Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 050353
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
853 PM PDT FRI SEP 4 2015

.UPDATE...COLD AIR MOVING IN PLACE THIS TONIGHT IS BRINGING
LOWERED SNOW LEVELS. SNOW LEVELS HAVE ALREADY DROPPED TO AROUND
6500 FEET BASED ON OBSERVATIONS NEAR CRATER LAKE. SNOW LEVELS ARE
EXPECTED TO LOWER DOWN TO AROUND 6000 TO 6500 FEET OVER MOST THE
AREA WITH SNOW LEVELS LOCALLY DOWN TO 5500 FT IN THE SOUTHERN
OREGON CASCADES. THIS MAY BRING A  LIGHT DUSTING OF SNOW IN
CONTINUED LIGHT SHOWERS TONIGHT OVER THE HIGHER CASCADES AND FOR
HIGHER MOUNTAINS EAST OF THE CASCADES.

&&

.PREV DISCUSSION... /ISSUED 832 PM PDT FRI SEP 4 2015/

SHORT TERM...SHOWERS HAVE BEGUN TO DECREASE ON WEST SIDE WITH
MOST THE ACTIVITY FROM THE CASCADES EAST AND ISOLATED
THUNDERSTORMS HAVE ALSO DECREASED AND BECOME LIMITED TO EAST SIDE
AREAS. MODELS CONTINUE TO SHOW THAT SHOWER WILL SHIFT EAST IN
RESPONSE TO THE UPPER LOW GRADUALLY MOVING INTO EASTERN OREGON
TONIGHT, THEN BECOMING CENTERED NORTHEAST OF THE CWA ON SATURDAY.
SOME LINGERING SHOWERS AND CLOUDS ARE EXPECTED ON THE BACKSIDE OF
THE TROUGH MAINLY ALONG THE CASCADES AND SISKIYOUS TONIGHT AND
OVER PORTIONS OF THE EAST SIDE, MAINLY LAKE AND MODOC COUNTIES,
TONIGHT INTO EARLY SATURDAY MORNING.

MODELS CONTINUE TO SHOW DECREASING CLOUD COVER BY EARLY MORNING
SATURDAY AND HAVE TRENDED QUICKER WITH THE SHOWER ACTIVITY MOVING
EAST OF THE AREA BY EARLY SATURDAY AFTERNOON. THE CLEARING SKIES
COMBINED WITH COLD AIR ADVECTION AND WINDS BECOMING LIGHT IS
EXPECTED TO BRING A FROST RISK FOR EASTERN VALLEYS SATURDAY
MORNING. THEN TEMPERATURES WILL WARM DURING THE DAY INTO THE 70S
FOR WEST SIDE VALLEYS AND INTO THE 60S FOR EAST SIDE VALLEYS.
THESE TEMPERATURES WILL BE MUCH COOLER THAN NORMAL FOR THIS TIME
OF YEAR DUE TO THE LINGERING COLD AIRMASS OVER THE AREA.

LATE SATURDAY INTO SUNDAY, EXPECT DRY WEATHER TO REMAIN OVER
THE AREA WITH A BROAD UPPER TROUGH TO THE NORTH AND A HIGH
PRESSURE RIDGE OFFSHORE. EXPECT A COOL START TO THE DAY WITH SOME
COLD AIR REMAINING IN PLACE, ESPECIALLY EAST OF THE CASCADES WHERE
FREEZING TEMPERATURES ARE LIKELY. THEN DAYTIME TEMPERATURES WILL
WARM UP ON SUNDAY WITH HIGHS IN THE 70S EAST OF THE CASCADES AND
HIGH IN THE LOWER 80S TO UPPER 70S FOR WEST SIDE VALLEYS.

