River Flood Watch 40, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
401 PM PST MON DEC 3 2012

.DISCUSSION...
YET ANOTHER MOISTURE RICH FRONTAL SYSTEM WILL BEGIN MOVING THROUGH
THE AREA TONIGHT PERSISTING INTO WEDNESDAY. DUE TO ALREADY
SATURATED GROUND AND THE PRECIPITATION EXPECTED...MORE FLOODING IS
EXPECTED ACROSS THE AREA. THE SEVERITY OF THIS FLOODING WILL
DEPEND ON PRECIPITATION INTENSITY AND LOCATION DETAILS...SOME OF
WHICH ARE STILL TO BE DETERMINED. THE MAIN POINT IS THAT THERE
WILL BE TWO WAVES OF ENHANCED PRECIPITATION ACROSS THE AREA. THE
BIG QUESTION IS WHETHER OR NOT THE SECOND WAVE WILL MERGE WITH THE
FIRST TUESDAY NIGHT INTO WEDNESDAY MORNING...SENDING A 56 TO 12
HOUR SURGE OF MODERATE TO VERY HEAVY PRECIPITATION ACROSS THE
AREA. THIS MOISTURE IS COMING FORM THE HAWAIIAN ISLAND AREA...AND
SNOW LEVELS WILL BE SHOOTING UP TO 8000 TO 9000 FEET FOR THE BULK
OF THIS PRECIPITATION EVENT.

PLEASE REFER TO THE AREAL FLOOD WATCH AND OTHER FLOOD WATCHES FOR
MORE INFORMATION. BTL

WIND...LATEST MODEL GUIDANCE CONTINUES TO POINT TOWARD A DAMAGING
WIND EVENT FOR PORTIONS OF THE FORECAST AREA. TONIGHT...SOUTHERLY
WINDS WILL INCREASE SHARPLY OVER THE COASTAL WATERS FIRST...THEN
IMPACT THE COAST BY LATE TONIGHT INTO EARLY TOMORROW MORNING. A GOOD
ONSHORE COMPONENT TO 5000 FOOT WINDS...AND A GRADUALLY LOWERING
STABLE LAYER...WILL HELP DEVELOP A COASTAL BARRIER JET. THIS MEANS
THAT WINDS WILL LIKELY PUSH HIGHER THAN MODEL GUIDANCE ALONG THE
COASTLINE AND OVER THE COASTAL WATERS. WIND GUSTS TO 65 MPH WILL
OCCUR ALONG THE COAST...AND WITH THE SOIL SATURATED PER RECENT HEAVY
RAINS...DOWNED TREES AND LOSS OF POWER IS LIKELY.

AS THE WARM FRONT PUSHES INLAND...THE SHASTA VALLEY AND AREAS EAST
OF THE CASCADES WILL START TO EXPERIENCE HIGH WINDS. THERE IS A
DECENT WESTERLY COMPONENT TO THE H7 WINDS...SO THERE IS LOWER
CONFIDENCE IN THE HIGH WINDS OCCURRING NEAR WEED IN THE SHASTA
VALLEY. HOWEVER...THE MFR-RDD GRADIENT IS STILL PUSHING 10MB...SO
THE POTENTIAL FOR DAMAGING WINDS IS REAL. EAST OF THE CASCADES A
LONG-DURATION WIND EVENT IS EXPECTED...LASTING FROM EARLY TUESDAY
MORNING THROUGH TUESDAY EVENING...WITH THE WESTERLY COMPONENT ALOFT
FAVORING SUMMER LAKE AREA AS GETTING THE STRONGEST WINDS.
LASTLY...BUT NOT LEAST...THE HIGHER TERRAIN OF THE ROGUE VALLEY WILL
SEE GUSTY WINDS TONIGHT INTO EARLY TUESDAY MORNING. WE HAVE ISSUED A
WIND ADVISORY FOR ASHLAND AND THE HILLS SURROUNDING THE ROGUE
VALLEY...WITH THE THOUGHT THAT LACK OF GOOD SOUTHEAST COMPONENT TO
WINDS ALOFT WILL PREVENT THE STRONGEST WINDS FROM SURFACING IN THE
CENTER OF MEDFORD AND OTHER LOWER PORTIONS OF THE VALLEY. TREES WILL
BE MORE SUSCEPTIBLE TO WIND DAMAGE GIVEN THE VERY WET SOILS FROM
RECENT HEAVY RAINFALL. IT IS EXPECTED THAT ONCE THE RAIN BEGINS ON
TUESDAY...WIND WILL DIMINISH IN THE VALLEY...AS IS TYPICAL.

PLEASE SEE THE WIND PRODUCTS AT NPWMFR FOR MORE DETAILS ON SPECIFIC
LOCATIONS AND TIMING.

&&

.AVIATION...
BASED ON THE 03/18Z TAF CYCLE

MVFR CEILINGS AND LOCAL MTN OBSCURATION ALONG THE COAST WILL SHIFT
INLAND TONIGHT...IMPACTING LOCATIONS ALONG AND WEST OF THE CASCADES
BY LATE TONIGHT. THE FRONT APPROACHING THE COAST WILL GENERATE
STRONG WINDS LATER TONIGHT AT THE COAST...WITH THE POTENTIAL FOR
AREAS OF LOW LEVEL WIND SHEAR AND WIDESPREAD TURBULENCE. EARLY
TUESDAY MORNING STRONG WINDS WILL BEGIN TO IMPACT THE SHASTA
VALLEY...HILLS AROUND THE ROGUE VALLEY...AND EAST SIDE. TURBULENCE
WILL BE WIDESPREAD BY TUESDAY MORNING. MODERATE TO HEAVY RAIN WILL
IMPACT THE COAST LATE TONIGHT AND SHIFT INLAND ON
TUESDAY...RESULTING IN MVFR CONDITIONS WITH ISOLATED IFR CEILINGS
AND VISIBILITY IN THE HEAVIEST PRECIPITATION. WIDESPREAD MOUNTAIN
OBSCURATION EAST OF THE CASCADES IS EXPECTED BY TUESDAY AFTERNOON.

