Hazardous Seas Warning 29, NWS Medford, OR

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MEDFORD OR
210 AM PST FRI MAR 11 2016

UPDATED MARINE DISCUSSION

.DISCUSSION...11/00Z NAM/GFS/EC IN.

THE NORTHERN HEMISPHERIC 500 MB HEIGHT PATTERN INITIALLY SHOWS A
WAVE NUMBER OF THREE AROUND THE GLOBE...WHICH IS USUALLY A
STAGNANT OR RETROGRESSIVE PATTERN. SURE ENOUGH...THERE IS REX
BLOCK OVER THE CENTRAL U.S. HOWEVER...IT WILL MORPH TO A FOUR
WAVE PATTERN LATER ON TODAY...AND THIS WILL SUPPORT A RESUMPTION
OF A PROGRESSIVE PATTERN. IF THE 10/12Z AND 11/00Z EC
VERIFIES...THE THREE WAVE PATTERN WILL RETURN DURING THE MIDDLE OF
NEXT WEEK WITH A SIGNIFICANT BLOCK SETTING UP ALONG THE WEST COAST
INTO NEXT WEEKEND.

CLOSER IN...IN BOTH SPACE AND TIME...THE PACIFIC NORTHWEST REMAINS
UNDER STRONG SOUTHWEST FLOW ALOFT BETWEEN AN OFFSHORE LONG WAVE
TROUGH AND THE AFOREMENTIONED REX BLOCK OVER THE CENTRAL U.S.
SHORT WAVES EJECTED BY THE OFFSHORE TROUGH WILL BRING CONTINUED
ROUNDS OF WIND AND PRECIPITATION TO THE AREA.

THE NEXT WAVE WILL MOVE ONSHORE FRIDAY AFTERNOON WITH MOST OF THE
ENERGY DIRECTED INTO CENTRAL CALIFORNIA. THAT'S WHERE THE BULK OF
THE PRECIPITATION WILL FALL. THE HEAVIEST PRECIPITATION OVER THE
MEDFORD CWA WILL EXTEND FROM THE MOUNT SHASTA AREA NORTHWEST
THROUGH WESTERN SISKIYOU COUNTY TO THE SOUTHERN OREGON COAST AND
COAST RANGE. PRECIPITATION WILL DEVELOP LATER THIS MORNING AND
DIMINISH THIS EVENING. HIGH TEMPERATURES FRIDAY WILL BE NEAR
CLIMATIC NORMALS FOR THIS DATE. WINDS WILL NOT BE A MAJOR
FACTOR...EXCEPT OVER THE SOUTHERN SHASTA VALLEY. WITH 700 MB FLOW
PEAKING AT ABOUT 45 KT...IT WILL BE BREEZY THERE WITH GUSTS TO 40
MPH POSSIBLE AT WEED.

THE NEXT WAVE WILL MOVE ONSHORE SATURDAY MORNING...AND THE ENERGY
ASSOCIATED WITH THIS ONE WILL BE DIRECTED FARTHER NORTH. THE
INITIAL TARGET WILL BE THE OREGON AND WASHINGTON COAST...BUT WILL
SHIFT FARTHER NORTH WITH TIME. THE PRECIPITATION FROM THIS WAVE
WILL STILL BE AROUND WHEN THE SURFACE FRONT ASSOCIATED WITH YET
ANOTHER WAVE MOVES ONSHORE LATE SATURDAY NIGHT. THE HEAVIEST
PRECIPITATION WITH THIS SYSTEM WILL BE ALONG THE COAST AND COAST
RANGE FROM CENTRAL OREGON DOWN THROUGH NORTHERN CALIFORNIA. POST-
FRONTAL SHOWERS WILL CONTINUE SUNDAY INTO MONDAY. ALL THIS WILL
OCCUR IN A COLDER THAN NORMAL ENVIRONMENT WITH SATURDAY HIGH
TEMPERATURES 5-10 DEGREES BELOW NORMAL AND SUNDAY HIGHS AROUND 5
DEGREES BELOW NORMAL.

BY THIS TIME FLOODING MAY BE A CONCERN DUE TO THE PERSISTENT AND
OCCASIONALLY HEAVY PRECIPITATION. THE MAIN THREAT WILL BE ALONG
THE COQUILLE RIVER FROM MYRTLE POINT TO THE OCEAN.

THERE IS GOOD POTENTIAL FOR A MAJOR SNOW EVENT AT HIGHER
ELEVATIONS FRIDAY NIGHT INTO SUNDAY NIGHT. STRONG SOUTHWEST TO
WEST FLOW ALOFT WILL PERSIST THROUGH THIS PERIOD...SO HIGHER
WEST AND SOUTHWEST FACING TERRAIN...SUCH AS THE CASCADES...MAY
GET QUITE A BIT OF UPSLOPE ENHANCED SNOW. SNOW LEVELS WILL RANGE
BETWEEN 3000 AND 5000 FEET THROUGHOUT THIS INTERVAL...SO AREAS
SUCH AS DIAMOND LAKE...CRATER LAKE...MOUNT ASHLAND...MOUNT
SHASTA...AND OTHER AREAS OVER 5000 FEET MAY WIND UP WITH 4 TO 6
FEET OF SNOW BY THE TIME IT ALL ENDS.

