Flood Watch 1, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
901 PM PST FRI JAN 15 2016

.DISCUSSION...STEADY LIGHT TO MODERATE PRECIPITATION IN
ASSOCIATION WITH A WARM FRONT IS MOVING INTO THE AREA FROM THE
SOUTHWEST THIS EVENING.SNOW LEVELS ARE EXPECTED TO RISE SOME WEST
OF THE CASCADES, BUT WILL BE SLOW TO COME UP EAST OF THE CASCADES.
CURRENTLY KLAMATH FALLS IS REPORTING LIGHT SNOW AND THERE COULD
BE A 1-2 HOUR PERIOD OF MODERATE SNOW WITHING THE HOUR. BECAUSE OF
THIS, DECIDED TO BUMP UP POPS AND QPF AMOUNTS FOR THIS EVENING AND
TONIGHT. MODEL SOUNDINGS AT KLAMATH FALLS IS NOT LOOKING AS
FAVORABLE FOR FREEZING RAIN LATE TONIGHT, BUT IT'S STILL POSSIBLE,
SO WE'LL LEAVE IN THE SLIGHT CHANCE OF FREEZING RAIN.

A PRELIMINARY LOOK AT THE 0Z NAM AND GFS SUGGEST ANY INCREASE IN
SNOW LEVELS MAY ONLY BE FOR ABOUT 12 HOURS OR LESS LATE TONIGHT
INTO SATURDAY MORNING, THEN SHOULD COME DOWN AGAIN SATURDAY
AFTERNOON. A BRIEF BREAK IS EXPECTED SATURDAY EVENING, THEN
ANOTHER WARM FRONT WILL BRING ANOTHER ROUND OF MODERATE TO HEAVY
PRECIPITATION TO THE COAST AND COASTAL MOUNTAINS EARLY SUNDAY
MORNING. THE MODELS SUGGEST SNOW LEVELS WILL COME UP, BUT NOT FOR
VERY LONG BEFORE THEY COME DOWN AGAIN LATE SUNDAY AFTERNOON AND
NIGHT. ALSO THE CORE OF HEAVIEST PRECIPITATION IS EXPECTED TO
SHIFT SOUTH INTO NORTHERN CAL SUNDAY AFTERNOON. GIVEN THE ABOVE
MENTIONED SCENARIOS, IT'S POSSIBLE THE POTENTIAL FOR FLOODING ON
SMALL STREAMS AND CREEKS COULD BE LESS. LATER SHIFTS WILL NEED TO
TAKE ANOTHER LOOK AT THIS. -PETRUCELLI

&&

.AVIATION...FOR THE 16/00Z TAF CYCLE...A WARM FRONT WILL
BRING INCREASING MID AND LOW LEVEL CLOUDS THIS EVENING AND
TONIGHT WITH AREAS MVFR CIGS AND MOUNTAIN OBSCURATIONS DEVELOPING
WEST OF THE CASCADES. A MIX OF IFR/MVFR CIGS AND VISIBILITIES
WILL DEVELOP IN SNOW EAST OF THE CASCADES AFTER 03Z.
ADDITIONALLY...STRONG WINDS ALOFT WILL PRODUCE LOW LEVEL WIND
SHEAR AT THE COAST AND VCTY KRBG TOWARDS MORNING. WINDS WILL
DECREASE TOMORROW AFTERNOON. /SVEN

&&

.MARINE...UPDATED 400 PM PST FRIDAY 15 JAN 2016...A STRONG FRONT WILL
BRING SOUTH GALES AND VERY STEEP WIND DRIVEN SEAS THIS EVENING
THROUGH SATURDAY MORNING. VERY HIGH AND VERY LONG PERIOD SWELL
WILL IMPACT THE WATERS SATURDAY AFTERNOON INTO SATURDAY NIGHT.
ANOTHER FRONT BRINGS GALES AND VERY STEEP SEAS SATURDAY NIGHT
INTO SUNDAY. ADDITIONAL FRONTS ARE EXPECTED THROUGH LATE NEXT
WEEK. /SVEN

&&

.PREV DISCUSSION... /ISSUED 419 PM PST FRI JAN 15 2016/

SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT...A WARM FRONT IS
OFFSHORE AND WILL MOVE ONSHORE THIS EVENING WITH AN OCCLUDING COLD
FRONT TRAILING CLOSE BEHIND. THIS WILL HAVE ITS MAIN IMPACT ON OUR
AREA LATE THIS EVENING INTO EARLY SATURDAY MORNING WITH HIGH
ELEVATION SNOW AND ALSO THE POTENTIAL FOR EAST SIDE VALLEY
FREEZING RAIN. A SHALLOW LAYER OF BELOW FREEZING AIR MAY BE IN
PLACE AS THE WET, WARMER AIR ALOFT SPREADS EAST OF THE CASCADES.
THE PROBABILITY OF FREEZING RAIN IS HIGHEST ALONG HIGHWAY 97 IN
KLAMATH COUNTY AND HAS ALSO BEEN MENTIONED FOR PORTIONS OF MODOC
AND NORTHEAST SISKIYOU COUNTIES. IT IS WORDED AS A SLIGHT CHANCE
OF FREEZING RAIN AS CONFIDENCE IS LOW TO MODERATE GIVEN THAT
INCREASING SOUTHERLY WINDS WILL PROMOTE MIXING AND CLOUD COVER
WILL KEEP TEMPERATURES THAT ARE NOW AT OR SLIGHTLY ABOVE FREEZING
FROM DROPPING MORE THAN A FEW DEGREES OVERNIGHT.

