High Surf Advisory 2, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
913 AM PST THU FEB 21 2013

.UPDATE...A QUICK UPDATE WAS ISSUED THIS MORNING TO ACCOUNT FOR
SLIGHTLY LOWER POPS AND QPF ACROSS MOST OF THE AREA TODAY. IT
LOOKS AS IF ANY PRECIPITATION WITH THE WEAK FRONT APPROACHING
LATER TODAY WILL BE CONFINED TO THE NW PORTION OF THE CWA THROUGH
THE CASCADES. EVERYTHING ELSE WITH THE GOING FORECAST IS IN GOOD
SHAPE.

THE FORECAST FOCUS TODAY WILL BE ON THE STRONGER FRONT DUE IN
FRIDAY. THE CURRENT WINTER WEATHER WATCH HIGHLIGHTS MOST OF THE
DETAILS FOR NOW AND CAN BE FOUND AT WSWMFR. AFTER A QUICK LOOK AT
THE MORNING MODEL RUNS, THE TIMING OF THIS EVENT LOOKS TO BE
FOCUSED ON THE HEAVIEST, STEADIEST PRECIPITATION STARTING THE
MIDDLE OF FRIDAY AFTERNOON AND ONLY LASTING UNTIL LATE FRIDAY
EVENING. AFTER THIS TIME THE PRECIPITATION INTENSITY WILL COME
DOWN SOME AS IT TURNS MORE SHOWERY. WINDS WILL ALSO BE A FACTOR
WITH THIS STORM. STRONG SOUTHWEST FLOW COULD REACH ADVISORY
CRITERIA OVER THE EAST SIDE. THE FLOW WILL THEN SHIFT TO MORE
WESTERLY AS THE FRONT PASSES THROUGH. THIS WILL SERVE TO ENHANCE
UPSLOPE OVER THE CASCADES AND COULD LEAD TO LOCALLY HIGHER SNOW
ACCUMULATIONS.

&&

.AVIATION...CONDITIONS FROM THE CASCADES WESTWARD WILL VARY
BETWEEN VFR AND MVFR THIS MORNING WITH HIGHER TERRAIN OBSCURED.
SOME OF THE DEEPER VALLEYS MAY HAVE AREAS OF IFR FOG FOR A FEW
HOURS PRIOR TO 18Z. EAST OF THE CASCADES, CONDITIONS ARE MOSTLY
VFR THOUGH LOCAL MVFR CIGS MAY BE ENCOUNTERED NEAR AND NORTH OF
SUMMER LAKE AND IN THE VICINITY OF THE WARNER MOUNTAINS. EXPECT
WIDESPREAD VFR CONDITIONS EAST OF THE CASCADES THIS AFTERNOON. A
WEAK FRONT MAY BRING AREAS OF MVFR CIGS ALONG AND WEST OF THE
CASCADES THIS AFTERNOON INTO THIS EVENING ALONG WITH A LITTLE
-RA/-SN. SPILDE

&&

.PREV DISCUSSION... /ISSUED 223 AM PST THU FEB 21 2013/

DISCUSSION...A SIGNIFICANT WINTER STORM IS EXPECTED FOR THE
CASCADES AS A STRONG COLD FRONT BLOWS THROUGH FRIDAY NIGHT.
LOWLAND SNOW WILL ALSO BE POSSIBLE AS COLD AIR POURS IN SATURDAY.

BUT FOR TODAY...LINGERING SNOW SHOWERS ARE CURRENTLY WORKING THEIR
WAY SOUTH THROUGH SISKIYOU COUNTY AND WILL BE OUT OF THE COUNTY
BY DAWN. BEYOND THAT, SHOWERS WILL BE LITTLE MORE THAN ISOLATED
THIS MORNING. HOWEVER, MOIST NORTHWEST FLOW CONTINUES, AND MID AND
HIGH CLOUD ASSOCIATED WITH THE NEXT DISTURBANCE CAN ALREADY BE SEEN
APPROACHING THE COAST. THIS WILL LIKELY SPREAD RAIN BACK INTO THE
COAST AND UMPQUA LATER THIS MORNING AND EARLY AFTERNOON. THERE IS
SOME MODEL DISAGREEMENT WITH THIS, AS THE GFS AND EC REMAIN
BULLISH WITH THE RAIN TODAY, WHEREAS THE NAM IS VIRTUALLY DRY.
GIVEN WHAT I SEE ON SATELLITE, I'VE SIDED WITH THE WETTER MODELS
FOR TODAY. ASIDE FROM THOSE AREAS, THE REST OF THE FORECAST AREA
WILL LIKELY BE DRY TODAY WITH INCREASING SUNSHINE THE FURTHER
SOUTH AND EAST YOU GO. PRECIPITATION WILL CONTINUE TO BE CONFINED
TO THE COAST, MOUNTAINS AND UMPQUA THROUGH TONIGHT AS WELL, WITH
THE REST OF THE AREA SEEING SCATTERED SHOWERS AT WORST.

