Freeze Watch 2, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
850 AM PST SAT JAN 8 2011

.DISCUSSION...AN UPDATE IS NOT NECESSARY THIS MORNING. THE COLD
FRONT THAT MOVED ACROSS WESTERN OREGON OVERNIGHT AND WEAKENED AND
DURING THE NEXT COUPLE OF HOURS IT WILL EXIT SOUTHEAST SISKIYOU AND
SOUTHERN MODOC COUNTY TO THE SOUTH. IN ITS WAKE...THERE ARE AREAS
OF LOW CLOUDS...AND A WIDE SWATH OF MID-LEVEL CUMULUS CLOUDS
OFFSHORE THAT WILL MOVE INTO SOUTHWEST OREGON FROM THE NORTHWEST
TODAY.

THE 12Z GFS HAS RECENTLY ARRIVED AND IT REMAINS DRIER IN THE LOWER
LEVELS WITH LESS INSTABILITY THAN INDICATED BY THE NAM. THUS...I
WILL LIKELY INCLUDE PATCHES OR AREAS OF VALLEY STRATUS AND FOG FOR
TONIGHT AND SUNDAY NIGHT INTO MONDAY.

A SIGNIFICANT CHANGE IN THE UPPER LEVEL PATTERN STILL LOOKS ON
TRACK TO BEGIN TUESDAY NIGHT WITH A SERIES OF WEATHER SYSTEMS
THROUGH THE END OF THE WEEK.

&&

.AVIATION...MVFR AND LOCAL IFR WILL LINGER THIS MORNING THEN CIGS
SHOULD INCREASE TO VFR IN THE AFTERNOON WITH LOCAL MVFR. MOUNTAINS
REMAIN OBSCURED THROUGH 20Z...THEN PARTLY OBSCURED IN THE
AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 250 AM PST SAT JAN 8 2011/

DISCUSSION...A WEAK COLD FRONT SLOWLY MOVES THOUGH THE AREA THIS
MORNING WITH NOT MUCH IN THE WAY OF PRECIPITATION. ANY PRECIPITATION
WILL BE MOSTLY IN THE MORNING AND VERY LIGHT. A MOIST NORTHWEST FLOW
ALOFT CONTINUES FOR THE REST OF THE WEEKEND WITH A FEW WEAK
DISTURBANCES MOVING THROUGH. THIS WILL BRING SCATTERED LIGHT
PRECIPITATION TO COOS AND DOUGLAS COUNTY AND NORTHERN PART OF THE
CASCADES. ELSEWHERE CONDITIONS SHOULD REMAIN DRY. SNOW LEVELS RANGE
BETWEEN 2500 AND 3000 FT TODAY...THEN LOWERING TO AROUND 2000 FT
TONIGHT. HOWEVER SNOW ACCUMULATIONS WILL BE MINOR DUE TO LIMITED
MOISTURE.

A COLDER AIRMASS WILL MOVE INTO THE AREA TONIGHT RESULTING IN LOWER
MIN TEMPERATURES ESPECIALLY EAST OF THE CASCADES WHERE READINGS WILL
BE IN THE SINGLE DIGITS TO MID TEENS. MEANWHILE TEMPERATURES WEST OF
THE CASCADES WILL BE BELOW FREEZING IN MANY LOCATIONS. THE COAST
COULD ALSO HAVE TEMPERATURES NEAR OR BELOW FREEZING BY SUNDAY
MORNING IF THERE IS ENOUGH CLEARING.

THE MODELS ARE IN GOOD AGREEMENT SHOWING A SHORTWAVE RIDGE BUILDING
INTO SOUTHWEST OREGON SUNDAY NIGHT THROUGH MONDAY. AT THE SAME
TIME...OFFSHORE FLOW DEVELOPS WHICH WILL BRING IN A DRY AND COLDER
AIRMASS. THE MAIN IMPACT WILL BE TEMPERATURES BELOW FREEZING IN MANY
LOCATIONS WEST OF THE CASCADES.

THE MODELS START TO DIFFER BEGINNING TUESDAY. THE EC SUGGEST
MOISTURE WILL START TO MOVE IN FROM THE SOUTHWEST TUESDAY
AFTERNOON...BUT NOT REACHING THE COAST UNTIL TUESDAY EVENING. THE
GFS IS SLOWER WITH MOISTURE HOLDING OFF UNTIL TUESDAY NIGHT. AT ANY
RATE...THIS WILL BE A START OF A CHANGE IN THE PATTERN IN WHICH
WE'LL TRANSITION FROM DRY AND STABLE CONDITIONS TO WET AND STORMY.
WHILE THE DETAILS DIFFER...THE MODELS ARE IN GOOD AGREEMENT IN
BRINGING STRONGER STORMS AND THE POTENTIAL FOR MODERATE TO HEAVY
PRECIPITATION TO OREGON AS EARLY AS NEXT TUESDAY AND LASTING INTO
NEXT WEEKEND.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL
     10 PM PST THIS EVENING FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST THIS EVENING FOR
     PZZ376.

DW