Small Craft Advisory for Winds 13, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
338 PM PST THU FEB 6 2014

.DISCUSSION...

SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT.

MUCH NEEDED PRECIPITATION HAS ARRIVED...AND FORTUNATELY...MOISTURE
WILL REMAIN IN THE AREA FOR SOME TIME. IMMEDIATE CONCERNS DURING
THE SHIRT TERM ARE RELATED TO SNOW LEVELS AND WINDS ACCOMPANYING A
COUPLE OF SURFACE LOWS AND THEIR ASSOCIATED FRONTS AS THEY MOVE
ONSHORE TONIGHT AND TOMORROW. THE GFS AND NAM ARE IN GOOD
AGREEMENT DURING THE SHORT TERM...AND HAVE BEEN THE PRIMARY
GUIDANCE THROUGH SATURDAY. THERE IS HIGH CONFIDENCE CONCERNING THE
MOISTURE MOVING ONSHORE AND INTO THE CWA...BUT THERE REMAINS
UNCERTAINTY REGARDING THE SNOW LEVELS...WHICH WILL FLUCTUATE
GREATLY BEFORE QUICKLY RISING SATURDAY.

THE SURFACE LOW CURRENTLY MOVING ONSHORE WILL BE THE PRIMER FOR A
STRONGER LOW SET TO PUS ONSHORE TOMORROW NIGHT. WHILE RAIN AND
SNOW IS ONGOING AND WILL CONTINUE THROUGH TONIGHT...MOISTURE WILL
INCREASE TOMORROW AND PRECIPITATION WILL BE MUCH HEAVIER. WITH
SNOW LEVELS EXPECTED TO REMAIN AROUND 2000 FEET...AND POSSIBLY
DROPPING TO AROUND 1500 FEET AT TIMES...THERE WILL BE SUBSTANTIAL
AMOUNTS OF SNOW TO FALL OVER THE HIGHER TERRAIN OF SOUTHERN OREGON
AND NORTHERN CALIFORNIA. AS THIS WILL BE THE FIRST MAJOR SYSTEM TO
IMPACT THE AREA IN SOME TIME...HAVE ISSUED WINTER WEATHER
ADVISORIES FOR AREAS BETWEEN 1500 AND 2000 FEET AND WINTER STORM
WARNINGS FOR ALL ELEVATIONS ABOVE 2000 FEET ON THE WEST SIDE. HAVE
ALSO ISSUED MULTIPLE HEADLINES FOR THE EAST SIDE AND NORTHERN
CALIFORNIA AS WELL...BUT THESE ARE MOSTLY BASED ON FORECAST SNOW
AMOUNTS. FOR MORE INFORMATION AND DETAILS REGARDING SNOW
AMOUNTS...PLEASE SEE THE WINTER WEATHER MESSAGE.

ANOTHER ASPECT OF SOME CONCERN WILL OCCUR TOMORROW AS THE SECOND
SURFACE LOW MOVES ONSHORE. THE LOW ILL APPROACH THE COAST FROM THE
SOUTHWEST...AND WITH STRONG UPPER LEVEL SUPPORT...IT HAS THE
POTENTIAL TO UNDERGO STRONG CYCLOGENESIS. THIS WOULD IN TURN
PRODUCE STRONG WINDS ALONG THE COAST AND OVER THE CASCADES. HAVE
ISSUED A HIGH WIND WATCH FOR THE COATS TOMORROW EVENING TO ACCOUNT
FOR THIS POSSIBILITY. FORECAST 850 MB WINDS ASSOCIATED WITH THE
LOW ARE APPROACHING 75 MPH FROM THE WEST ALONG THE NORTHERN
CASCADES. WITH HEAVY SNOW IN THE AREA...AND WINDS CHANNELING
THROUGH THE PASSES AND BETWEEN PEAKS...THERE IS THE POSSIBILITY OF
SOME DAMAGING WINDS THERE AS WELL.

SOUTHERLY FLOW OVER THE MOUNT SHASTA AREA OF NORTHERN CALIFORNIA
WILL PRODUCE UPSLOPING THERE...AND WITH HEAVIER PRECIPITATION
RATES EXPECTED...SNOW LEVELS THERE WILL REMAIN LOWER THAN
SURROUNDING AREAS THROUGHOUT THE EVENT. RESIDENTS SHOULD BE
PREPARED FOR SNOW TO PERSIST LONGER HERE THAN ELSEWHERE...LASTING
WELL INTO SATURDAY EVENING BEFORE SNOW LEVELS RISE ABOVE THE MORE
HEAVILY POPULATED AREAS.