A POTENT SYSTEM MOVING THROUGH THE ALEUTIANS RIGHT NOW WILL BLOW
THROUGH THE PACNW FRIDAY NIGHT AND SATURDAY. THIS SYSTEM WILL BE
ONE OF THE STRONGER ONES WE'VE SEEN IN A WHILE, BRINGING WIND,
MODERATE TO HEAVY PRECIPITATION, AND PLUNGING SNOW LEVELS. RIGHT
NOW, WINDS DON'T LOOK QUITE STRONG ENOUGH TO WARRANT ANY
HEADLINES OVER LAND, BUT IT WILL BE WINDY ALONG THE COAST, IN THE
MOUNTAINS, AND EAST SIDE BEGINNING FRIDAY AT THE COAST AND MOVING
EAST BY SATURDAY MORNING.

SNOW IS A DIFFERENT STORY, THOUGH. THIS IS A CLASSIC SYSTEM FOR
HEAVY SNOW IN THE CASCADES. WHILE SNOW LEVELS MAY BRIEFLY SPIKE
ABOVE PASS LEVELS FRIDAY AFTERNOON, THEY WILL PLUNGE QUICKLY AS
THE FRONT GOES THROUGH. STRONG WEST FLOW WILL PROMOTE VERY HEAVY
OROGRAPHIC SNOW IN THE CASCADES, WITH POTENTIALLY VERY INTENSE
SNOW RATES FOR A PERIOD FRIDAY NIGHT. ALL TOGETHER, QPF AND
INCREASINGLY HIGH SNOW RATIOS FRIDAY NIGHT ARE YIELDING AT LEAST
A FOOT OF SNOW OVER THE RANGE, AND SOME AREAS SUCH AS CRATER AND
DIAMOND LAKE COULD SEE UP TO 18 INCHES. THE LOWER PASS ALONG
HIGHWAY 140 PROBABLY WON'T SEE THAT KIND OF ACCUMULATION BUT 8
INCHES OR MORE IS POSSIBLE. A WINTER STORM WATCH WILL BE ISSUED
FOR THESE AREAS.

MODERATE TO HEAVY SNOW WILL CERTAINLY FALL OVER THE OTHER
MOUNTAINS AS WELL, BUT IT DOESN'T LOOK LIKE THIS STORM IS ORIENTED
QUITE RIGHT FOR A BIG DUMP AT SISKIYOU SUMMIT. NEVERTHELESS,
TRAVELERS WILL ENCOUNTER WINTRY CONDITIONS OVER ALL PASSES AT SOME
POINT FRIDAY NIGHT INTO SATURDAY. SPEAKING OF WHICH, THE LOWER
VALLEYS MAY ALSO SEE SNOW SATURDAY MORNING. GUIDANCE SHOWS COLD
AIR POURING IN WITH 850S DROPPING TO AS LOW AS -7C AND THICKNESSES
ON THE ORDER OF 522 DM. THIS IS PLENTY COLD ENOUGH TO GET SNOW
DOWN TO 1000 FEET OR SO, AND THE ONLY QUESTION IS IF MUCH PRECIP
WILL BE LEFT. AT THIS TIME, THERE WILL PROBABLY BE ENOUGH PRECIP
TO PRODUCE A DUSTING TO A COUPLE OF INCHES AT MOST LOCATIONS ABOVE
1000 FEET SATURDAY. I CAN'T REALLY SAY WHERE YET, BUT THE USUAL
SUSPECTS INCLUDE THE HILLS AROUND THE ROGUE VALLEY, SEXTON SUMMIT,
CAMAS MOUNTAIN, JACKSONVILLE HILL, AND HAYES HILL. WE'VE STILL GOT
TIME TO SORT THAT OUT. NO CHANGES WERE MADE TO THE FORECAST BEYOND
SATURDAY, AND SO THE PREVIOUS EXTENDED DISCUSSION FOLLOWS. -WRIGHT

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WATCH FROM FRIDAY AFTERNOON THROUGH LATE FRIDAY
     NIGHT FOR ORZ027.
     WINTER STORM WATCH FROM FRIDAY AFTERNOON THROUGH LATE FRIDAY
     NIGHT FOR ORZ028.

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM FRIDAY MORNING THROUGH
 	FRIDAY EVENING FOR PZZ350-356-370-376.
 	HAZARDOUS SEAS WATCH FROM FRIDAY MORNING THROUGH SATURDAY
	EVENING FOR PZZ350-356-370-376.
 	SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 7 AM PST FRIDAY
	FOR PZZ350-356-370-376.

MSO/BPN/MAP