FXUS66 KMFR 252244
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
244 PM PST FRI DEC 25 2009

.SHORT TERM...A STRONG UPPER RIDGE REMAINS OVER THE REGION
HOWEVER AN UPPER TROUGH IS NEARING FROM THE EASTERN PACIFIC. AS
THE UPPER RIDGE WEAKENS AND SHIFTS EAST...THE TROUGH IS EXPECTED
TO SPREAD CLOUDS AND SOME LIGHT RAIN/SNOW ACROSS THE REGION
SATURDAY NIGHT THROUGH SUNDAY. MEANWHILE...CONDITIONS WILL REMAIN
STATUS-QUO. THUS...WE'VE HOISTED ANOTHER DENSE FOG ADVISORY FOR
THE ROGUE BASIN TONIGHT...BUT HAVE NOT INCLUDED THE UMPQUA.
VISIBILITY REMAINED GOOD AT ROSEBURG LAST NIGHT...AND WE DO NOT
EXPECT A SIGNIFICANT IMPACT THERE AGAIN TONIGHT. THE EVENING
SHIFT WILL HAVE TO EVALUATE TRENDS AND DETERMINE IF THE ADVISORY
SHOULD BE EXPANDED. THE FREEZING FOG IN THE ROGUE BASIN WILL AGAIN
RESULT IN ICY SURFACES AND MAYBE SOME EARLY-MORNING SNOW AT THE
MEDFORD AIRPORT PENDING MORE GROUND-BASED FOG SEEDING. THE AIR
STAGNATION ADVISORY CONTINUES UNCHANGED.

FEEL THE NAM12 MIGHT BE THE BETTER MODEL TO FOLLOW WITH THIS
PRECIP EVENT COMING IN LATE SATURDAY THROUGH SUNDAY. IT IS THE
DRIER SOLUTION AND SEEMS MORE REALISTIC GIVEN THE DRY ANTECEDENT
CONDITIONS AND SOUTH TO SOUTHEAST FLOW. THE BEST RAIN/SNOW CHANCES
WILL BE ALONG THE COAST...COAST RANGE...AND SISKIYOU COUNTY. SOME
PRECIP CHANCES WILL CONTINUE MAINLY WEST OF THE CASCADES INTO
MONDAY AS THE UPPER LOW CENTER WRAPS NORTHWARD OFF THE COAST. THE
MODELS ARE STRUGGLING FOR CONSISTENCY IN HOW FAR INLAND THIS LOW
MAKES IT...SO THERE'S NOT A LOT OF CONFIDENCE IN THE FINER DETAILS.
EITHER WAY...THE WHOLE EVENT SHOULD BE LOW QPF AND OF MINOR IMPACT
WITH SNOW LEVELS NEAR THE PASSES. INCOMING CLOUDS AND A LITTLE
WIND SHOULD PREVENT THE WESTERN VALLEY TEMPERATURES FROM FALLING
BELOW FREEZING SATURDAY NIGHT...BUT IT MIGHT BE CLOSE AND THERE IS
A TOUCH OF CONCERN FOR POTENTIAL FREEZING RAIN WHICH BEARS WATCHING.
STAVISH

.LONG TERM...ECMWF AND GFS ARE BOTH IN GOOD AGREEMENT WITH THE
SYSTEM THAT MOVES THROUGH THE REGION TUESDAY NIGHT...WITH ALMOST
IDENTICAL JET PROGNOSIS. BOTH REMAIN IN GOOD AGREEMENT WITH WEAK
RIDGE BUILDING BEHIND THIS SYSTEM ON THURSDAY. THE JET SOLUTION
BEGINS TO VARY A BIT WITH THE EC DIGGING THE JET DOWN A BIT
FARTHER SOUTH...DEEPENING THE UPPER TROUGH MORE THAN THE NEAR
ZONAL GFS SOLUTION. HOWEVER...THE TIMING OF FRIDAYS SYSTEM IS
STILL VERY CLOSE WITH BOTH MODELS AND THIS HAS GIVEN ME GREATER
CONFIDENCE TO WALK UP THE POPS SUBSTANTIALLY ON ALL THE SYSTEMS
THAT ARE MOVING THROUGH THE EXTENDED PERIODS. SVEN

&&

.AVIATION...IFR WILL BE PREVALENT ACROSS THE ROGUE AND UMPQUA
BASINS TONIGHT THROUGH SATURDAY WITH FREEZING FOG AND SOME
MORNING SNOW POSSIBLE DUE TO SEEDING AT THE MEDFORD AIRPORT.
OTHERWISE...VFR AREA-WIDE NEXT 24 HRS.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 4 PM PST SATURDAY FOR ORZ023-
     ORZ024-ORZ025-ORZ026-ORZ029-ORZ030-ORZ031.
     HIGH SURF ADVISORY FROM 9 AM SATURDAY TO 4 PM PST SUNDAY FOR 
     ORZ021-ORZ022.
     DENSE FOG ADVISORY UNTIL 10 AM PST SATURDAY FOR ORZ024-ORZ026.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 
     10 PM THIS EVENING TO 4 AM PST TUESDAY FOR PZZ350-PZZ356-
     PZZ370-PZZ376.

$$