Debris Flow in Oregon, December 30 to 31, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
904 AM PST FRI DEC 30 2005

.UPDATE...MODERATE TO HEAVY PRECIPITATION IS OCCURRING OVER
SOUTHEAST WASHINGTON AND EASTERN OREGON. SOUTHERLY WINDS ALOFT ARE
PRODUCING RISING SNOW LEVELS...PARTICULARLY IN OREGON. FLOODING
HAS BEEN REPORTED AT UNDER PASSES IN BEND AND BELOW STEEP TERRAIN
IN WASCO COUNTY. WITH RISING SNOW LEVELS AND CONTINUING RAIN
ISSUED A SMALL STREAM AND URBAN FLOOD ADVISORY FOR WASCO...
JEFFERSON...AND DESCHUTES COUNTIES. NUMEROUS HEAVY SNOW WARNINGS
IN NORTHEAST OREGON AND NORTHWEST BLUES IN WASHINGTON WILL EXPIRE
AT NOON. WILL MONITOR TEMPERATURES BUT AT THIS TIME EXPECT THE
SNOW TO CHANGE TO RAIN BY THEN. IN YAKIMA...KITTITAS...AND
KLICKITAT COUNTY IN WASHINGTON WARNING CURRENTLY IN EFFECT UNTIL
MIDNIGHT. EXPECT LOWER SNOW LEVELS IN WASHINGTON BUT PROBABLY WILL
END WARNING EARLY IN YAKIMA AND KITTITAS VALLEYS AND LEAVE UP FOR
CASCADES. SNOW ACCUMULATIONS BELOW 1500 FEET IN YAKIMA ARE
NEGLIGIBLE...AND TEMPERATURES ARE RISING IN KITTITAS VALLEY.
COONFIELD

&&

.PREV DISCUSSION... (ISSUED 235 AM PST FRI DEC 30 2005)

SHORT TERM...TODAY THROUGH SUNDAY...A SIGNIFICANT STORM SYSTEM IS
CURRENTLY CROSSING THE PACIFIC NORTHWEST...WITH NEARLY ALL LOCATIONS
RECEIVING PRECIPITATION OVERNIGHT...WITH CATEGORICAL POPS CONTINUING
THROUGH MUCH OF THE DAY...AND INTO FRIDAY EVENING ACROSS THE HIGHER
ELEVATIONS...AS A STRONG JET CROSSES THE REGION. IN
ADDITION...SOUTHERLY WINDS HAVE INCREASED IN THE GRANDE RONDE
VALLEY...NEAR ADVISORY CRITERIA AS OF 2 AM. WILL PUSH THE TIMING OF
THE WIND ADVISORY UP TO FCST ISSUANCE TIME...WITH THE ADVISORY
EXPIRING AT 10 PM TONIGHT.

FOR CENTRAL WASHINGTON...RAIN IN THE EVENING BELOW 2000 FEET HAS
CHANGED TO SNOW FOR MOST LOCATIONS ABOVE 1000 FEET...ALTHOUGH WITH
TEMPERATURES IN THE MID 30S AT ELLENSBURG...ACCUMULATING SNOWS
PROBABLY NOT OCCURRING YET. FROM OBSERVATIONS AND SPOTTER
REPORTS...PRECIP TYPE HAS BEEN RAIN...SNOW...OR A MIX OF RAIN AND
SNOW. IN ADDITION...MODEL SOUNDINGS SHOW A LACK OF A WARM LAYER
ALOFT ABOVE THE COOLER AIR NEAR THE GROUND TO SUPPORT SLEET OR
FREEZING RAIN. THUS...WILL CANCEL THE WINTER STORM WARNING...USING A
HEAVY SNOW WARNING INSTEAD FOR CENTRAL WASHINGTON THROUGH MIDNIGHT
FRIDAY NIGHT.

FURTHER SOUTH...SNOW ACROSS CENTRAL OREGON HAS CHANGED OVER TO RAIN
ACROSS MOST LOCATIONS AS WARMER AIR IS MOVING SOUTH TO NORTH ACROSS
THE REGION. THIS TREND WILL CONTINUE TODAY...WITH SNOW LEVELS ACROSS
THE EASTERN OR/WA MTNS RISING TO 5000 FEET OR SO BY THIS AFTN...THUS
EXPECT MORNING ACCUMULATIONS OF 2 TO 3 INCHES...BELOW ADVISORY
CRITERIA.

