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[Printable]
950
FXUS66 KMFR 231215
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
515 AM PDT WED APR 23 2014

.DISCUSSION...CURRENT WATER VAPOR IMAGE SHOWS WEAK RIDGING BUILDING
OVER THE AREA. THIS WILL BRING A BRIEF BREAK IN PRECIPITATION INTO
EARLY THIS MORNING. A WARM FRONT IS ON IT`S WAY AND STEADY
PRECIPITATION WILL RETURN ALONG THE COAST LATE THIS MORNING, THEN
SPREADING INLAND THIS AFTERNOON. THE NAM AND GFS DIFFER WHERE THE
HEAVIEST PRECIPITATION WILL BE. CURRENT THINKING IS THAT MOST OF IT
WILL BE ALONG THE COAST, COASTAL MOUNTAINS AND NORTHERN CASCADES.
SNOW LEVELS WILL INCREASE ABOVE ALL PASS LEVELS TO 6000-6500 FEET BY
THIS AFTERNOON AND WILL REMAIN BETWEEN 6000-6500 FEET THROUGH
TONIGHT WITH THE WARM FRONT LIFTING NORTH OF THE AREA.

WHATEVER WEAK RIDGING IS LEFT WILL SHIFT EAST AND AN UPPER TROUGH
WILL MOVE INTO THE AREA THURSDAY. THIS WILL SEND A COLD FRONT INTO
THE NORTHWEST PART OF THE FORECAST AREA THURSDAY MORNING, THEN PUSH
SOUTHEAST DURING THE DAY. SNOW LEVELS START OUT NEAR 6000 FEET, BUT
WILL LOWER TO AROUND 5000-5500 FEET BY LATE AFTERNOON WITH THE
COOLEST AIR MASS STILL OFFSHORE BY THEN. GUSTY WINDS ARE EXPECTED
EAST OF THE CASCADES, BUT WERE NOT EXPECTING THEM TO REACH ADVISORY
CRITERIA. LATER SHIFTS MAY NEED TO TAKE ANOTHER LOOK AT THIS.

A BROAD UPPER TROUGH WILL DIG OFFSHORE THURSDAY NIGHT WITH A STRONG
SHORTWAVE ROTATING AROUND THE BASE OF THE TROUGH BY FRIDAY MORNING.
AT THE SAME TIME COLD AIR ALOFT WITH 500 MB TEMPS BETWEEN -28 AND
-31 C WILL MOVE INTO SOUTHWEST OREGON. THE MODELS ALSO SUGGEST MID
LEVEL LAPSE RATES BETWEEN 7-8 DEGREES C/KM MOVING IN. FOR THE
REASONS NOTED ABOVE, WOULD NOT BE SURPRISED IF THERE ARE ISOLATED
THUNDERSTORMS ALONG THE WATERS INTO SOUTHWEST OREGON AND NORTHERN
CAL, SO PUT IN A SLIGHT CHANCE MENTION IN THE FORECAST.

FRIDAY SHOULD BE MUCH LIKE TUESDAY WITH SCATTERED SHOWERS OVER MOST
OF THE AREA AS THE UPPER TROUGH MOVES OVERHEAD ALONG WITH COLD AIR
ALOFT. THE UPPER TROUGH WILL CONTINUE TO DIG SOUTHEAST AND WEAK
RIDGING WILL BUILD IN FRIDAY NIGHT INTO SATURDAY. ANOTHER FRONTAL
BOUNDARY WILL BE OFFSHORE AND THE EC AND GFS ARE IN SIMILAR
AGREEMENT BRINGING THAT INTO THE AREA SATURDAY NIGHT. IF THIS
REMAINS CONSISTENT, THEN WE COULD CATCH A BREAK IN THE WEATHER WITH
LITTLE OR NO PRECIPITATION ON SATURDAY. HAVE TRENDED POPS DOWNWARD TO
REFLECT THIS, BUT THEY MAY NEED TO BE ADJUSTED DOWN FURTHER.
-PETRUCELLI


&&

.AVIATION...BASED ON 23/12Z TAF CYCLE...LIGHT PRECIPITATION WILL
SLOWLY INCREASE WEST OF THE CASCADES TODAY...WITH GENERALLY VFR
CONDITIONS EXPECTED TO DECREASE WEST OF THE CASCADES BY MID TO LATE
AFTERNOON AS THE NEXT FRONT ENTERS THE REGION LATER TODAY. AS A
RESULT...RAIN...MVFR CEILINGS...AND LOW LEVEL MOUNTAIN OBSCURATION
WILL RETURN DURING THE LATE AFTERNOON AND EVENING...MOSTLY ALONG AND
WEST OF THE CASCADES. GUSTY WINDS...SHOWERS AND MOSTLY VFR
CONDITIONS WILL PREVAIL OVER THE EAST SIDE AS WELL AS THE COAST AND
COASTAL WATERS. FREEZING LEVELS OVER AROUND 3500 FT WILL RISE TO
NEAR 5000 FT BY THIS AFTERNOON. -SVEN

&&

.MARINE...UPDATED 0515 AM PDT. WEST SWELLS OF AROUND 10 FEET WILL
CONTINUE TO PRODUCE STEEP SEAS OVER MUCH OF THE AREA THROUGH
WEDNESDAY. WINDS WILL SHIFT TO SOUTH AND START TO INCREASE LATER
THIS MORNING AS A STRONGER FRONTAL SYSTEM APPROACHES. SOUTH WINDS
WILL INCREASE TO GALE FORCE LATE MORNING AS A COLD FRONT GOES
THROUGH. WINDS DECREASE BRIEFLY LATER TODAY BUT THEN PICK UP AGAIN
TONIGHT INTO THURSDAY AS A STRONG FRONT MOVES THROUGH. WINDS WILL
LIKELY BE ACCOMPANIED BY VERY STEEP SEAS AS WIND WAVES AND CONTINUED
WEST SWELL BUILD INTO HIGH, CONFUSED AND CHOPPY SEAS. ANOTHER FRONT
WILL BRING STRONG WINDS AND STEEP SEAS TO
THE REGION THIS WEEKEND AS WELL. SVEN

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM
THIS
     MORNING TO 11 AM PDT THURSDAY FOR PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING FROM 11 AM THIS MORNING TO 11 AM PDT
     THURSDAY FOR PZZ350-356-370-376.
     GALE WARNING FROM 11 AM THIS MORNING TO 11 AM PDT THURSDAY FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM PDT
THURSDAY
     FOR PZZ356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM PDT THIS
     MORNING FOR PZZ350-370-376.

$$









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