High Wind in Oregon, September 28 to 30, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
736 AM PDT SAT SEP 28 2013

.DISCUSSION...DID A QUICK UPDATE TO INCREASE POPS A BIT FOR THIS
MORNING WITH SOME LIGHT RAIN MOVING THROUGH MEDFORD AND INTO THE
CASCADES. NO OTHER CHANGES HAVE BEEN MADE. SPILDE

&&

.AVIATION...A VERY POTENT COLD FRONT WILL ARRIVE THIS AFTERNOON
AND EVENING. AREAS OF IFR CIGS WILL CONTINUE ALONG THE COAST THIS
MORNING WITH LOCAL MVFR CIGS EXTENDING INLAND INTO THE UMPQUA
BASIN. THEN EXPECT A MIX OF IFR/MFR CIGS ALONG THE COAST THIS
AFTERNOON INTO THIS EVENING. SOUTHERLY WINDS ARE INCREASING AND
WILL PRODUCE AREAS OF SPEED SHEAR TODAY AND TONIGHT. WINDS ALOFT
WILL BECOME STRONG ACROSS SOUTHERN OREGON AND NORTHERN CALIFORNIA
BY THIS AFTERNOON WITH SOUTHWEST 25 TO 50 KT WINDS BELOW 8K FT
AGL. THE FRONT WILL ALSO BRING HEAVY RAIN THIS EVENING AND TONIGHT
THAT WILL REDUCE VISIBILITIES AT AND NEAR THE COAST. THIS HEAVY
RAIN WILL SPREAD FARTHER INLAND LATE TONIGHT. AREAS OF MVFR CIGS
WILL DEVELOP BETWEEN 06Z-12Z TONIGHT FROM THE CASCADES WEST WITH
WIDESPREAD MOUNTAIN OBSCURATIONS DEVELOPING AS WELL. CC

&&

.PREV DISCUSSION... /ISSUED 447 AM PDT SAT SEP 28 2013/

DISCUSSION...
A STRONG PARENT LOW IN THE GULF OF ALASKA WITH A CENTRAL PRESSURE
NEAR 970MB THIS MORNING IS DRIVING A WELL DEVELOPED FRONTAL SYSTEM
INTO WESTERN CANADA AND THE PACIFIC NORTHWEST THIS MORNING. STRONG
NORTH WINDS AT JET STREAM LEVEL LIKELY IN EXCESS OF 170 KNOTS ON
THE WEST SIDE OF THE UPPER LEVEL TROUGH CARVING OUT THIS LOW
CONTINUE TO DIG THE UPPER LEVEL TROUGH SOUTHWARD TOWARD OUR AREA.
A MYRIAD OF WIND, WAVE, WIND, AND HEAVY PRECIPITATION RELATED
HEADLINES ARE IN EFFECT FOR A ONE-TWO PUNCH FROM THIS UNUSUALLY
STRONG FOR SEPTEMBER UPPER LEVEL TROUGH. ULTIMATELY, THIS UPPER
LEVEL TROUGH HAS ORIGINS FROM THE WESTERN PACIFIC, WITH REMNANTS
OF FORMER TYPHOON PABUK AND THE MADDEN-JULIAN OSCILLATION.

OVER THE LAST 24 HOURS A LEADING SHORTWAVE TROUGH AHEAD OF THE
PRIMARY TROUGH HAS RESULTED IN LIGHT TO MODERATE RAINFALL ACROSS
MOSTLY COOS AND DOUGLAS COUNTIES. A FEW SITES IN THE NORTHERN
PORTIONS OF THESE COUNTIES HAVE RECEIVED 0.50" TO 1", HOWEVER.