FOR SATURDAY/SUNDAY...MOIST W/SW FLOW WILL CONTINUE...ALTHOUGH UPPER
LEVEL DYNAMICS NOT AS IMPRESSIVE AS WITH THE SYSTEM CROSSING TODAY.
WILL USE ABOVE NORMAL POPS...WITH GENERALLY CHC POPS FOR THE
LOWLANDS...AND LIKELY POPS MTNS.

LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...THE LONGER RANGE MODELS
ARE NOW SHOWING A DRIER FORECAST AFTER 00Z WEDNESDAY OF NEXT WEEK.
HOWEVER BETWEEN SUNDAY AND WEDNESDAY IT CONTINUES TO LOOK QUITE WET
AND UNSETTLED AS FREQUENT WEATHER SYSTEMS MOVE INTO THE REGION IN A
PROGRESSIVE FLOW ALOFT. SNOW LEVELS WILL REMAIN MODERATELY HIGH
THROUGH THE PERIOD CAUSING MOST OF THE PRECIPITATION TO FALL AS RAIN
EXCEPT THE HIGHER MOUNTAINS AND PLATEAUS WHICH MAY RECEIVE SNOW...
ESPECIALLY AT NIGHT. DEPENDING ON HOW MUCH LIQUID EQUIVALENT FALLS
THERE COULD BE ENOUGH FOR SNOW ADVISORY/WARNING IN THE HIGHER
ELEVATIONS. FOR NOW WILL JUST MENTION THAT POSSIBILITY HERE. AFTER
WEDNESDAY PRECIPITATION BECOMES MORE SHOWERY WITH OCCASIONAL BREAKS
OF SUN AS AN UPPER RIDGE TRIES TO DEVELOP OVER THE REGION. THE ONLY
CAVEAT IS THAT THIS TIME OF YEAR UNDER AN UPPER RIDGE THERE IS A
STRONG TENDENCY FOR LOW CLOUDS AND FOG TO FORM OVER THE COLUMBIA
BASIN AND ADJACENT VALLEYS/FOOTHILLS OF THE BLUES. THIS WILL TEND TO
KEEP TEMPERATURES DOWN DURING THE DAYTIME AND UP AT NIGHT WHILE THE
MOUNTAINS BECOME WARMER DURING THE DAY AND COLDER AT NIGHT.

AVIATION...IFR/LIFR CONDITIONS WILL PERSIST AT TAF KYKM AS SNOW
FALLS THIS MORNING WITH LOW CEILINGS AND VISIBILITY. ELSEWHERE TAFS
SITES ARE MOSTLY REPORTING RAIN...HOWEVER THERE HAVE ALSO BEEN
OCCASIONAL LOW CEILINGS (BELOW 1000) FEET AT THOSE TAF SITES
(KPDT...KALW...KRDM...KPSC AND KDLS) AS WELL. CONDITIONS WILL
IMPROVE THIS AFTERNOON AS THE CURRENT STORM BEGINS TO MOVE OUT AND
WILL ALLOW MOST AREAS TO BE EITHER VFR OR AT LEAST MVFR BY TONIGHT.

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...HEAVY SNOW WARNING UNTIL NOON PST TODAY FOR ORZ506.

     HEAVY SNOW WARNING UNTIL NOON PST TODAY FOR ORZ502.

     HEAVY SNOW WARNING UNTIL NOON PST TODAY FOR ORZ503.

     BLOWING SNOW ADVISORY UNTIL NOON PST TODAY FOR ORZ049.

     WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR ORZ049.

     HEAVY SNOW WARNING UNTIL NOON PST TODAY FOR ORZ050.

     URBAN AND SMALL STREAM FLOOD ADVISORY FOR ORC017/031/065

WA...HEAVY SNOW WARNING UNTIL NOON PST TODAY FOR WAZ030.

     HEAVY SNOW WARNING UNTIL MIDNIGHT PST TONIGHT FOR WAZ501.

