Small Craft Advisory 24, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
232 PM PDT FRI OCT 30 2015

.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...A WARM FRONTAL
BOUNDARY HAS BROUGHT RAIN TO MAINLY COOS AND DOUGLAS COUNTIES
TODAY...AND THE OVERRUNNING THAT'S GENERATING THE PRECIPITATION
WILL CONTINUE THROUGH TONIGHT. FURTHER INLAND...MOST AREAS ARE DRY
WITH TEMPERATURES AGAIN ABOUT NORMAL FOR THIS TIME OF YEAR.
TOMORROW AN ATMOSPHERIC RIVER (AR) WILL TAKE AIM ON THE OREGON
COAST AND MAKE FOR A WET HALLOWEEN AFTERNOON AND EVENING AT THE
COAST AND INTO THE UMPQUA VALLEY. THIS AR EVENT WILL BE
BRIEF...MOVING FROM NORTHWEST TO SOUTHEAST OF THE FORECAST AREA
SATURDAY EVENING INTO SUNDAY MORNING...BUT THERE WILL BE MORE
CHANCES FOR PRECIPITATION AFTER THE AR DEPARTS...LATER IN THE
WEEKEND AND EARLY NEXT WEEK. THE MOISTURE ASSOCIATED WITH THIS AR
IS SIGNIFICANT...IN THE TOP 2 PERCENT OF MOISTURE TRANSPORT ONE
CAN EXPECT AT THIS TIME OF YEAR AT THE COAST. THEREFORE...PERIODS
OF HEAVY RAIN ARE EXPECTED AT THE COAST SATURDAY EVENING...JUST
ABOUT THE TIME WHEN TRICK-OR-TREATERS ARE OUT AND ABOUT. DRIVERS
CAN EXPECT LOWER VISIBILITIES WITH THE RAIN AND SHOULD WATCH OUT
FOR THE LITTLE ONES. ADDITIONALLY...RECENT LEAF FALL COULD RESULT
IN SOME MINOR URBAN FLOODING WHERE DRAINS ARE CLOGGED. 1 TO 2
INCHES OF RAIN ARE EXPECTED AT THE COAST AND COAST RANGE SATURDAY
INTO SATURDAY NIGHT. ADDITIONALLY...GUSTY COASTAL WINDS WILL
ACCOMPANY THIS RAIN SATURDAY AFTERNOON AND EVENING.

FURTHER INLAND...RAIN WILL REACH PLACES LIKE THE ROGUE VALLEY
SATURDAY EVENING...WITH LATEST HIGH RESOLUTION MODELS SUGGESTING
THAT TRICK-OR-TREATERS SHOULD STAY MOSTLY DRY FOR THE FIRST HALF OF
THE EVENING. THE FURTHER SOUTH AND EAST IN THE ROGUE AND BEAR CREEK
VALLEYS...THE LONGER IT WILL TAKE FOR RAIN TO ARRIVE GIVEN SOME
EXPECTED DOWNSLOPING. EAST OF THE CASCADES WILL ONLY SEE A TENTH TO
A QUARTER INCH OF RAINFALL...MOSTLY LATE SATURDAY NIGHT AND SUNDAY
MORNING. WINDS WILL HAVE A LARGER IMPACT THAN RAIN ON THE EAST
SIDE...WHERE A WIND ADVISORY AT NPWMFR SPECIFIES GUSTS OF 40-50
MPH IN THE FAVORED LOCATIONS LIKE HIGHWAY 31 NEAR SUMMER LAKE AND
THE WARNER MOUNTAINS.

SNOW LEVELS WILL BEGIN TO LOWER BEHIND THE COLD FRONT...REACHING
ABOUT 5000 FEET SUNDAY NIGHT INTO MONDAY MORNING...JUST IN TIME FOR
A SHORTWAVE TROUGH AND SHOT OF LIGHT TO MODERATE PRECIPITATION. THIS
MEANS SNOWFALL IS EXPECTED IN THE HIGHEST PASSES OF THE
CASCADES...NEAR CRATER LAKE AND DIAMOND LAKE...AND POSSIBLY HIGHWAY
140 NEAR LAKE OF THE WOODS. ROAD SURFACE TEMPERATURES COULD VERY
WELL PREVENT SNOW FROM ACCUMULATING ON THE PASSES...BUT VISIBILITIES
WILL LOWER IN SNOW AND SLICK ROADS ARE EXPECTED. SOME OF OUR HIGHEST
OBSERVING SITES LIKE CRATER LAKE NATIONAL PARK NEAR 7000
FEET...COULD RECEIVE 3 TO 6 INCHES TOTAL SNOW. INTERSTATE 5 AT
SISKIYOU SUMMIT SHOULD BE JUST WET SUNDAY NIGHT...WITH THE
POTENTIAL OF A RAIN/SNOW MIX BUT WE ARE NOT EXPECTING ANY
ACCUMULATING SNOWS.

