High Surf Advisory 17, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
452 AM PST THU MAR 10 2016

.DISCUSSION...THERE ARE FIVE FRONTS THAT WILL BE OUR PRIMARY
WEATHER PRODUCERS THROUGH MONDAY. ONE TODAY WITH LINGERING STRONG
EAST SIDE WINDS THIS MORNING AS THE MAIN IMPACT...THE NEXT ON
FRIDAY THAT WILL MAINLY IMPACT SOUTHERN SISKIYOU COUNTY AND
SOUTHWARD ACROSS CALIFORNIA...A THIRD COLD FRONT TO BE FOCUSED ON
OUR AREA SATURDAY OF WHICH THE MODELS HAVE TRENDED SLIGHTLY WEAKER
BUT STILL WARRNTS BEING CALLED A STRONG FRONT...THE FOURTH ON
SUNDAY THROUGH SUNDAY NIGHT THAT HAS TRENDED STRONGER AND WETTER
AND LASTLY A SURFACE TROUGH ON MONDAY WITH LIGHT TO MODERATE
MAINLY WEST SIDE PRECIPITATION BUT ALSO LOWERING SNOW LEVELS.

A STRONG COLD FRONT IS ACTING LARGELY AS FORECAST AND HAS BROUGHT
GUSTY SOUTHERLY WINDS AND MODERATE TO HEAVY PRECIPITATION LAST
EVENING INTO THIS MORNING. A WIND ADVISORY AND HIGH WIND WARNING
FOR MUCH OF THE CASCADES AND WEST SIDE HAS ENDED BUT CONTINUES FOR
THE EAST SIDE INTO MID-MORNING. THE FRONT AND ITS MAIN ASSOCIATED
BAND OF PRECIPITATION HAS MOVED EAST OF THE COAST AND THE UMPQUA
VALLEY AND WILL CONTINUE TO SLOWLY BOTH MOVE EAST AND WEAKEN
TODAY. 24 HOUR RAINFALL AT THE COAST RANGED FROM AROUND AN INCH TO
TWO AND A HALF INCHES AND FROM AROUND A HALF INCH TO AN INCH AND A
HALF INLAND WEST OF THE CASCADES. THE WEST SIDE WILL RECEIVE
ANOTHER FEW HOURS OF RAINFALL THEN PRECIPITATION WILL BE FOCUSED
FROM THE MOUNT SHASTA AREA ACROSS THE EAST SIDE INTO THIS
AFTERNOON. MEANTIME...A SHORTWAVE WILL LIKELY BRING LIGHT WEST
SIDE POST-FRONTAL SHOWERS. THERE IS ABOUT A 10 PERCENT CHANCE OF A
THUNDERSTORM AT THE DOUGLAS COUNTY COAST THIS AFTERNOON AS THE
SHORTWAVE MOVES INLAND. THE SNOW LEVEL AROUND 7000 FEET WILL LOWER
TO AROUND 5000 FEET BEHIND THE FRONT WITH JUST UP TO A FEW INCHES
OF SNOW EXPECTED IN THE CASCADES TODAY. PRECIPITATION AMOUNTS TODAY
WILL BE HIGHEST NEAR MOUNT SHASTA WITH AROUND AN INCH EXPECTED BUT
ALSO AROUND A TENTH TO A HALF INCH ACROSS THE EAST SIDE.

THERE WILL BE A BRIEF BREAK BETWEEN SYSTEMS THIS EVENING WITH A
FEW LINGERING SHOWERS AND SNOW SHOWERS OVER THE WARNER MOUNTAINS.

THE NEXT FRONT ON FRIDAY WILL FOCUS ON CALIFORNIA WITH THE SURFACE
LOW FORECAST TO MOVE ACROSS THE SAN FRANCISCO BAY AREA. WET
SOUTHERLY FLOW WILL PRODUCE MODERATE UPSLOPE RAIN AND SNOW AROUND
MOUNT SHASTA AND PERIODS OF LIGHT PRECIPITATION ELSEWHERE IN OUR
AREA WITH A SNOW LEVEL AROUND 5500 FEET.

THE THIRD FRONT IS STILL EXPECTED TO ARRIVE AT THE WASHINGTON AND
OREGON COAST BY THE END OF FRIDAY NIGHT THEN PRODUCE A WET AND
WINDY SATURDAY WITH GALES IN THE COASTAL WATERS AND INLAND WINDS
THAT HAVE A HIGH PROBABILITY OF REACHING ADVISORY STRENGTH IN THE
SHASTA VALLEY AND ON THE EAST SIDE. IN COORDINATION WITH
NEIGHBORING OFFICES AND IN LINE WITH THE LATEST DATA...QPF
AMOUNTS HAVE BEEN SLIGHTLY REDUCED. BUT...HEAVY RAIN IS STILL
LIKELY AT THE COAST WITH MODERATE PRECIPITATION INLAND AND A SNOW
LEVEL EXPECTED AROUND 4000 FEET. THIS FRONT COULD PRODUCE ADVISORY
LEVEL SNOWFALL ON MANY OF THE MAJOR PASSES. LIGHT TO MODERATE
RAIN AND SNOW SHOWERS ARE LIKELY TO CONTINUE SATURDAY NIGHT.

