Gale Warning 54, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
103 AM PST SUN DEC 7 2014

.DISCUSSION...07/00Z NAM/GFS IN.

AN UPPER LEVEL RIDGE IS CURRENTLY OVER THE PACIFIC NORTHWEST.
A FEW LIGHT SHOWERS PERSIST HERE AND THERE...MOSTLY ON THE EAST
SIDE. MOST AREAS ARE DRY WITH LOW CLOUDS AND FOG IN SOME OF THE
VALLEYS...AND CIRRUS ABOVE.

THE HEMISPHERIC PATTERN SHOWS A WAVE NUMBER OF 4 AROUND THE
GLOBE...DOWN FROM 5 A FEW DAYS AGO. THIS SUGGESTS THAT THE
OVERALL PATTERN WILL BECOME LESS PROGRESSIVE OVER THE NEXT
SEVERAL DAYS. THE COLDEST AIR REMAINS OVER THE HUDSON BAY AREA
WITH A SECONDARY MAX OVER THE SPITZBERGEN ISLANDS.

THE RIDGE WILL MOVE OUT TO THE EAST SUNDAY...AND THEN THE PATTERN
WILL INDEED STALL. A LONG WAVE TROUGH WILL SET UP BETWEEN 15OW AND
160W AND PARK THERE THROUGH AT LEAST WEDNESDAY. SOUTHWEST FLOW
ALOFT WILL SET UP OVER THE PACIFIC NORTHWEST MONDAY AND STRENGTHEN
THROUGH WEDNESDAY. SHORT WAVES EJECTING FROM THE TROUGH WILL
BRINGS ROUNDS OF WIND AND PRECIPITATION TO THE MEDFORD CWA.

THE FIRST OF THESE WAVES WILL MOVE ONSHORE SUNDAY EVENING. THE
ASSOCIATED FRONT WILL FALL APART AS IT MOVES ONSHORE AS MOST OF
THE UPPER LEVEL SUPPORT WILL BE CONFISCATED BY AN UPSTREAM SYSTEM.
THE BULK OF THE PRECIPITATION WILL FALL OVER CURRY COUNTY AND FAR
WESTERN SISKIYOU COUNTY. LIGHTER AMOUNTS WILL FALL INLAND AS THE
FRONT WEAKENS...AND MOST AREAS WILL SEE SOME MEASURABLE
PRECIPITATION SUNDAY NIGHT INTO MONDAY...EVEN EAST OF THE
CASCADES.

ANOTHER WAVE WILL PUSH ANOTHER FRONT ONSHORE MONDAY EVENING...AND
THIS ONE HOLDS TOGETHER A BIT BETTER THAN THE SUNDAY NIGHT SYSTEM.
ONCE AGAIN THE HEAVIEST PRECIPITATION WILL FALL OVER CURRY COUNTY.

SNOW WILL NOT BE A FACTOR WITH ANY OF THESE SYSTEMS AS THE SNOW
LEVEL WILL REMAIN ABOVE ALL BUT THE HIGHEST PEAKS...ABOVE AT LEAST
6000 FEET AND OFTEN HIGHER.

THE BIG KAHUNA WILL MOVE IN WEDNESDAY...AND THAT IS COVERED IN
THE EXTENDED DISCUSSION.

EXTENDED FORECAST DISCUSSION FROM THE SATURDAY AFTERNOON
AFD...WEDNESDAY THROUGH SUNDAY. AGREEMENT OF THE 12Z MODELS DURING
THE EXTENDED PERIOD IS ABOVE AVERAGE. THUS, ADJUSTMENTS WERE MADE
TO: INCREASE THE PROBABILITY OF PRECIPITATION (POP) WEDNESDAY INTO
THURSDAY NIGHT, DECREASE THE POP FRIDAY INTO SATURDAY NIGHT,
INCREASE TEMPERATURES SLIGHTLY WEDNESDAY AFTERNOON WITH SOUTHERLY
DOWNSLOPE WINDS EXPECTED IN THE ROGUE AND SHASTA VALLEYS, AND TO
DECREASE TEMPERATURES THURSDAY NIGHT THROUGH SATURDAY NIGHT.

THE FOCUS OF THE EXTENDED PERIOD IS UPON AN ATMOSPHERIC RIVER EVENT
WITH SIGNIFICANT RAINFALL AND STRONG SOUTHERLY WINDS POSSIBLE
WEDNESDAY THROUGH THURSDAY. THIS EVENT IS ALSO FORECAST TO HAVE
ABOVE NORMAL SNOW LEVELS AT AROUND 7000 FEET FALLING TO AROUND 5500
FEET. RAINFALL AMOUNTS LOOK TO BE HIGHEST ALONG THE OREGON AND FAR
NORTHERN CALIFORNIA COAST ON WEDNESDAY WITH THE FOCUS SHIFTING
SOUTHEAST TO THE AREA EXTENDING FROM MT SHASTA TO SAN FRANCISCO AND
SACRAMENTO ON THURSDAY. THE PORTIONS OF OUR AREA TYPICALLY PRONE TO
STRONG SOUTH WINDS WILL HAVE THE HIGHEST RISK OF REACHING ADVISORY
OR WARNING LEVELS. THOSE ARE THE COAST, MOUNTAINS, SOUTHERN SHASTA
VALLEY, AND THE EAST SIDE (ESPECIALLY IN NORTHERN LAKE COUNTY IN THE
VICINITY OF SUMMER LAKE AND SILVER LAKE). THE WIND AND PRECIPITATION
FORECAST WILL BE FINE TUNED AS THIS EVENT DRAWS NEARER. BUT, THE
STRONGEST WINDS AND HEAVIEST PRECIPITATION AMOUNTS ARE FORECAST TO
OCCUR WEDNESDAY NIGHT WITH GUSTS OF 55 TO 70 MPH NEAR WEED AND
SUMMER LAKE.