THERE WILL ALSO BE LIGHT TO MODERATE SNOW THIS EVENING THROUGH
SATURDAY MORNING OF 3 TO 6 INCHES AT ELEVATIONS ABOVE 5000 TO
5500 FEET...EXCEPT LOCALLY DOWN TO 4000 FEET IN SOUTHERN SISKIYOU
COUNTY.

SOUTHERLY WINDS WILL INCREASE THIS EVENING AND BECOME STRONG WITH
GUSTS TO 70 MPH AT COASTAL HEADLANDS INTO SATURDAY MORNING. WINDS
WILL ALSO BECOME STRONG WITH GUSTS TO 60 MPH IN THE SOUTHERN
SHASTA VALLEY AND IN LAKE COUNTY LATE TONIGHT THROUGH SATURDAY.

POST-FRONTAL SHOWERS AND SNOW SHOWERS WILL TAPER OFF SATURDAY
AFTERNOON THEN THERE WILL BE A BRIEF BREAK SATURDAY NIGHT WITH A
CHANCE OF VERY LIGHT SHOWERS/SNOW SHOWERS AHEAD OF ANOTHER STRONG
FRONT THAT WILL REACH THE COAST TOWARD THE END OF SATURDAY NIGHT.
-DW

LONG TERM...SUNDAY THROUGH FRIDAY...MODELS ARE IN GOOD AGREEMENT
ON A STRONG FRONT ARRIVING SATURDAY NIGHT AND MOVING THROUGH THE
FORECAST AREA SUNDAY. STRONG WINDS AND RISING RIVERS WILL LIKELY
BE THE MAIN IMPACT FROM THIS SYSTEM.

THE GFS AND NAM DEPICT 70KT 700MB SOUTHWEST FLOW SUNDAY
MORNING...WHICH WILL TRANSLATE TO ADVISORY OR WARNING WINDS IN THE
SHASTA VALLEY AND AREAS OF THE EAST SIDE LIKE SUMMER LAKE. WE HAVE
CONTINUED A HIGH WIND WATCH IN THESE LOCATIONS FOR THE SATURDAY
NIGHT INTO SUNDAY MORNING TIMEFRAME. WIND COMPONENTS ALOFT WILL
LIKELY BE TOO WESTERLY FOR STRONG WINDS TO SURFACE IN MUCH OF THE
ROGUE VALLEY...BUT HAVE BUMPED UP WINDS IN THE SOUTHERN ROGUE VALLEY
NEAR ASHLAND TO NEAR-ADVISORY CRITERIA.

PRECIPITATION SATURDAY NIGHT INTO SUNDAY WILL BE MODERATE TO
HEAVY...AND HEAVIEST IN CURRY...JOSEPHINE...AND SISKIYOU COUNTIES.
SNOW LEVELS WILL AVERAGE BETWEEN 6000 AND 7000 FEET DURING THE
SYSTEM. 3 TO 4 INCHES OF PRECIPITATION IS EXPECTED AT THE CURRY
COUNTY COAST AND WESTERN SISKIYOU COUNTY...WITH ABOUT 2 INCHES IN
THE MOUNT SHASTA AREA. WITH PLENTY OF SNOWPACK IN THE 4000-6000 FOOT
RANGE...SOME OF THAT WILL LIKELY MELT AND RUN OFF INTO THE RIVERS
AND STREAMS.  WE HAVE ISSUED A HYDROLOGIC OUTLOOK AT ESFMFR FOR THE
POTENTIAL FOR SMALL STREAM FLOODING IN CURRY...JOSEPHINE...AND CURRY
COUNTIES.

ANOTHER SYSTEM...WITH LOWER SNOW LEVELS AROUND 5000 FEET...WILL MOVE
THROUGH MONDAY NIGHT BUT WILL FEATURE LESS PRECIPITATION THAN THE
PREVIOUS STORM.

WE'LL BE MONITORING THIS TIME
PERIOD CLOSELY FOR THE POTENTIAL FOR FLOODING, SINCE SOILS WILL
ALREADY BE SATURATED...SNOW LEVELS WILL BE RISING AND PLENTY OF
ADDITIONAL RAINFALL IS EXPECTED.

