
IMPROVING VIS AND SOME BREAKUP INTO EVENING...THROUGH IFR CIGS TO
LIKELY PREVAIL AGAIN THROUGH TONIGHT IN THE ROGUE BASIN. MVFR
CIGS WILL MOVE INTO THE SOUTH COAST THROUGH LATE MORNING AND
REMAIN THROUGH OVERNIGHT WITH LIGHT RAIN SPREADING FROM SW TO INTO
N CAL AND ORE. MTNS BECOMING OBSCURED AND CIGS AREA-WIDE LOWERING
TO MVFR THROUGH TONIGHT.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR ORZ023-
     ORZ024-ORZ025-ORZ026-ORZ029-ORZ030-ORZ031.
     HIGH SURF ADVISORY UNTIL 4 PM PST SUNDAY FOR ORZ021-ORZ022.
     DENSE FOG ADVISORY UNTIL 10 AM PST THIS MORNING FOR ORZ024-
     ORZ026.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 4 PM 
     THIS AFTERNOON TO 4 PM PST SUNDAY FOR PZZ370-PZZ376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST TUESDAY 
     FOR PZZ350-PZZ356-PZZ370-PZZ376.

$$