Hazardous Seas Warning 52, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
244 PM PST SAT NOV 10 2012

.SHORT TERM...AS THE COLD TROUGH CONTINUES TO SHIFT EASTWARD AND
WEAK HIGH PRESSURE BUILDS INTO THE AREA TODAY INTO
TONIGHT...EXPECT DIMINISHING SHOWER ACTIVITY. ISOLATED TO
SCATTERED SHOWERS ARE CONTINUING OVER THE AREA THIS AFTERNOON AND
ARE EXPECTED TO DIMINISH OVERNIGHT. EXPECT COLD TEMPERATURES
ACROSS THE AREA TONIGHT WITH AREAS OF FOG POSSIBLE...ESPECIALLY
FOR INLAND WEST SIDE VALLEYS.

THEN...THE NEXT FRONTAL SYSTEM WILL PUSH TOWARDS THE COAST
TOMORROW. THIS SYSTEM WILL BRING INCREASING CLOUDS INTO THE AREA
SUNDAY MORNING WITH AREAS OF LIGHT RAIN EXPECTED TO DEVELOP ALONG
THE COAST DURING THE DAY SUNDAY. PRECIPITATION IS FORECAST TO
SPREAD INLAND INTO AREAS FROM THE CASCADES WEST SUNDAY EVENING.
SNOW LEVELS ARE EXPECTED TO RISE LATE SUNDAY AFTERNOON INTO EARLY SUNDAY
EVENING TO 4000 TO 6000 FEET. HOWEVER...PRECIPITATION EAST OF THE
CASCADES WILL LIKELY BEGIN LATE IN THE EVENING AND OVERNIGHT WITH
SNOW LEVELS AT VALLEY FLOORS. LIGHT SNOW IS LIKELY MONDAY MORNING
FOR EAST SIDE AREAS. THEN SNOW LEVEL GRADUALLY RISE IN THE LATE
MORNING AND AFTERNOON TO 5500 TO 6000 FEET. LIGHT SNOW MAY BRING
1 TO 3 INCHES OF SNOW ACCUMULATION TO EAST SIDE AREAS SUNDAY NIGHT
AND MORNING MORNING. LOWER SNOW LEVELS ARE ALSO POSSIBLE IN THE
MOUNT SHASTA AREA SUNDAY NIGHT AND MONDAY...HOWEVER PRECIPITATION
IS EXPECTED TO BE VERY LIGHT.

MODELS HAVE DIFFERED ON HOW QUICKLY SNOW LEVELS WILL
RISE...ESPECIALLY FOR AREAS EAST OF THE CASCADES. THE 12Z GFS
SHOWS A WARM LAYER ALOFT MOVING INTO THE AREA MONDAY MORNING AND
INDICATES A SLIGHT CHANCE FOR SLEET BRIEFLY BEFORE SNOW CHANGES
OVER THE RAIN FOR LOCATIONS EAST OF THE CASCADES. HOWEVER SINCE
THE GFS SHOWS THE DEW POINT ALOFT REMAINS AT OR BELOW FREEZING
OVER THESE AREAS...THINK THAT SNOW CHANGING TO RAIN IS MORE
LIKELY. ALSO THE NAM AND ECMWF SHOW A COOLER LAYER AT OR BELOW
FREEZING ALOFT MONDAY MORNING INDICATIVE OF SNOW. HAVE KEPT SNOW
LEVELS NEAR VALLEY FLOORS EAST OF THE CASCADES MONDAY MORNING WITH
SNOW LEVELS GRADUALLY RISING MONDAY AFTERNOON.

MODELS HAVE ALSO SHOWED VARIABILITY ON THE AMOUNT OF PRECIPITATION
WITH THIS FRONT. OVERALL MODELS INDICATE LIGHT PRECIPITATION EAST OF
THE CASCADES WITH LIGHT TO MODERATE PRECIPITATION FROM THE
CASCADES WEST. HAVE LEANED TOWARDS A BLEND OF THE ECMWF AND NAM.
THE GFS SHOWS DECREASING ACTIVITY ACROSS THE CWA BY MONDAY EVENING
AND NIGHT WHILE THE SREF...ECMWF...AND NAM INDICATE CONTINUED
LIGHT SHOWERS AS THE FRONTAL BOUNDARY LINGERS OVER THE AREA AND
GRADUALLY WEAKENS. HAVE KEPT THE CHANCE OF PRECIPITATION HIGHER
CORRESPONDING TO THE ECMWF AND NAM DURING THIS PERIOD.