.LONG TERM...MONDAY THROUGH FRIDAY...PLENTY OF MOISTURE REMAINS
FOR THE FIRST PART OF NEXT WEEK. THE MODELS SHOW THE UPPER TROUGH
AXIS OVER OUR AREA MONDAY MORNING, THEN SHIFTING SOUTH IN THE
AFTERNOON AS A SHORTWAVE TROUGH DIGS SOUTH AND MOVES THROUGH THE
SIERRA NEVADAS. THEREFORE THE BULK OF THE PRECIPITATION WILL BE IN
NORTHERN CAL MONDAY MORNING, THEN SHIFTING SOUTH. HOWEVER COLDER
AIR ALOFT WILL MOVE IN AND PLENTY OF PVA REMAINS ALONG WITH A
MOIST NORTHWEST FLOW. SO WE CAN EXPECT SHOWERS TO CONTINUE MAINLY
ALONG AND WEST OF THE CASCADES MONDAY. PRECIPITATION AMOUNTS WILL
VARY, BUT THEY WILL TEND TO BE HIGHER ALONG THE NORTHWEST FACING
SLOPES OF THE CASCADES AND SISKIYOUS. SNOW LEVELS MONDAY MORNING
WILL START OUT AROUND 4500 FEET, HOWEVER SURFACE ROAD TEMPERATURES
ARE STILL EXPECTED TO BE FAIRLY WARM, SO THERE'S A CHANCE MOST
ACCUMULATING SNOW WILL BE CONFINED TO DIAMOND LAKE AND CRATER LAKE
AREAS EARLY MONDAY. SNOW LEVELS WILL COME UP SOME MONDAY AFTERNOON
SO THE CHANCE FOR ACCUMULATING SNOW ON ROADS SHOULD BE LOW.

MOIST NORTH TO NORTHWEST FLOW CONTINUES TUESDAY WITH OFF/ON SHOWERS
JUST ABOUT ANYWHERE, BUT MOST SHOULD REMAIN WEST OF THE CASCADES.
WE'LL CATCH A BREAK IN THE WEATHER WEDNESDAY AND POSSIBLY THURSDAY.
HOWEVER THURSDAY IS MORE UNCERTAIN BECAUSE THE ECMWF SHOWS A WEAK
SHORTWAVE APPROACHING OUR AREA LATE THURSDAY MORNING BRINGING A
CHANCE OF SHOWERS LATE THURSDAY MORNING AND AFTERNOON. HOWEVER
SUSPECT THE QPF FIELD DEPICTED BY THE ECMWF MAY BE OVERDONE GIVEN
THE WEAKNESS AND TRAJECTORY OF THE SHORTWAVE. IN CONTRAST THE GFS
SHOWS WEAK RIDGING WITH MUCH WEAKER SHORTWAVES MOVING THROUGH IT.
PREVIOUS FORECAST HAD A CHANCE OF SHOWERS AND GIVEN THE DIFFERENCES
IN THE MODELS, WE'LL LEAVE IN FOR NOW. -PETRUCELLI

&&

.AVIATION...FOR THE 30/18Z TAF CYCLE...CIGS TO LOWER THIS MORNING
INTO THIS AFTERNOON ALONG THE COAST AND IN THE UMPQUA BASIN WITH
MOSTLY MVFR WITH PERIODS OF IFR AND SCATTERED SHOWERS OR AREAS OF
LIGHT RAIN. CIGS LOWER TO IFR LATER THIS AFTERNOON AND TONIGHT AS
WINDS INCREASE. AT LEAST PARTIAL TERRAIN OBSCURATIONS THIS MORNING
WILL OCCUR FROM THE CASCADES WESTWARD BUT THESE WILL BECOME TOTAL AS
THE DAY PROGRESSES. THE REMAINDER OF THE AREA WILL BE VFR WITH NO
MORE THAN A PASSING SHOWER OVER THE NEXT 24 HOURS. SCHAAF

&&

.MARINE...UPDATED 2 PM PDT THURSDAY 29 OCT 2015...A WARM FRONT
WILL LINGER IN THE AREA THIS AFTERNOOON, BUT BOTH SOUTHWEST WINDS
AND SEAS SHOULD REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH
THIS AFTERNOON. SEAS WILL BEGIN TO BUILD THIS EVENING AHEAD OF A
COLD FRONT...WHICH WILL MOVE THROUGH THE WATERS SATURDAY...THEN
ONSHORE SATURDAY NIGHT. THIS WILL BRING GALES TO THE NORTHERN
WATERS AND SMALL CRAFT ADVISORY CONDITIONS MOST OTHER PLACES. THE
WINDS COMBINED WITH A STEEP WEST NORTHWEST SWELL WILL RESULT IN
VERY HAZARDOUS SEAS. OFFSHORE HIGH PRESSURE WILL BUILD INTO THE
AREA ON SUNDAY...BUT SEAS WILL LIKELY REMAIN STEEP TO VERY STEEP
THROUGH EARLY NEXT WEEK. A VERY LARGE WEST SWELL WILL BUILD INTO
THE WATERS ON SUNDAY. SK

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY FROM 11 AM PDT SATURDAY TO 4 AM PST SUNDAY FOR
     ORZ030-031.

CA...WIND ADVISORY FROM 11 AM PDT SATURDAY TO 4 AM PST SUNDAY FOR
     CAZ085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 5 AM PDT SATURDAY TO 4 AM PST SUNDAY
     FOR PZZ350-356-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 11 PM PDT THIS
     EVENING TO 10 PM PST SUNDAY FOR PZZ350-356-376.
     HAZARDOUS SEAS WARNING FROM 5 PM PDT SATURDAY TO 4 AM PST SUNDAY
     FOR PZZ350.
     SMALL CRAFT ADVISORY FROM 5 AM TO 5 PM PDT SATURDAY FOR PZZ370.
     HAZARDOUS SEAS WARNING FROM 5 AM PDT SATURDAY TO 10 PM PST
     SUNDAY FOR PZZ370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT SATURDAY
     FOR PZZ370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 4 AM TO 10 PM PST
     SUNDAY FOR PZZ370.
     HAZARDOUS SEAS WARNING FROM 5 PM PDT SATURDAY TO 10 PM PST
     SUNDAY FOR PZZ376.

NSK/MAP/MAP