WITH RISING SNOW LEVELS...ALL PRECIPITATION WEST OF THE CASCADES
SHOULD TURN TO RAIN BY SATURDAY MORNING. AS SNOW WILL CONTINUE
OVER EASTERN SISKIYOU COUNTY AND THE EAST SIDE FOR SEVERAL MORE
HOURS...WINTER HEADLINES WILL CONTINUE THERE UNTIL SATURDAY
AFTERNOON. ONCE THE LOW PASSES...SHOWERS WILL CONTINUE TO LINGER
THROUGH SATURDAY NIGHT AND INTO SUNDAY.

EXTENDED TERM...SUNDAY THROUGH THURSDAY NIGHT.

THE ACTIVE PATTERN IS SET TO CONTINUE THROUGH THE REMAINDER OF
THE FORECAST PERIOD...WITH MODELS DEPICTING NUMEROUS WAVES MOVING
INTO THE FORECAST AREA. THERE WILL BE A FEW BREAKS IN THE
ACTION...SPECIFICALLY MONDAY AND TUESDAY...BUT FOR THE MOST
PART...EXPECT A WET WEEK.

GENERALLY SPEAKING...THE PATTERN DURING THE LONG TERM WILL CONSIST
OF A BROAD LOW AMPLITUDE RIDGE OVER WEST COAST...WITH SWIFT WESTERLY
FLOW PUSHING ONSHORE ALONG THE NORTHERN CALIFORNIA AND SOUTHERN
OREGON COASTS. MULTIPLE IMPULSES WITHIN THIS FLOW WILL PUSH
ONSHORE...AND EACH ONE WILL BRING A ROUND OF PRECIPITATION.
HOWEVER...SUCH FEATURES ARE NOTORIOUSLY DIFFICULT TO FORECAST...THUS
THERE IS MUCH UNCERTAINTY REGARDING THE EXACT TIMING AND STRENGTH OF
EACH INDIVIDUAL WAVE. WHAT IS CERTAIN IS THAT THE AREA WILL REMAIN
WET...AND WITH A TAP TO TROPICAL MOISTURE...AS EVIDENCED BY FORECAST
IVT AND MODEL MOISTURE PLUMES. ASIDE FROM A BRIEF AMPLIFICATION OF
THE RIDGE ON MONDAY AND TUESDAY WHICH ESSENTIALLY BLOCKS THIS
FEED...THE MOISTURE FLOW REMAINS TARGETED IN OUR GENERAL DIRECTION.

CONSIDERING THE RIDGE AND THE SOURCE OF THE FLOW...WE ARE LIKELY TO
SEE TEMPERATURES RISE...AND SUBSEQUENTLY...SNOW LEVELS WILL ALSO
BECOME QUITE HIGH. TEMPERATURES WILL RISE TO 10 TO 15 DEGREES ABOVE
SEASONAL NORMALS...AND SNOW LEVELS WILL HOVER ABOVE 5000 FEET FOR
THE REMAINDER OF THE FORECAST. THEREFORE...THE BULK OF THE AREA WILL
SEE RAIN...WITH ONLY THE HIGHEST PEAKS LIKELY TO RECEIVE SNOW THIS
WEEK.

&&

.AVIATION...BASED ON THE 06/18Z TAF CYCLE.

A LOW PRESSURE SYSTEM WILL MOVE ACROSS SOUTHWEST OREGON THIS
AFTERNOON AND EVENING. THIS WILL KEEP PRECIPITATION OVER THE AREA
FOR THE DURATION OF THE TAF PERIOD. A MIX OF RAIN AND SNOW OR JUST
SNOW OVER THE WEST SIDE THIS MORNING HAS TRANSITIONED TO RAIN AS
FREEZING LEVELS HAVE RISEN TO ABOVE 2000 FEET. ALL SNOW IS EXPECTED
IN THE MOUNTAINS AND EAST SIDE. GENERALLY VFR CIGS AND VIS HAVE
BEGUN TO DETERIORATE TO MVFR OVER ALL AREAS TODAY AS PRECIPITATION
HAS INCREASED IN COVERAGE AND INTENSITY. LOCAL IFR IS POSSIBLE IN
SNOW EAST OF THE CASCADES THIS AFTERNOON AND EVENING. THE MOUNTAINS
WILL BE OBSCURED THROUGH TONIGHT AND MOUNTAIN WAVE TURBULENCE WILL
INCREASE ON THE EAST SIDE THIS EVENING AS THE LOW JUMPS THE CASCADES
AND THE FLOW BECOMES WESTERLY AT ALL LEVELS.