TODAY PRECIPITATION WILL BE ACROSS THESE SAME AREAS, THOUGH
ACTIVITY WILL LIKELY ORIENT SUCH THAT IT SPREADS A BIT SOUTHWARD
ALONG THE COAST AND COAST RANGE INTO CURRY COUNTY WITH LESS IN
CENTRAL AND EASTERN DOUGLAS COUNTY OVER THE COURSE OF THE DAY. FOR
MANY AREAS, TO INCLUDE MEDFORD, HIGH TEMPERATURES WILL BE THE
HIGHEST THAT HAVE BEEN OBSERVED FOR THE LAST WEEK, REACHING INTO
THE 60S AND 70S FOR HIGHS. WINDS WILL INCREASE ACROSS THE REGION,
ESPECIALLY ALONG THE COAST, EAST SIDE, AND OVER THE HIGHER
TERRAIN. WE MOVED UP THE START TIME FOR THE HIGH WIND WARNING IN
THE SHASTA VALLEY TO LATE THIS EVENING DUE TO A PRESSURE GRADIENT
REACHING 6 TO 8 MILLIBARS BETWEEN MEDFORD AND REDDING AND WINDS
ALOFT INCREASING TO 55 KNOTS AT 700MB. STILL, THE STRONGEST WINDS
FOR MOST AREAS WILL COME ON SUNDAY AFTERNOON AND EVENING. THE
OTHER ADJUSTMENT TO THE WIND HEADLINES WAS TO ADD A HIGH WIND
WATCH FOR SUNDAY AFTERNOON AND EVENING AT THE COAST DUE TO THE
SECOND STRONG WAVE OF LOW PRESSURE PUSHING THE TRIPLE POINT OF THE
ASSOCIATED FRONTAL SYSTEM ONTO THE COAST. 925MB WINDS ON THE NAM
REACH 55 TO 65 KNOTS WITH BOTH TODAY'S FRONT AND THE SUNDAY
AFTERNOON AND EVENING FRONT, THOUGH THEY ARE A TAD STRONGER WITH
THE SECOND ONE, ESPECIALLY ALONG AND NEAR THE CURRY COUNTY COAST.
STANDARDIZED ANOMALIES FROM BOTH THE NAEFS AND GEFS INDICATE
ANOMALIES OF 5 TO 6+ STANDARD DEVIATIONS OF NORMAL FOR 850MB AND
700MB WINDS ACROSS THE AREA DURING MUCH OF THE PERIOD IN WHICH WE
HAVE WIND HEADLINES. RETURN INTERVALS FOR 850MB AND 700MB WINDS
FOR THIS DATE FOR OUR AREA ARE 30 YEARS TO NOT OBSERVED FOR THE 30
YEARS OF CLIMATE DATA USED FOR THIS MEASURE OF COMPARISON!

ALL OF THIS WIND WILL, OF COURSE, LEAD TO TREMENDOUS
OROGRAPHICALLY ENHANCED PRECIPITATION. FOR MUCH OF THE AREA IT
WILL NOT BE UNTIL LATE THIS AFTERNOON THROUGH EARLY SUNDAY WHEN
PRECIPITATION WILL REALLY GET GOING. PRECIPITABLE WATER RETURN
INTERVALS ARE MORE ON THE ORDER OF A ONCE IN TEN YEAR TYPE OF
EVENT. ADJUSTMENTS TO THE PRECIPITATION AMOUNTS FORECAST FOR THE
DOUBLE-WHAMMY WERE MAINLY TIMING RELATED, WITH LITTLE CHANGE TO
OVERALL AMOUNTS. PER CONSISTENT SIGNALS IN THE GFS BASED MEX
BULLETINS AND EUROPEAN MODEL BASED ECX BULLETINS, THERE IS GROWING
CONFIDENCE THAT THE ENTIRE WEST SIDE OF OREGON SHOULD SEE STORM
TOTALS OVER AN INCH. PUSHED MEDFORD AND ASHLAND VALLEY TOTALS UP A
BIT TO 1.5 INCHES, AS GUIDANCE HAS BEEN HONING IN ON MID-RANGE
AMOUNTS ABOUT THERE. AMOUNTS FOR CURRY AND WESTERN JOSEPHINE
COUNTIES ARE MOSTLY 4 TO 8 INCHES WITH 3 TO 5 INCH AMOUNTS FOR MUCH
OF DOUGLAS, COOS, JOSEPHINE, AND FAR WESTERN SISKIYOU COUNTIES.

