Debris Flow in California, January 17, 2016

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
444 AM PST SUN JAN 17 2016

.DISCUSSION...
A STRONG PLUME OF MOISTURE IS FEEDING INTO THE FORECAST AREA THIS
MORNING FROM THE SOUTHWEST, AS IS CLEARLY EVIDENT ON SATELLITE AND
REGIONAL RADAR IMAGERY. SOME RUMBLES OF THUNDER OVER THE COASTAL
WATERS EARLIER THIS MORNING HAVE MORPHED INTO A BROAD AREA OF
MODERATE RAINFALL NOW MOVING RAPIDLY INTO SOUTHWESTERN OREGON AND
NORTHWESTERN CALIFORNIA. OVER THE LAST HOUR BROOKINGS HAS REPORTED
0.36" OF RAIN ALONG WITH SOME MODERATELY GUSTY WINDS. FLASH FLOOD
WATCHES REMAIN IN EFFECT FOR PORTIONS OF CURRY...JOSEPHINE...AND
SISKIYOU COUNTIES WHERE EXCESSIVE RAINFALL RATES AND MID-ELEVATION
SNOW MELT ARE EXPECTED TO LEAD TO RAPID AND SIGNIFICANT RISES ON
STREAMS AND CREEKS. ADDITIONALLY...THE STABILITY OF BURN SCARS IN
WESTERN SISKIYOU COUNTY AT THE JULY AND HAPPY CAMP WILDFIRE COMPLEXES
ARE LIKELY TO BE TESTED TODAY. IF FLOODING APPEARS IMMINENT ON
RADAR AND/OR BASED ON OBSERVATIONS THESE FLOOD WATCHES WILL BE
UPGRADED TO WARNINGS.

SNOW LEVELS TODAY ARE EXPECTED TO RISE TO ABOUT 7KFT ACROSS THE
AREA CAUSING MID-ELEVATION SNOW MELT. ABOVE 5.5KFT SUSPECT THAT
ANY RAIN WILL BE EASILY ABSORBED BY OUR ROBUST SNOWPACK, AND SNOW
LEVELS WILL FALL TO ABOUT 5500 FEET THIS EVENING. SIGNIFICANT SNOW
ACCUMULATIONS TODAY WILL BE CONFINED TO AREAS ABOVE 7KFT, WITH
SOME LIGHT ACCUMULATION POSSIBLE DOWN TO ABOUT 5500 FEET. THE
EUROPEAN MODEL GUIDANCE WAS PREFERRED AGAIN WITH THIS PACKAGE FOR
THE SNOW LEVEL FORECAST DUE TO ITS GOOD SPATIAL REPRESENTATION OF
CURRENT SNOW LEVELS AS COMPARED TO AREA OBSERVATIONS. IT IS
ENCOURAGING THAT OTHER MODELS TRENDED MORE TOWARD THIS MODEL IN
THE LAST 24 HOURS. DURING PEAK PRECIPITATION RATES TODAY I LOWERED
SNOW LEVELS TO 500-1000 FEET BELOW GUIDANCE DUE TO CONSISTENT
HISTORY OF THIS OCCURRING IN SUCH EVENTS. THIS MIGHT NOT BE LOW
ENOUGH, BUT SHOULD PROVIDE A GOOD AVERAGE MOST LIKELY SCENARIO DUE
TO POSSIBLE DIFFERENCES BETWEEN MODEL FORECAST FIELDS AND REALITY.

REGARDING WINDS, HEADLINES WERE LEFT INTACT FOR TODAY THROUGH THIS
EVENING. THUS FAR, WINDS HAVE BEEN A BIT ON THE LOW SIDE, AND
MODEL GUIDANCE HAS TRENDED DOWN SLIGHTLY, INDICATING TWO BANDS OF
WIND MAXIMA MOVING THROUGH RATHER THAN ONE CONSOLIDATED MAXIMUM.
THERE ARE CONVECTIVE ELEMENTS TO THIS STRONG FRONTAL SYSTEM,
HOWEVER, AND THIS CAN EASILY LEAD TO BRIEFLY GUSTY AND POTENTIALLY
DAMAGING WINDS AS DEPICTED BY CURRENT HEADLINES. IN THE ROGUE
VALLEY IT IS POSSIBLE WE COULD SEE SOME GUSTY SOUTHWEST WINDS IN
THE MEDFORD AREA THIS AFTERNOON OR EVENING, THOUGH THE MAJORITY OF
MODEL GUIDANCE INDICATES THIS WILL NOT OCCUR.