ON TUESDAY...THE AREA IS IN A ZONAL FLOW PATTERN WITH A FLAT RIDGE
CENTERED TO THE SOUTH AND AN UPPER TROUGH WELL OFFSHORE. MODELS ARE
IN AGREEMENT SHOWING A WEAK DISTURBANCE MOVING INTO THE COAST AND
ACROSS AREAS NORTH OF THE CWA. EXPECT SOME AREAS OF RAIN POSSIBLE
ALONG THE COAST. ACROSS INLAND AREAS THOUGH...EXPECT DECREASING
CHANCES FOR SHOWERS BY TUESDAY AFTERNOON AND EVENING.

.LONG-TERM...WEDNESDAY THROUGH SATURDAY...BOTH THE GFS
AND EC SUGGEST SOME RIDGING OVER THE REGION WEDNESDAY AHEAD OF AN
OFFSHORE...NEARLY CUT OFF LOW. THEREFORE...SOME WARMING IS EXPECTED
MOST PLACES AND INCREASED CHANCES FOR MORNING FOG IN THE VALLEYS. WE
ARE TRENDING TOWARD THE SEASON FOR SIGNIFICANT AND LONG-LASTING
FOG...SO EXPECT FOG TO CLEAR OFF LATE MORNING OR EARLY AFTERNOON.
THE OFFSHORE LOW OPENS UP SOME THURSDAY NIGHT AND BOTH MODELS AGREE
THAT SOME PRECIPITATION WILL SPREAD INTO THE FORECAST AREA...FROM
SOUTH TO NORTH. WINTER WEATHER IMPACTS SHOULD BE MINIMAL GIVEN THAT
THE QPF AMOUNTS PROBABLY WILL REMAIN BELOW A QUARTER INCH FOR MOST
PLACES...AND MORE IMPORTANTLY THE SNOW LEVEL SHOULD BE ABOVE 5000
FEET MSL IN MOST PLACES.  MODELS DIVERGE LATE NEXT WEEK AND INTO THE
WEEKEND...WITH THE GFS FASTER WITH A WET SYSTEM MOVING IN SATURDAY
MORNING...AND THE ECMWF STAYING DRY THROUGH SATURDAY.  WE HAVE
DECIDED TO NUDGE TOWARD THE ECMWF...BUT KEPT MOST POPS NEAR CLIMO TO
GIVE SOME CREDENCE TO THE GFS. /SK

&&

.AVIATION...THE REGION IS DRYING TODAY AFTER SEVERAL DAYS OF
SHOWERS...LOW CEILINGS...AND LOW VISIBILITY. TODAY EXPECT A FEW
SHOWERS WEST OF THE CASCADES AND GENERALLY VFR CONDITIONS WITH
OCCASIONAL MVFR CEILINGS IN SHOWERS. MOUNTAIN OBSCURATION WILL BE
LIMITED TODAY TO THE HIGHEST TERRAIN...BUT TONIGHT MOUNTAIN
OBSCURATION WILL RETURN TO MOST OF THE AREA. ADDITIONALLY...THERE
IS THE POTENTIAL FOR IFR CONDITIONS IN FOG TONIGHT OVER WEST SIDE
VALLEYS. THE EAST SIDE SHOULD REMAIN VFR IN A VERY DRY AIR MASS.
/SK

&&

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

CA...NONE.

PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 10 AM TO 10 PM PST SUNDAY
     FOR PZZ350-356.
     GALE WARNING FROM 10 PM SUNDAY TO 10 AM PST MONDAY FOR
     PZZ350-356.
     HAZARDOUS SEAS WARNING FROM 10 AM SUNDAY TO 1 PM PST MONDAY FOR
     PZZ350-356.
     SMALL CRAFT ADVISORY FOR WINDS FROM 4 AM TO 4 PM PST SUNDAY FOR
     PZZ370.
     GALE WARNING FROM 4 PM SUNDAY TO 10 AM PST MONDAY FOR PZZ370.
     HAZARDOUS SEAS WARNING FROM 4 AM SUNDAY TO 1 PM PST MONDAY FOR
     PZZ370-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 7 AM TO 4 PM PST SUNDAY FOR
     PZZ376.
     GALE WARNING FROM 7 PM SUNDAY TO 10 AM PST MONDAY FOR PZZ376.

CC