WEAKER WAVES WILL FOLLOW SUNDAY NIGHT AS THE LONG WAVE TROUGH
FINALLY MOVES ONSHORE IN A MUCH WEAKENED STATE. POST-FRONTAL
SHOWERS WILL PERSIST THROUGH THIS INTERVAL. MONDAY HIGHS WILL BE
SIMILAR TO THE SATURDAY HIGHS...5 TO 10 DEGREES BELOW NORMAL.

AN AMPLIFYING RIDGE WILL BUILD INTO THE WEST COAST MONDAY...
EVENTUALLY BECOMING THE CENTERPIECE OF AN OMEGA BLOCK. THE RIDGE
WILL REMAIN ALONG THE WEST COAST THURSDAY NIGHT INTO SATURDAY.
SHOWERS WILL GRADUALLY DIMINISH MONDAY INTO WEDNESDAY AS THE RIDGE
AMPLIFIES AND PUSHES THE STORM TRACK BACK NORTH.

THURSDAY AND FRIDAY WILL LIKELY BE DRY. TEMPERATURES WILL WARM
TUESDAY THROUGH FRIDAY WITH INLAND HIGHS REACHING 10 TO 15 DEGREES
ABOVE NORMAL BY NEXT FRIDAY.

&&

.AVIATION...FOR THE 11/06Z TAF CYCLE...MVFR WITH AREAS OF IFR CAN
BE EXPECTED IN THE UPSLOPE AREAS NEAR MOUNT SHASTA AS MOISTURE
RETURNS FROM THE SOUTH OVERNIGHT. LIGHT RAIN MAY ALSO BRING CIGS
DOWN TO MVFR AT TIMES ACROSS THE REMAINDER OF NORCAL AND SOUTHERN
KLAMATH/LAKE COUNTIES. HIGHER TERRAIN OBSCURATIONS ARE LIKELY
OVERNIGHT. LOW PRESSURE MOVES SOUTH OF THE REGION FRIDAY WITH
OCCASIONAL LIGHT RAIN AND A MIX OF MVFR/VFR CIGS WITH
TERRAIN OBSCURATIONS THROUGH THE DAY. SPILDE

&&

.MARINE...UPDATED 200 AM PST FRI 11 MAR 2016...STEEP AND
HAZARDOUS SWELL DOMINATED SEAS WILL SUBSIDE EARLY THIS MORNING.
LOW PRESSURE NEAR 38N/130W IS EXPECTED TO WEAKEN AS IT MOVES EAST
INTO NORTHERN CAL. HOWEVER THE 6Z NAM SHOWS ANOTHER SURFACE LOW
DEVELOPING AROUND 4 AM PST THIS MORNING AND MOVING NORTH OVER THE
OUTER WATERS. THE LATEST RUN OF THE RAP ALSO HINTS AT THIS. IF
THIS SCENARIO PLAYS OUT, THEN SOUTH WINDS WILL INCREASE, POSSIBLY
REACHING SMALL CRAFT ADVISORY MAINLY SOUTH OF CAPE BLANCO THIS
MORNING. CONFIDENCE IS LOW ON THIS SCENARIO, BUT WILL NEED TO BE
MONITORED CLOSELY. SOUTH WINDS WILL INCREASE AHEAD OF A STRONG
COLD FRONT LATE THIS EVENING AND REACH GALE FORCE TONIGHT, BUT IT
LOOKS LIKE IT WILL ONLY BE FOR A 6 HOUR PERIOD. THE MODELS ARE IN
GOOD AGREEMENT WITH FRONT REACHING THE COAST AROUND 4 AM PST
SATURDAY, THEN MOVING ONSHORE. THE NEXT STORM IS EXPECTED SUNDAY
MORNING. THIS ONE WILL WARRANT CLOSE WATCHING. THE EC AND GFS SHOW
A SURFACE LOW DEVELOPING NEAR 135W SATURDAY EVENING, RAPIDLY
DEEPENING AND MOVING INSIDE OF 130 W EARLY SUNDAY MORNING, THEN
MOVING NORTHEAST TOWARDS THE WASHINGTON COAST LATER SUNDAY
MORNING. THE TRACK OF THE LOW AS IT RAPIDLY DEEPENS MAY BE TOO FAR
NORTH TO WARRANT STORM FORCE WINDS, BUT GALES ARE LIKELY. FOR NOW
IN ORDER TO AVOID CONFUSION, WE'LL HOLD OFF ON ANY HEADLINES UNTIL
THE FIRST GALE WARNING EXPIRES. IF THAT WEREN'T ENOUGH, VERY HIGH
AND VERY LONG PERIOD SWELL IS ALSO EXPECTED TO MOVE IN SUNDAY
MORNING. THE COMBINATION OF WIND WAVES AND HIGH SWELL COULD RESULT
IN DANGEROUS SEAS AND MARINERS ARE URGED TO REMAIN IN PORT UNTIL
THIS PERIOD OF STORMY WEATHER ENDS. -PETRUCELLI

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH MONDAY
        AFTERNOON FOR ORZ027-028.

CA...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH LATE SUNDAY
        NIGHT FOR CAZ082.
     WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH MONDAY EVENING
        FOR CAZ080.
     WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY EVENING
        FOR CAZ083.

PACIFIC COASTAL WATERS...GALE WATCH FROM FRIDAY EVENING THROUGH
        SATURDAY MORNING FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST FRIDAY
        FOR PZZ350-356-370-376.

15/15/10