A STRONG FRONT ON SUNDAY MAY BRING STORM FORCE WINDS TO THE
COASTAL WATERS AND ANOTHER EPISODE OF HIGH WINDS TO MANY OF THE
SAME AREAS WHICH RECEIVED THEM LAST NIGHT...THE COAST...SHASTA
VALLEY...HIGHER TERRAIN AND MUCH OF THE EAST SIDE. THIS SYSTEM IS
LIKELY TO PRODUCE SIGNIFICANT PRECIPITATION THROUGH SUNDAY NIGHT
WITH SNOW LEVELS FORECAST TO BE MAINLY AROUND 5000 FEET. THE
STRONG WINDS...SATURATED SOILS AND HEAVY RAIN BRING CONCERN FOR
POWER OUTAGES...FLOODING (MAINLY BUT NOT EXCLUSIVELY FLOODING OF
STREETS AND STREAMS)...AND TRAVEL DIFFICULTIES.

A SURFACE TROUGH IN A WESTERLY FLOW IS EXPECTED TO BRING LIGHT TO
MODERATE MAINLY WEST SIDE SHOWERS AND SNOW SHOWERS MONDAY INTO
MONDAY NIGHT THEN A WEAKER DISTURBANCE WILL CONTINUE A CHANCE OF
LIGHT SHOWERS AND SNOW SHOWERS ON TUESDAY. THE GFS AND ECMWF HAVE
TRENDED TOWARD BETTER AGREEMENT THAT THE PATTERN WILL CHANGE
TUESDAY NIGHT WITH HIGH PRESSURE ARRIVING AND PERSISTING INTO LATE
IN THE WEEK.

&&

.AVIATION...FOR THE 10/06Z TAF CYCLE...AS A STRONG COLD FRONT OVER
SOUTHWEST OREGON AND SISKIYOU COUNTY EARLY THIS MORNING MOVES
EAST...GUSTY WINDS WILL LEAD TO TURBULENCE AND BUMPY RIDES IN AND
OUT OF THE TERMINALS THROUGH THURSDAY MORNING FOR MANY AREAS,
THOUGH EXPECT WINDS WILL DIMINISH THROUGH THE DAY. RAIN ALONG THE
FRONTAL BAND OVERNIGHT INTO THURSDAY MORNING WILL LOWER CIGS DOWN
TO MVFR AT LEAST WITH TERRAIN BECOMING TOTALLY OBSCURED. AREAS OF
IFR CIGS WILL OCCUR IN THE SHASTA REGION. EXPECT RAIN TO TAPER OFF
TO SHOWERS LATE THURSDAY MORNING ALONG THE COAST AND THURSDAY
AFTERNOON INLAND. PRECIPITATION SHOULD END FOR MOST, IF NOT ALL,
SITES BY EVENING. -SPILDE

&&

.MARINE...UPDATED 305 AM PST THU 10 MAR 2016...HAZARDOUS VERY STEEP
SEAS AND GUSTY WINDS CONTINUE THIS MORNING BEHIND A STRONG FRONT.
MARINERS ARE URGED TO EXERCISE EXTREME CAUTION OR REMAIN IN PORT
UNTIL THIS PERIOD OF STORMY WEATHER ENDS. WINDS AND SEAS ARE
EXPECTED TO DIMINISH TONIGHT INTO FRIDAY MORNING...BUT A NEW SERIES
OF STRONG STORMS ARE EXPECTED THIS WEEKEND. THE NEXT STRONG FRONT
ARRIVES FRIDAY NIGHT...AND LATEST MODEL TRENDS SUGGEST SOUTHERLY
GALES ARE POSSIBLE WITH THE FRIDAY NIGHT FRONT. ANOTHER
POTENTIALLY STRONG FRONT WILL ARRIVE SUNDAY MORNING. -SK

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF WARNING UNTIL 6 AM PST EARLY THIS MORNING FOR
     ORZ021-022.
     HIGH WIND WARNING UNTIL 10 AM PST THIS MORNING FOR ORZ029>031.

CA...HIGH WIND WARNING UNTIL 10 AM PST THIS MORNING FOR CAZ084-085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM
     4 PM THIS AFTERNOON TO 10 AM PST FRIDAY FOR PZZ350-356-370-376.
     GALE WARNING UNTIL 6 AM PST EARLY THIS MORNING FOR PZZ350-370.
     HAZARDOUS SEAS WARNING UNTIL 4 PM PST THIS AFTERNOON FOR
     PZZ350-356-370-376.

DW/SK