ANYONE TRAVELING INTO THE MOUNTAINS TONIGHT THROUGH MONDAY SHOULD
RETHINK THEIR PLANS OR PREPARE FOR SERIOUS STORM CONDITIONS. WHILE
SNOW LEVELS WILL BE HIGH, PRIMARILY ABOVE 10KFT, WINDS WILL BE
STRONG, GUSTING IN THE 60 TO 80 MPH RANGE TONIGHT THROUGH MONDAY
ABOVE 6KFT. DANGEROUS BLIZZARD CONDITIONS WILL DEVELOP ON MOUNT
SHASTA ABOVE ABOUT 10KFT TONIGHT THROUGH SUNDAY. FOR SPECIFIC
CONDITIONS FOR YOUR AREA OF INTEREST, USE THE POINT-AND-CLICK
FORECAST ON OUR WEB SITE.

BY MONDAY AFTERNOON CONDITIONS WILL RETURN BACK CLOSER TO NORMAL
WITH SHOWERY NORTHWEST FLOW. AT THIS POINT IT APPEARS WE WILL SEE
A WARM-UP BY NEXT WEEKEND, BUT CONFIDENCE IN THE EXTENDED FORECAST
REMAINS LOW DUE TO RECENT POOR MODEL PERFORMANCE FOR THE MID-
LONGER RANGE IN THE CURRENT PATTERN. BTL

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 11 AM TO 11 PM PDT SUNDAY FOR ORZ029>031.
     WIND ADVISORY FROM 11 AM THIS MORNING TO 11 AM PDT SUNDAY FOR
     ORZ029>031.
     HIGH WIND WARNING FROM 11 AM TO 11 PM PDT SUNDAY FOR ORZ024.
     HIGH SURF ADVISORY FROM 11 AM SUNDAY TO 5 AM PDT MONDAY FOR
     ORZ022.
     HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 2 AM PDT SUNDAY
     FOR ORZ021.
     FLASH FLOOD WATCH FROM 5 PM PDT THIS AFTERNOON THROUGH LATE
     SUNDAY NIGHT FOR ORZ023>025.
     WIND ADVISORY FROM 11 AM TO 11 PM PDT SUNDAY FOR ORZ023-025-026.
     HIGH WIND WARNING FROM 8 AM TO 11 PM PDT SUNDAY FOR ORZ027-028.
     HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING FOR
     ORZ021-022.
     HIGH SURF ADVISORY FROM 11 AM SUNDAY TO 5 AM PDT MONDAY FOR
     ORZ021.

CA...FLASH FLOOD WATCH FROM 5 PM PDT THIS AFTERNOON THROUGH LATE
     SUNDAY NIGHT FOR CAZ080.
     HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO 11 PM PDT SUNDAY FOR
     CAZ081.
     WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 11 PM PDT THIS EVENING
     FOR CAZ081.
     WIND ADVISORY FROM 11 AM TO 11 PM PDT SUNDAY FOR CAZ084-085.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 2 PM PDT
     THIS AFTERNOON FOR PZZ356-376.
     HAZARDOUS SEAS WARNING FROM 2 PM THIS AFTERNOON TO 5 PM PDT
     MONDAY FOR PZZ356-376.
     GALE WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT SUNDAY FOR
     PZZ356-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 PM PDT THIS
     AFTERNOON FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 AM PDT THIS MORNING FOR
     PZZ350-370.
     STORM WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
     PZZ350-370.
     HAZARDOUS SEAS WARNING FROM 11 AM THIS MORNING TO 8 PM PDT
     MONDAY FOR PZZ350-370.
     STORM WARNING FROM 11 AM THIS MORNING TO 11 PM PDT THIS EVENING
     FOR PZZ350-370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 AM PDT THIS
     MORNING FOR PZZ350-370.

MAS/BTL/CMC