AFTER TODAY THROUGH TONIGHT'S STORM THE FOCUS WILL SHIFT TO MONDAY
NIGHT THOUGH TUESDAY WHEN AN AREA OF LOW PRESSURE IS EXPECTED TO
INTENSIFY AS IT MOVES TOWARD THE SOUTHERN OREGON COAST. THERE
CONTINUES TO BE A LOT OF SPREAD IN THE MODELS ON DETAILS WITH
THIS SYSTEM. MODEL TRENDS IN THE LAST 24 HOURS INDICATE ANOTHER
ROUND OF SUBSTANTIAL WIND AND RAIN, BUT NOTHING EXCESSIVE. SNOW
LEVELS ALSO LOOK TO BE LOWER, NEAR 5000-5500 FEET. GIVEN THE
SIGNIFICANT WATER CONTENT OF THE SNOWPACK AT MID-ELEVATIONS, IT
WILL BE WORTH MONITORING STREAM FLOW RESPONSE TO THE OVERALL
UPWARD SHIFT IN SNOW LEVELS. IF NOTHING ELSE, SUSPECT WE'LL
INCREASE FILL RATES FOR OUR STILL ROOMY AREA RESERVOIRS. BTL

&&

.AVIATION...FOR THE 17/06Z TAF CYCLE...IFR/LIFR FOG HAS FORMED AT
KMFR THIS EVENING, BUT SHOULD BE SHORT-LIVED AS A STRONG FRONT
APPROACHES THE COAST WITH SOME SOUTHEAST WINDS MIXING THINGS UP AFTER
ABOUT 09Z. LOW-LEVEL WIND SPEED SHEAR WILL ALSO BE A THREAT FOR THE
NEXT 6-12 HOURS WITH RELATIVELY LIGHT WINDS NEAR THE GROUND AND
SOUTH WINDS OF 40-50KT ABOUT 1500-2000 FT AGL. EXPECT WIDESPREAD
MVFR ON SUNDAY WITH TERRAIN BECOMING TOTALLY OBSCURED AS PRECIPITATION
FROM THE FRONT MOVES INLAND. BRIEF IFR IS POSSIBLE IN HEAVIER
PRECIPITATION. THE STRONG WINDS ALOFT WILL ALSO PRODUCE TURBULENCE.
SPILDE

&&

.MARINE...UPDATED 945 PM PST SATURDAY 16 JAN 2016...ANOTHER PERIOD
OF GALE FORCE WINDS IS EXPECTED LATE THIS EVENING THROUGH SUNDAY
MORNING. VERY HIGH SWELL DOMINATED SEAS WITH VERY HIGH AND VERY LONG
PERIOD WEST SWELL WILL PERSIST TONIGHT INTO SUNDAY AND COMBINE WITH
VERY STEEP WIND WAVES TO BRING CHAOTIC AND HAZARDOUS SEAS TO THE
WATERS. VERY HIGH AND VERY STEEP SEAS WILL GRADUALLY LOWER LATE
SUNDAY NIGHT. ADDITIONAL STRONG FRONTS ARE EXPECTED THROUGH LATE
NEXT WEEK...RESULTING IN PERIODS OF STRONG SOUTH WINDS AND VERY
STEEP SEAS. SVEN/SPILDE

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING UNTIL 10 PM PST THIS EVENING FOR ORZ030-031.
     FLOOD WATCH THROUGH LATE TONIGHT FOR ORZ022-024.
     HIGH SURF ADVISORY UNTIL 4 AM PST MONDAY FOR ORZ021-022.
     WIND ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR ORZ026.
     WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR ORZ029.

CA...HIGH WIND WARNING UNTIL 10 PM PST THIS EVENING FOR CAZ085.
     FLOOD WATCH THROUGH LATE TONIGHT FOR CAZ080-082.
     WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR CAZ084.
     FLASH FLOOD WATCH UNTIL 4 PM PST THIS AFTERNOON FOR CAZ080.
     HIGH WIND WARNING UNTIL 10 PM PST THIS EVENING FOR CAZ081.

PACIFIC COASTAL WATERS...
- GALE WARNING UNTIL 10 AM PST THIS MORNING FOR PZZ350-356-370-376.
- HAZARDOUS SEAS WARNING UNTIL 4 AM PST MONDAY FOR PZZ350-356.
- HAZARDOUS SEAS WARNING FROM 10 AM THIS MORNING TO 4 AM PST
  MONDAY FOR PZZ370-376.

BTL/CC/SPILDE