MODEL AGREEMENT IS NOT IN LOCK STEP WITH THE PROGRESSION OF THE
PATTERN FRIDAY INTO THE WEEKEND. THE FORECAST LEANS TOWARD THE
FASTER PROGRESSION OF THE GFS WHICH IS A COLDER AND LESS WET THAN
SOLUTION THAN THE ECMWF FOR FRIDAY MORNING INTO THE WEEKEND. THE 18Z
GFS HAS TRENDED EVEN FASTER THAN ITS 12Z RUN, WHICH LENDS SOME
SUPPORT TO THE CURRENT FORECAST. A PROGRESSIVE SOLUTION WOULD RESULT
IN A COLD, SHOWERY PATTERN OF NORTHERLY FLOW WHILE A SLOWER
PROGRESSION OF THE UPPER LEVEL PATTERN WOULD CONTINUE A WET AND
RELATIVELY MILD SOUTHWEST FLOW ALOFT. /DW

&&

.AVIATION...BASED ON THE 08/06Z TAF CYCLE...IFR CIGS/VSBYS HAVE
DEVELOPED AT KRBG. EXPECT VALLEYS LIKE THE ROGUE...ILLINOIS...AND
UMPQUA TO GET THEIR FAIR SHARE OF LIFR CONDITIONS AS THE NIGHT
PROGRESSES. CONFIDENCE IN COASTAL FOG NEAR NORTH BEND IS LOW...AND
GIVEN THAT BOTH DYNAMIC AND STATISTICAL GUIDANCE SUGGEST VFR
CONDITIONS OVERNIGHT...HAVE KEPT NORTH BEND VFR THROUGH THE NIGHT.
ANY VALLEY FOG/LOW CLOUDS THAT FORM TONIGHT SHOULD LIFT TO VFR
LATE TOMORROW MORNING OR EARLY AFTERNOON. STRONG SOUTHERLY FLOW
TOMORROW WILL BRING GUSTY SURFACE WINDS TO THE SHASTA VALLEY AND
PERHAPS THE SOUTHERN PORTION OF THE ROGUE VALLEY NEAR ASHLAND.
TURBULENCE WILL INCREASE TOMORROW...ESPECIALLY NEAR WEST TO EAST
ORIENTED TERRAIN. RAIN FROM THE NEXT FRONT WILL ARRIVE SUNDAY
EVENING. SK

&&

.MARINE...UPDATED 1000 PM PST SAT DEC 6 2014...THE NEXT FRONT IS
EXPECTED TO MOVE TOWARDS THE WATERS SUNDAY AFTERNOON. SOUTH WINDS
WILL INCREASE AHEAD OF THE FRONT SUNDAY MORNING. MODELS SHOW 925 MB
WINDS INCREASING TO 40 KTS OVER THE SOUTHERN OUTER WATERS BY 12Z
SUNDAY, THEN NEAR 50 KTS OVER MOST OF THE WATERS SUNDAY AFTERNOON.
AT THE SAME TIME 850 WINDS ARE ALSO EXPECTED TO BE NEAR 50 KTS WITH
A SLIGHT ONSHORE COMPONENT. GIVEN THE ABOVE MENTIONED SCENARIOS, WE
COULD HAVE GALE FORCE WINDS WITH STEEP WIND DRIVEN SEAS FROM LATE
SUNDAY MORNING INTO SUNDAY EVENING. THE FRONT WILL MOVE INLAND
SUNDAY AND WINDS AND SEAS WILL DECREASE, BUT ONLY FOR A BRIEF TIME.
ANOTHER FRONTAL BOUNDARY WILL BE SETTING UP NORTH OF THE WATERS
MONDAY THROUGH TUESDAY AND IT'S A GOOD BET WE'LL HAVE ANOTHER ROUND
OF GALES AND STEEP WIND DRIVEN SEAS.

THE LAST COUPLE OF RUNS OF THE WAVE WATCH BULLETIN AND ENP MODEL
HAVE BACKED OFF AND DELAYED THE HEAVY WEST SWELL NEXT TUESDAY,
WEDNESDAY AND THURSDAY. THEY ARE STILL EXPECTED TO BE IN THE 14 TO
18 FOOT RANGE TUESDAY AND WEDNESDAY, THEN 18 TO 20 FEET THURSDAY.
HOWEVER HIGH END SMALL CRAFT AND POSSIBLY GALE FORCE WINDS WILL
CONTINUE, THUS RESULTING IN HEAVY SEAS NEAR OR OVER 20 FEET.

HOWEVER THE BULLETINS ARE STILL ON TRACK AT BRINGING A LONG PERIOD
SWELL OF 14 FEET OR LONGER INTO OUR WATERS MONDAY...ALBEIT AT A LOW
WAVE HEIGHT UNTIL TUESDAY. THESE LONG PERIOD SWELLS WILL AFFECT
OCEAN BOTTOM AT DEPTHS UP TO 800 FEET AS EARLY AS MONDAY. FB

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM SUNDAY MORNING THROUGH SUNDAY
        AFTERNOON FOR PZZ370-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 7 AM TO 10 AM PST SUNDAY
        FOR PZZ370-376.
     HAZARDOUS SEAS WATCH FROM SUNDAY MORNING THROUGH SUNDAY
        AFTERNOON FOR PZZ370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 7 AM TO 10 AM
        PST SUNDAY FOR PZZ370-376.

15/15/10