&&

.MARINE...A SERIES OF LOW PRESSURE SYSTEMS WILL CONTINUE TO MOVE
THROUGH THE WATERS OVER THE NEXT SEVERAL DAYS. THE FIRST WILL MOVE
THROUGH THIS EVENING AND WHILE WINDS WILL NOT BE PARTICULARLY
STRONG...THEY WILL BE SHIFTING AROUND TO THE WEST THIS AFTERNOON
AS THE LOW MOVES INLAND. ANOTHER LOW COMES FROM THE SOUTHWEST
FRIDAY AND MOVES ACROSS THE WATERS. THIS WILL PRODUCE A PERIOD OF
NEAR GALE FORCE SOUTHERLIES OVER THE SOUTHERN WATERS...THEN WINDS
SHIFT WEST AGAIN. YET A THIRD LOW WILL MOVE BY TO THE NORTH ON
SUNDAY. WINDS WILL NOT BE VERY STRONG WITH THIS ONE BUT IT WILL
BRING MORE RAIN AND SHIFTING WINDS. THE STORM TRACK REMAINS AIMED
AT OUR AREA INTO NEXT WEEK AS WELL WITH ANOTHER STRONG LOW
POSSIBLE ON TUESDAY WITH SOUTHERLY GALES AND RAIN EXPECTED.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 10 AM PST SATURDAY FOR ORZ029>031.
     WINTER STORM WARNING FROM 4 AM FRIDAY TO 10 AM PST SATURDAY FOR
     ORZ029>031.
     WINTER STORM WARNING FROM 4 AM TO 10 PM PST FRIDAY ABOVE 2000
     FEET FOR FOR ORZ024>026.
     HIGH WIND WATCH FROM FRIDAY AFTERNOON THROUGH LATE FRIDAY NIGHT
     FOR ORZ021-022.
     WINTER WEATHER ADVISORY UNTIL 10 PM PST FRIDAY ABOVE 3000 FEET
     FOR FOR ORZ023>026.
     WINTER STORM WARNING FROM 4 AM TO 10 PM PST FRIDAY FOR
     ORZ027-028.
     WINTER WEATHER ADVISORY UNTIL 4 AM PST FRIDAY FOR ORZ027-028.

CA...WINTER WEATHER ADVISORY UNTIL 10 AM PST SATURDAY FOR
     CAZ082-083-085.
     WINTER STORM WARNING FROM 4 AM FRIDAY TO 10 AM PST SATURDAY FOR
     CAZ082>085.
     WINTER WEATHER ADVISORY UNTIL 10 PM PST FRIDAY ABOVE 3000 FEET
     FOR FOR CAZ080-081.
     WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 10 AM PST SATURDAY
     FOR CAZ084.
     WINTER STORM WARNING FROM 4 AM TO 10 PM PST FRIDAY ABOVE 3000
     FEET FOR FOR CAZ080-081.

PACIFIC COASTAL WATERS...GALE WATCH FROM FRIDAY AFTERNOON THROUGH
     FRIDAY EVENING FOR PZZ356-376.
     HAZARDOUS SEAS WATCH FROM FRIDAY AFTERNOON THROUGH FRIDAY
     EVENING FOR PZZ356-376.
     GALE WATCH FROM FRIDAY AFTERNOON THROUGH FRIDAY EVENING FOR
     PZZ350-370.
     HAZARDOUS SEAS WATCH FROM FRIDAY AFTERNOON THROUGH FRIDAY
     EVENING FOR PZZ350-370.
     WINTER WEATHER ADVISORY FROM 4 AM FRIDAY TO 10 AM PST SATURDAY
     FOR PZZ310.

BPN