FXUS66 KMFR 222318
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
318 PM PST TUE DEC 22 2009

.DISCUSSION...
SNOW SHOWERS ARE WINDING DOWN ACROSS THE AREA THIS
EVENING...THOUGH WE DID JUST RECENTLY GET SOME SNOW PELLETS HERE
AT THE MEDFORD AIRPORT FOR A LITTLE HOLIDAY CHEER. WITH THE JET STREAM
PUSHING ACROSS THE MOUNTAINS AND EAST SIDE THIS AFTERNOON AND EVENING
THERE IS SOME CONCERN FOR SOME BLOWING SNOW...PRIMARILY ABOVE 4500
FEET IN THE HIGHER MOUNTAINS WHERE WINDS WILL BE STRONGEST AND
SNOW DENSITIES WERE THE LOWEST. IN FACT...THERE APPEARS TO BE A
BLIZZARD GOING ON NEAR AND ABOVE TREELINE ON MOUNT SHASTA AT THIS
TIME. EARLIER...GREY BUTTE GUSTED TO 85 MPH AT 8000 FEET.

FOR LOWER ELEVATIONS TONIGHT WILL BE THE TRANSITION FROM THE COLD
POLAR EXPRESS THAT MOVED THROUGH IN THE LAST 24 HOURS TO THE
INFAMOUS VALLEY INVERSION WITH FIG AND FREEZING FOG. DUE TO
LINGERING WIND ALOFT AND A BUILDING INVERSION EXPECT THAT THE FOG
THAT FORMS TONIGHT WILL TAKE A WHILE TO FORM
AND...THEREFORE...WILL BE LIMITED ACROSS THE WEST SIDE VALLEY ON
WEDNESDAY. HOWEVER...TOMORROW NIGHT THROUGH AT LEAST THE MORNING
OF THE 26TH IT APPEARS THAT FOG AND FREEZING FOG...CENTERED IN THE
ROGUE...UMPQUA...AND ILLINOIS VALLEYS AT MEDFORD...ROSEBURG...AND
GRANTS PASS IS LIKELY TO BE A MORE SIGNIFICANT PROBLEM. IT WILL BE
LOCALLY DENSE...MAY CREATE SOME SLICK SPOTS ON AREA ROADWAYS...AND
WILL BE A HAZARD TO AVIATION. IT IS LIKELY THAT THE CENTERS OF
THESE FOG AREAS WILL HAVE DIFFICULTY SHAKING THE FOG DURING FROM
THE 24TH THROUGH THE 26TH...AS THE INVERSION WILL BE VERY STRONG.

THEREAFTER MODEL GUIDANCE CONTINUES TO INDICATE THAT THE STORM
APPROACHING THIS WEEKEND WILL WEAKEN AND POSSIBLY FIZZLE OR GO
SOUTH. WHILE A BREAKDOWN IN THE HIGH PRESSURE RIDGE WILL COMMENCE
AFTER CHRISTMAS DAY IT APPEARS THAT IT WILL TAKE UNTIL SOMETIME
BETWEEN 27TH AND THE 30TH FOR PRECIPITATION TO PUSH ACROSS THE
REGION. THEREAFTER...SIGNALS ARE VERY MIXED.

&&

.AVIATION...
VFR CONDITIONS EXIST ACROSS MOST VALLEY LOCATIONS THIS
AFTERNOON...EXCEPT ALONG THE NORTH SLOPES AND CRESTS OF THE HIGHER
TERRAIN WHERE PARTIAL TO TOTAL TERRAIN OBSCURATIONS EXIST. SNOW
SHOWERS WILL CONTINUE TO WIND DOWN AND CLOUDS WILL DIMINISH. WEST
SIDE FOG IS EXPECTED TONIGHT ACROSS INLAND AREAS...MAINLY IN THE
ILLINOIS...ROGUE...AND UMPQUA VALLEYS. THIS FOG IS LIKELY TO BE
SLOW TO FORM DUE TO LINGERING WIND AND COLD AIR ALOFT
TONIGHT...AND IS MORE LIKELY TO FORM MORE TOWARD SUNRISE INTO THE
EARLY MORNING. EXPECT ALL AREAS EXCEPT POSSIBLY GRANT PASS TO GET
OUT OF THE FOG WEDNESDAY AFTERNOON. SUFFICE IT TO SAY THAT FOG
AND FREEZING FOG IS LIKELY TO BECOME MORE OF A PROBLEM ON THE 24TH
AND 25TH AS THE INVERSION STRENGTHENS.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FROST ADVISORY FROM 10 PM THIS EVENING TO 9 AM PST WEDNESDAY FOR 
     ORZ021.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS 
     UNTIL 4 AM PST WEDNESDAY FOR PZZ350-PZZ356-PZZ370-PZZ376.

$$

PUBLIC AND SHORT TERM: LUTZ
LONG TERM AND FIRE: SVEN
MARINE AND AVIATION: SUGDEN AND SVEN