AVIATION...FOR THE 05/00Z TAF CYCLE... SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS EAST OF THE COASTAL RANGE WILL CONTINUE
THROUGH THIS EVENING. THESE WILL CAUSE PARTIAL TERRAIN
OBSCURATIONS AND ISOLATED MVFR CONDITIONS. OVERNIGHT...AREAS OF
MVFR AND LOCAL IFR IS EXPECTED IN LOW CLOUDS ON THE NORTH AND
NORTHWEST SLOPES IN SOUTHWEST OREGON. OTHERWISE, CONDITIONS WILL
BE VFR THROUGH SATURDAY EVENING. /DW

MARINE...UPDATED 530 PM PDT FRIDAY 4 SEPTEMBER 2015...MODERATE TO
STRONG NORTH WINDS WILL LIKELY CONTINUE THROUGH NEXT WEEK WITH THE
STRONGEST WINDS DURING THE AFTERNOON AND EVENING HOURS AND SOUTH
OF CAPE BLANCO BEYOND 10 NAUTICAL MILES FROM SHORE. WINDS ARE
LIKELY TO BE STRONGEST ON MONDAY WITH GALES POSSIBLE OVER THE
OUTER PORTION OF THE SOUTHERN WATERS ON MONDAY AND TUESDAY. /DW

PREV DISCUSSION (EDITED)... /ISSUED 556 PM PDT FRI SEP 4 2015/

UPDATE...AN UPPER LOW IS BRINGING SHOWERS WITH ISOLATED
THUNDERSTORMS TO THE AREA THIS EVENING. HAVE UPDATED THE FORECAST
TO INCLUDE ISOLATED THUNDERSTORMS IN THE UMPQUA AREA  THIS
EVENING SINCE ISOLATED THUNDERSTORMS ARE STILL OCCURRING OVER
THIS AREA. MODELS INDICATE THAT SHOWER ACTIVITY WILL GRADUALLY
PUSH EASTWARD AS THE UPPER LOW MOVES TO THE EAST TONIGHT.

DURING THE MORNING SATURDAY, EXPECT THE LOW TO BECOME CENTERED
NORTHEAST OF THE AREA. SOME CONTINUED MOISTURE IN NORTHWEST FLOW
AROUND THE BACKSIDE OF UPPER TROUGH, WILL KEEP SOME LINGERING
CLOUDS AND SHOWERS IN PLACE, MAINLY ALONG THE CASCADES AND
SISKIYOUS AND INTO EASTERN AREAS, MAINLY IN EASTERN LAKE COUNTY.
COLD AIR ADVECTION IS EXPECTED TO LOWER THE MORNING TEMPERATURES
IN EAST SIDE AREAS INTO THE MID 30S. THIS COLD AIR COMBINED WITH SOME
PARTIAL CLEARING OF THE SKIES DURING THE EARLY MORNING MAY ALLOW
FOR TEMPERATURES TO LOWER FURTHER DOWN INTO THE LOWER 30S. THE  LOW
TEMPERATURES COMBINED PARTIALLY CLEAR SKIES AND LIGHT WINDS MAY BRING
ANOTHER NIGHT WITH FROST POTENTIAL IN EAST SIDE VALLEYS. WHILE
THERE REMAINS SOME UNCERTAINTY ON HOW COLD CONDITIONS WILL GET
EARLY SATURDAY MORNING, MAINLY DUE TO CLOUD COVER, HAVE OPTED
TO ADD AREAS OF FROST ESPECIALLY GIVEN THAT THE LATEST HRRR HIGH
RESOLUTION MODEL RUN WHICH SUPPORTS CLEARING BETWEEN 10Z-15Z. HAVE
ISSUED A FROST ADVISORY FOR EASTERN VALLEYS.


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FROST ADVISORY FROM 3 AM TO 8 AM PDT SATURDAY FOR ORZ029>031.
     FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
     ORZ029>031.

CA...FROST ADVISORY FROM 3 AM TO 8 AM PDT SATURDAY FOR CAZ084-085.
     FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
     CAZ084-085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR PZZ376.
     SMALL CRAFT ADVISORY FROM 2 PM SATURDAY TO 11 PM PDT SUNDAY FOR
     PZZ376.
     SMALL CRAFT ADVISORY FROM 2 PM TO 11 PM PDT SATURDAY FOR PZZ356.

$$

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