     HEAVY SNOW WARNING UNTIL MIDNIGHT PST TONIGHT FOR WAZ502.

     HEAVY SNOW WARNING UNTIL MIDNIGHT PST TONIGHT FOR WAZ026-WAZ027.

&&

TI:YGG
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
76/82/82

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
1117 AM PST FRI DEC 30 2005

WAZ024-501-502-026>030-ORZ041>044-049-050-501>506-311200-
EAST SLOPES OF THE CENTRAL CASCADES-
EAST SLOPES OF THE SOUTHERN CASCADES-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-EASTERN COLUMBIA RIVER GORGE OF OREGON-
NORTH CENTRAL OREGON-CENTRAL OREGON-
LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-WALLOWA COUNTY-
FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
1117 AM PST FRI DEC 30 2005

UPDATED FOR UPGRADE OF URBAN AND SMALL AND SMALL STREAM ADVISORY TO
URBAN AND SMALL STREAM WARNING FOR DESCHUTES...JEFFERSON AND
WASCO COUNTIES.

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...TODAY AND TONIGHT

SNOW
     EAST SLOPES OF THE CENTRAL CASCADES, EAST SLOPES OF THE
     SOUTHERN CASCADES, KITTITAS VALLEY, YAKIMA VALLEY, NORTHWEST
     BLUE MOUNTAINS, WALLOWA COUNTY, NORTHERN BLUE MOUNTAINS OF
     OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON, OCHOCO-JOHN DAY
     HIGHLANDS

STRONG WIND AND BLOWING SNOW
     GRANDE RONDE VALLEY

FLOODING
    NORTH CENTRAL OREGON, CENTRAL OREGON

A STRONG PACIFIC STORM SYSTEM IS CROSSING THE REGION TODAY AND
TONIGHT BRINGING MODERATE TO HEAVY PRECIPITATION.  A HEAVY SNOW
WARNING HAS BEEN  ISSUED...REFER TO AWIPS ID PDXWSWPDT...OR WMO
HEADER WWUS46 KPDT FOR FURTHER DETAILS.  MODERATE TO HEAVY RAIN AND
RISING SNOW LEVELS IS LEADING TO PONDING IN LOW LYING AREAS AND
FLOODING OF SMALL CREEKS AND STREAMS.  AN URBAN AND SMALL STREAM
FLOOD WARNING HAS BEEN ISSUED FOR WASCO...JEFFERSON...AND DESCHUTES
COUNTIES.  SEE AWIPS ID PDXFLWPDT OR WMO HEADER WGUS46 FOR DETAILS.

VERY WINDY SOUTHERLY WINDS OF 30 TO 40 MPH GUSTING TO 55 MPH WILL
CONTINUE ACROSS THE SOUTHERN GRANDE RONDE VALLEY THROUGH THIS
EVENING. STRONG WINDS AND FALLING SNOW HAVE REDUCED VISIBILITY ABOVE
3000 FEET IN THE GRANDE RONDE VALLEY. VISIBILITY WILL BE LESS THAN
1/4 MILE AT TIMES. THIS INCLUDES NORTH POWDER AND I-84 THROUGH LADD
CANYON.  A BLOWING AND DRIFTING SNOW ADVISORY HAS BEEN
ISSUED...REFER TO AWIPS ID PDXWSWPDT...OR WMO HEADER WWUS46 KPDT FOR
FURTHER DETAILS.

MODERATE TO HEAVY RAIN AND RISING SNOW LEVELS IS LEADING TO PONDING
IN LOW LYING AREAS AND FLOODING OF SMALL CREEKS AND STREAMS IN
CENTRAL AND NORTH CENTRAL OREGON.  AN URBAN AND SMALL STREAM FLOOD
ADVISORY HAS BEEN ISSUED FOR WASCO...JEFFERSON...AND DESCHUTES
COUNTIES.  SEE AWIPS ID PDXFLSPDT OR WMO HEADER WGUS88 FOR DETAILS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

UNSETTLED WEATHER WILL CONTINUE THROUGH MUCH OF NEXT WEEK...AS
A SERIES OF MOIST PACIFIC STORM SYSTEMS WILL CROSS THE REGION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PENDLETON/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.