A PROGRESSIVE PACIFIC JET STREAM WILL CONTINUE TO SEND STORM SYSTEMS
INTO THE PACIFIC NORTHWEST NEXT WEEK. THE SPEED WITH WHICH SHORT
WAVES PROPAGATE EASTWARD FROM THE PACIFIC WILL DICTATE TIMING
DETAILS, BUT EITHER WAY, THE WET PATTERN SHOULD CONTINUE.

THE 12Z OPERATIONAL GFS/ECWMF ARE IN PRETTY GOOD AGREEMENT ON
TUESDAY...BOTH SHOWING A STRONG LOW PRESSURE SYSTEM MOVING INSIDE
130W...THEN MOVING INLAND NEAR THE WASHINGTON COAST BY 12Z
WEDNESDAY. THERE IS SOME DEGREE OF SPREAD IN THE ENSEMBLES (SOME
SHOW A WEAKER WAVE MOVING INLAND), BUT SEVERAL MEMBERS ALSO PROVIDE
SUPPORT FOR THE OPERATIONAL RUNS. HAVE OPTED FOR A BLEND HERE, WITH
A PERIOD OF STRONG SOUTH WINDS POSSIBLE IN OUR COASTAL WATERS AND
ALONG THE COAST TUESDAY AFTERNOON AND NIGHT WITH MODERATE
PRECIPITATION AT THE COAST AND LIGHTER PRECIP INLAND. DUE TO THE
PROGRESSIVE JET, THIS SYSTEM WILL BE MOVING FAIRLY QUICKLY, SO
PRECIPITATION SHOULD TRANSITION TO SHOWERS AND DIMINISH BY WEDNESDAY
MORNING.

HOWEVER, THE MODELS NOW SHOW THE NEXT FRONTAL SYSTEM QUICK ON ITS
HEELS, SO ANY BREAK WEDNESDAY WILL PROBABLY BE SHORT-LIVED. IT
ARRIVES AT THE COAST WEDNESDAY AFTERNOON/EVENING THEN PUSHES ONSHORE
WEDNESDAY NIGHT INTO THURSDAY. MODELS ARE SHOWING A SURGE IN SNOW
LEVELS TO 6000-7000 FEET WITH THIS SYSTEM, SO HAVE RAISED THEM
ACCORDINGLY, ALONG WITH THE CORRESPONDING MAX/MIN TEMPERATURES
DURING THE TIME PERIOD.

BY THURSDAY NIGHT AND FRIDAY, MODELS DIVERGE IN THEIR SOLUTIONS AS
TO HOW FAST THURSDAY'S SYSTEM PUSHES SOUTHEASTWARD THROUGH THE AREA.
THE ECMWF INDICATES A DEEPENING TROUGH OFFSHORE WHICH WOULD SLOW ITS
PROGRESSION, BUT THE GFS REMAINS MORE PROGRESSIVE. ONCE AGAIN, WE'LL
BE KEEPING A CLOSE EYE ON PRECIPITATION AMOUNTS WITH THESE SYSTEMS
AS FLOODING WILL LIKELY BE THE MAIN THREAT AS WE HEAD INTO NEXT
WEEK. -NSK/SPILDE

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 1 AM TO 4 PM PST SATURDAY FOR ORZ030-031.
     WINTER WEATHER ADVISORY UNTIL 7 AM PST SATURDAY FOR ORZ029-030.
     HIGH WIND WATCH FROM LATE SATURDAY NIGHT THROUGH LATE SUNDAY
     NIGHT FOR ORZ030-031.
     HIGH SURF ADVISORY FROM NOON SATURDAY TO 4 PM PST SUNDAY FOR
     ORZ021-022.
     WINTER WEATHER ADVISORY UNTIL 10 AM PST SATURDAY FOR ORZ027-028.

CA...HIGH WIND WARNING FROM 1 AM TO 4 PM PST SATURDAY FOR CAZ085.
     WINTER WEATHER ADVISORY UNTIL 7 AM PST SATURDAY FOR CAZ084-085.
     HIGH WIND WATCH FROM LATE SATURDAY NIGHT THROUGH LATE SUNDAY
     NIGHT FOR CAZ085.
     WINTER WEATHER ADVISORY UNTIL 10 AM PST SATURDAY FOR CAZ083.
     WINTER WEATHER ADVISORY UNTIL 10 AM PST SATURDAY FOR CAZ082.
     HIGH WIND WARNING UNTIL 4 PM PST SATURDAY FOR CAZ081.
     HIGH WIND WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING
     FOR CAZ081.

PACIFIC COASTAL WATERS...GALE WARNING UNTIL 10 AM PST SUNDAY FOR PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING UNTIL 4 AM PST MONDAY FOR PZZ350-356.
     HAZARDOUS SEAS WARNING FROM 10 AM SUNDAY TO 4 AM PST MONDAY FOR
     PZZ370-376.