&&

.HYDROLOGY...
URBAN AND SMALL STREAM FLOODING IS LIKELY DURING THIS NEXT EVENT.
ADDITIONALLY...SOME CREEKS AND MAIN STEM RIVERS MAY ALSO REACH
ACTION OR FLOOD STAGE. BTL

&&

.CLIMATE...
YESTERDAY ENDED A 4 DAY PERIOD AT MEDFORD AIRPORT WITH 4.39
INCHES OF PRECIPITATION. THIS RANKED 19TH IN THE CLIMATE RECORD
FOR ALL TIME WETTEST 4 DAY PERIODS...AND WAS THE WETTEST 4 DAYS
PERIOD SINCE NOVEMBER 23RD OF 1998.

THE ASHLAND COOP SITE RECEIVED 4.78 INCHES DURING THIS SAME
PERIOD...WHICH RANKS AS THE 8TH WETTEST 4 DAY PERIOD ON
RECORD...AND WETTEST SINCE NOVEMBER 24TH OF 1998.

&&

.PREV DISCUSSION... /ISSUED 908 AM PST MON DEC 3 2012/

DISCUSSION...
WITH THE GROUND STILL TRYING TO DRAIN OUT EXCESS WATER TODAY AND
ANOTHER SIGNIFICANT PRECIPITATION PRODUCING STORM SYSTEM DUE IN
TONIGHT THROUGH EARLY WEDNESDAY, OUR FOCUS HAS SHIFTED MOSTLY TO
THE UPCOMING HYDROLOGIC CONCERNS. THOSE WHO LIVE ON OR NEAR
STREAMS...CREEKS...AND RIVERS ACROSS THE AREA SHOULD BE PREPARED
FOR HIGH FLOWS AND THE POTENTIAL OF FLOODING TUESDAY THROUGH
WEDNESDAY. AT THE CURRENT TIME, NO MAIN STEM RIVERS ARE FORECAST BY
THE RIVER FORECAST CENTER TO FLOOD, BUT THE POTENTIAL FOR
FLOODING...EVEN ON THE MAIN STEMS CURRENTLY EXISTS.

THE INCOMING SYSTEM WILL HAVE ALARMINGLY HIGH SNOW LEVELS WITH
RAIN IN SNOW EXPECTED IN OUR MOUNTAINS. THE SNOW PACK REALLY IS AT
6000 FEET AND ABOVE AND MAINLY FROM THE CASCADES WESTWARD. WHILE
THIS MEANS THE AVAILABLE EXTRA WATER FROM THE SNOWPACK IS
LIMITED...IT APPEARS WE COULD ADD AN ADDITIONAL 1 TO 2 INCHES OF
RUNOFF FROM THE MOUNTAINS WITH THIS NEXT STORM. ADD TO THAT WATER
AMOUNTS OF FROM THE PRECIPITATION FALLING OF 2 TO 4 INCHES OVER
ABOUT A 36 HOUR PERIOD OVER THE CASCADES AND SISKIYOUS, 1 TO 3
INCHES FOR THE WEST SIDE VALLEYS, AND 3 TO 6 INCHES ACROSS CURRY,
JOSEPHINE AND WESTERN SISKIYOU COUNTIES. THUS, THE CURRENT
HYDROLOGIC OUTLOOK IS LIKELY TO BECOME AN AREAL FLOOD WATCH OVER
MUCH OF THE WEST SIDE LATER TODAY. WE DO EXPECT UPDATED FORECASTS
FROM THE RIVER FORECAST CENTERS FOR THE MAIN STEM RIVERS...AS WELL.

NO IMMEDIATE UPDATES WILL BE MADE TO THE FORECAST THIS MORNING.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING FROM 2 AM TO 7 PM PST TUESDAY FOR ORZ030-031.
     FLOOD WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON FOR
     ORZ025>030.
     HIGH WIND WARNING FROM MIDNIGHT TONIGHT TO 10 AM PST TUESDAY FOR
     ORZ021-022.
     FLOOD WATCH FROM 10 PM PST THIS EVENING THROUGH WEDNESDAY
     MORNING FOR ORZ021>024.
     HIGH SURF ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST TUESDAY
     FOR ORZ021-022.
     WIND ADVISORY FROM 2 AM TO 7 PM PST TUESDAY FOR ORZ029.
     WIND ADVISORY FROM 10 PM THIS EVENING TO 7 AM PST TUESDAY FOR
     ORZ026.

CA...FLOOD WATCH FROM LATE TONIGHT THROUGH WEDNESDAY AFTERNOON FOR
     CAZ082-083.
     FLOOD WATCH FROM 10 PM PST THIS EVENING THROUGH WEDNESDAY
     MORNING FOR CAZ080-081.
     WIND ADVISORY FROM 2 AM TO 7 PM PST TUESDAY FOR CAZ084-085.
     HIGH WIND WARNING FROM 1 AM TO 4 PM PST TUESDAY FOR CAZ081.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST THIS EVENING FOR
     PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING FROM 10 PM THIS EVENING TO 1 PM PST
     TUESDAY FOR PZZ350-356-370-376.
     STORM WARNING FROM 10 PM THIS EVENING TO 1 PM PST TUESDAY FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST THIS
     EVENING FOR PZZ350-356-370-376.

BTL/NSK/MSO/CDG