Hazardous Seas Warning 63, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
105 AM PDT TUE OCT 21 2014

.DISCUSSION...21/00Z NAM/GFS IN.

THE PROGRESSIVE WET PATTERN CONTINUES FOR THE MEDFORD CWA WITH
MULTIPLE FRONTS MOVING ONSHORE OVER THE NEXT WEEK.

ONE FRONT IS NOW DEPARTING THE MEDFORD CWA...LEAVING BEHIND
SHOWERS UNDER AN UPPER TROUGH ALOFT. SOME ISOLATED THUNDERSTORMS
DEVELOPED EARLIER TONIGHT BUT THOSE HAVE SINCE DISSIPATED. THE
SHOWERS WILL DIMINISH LATER THIS MORNING AS A SHORT WAVE RIDGE
MOVES THROUGH...BUT THE BREAK WILL BE BRIEF...AT LEAST ALONG THE
COAST. SNOW LEVELS WILL BOTTOM OUT AT 5500-6000 FEET...SO SNOW
WILL REMAIN ABOVE THE PASSES.

AN OFFSHORE LONG WAVE TROUGH WILL SLOWLY APPROACH THE COAST...
BRINGING INCREASING SOUTHWEST FLOW ALOFT. SHORT WAVES EJECTING
FROM THE TROUGH WILL PUSH A FRONT ONSHORE WEDNESDAY...BUT THIS
FRONT WILL STALL AS IT BECOMES PARALLEL TO THE UPPER LEVEL FLOW.
WAVES WILL DEVELOP ALONG THE BOUNDARY AND MOVE FROM SOUTHWEST TO
NORTHEAST IN RESPONSE TO THE SHORT WAVES MOVING THROUGH ALOFT.
THEREFORE...THE FRONT WILL REMAIN ACTIVE BUT IT WILL BE VERY SLOW
TO PROGRESS. IT WILL FINALLY MAKE SOME SIGNIFICANT PROGRESS INLAND
THURSDAY...BUT IT WILL WEAKEN AS IT DOES SO AS THE BEST UPPER
LEVEL SUPPORT WILL REMAIN OFFSHORE.

EXPECT A LOT OF RAIN WITH THIS SYSTEM ALONG THE COAST AND IN THE
COAST RANGE...1-2 INCHES WEDNESDAY AND 2-4 INCHES WEDNESDAY NIGHT.
HEAVIER RAIN WILL SPREAD INTO THE UMPQUA BASIN LATER WEDNESDAY...BUT
IT WON'T DEVELOP OVER THE ROGUE VALLEY UNTIL WEDNESDAY NIGHT DUE
TO DOWNSLOPING. ONCE IT DOES THE ROGUE VALLEY COULD GET 0.25-0.50
INCHES. SHOWERS WILL CONTINUE INTO THURSDAY BUT AMOUNTS WILL BE
LIGHTER AS THE COOLER AIR ALOFT WILL REMAIN OFFSHORE. SNOW LEVELS
WILL REMAIN ABOVE ALL BUT THE HIGHEST PEAKS.

AS FAR AS WINDS GO...MODERATE TO STRONG WINDS ARE LIKELY AHEAD OF
THE FRONT WEDNESDAY AND WEDNESDAY EVENING...ESPECIALLY EAST OF
THE CASCADES AND THEY COULD REACH ADVISORY OR WARNING LEVELS NEAR
AND JUST EAST OF SUMMER LAKE WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING. MODELS SHOW 700 MB WINDS INCREASING AND PEAKING OUT
BETWEEN 40-50 KTS WEDNESDAY NIGHT INTO THURSDAY MORNING.
THE OTHER WINDY SPOT WILL BE THE SHASTA VALLEY...WHERE THEY WILL
LIKELY REACH ADVISORY CRITERIA. THE 700 MB WINDS ARE MORE
WESTERLY...BUT THE MEDFORD TO REDDING GRADIENT WILL PEAK AT AROUND
-5.0 MB WEDNESDAY EVENING.

THE LONG WAVE TROUGH WILL FINALLY MOVE ONSHORE FRIDAY NIGHT. THIS
WILL INDUCE A STRONG WAVE TO DEVELOP ALONG THE FRONTAL BOUNDARY
OFFSHORE...REJUVENATING THE FRONT AND PUSHING IT ONSHORE FRIDAY.

MEDIUM RANGE DISCUSSION FROM THE MONDAY AFTERNOON AFD...FRIDAY
THROUGH MONDAY. A LARGE UPPER TROUGH WILL MOVE TO AROUND 130W ON
FRIDAY...AND A STRONG SHORTWAVE WILL ROUND ITS BASE CAUSING THE
TROUGH TO BECOME NEGATIVELY TILTED. SURFACE LOW PRESSURE IS
EXPECTED TO FORM UNDER THE AREA OF UPPER DIFFLUENCE AND MOVE NORTH
ALONG THE COAST. THIS WILL DRAG THE FRONT FROM THURSDAY BACK NORTH
AS A WARM FRONT ON FRIDAY. WHILE THERE ARE SOME MODEL DIFFERENCES
REGARDING THE SPECIFICS...THIS WILL LIKELY BRING RAIN TO MUCH OF
THE AREA...ESPECIALLY THE WEST SIDE AND SOUTH FACING MOUNTAIN
RANGES. IN FACT DEEP MOIST SOUTHWEST FLOW REMAINS AIMED AT THE
CURRY COAST AND MOUNTAINS AND WESTERN SISKIYOU MOUNTAINS AS THE
FRONT DROPS IN THURSDAY...AS IT LIFTS BACK NORTH AS A WARM FRONT
FRIDAY...AND INTO THE WEEKEND. THIS COULD BE A VERY BIG RAIN
MAKER FOR THESE AREAS AS THIS MOIST FLOW IS WRUNG OUT OVER THE
TERRAIN.

