High Surf Advisory 20, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
205 PM PDT TUE APR 12 2016

.DISCUSSION...

.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...THE TRAILING EDGE OF A
COLD FRONT WILL PASS THROUGH THE AREA THIS EVENING AND TONIGHT, BUT
THERE SHOULD BE LITTLE IMPACT FROM THIS SYSTEM OTHER THAN SOME
SHOWERS AND BREEZY WINDS ALONG THE COAST AND OTHER AREAS WEST OF THE
CASCADES. MEANWHILE, AN AREA OF CONVERGENCE OVER THE EATS SIDE WILL
SLOWLY SLIDE EAST, ALSO PRODUCING LIGHT SHOWERS THROUGH THIS
EVENING.

WHILE THERE WILL BE LITTLE PRECIPITATION, MAINLY ONLY LINGERING
SHOWERS, DURING THE DAY ON WEDNESDAY, SOUTHWEST WINDS WILL BE
INCREASING AHEAD OF THE NEXT FRONT. THE COLD FRONT AND A TRAILING
SURFACE TROUGH ASSOCIATED WITH THE AXIS OF A COLD UPPER LOW WILL
BRING MAINLY LIGHT TO MODERATE PRECIPITATION AMOUNTS WEDNESDAY
EVENING THROUGH THURSDAY. WINDS WILL BE STRONGEST AT THE COAST WITH
GUSTS TO 50 MPH POSSIBLE AT HEADLANDS LATE WEDNESDAY MORNING INTO
WEDNESDAY EVENING. INLAND WINDS WILL ALSO BE GUSTY, MAINLY EAST OF
THE CASCADES, WHERE GUSTS TO 35 MPH ARE LIKELY. WINDS WILL BE GUSTY
AGAIN ON THURSDAY THOUGH NOT QUITE AS STRONG AT THE COAST AS ON
WEDNESDAY. BUT ON THE EAST SIDE THERE WILL LIKELY BE AREAS WHERE
SOUTHWEST TO WEST WINDS ARE STRONGER ON THURSDAY AFTERNOON AND
EVENING THAN ON WEDNESDAY AFTERNOON AND EVENING. WINDS WILL
APPROACH, BUT ARE NOT EXPECTED TO REACH, ADVISORY CRITERIA, BUT
RIDGELINES AND EXPOSED HEADLANDS COULD SEE PERIODS OF STRONG GUSTS.

MODERATE TO HEAVY PRECIPITATION APPEARS LIKELY WITH THE FRONT, WITH
THE HEAVIEST AMOUNTS ALONG THE COAST AND IN THE WEST SIDE MOUNTAINS.
WITH A SIGNIFICANT COLD POOL ALOFT, THIS SYSTEM WILL ALSO BRING THE
CHANCE FOR THUNDERSTORMS OVER THE WATERS AND NEAR THE COAST
WEDNESDAY NIGHT, THEN SHIFTING TO THE EAST SIDE FOR THURSDAY
AFTERNOON. SNOW LEVELS WILL DROP WEDNESDAY NIGHT INTO THURSDAY FROM
AROUND 5500 FEET TO 3500 FEET WITH MOST OF THE ACCUMULATION OVER THE
KALMIOPSIS WILDERNESS IN THE COASTAL RANGE, AND THE CREST OF THE
CASCADES WHERE UPSLOPE LIFT WILL BE STRONGEST. SNOW LEVELS ON
THURSDAY ARE LIKELY TO RISE MODESTLY TO AROUND 4000 FEET WITH THE
HEATING OF THE DAY. THE IMPACT OF THIS SNOWFALL ON PASSES WILL
LIKELY BE LIMITED WITH MELTING FROM VERY WARM SOIL AND ROAD SURFACE
TEMPERATURES. HOWEVER, AN ADVISORY MAY BE NEEDED, AS COOLING
TEMPERATURES AND PRECIPITATION, HEAVY AT TIMES, COULD ALLOW FOR SOME
ACCUMULATION THURSDAY MORNING.

