FXUS66 KMFR 071106
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
306 AM PST MON DEC 7 2009

.SHORT TERM...AN UPPER TROUGH IS CURRENTLY OVER THE REGION WITH AN
UPPER LOW IS CENTERED NEAR THE COAST OF NORTHERN CALIFORNIA. THIS
LOW IS FORECAST TO MOVE SOUTHEAST INTO CENTRAL CALIFORNIA TODAY.
CURRENT SHOWER ACTIVITY IS LIGHT AND LIMITED TO AREAS IN NORTHERN
CALIFORNIA AND INTO SOUTHEAST OREGON. EXPECT SHOWERS TO REMAIN
LIGHT AND MAINLY ISOLATED TO SCATTERED EAST OF THE CASCADES TODAY
WITH BEST CHANCE OF SHOWERS IN MODOC AND SOUTHEASTERN LAKE
COUNTY. THESE SHOWERS WILL SHIFT EAST OF THE AREA DURING THE EVENING.

COLD NORTHERLY FLOW WILL BRING COLDER THAN NORMAL OVERNIGHT AND
MORNING TEMPERATURES TO THE AREA MONDAY NIGHT INTO TUESDAY
MORNING. A WEAK SHORTWAVE TROUGH IS FORECAST TO MOVE DOWN FROM
CANADA INTO THE AREA TUESDAY. MODELS ARE IN GOOD AGREEMENT SHOWING
THIS DISTURBANCE HAVING LITTLE MOISTURE WITH IT...ONLY BRINGING
SOME CLOUDS TO THE AREA. THE MAIN IMPACT OF THIS DISTURBANCE WILL
BE TO KEEP DRY NORTHERLY FLOW OVER THE AREA TUESDAY INTO TUESDAY
NIGHT WITH CONTINUED COLD OVERNIGHT TEMPERATURES. A WEAK RIDGE
OFFSHORE IS FORECAST TO NUDGE INTO THE PACNW WEDNESDAY AS THE
UPPER TROUGH OVER THE REGION SHIFTS EASTWARD...ALLOWING FLOW
ALOFT TO BECOME NORTHWESTERLY. THIS WILL WARM RIDGE TOP
TEMPERATURES SLIGHTLY. HOWEVER...INLAND VALLEYS WILL LIKELY SEE COLD
AIR CONTINUE INTO THURSDAY MORNING BEFORE MODERATING ON FRIDAY. 

.LONG TERM...AN ACTIVE WESTERLY JET STREAM IS EXPECTED TO BRING A
WET PATTERN INTO CENTRAL AND NORTHERN CALIFORNIA
FRIDAY...EXTENDING INTO SOUTHWEST OREGON ON SATURDAY. THIS WILL
BRING WETTER AND MILDER CONDITIONS AS DISTURBANCES MOVE INTO THE
REGION FROM THE PACIFIC. THE GFS AND ECMWF BOTH SHOW THIS PATTERN
CONTINUING INTO EARLY NEXT WEEK.

&&

.AVIATION...THIS MORNING...VFR CONDITIONS EXCEPT AREAS OF MVFR
CIGS AND LOCALIZED IFR ASSOCIATED WITH ISOLATED TO SCATTERED LIGHT
SNOW SHOWERS OVER NORTHERN CALIFORNIA AND EAST OF THE CASCADES IN
OREGON. THEN EXPECT MVFR CIGS TO BECOME ISOLATED DURING THE
AFTERNOON INTO THE EVENING AS SHOWERS DECREASE. AREAS OF MOUNTAIN
OBSCURATIONS WILL CONTINUE OVER NORTHERN CALIFORNIA AND FROM THE
CASCADES EAST IN SOUTHERN OREGON TODAY...BECOMING ISOLATE IN THE
AFTERNOON INTO THE EVENING.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FREEZE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY MORNING FOR 
     ORZ021-ORZ022.
     FREEZE WARNING UNTIL 9 AM PST THIS MORNING FOR ORZ021-ORZ022.
     FREEZE WARNING FROM 11 PM THIS EVENING TO 9 AM PST TUESDAY FOR 
     ORZ021-ORZ022.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS 
     UNTIL 10 AM PST THURSDAY FOR PZZ350-PZZ356-PZZ370-PZZ376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST THIS EVENING FOR 
     PZZ370-PZZ376.

$$

CC