THE KEY QUESTION REGARDING THE WINDS IS THE LOCATION AND STRENGTH OF
THE SURFACE LOW. THERE IS AT LEAST SOME POTENTIAL FOR STRONG WINDS
OVER THE WATERS...COAST...AND MOUNTAINS ON FRIDAY. GIVEN THE
UNCERTAINTY OF THE LOW POSITION...WE WEREN'T ABLE TO GET SPECIFIC
JUST YET. WE DID RAISE THE POPS FOR FRIDAY HOWEVER. THIS WILL
NEED TO BE WATCHED CLOSELY FOR WIND CONCERNS.

THE MAIN TROUGH AXIS MOVES INLAND SATURDAY WITH SHOWERS AND LOWER
SNOW LEVELS (AROUND 6000 FT). A WEAK RIDGE BUILDS IN ON SUNDAY WITH
LOWER CHANCES FOR RAIN. THE MODELS ALL ADVERTISE ANOTHER FRONT EARLY
NEXT WEEK...BUT DIFFER ON THE STRENGTH. WE'VE OBVIOUSLY TURNED A
CORNER INTO TYPICAL FALL WEATHER, AND THIS PATTERN LOOKS LIKE IT
HAS SOME STAYING POWER WHICH SHOULD HELP WITH OUR WATER ISSUES.
-WRIGHT

&&

.AVIATION...21/06Z TAF CYCLE...ISOLATED SHOWERS WILL CONTINUE
WITH LOWERING CEILINGS IN VALLEYS WEST OF THE CASCADES LEADING TO
AREAS OF MVFR BETWEEN 12Z AND 17Z. CLOUDS WILL DIMINISH TUESDAY
MORNING INTO TUESDAY AFTERNOON BUT VFR CEILINGS WILL RETURN TO THE
COAST BY LATE AFTERNOON AND SPREAD INLAND TUESDAY EVENING. -DW

&&

.MARINE...UPDATED 1000 PM PDT MON 20 OCT 2014...A SERIES OF
DISTURBANCES WILL IMPACT THE MARINE WATERS OVER THE NEXT WEEK.
LATE TONIGHT, WIND WAVES WILL DECREASE AND WESTERLY SWELL WILL
BEGIN TO GRADUALLY LOWER. BUT, SEAS WILL REMAIN STEEP AND ABOVE 10
FEET. SOUTH WINDS WILL INCREASE TO SMALL CRAFT ADVISORY LEVELS
AGAIN TUESDAY MORNING WITH GALES LIKELY FROM LATE TUESDAY
AFTERNOON ALL THE WAY INTO WEDNESDAY EVENING AS THE STRONGEST
FRONT OF THE WEEK SLOWLY MOVES EAST. IT IS EXPECTED TO REACH THE
WATERS WEDNESDAY MORNING THEN MOVE INLAND WEDNESDAY EVENING. GIVEN
THE SLOW MOVEMENT OF THE FRONT, ALONG WITH HIGH END SMALL CRAFT TO
GALE WINDS AND BUILDING WEST SWELL, VERY STEEP AND CHAOTIC SEAS
ARE EXPECTED WITH A COMBINED HEIGHT OF 10 TO 13 FT ON TUESDAY
BUILDING TO 15 TO 17 FT WEDNESDAY.

THE HIGH AND STEEP WEST SWELL IS LIKELY TO BECOME DOMINANT AGAIN BY
THURSDAY. SWELL IS EXPECTED TO DIMINISH SLIGHTLY THURSDAY INTO
FRIDAY BUT THERE WILL BE A PERIOD OF MODERATE SOUTHWEST WINDS LATE
THURSDAY NIGHT INTO EARLY FRIDAY AS A WARM FRONT LIFTS ACROSS THE
WATERS. ANOTHER STRONG COLD FRONT MAY FOLLOW FRIDAY INTO SATURDAY.
/DW

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM TUESDAY EVENING THROUGH
        WEDNESDAY EVENING FOR PZZ356.
     SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM TO 11 PM PDT TUESDAY
        FOR PZZ356.
     HAZARDOUS SEAS WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
        EVENING FOR PZZ356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT TUESDAY
        FOR PZZ350-356.
     GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY AFTERNOON
        FOR PZZ370.
     SMALL CRAFT ADVISORY FOR WINDS FROM 9 AM TO 5 PM PDT TUESDAY FOR
        PZZ370.
     HAZARDOUS SEAS WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
        AFTERNOON FOR PZZ370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM PDT TUESDAY
        FOR PZZ370-376.
     GALE WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING FOR
        PZZ376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 9 AM TO 5 PM PDT TUESDAY FOR
        PZZ376.
     HAZARDOUS SEAS WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
        EVENING FOR PZZ376.
     GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR
        PZZ350.
     SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM TO 11 PM PDT TUESDAY
        FOR PZZ350.
     HAZARDOUS SEAS WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY
        AFTERNOON FOR PZZ350.

15/15/06