POST-FRONTAL SHOWERS IN A NORTHWEST FLOW ALOFT ARE EXPECTED TO
GRADUALLY DIMINISH THURSDAY NIGHT INTO EARLY FRIDAY MORNING. HIGH
PRESSURE WILL FOLLOW WITH A STRONG WARMING TREND BEGINNING FRIDAY.
-BPN/DW

.LONG TERM...SATURDAY THROUGH WEDNESDAY...THE RIDGE IS EXPECTED
TO CONTINUE BUILDING IN OVER THE WEEKEND WHICH WILL KEEP RAIN
CHANCES MINIMAL, BUT IT WILL ALLOW FOR TEMPERATURES TO RISE
SIGNIFICANTLY. TEMPERATURES ARE FORECAST TO BE ABOUT 10 TO 15
DEGREES ABOVE NORMAL ON SATURDAY. THIS PATTERN WILL ALLOW FOR
AFTERNOON HIGH TEMPERATURES TO INCREASE EVEN MORE, AND MANY
LOCATIONS IN OUR FORECAST AREA COULD CHALLENGE THE CURRENT
RECORDS.

EARLY NEXT WEEK, A SHIFT IN THE PATTERN WILL OCCUR ONCE MORE AND
PRECIPITATION WILL REENTER THE FORECAST. THE REAL QUESTION IS WHEN
THIS CHANGE IS EXPECTED TO OCCUR. THE GFS IS EXTREMELY PROGRESSIVE
AND BREAKS DOWN THE RIDGE AS EARLY AS MONDAY AFTERNOON WHILE THE
ECMWF PUSHES THE TROUGH NORTHWARD OVER THE RIDGE BRINGING IN ONLY
LINGERING SHOWERS. AS A RESULT OF THE LOW CONFIDENCE IN THE
FORECAST, HAVE RETAINED MUCH OF THE PREVIOUS FORECAST WITH THE RIDGE
BREAKING DOWN A BIT LATER DUE TO THE LOW PRESSURE SYSTEM WEAKENING.
THEREFORE SOME SHOWERS WILL BE POSSIBLE FOR THE COAST AND UMPQUA
BASIN AS WELL AS PARTS OF WESTERN SISKIYOU COUNTY BEGINNING MONDAY
EVENING AND SPREADING EASTWARD BY TUESDAY. -SCHAAF

&&

.AVIATION...FOR THE 12/18Z TAF CYCLE...ISOLATED TO SCATTERED
SHOWERS WILL CONTINUE EAST OF THE CASCADES AND OVER NORTHERN
CALIFORNIA THIS AFTERNOON. MAINLY VFR CIGS ARE EXPECTED
AREAWIDE...BUT ISOLATED MVFR CIGS ARE POSSIBLE THIS EVENING INTO
TONIGHT ALONG THE COAST AND INTO THE UMPQUA BASIN AS A WEAK FRONT
MOVES INLAND. AREAS OF MOUNTAIN OBSCURATIONS ARE EXPECTED TODAY
INTO TONIGHT. -SCHAAF/CC

&&

.MARINE...UPDATED 200 PM PDT TUE 12 APR 2016...THE PATTERN WILL
BECOME MORE ACTIVE THIS WEEK WITH A SERIES OF OF FRONTS MOVING
THROUGH THE WATERS TODAY THROUGH THURSDAY. FIRST A WEAK COLD FRONT
WILL MOVE THROUGH THE WATERS TODAY FOLLOWED BY ONE WITH A BIT MORE
STRENGTH DURING WEDNESDAY EVENING. LOOK FOR GALES TO DEVELOP
DURING THIS TIME. AS THIS SYSTEM PASSES, HIGH AND STEEP SEAS WILL
FOLLOW THURSDAY.

FOR THE EXTENDED,  HIGH PRESSURE WILL DEVELOP AND SETTLE IN ACROSS
THE PAC NW.  LOW TO MODERATE SEAS WILL DEVELOP DURING THIS TIME.

-SMITH

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM WEDNESDAY MORNING THROUGH LATE WEDNESDAY NIGHT
     FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FROM 11 AM WEDNESDAY TO 5 AM PDT THURSDAY
     FOR PZZ350-356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 11 PM THIS EVENING
     TO 11 AM PDT WEDNESDAY FOR PZZ350-356-370-376.

BPN/BMS/CZS