000
FXUS66 KPDT 061133 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
335 AM PST TUE JAN 6 2009
UPDATED AVIATION DISCUSSION
.SHORT TERM...TODAY THROUGH WEDNESDAY...THE NEXT WEATHER SYSTEM TO
IMPACT THE PACIFIC NORTHWEST IS SPREADING PRECIPITATION OVER THE
AREA EARLY THIS MORNING. MAIN CONCERN FOR TODAY IS LOW LEVEL COLD
AIR THAT REMAINS IN THE YAKIMA VALLEY AND THE WASHINGTON COLUMBIA
BASIN. CURRENT TEMPERATURES ARE IN THE TEENS AND 20S IN THESE
LOCATIONS. HAVE ISSUED A FREEZING RAIN ADVISORY AS WARM ADVECTION
PRECIPITATION COULD RESULT IN A PERIOD OF FREEZING RAIN. FOR THE
REMAINDER OF THE FORECAST AREA EXPECT TO SEE MOSTLY RAIN WITH
MOUNTAIN SNOW. 00Z SLE SOUNDING SHOWED THE FREEZING LEVEL AT 4300
FEET AND THIS SHOULD GO UP TODAY. SOUTHWEST WINDS WILL BE INCREASING
TODAY AS SURFACE GRADIENTS AND WINDS ALOFT INCREASE. THESE WINDS
SHOULD EVENTUALLY MIX OUT THE COLD AIR IN THE BASIN AND YAKIMA
VALLEY. FOR TONIGHT AND WEDNESDAY THE MAJORITY OF THE PRECIPITATION
WILL BE IN THE CASCADES AS STRONG WESTERLY FLOW BRINGS IN ABUNDANT
MOISTURE. PRECIPITABLE WATER VALUES ARE QUITE HIGH. THE BLUES WILL
BE ANOTHER AREA TO RECEIVE DECENT AMOUNTS. AIRMASS CONTINUES TO WARM
AND SNOW LEVELS WILL RISE MORE. THIS WILL PRODUCE MOSTLY RAIN WITH
SNOW ONLY AT THE HIGHER MOUNTAINS. HYDRO CONCERNS WILL START
INCREASING ON WEDNESDAY AS RAIN AND SNOWMELT CAUSE RIVERS AND
STREAMS TO START RISING. 94
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY. STRATIFORM RAIN AND
HIGH SNOW LEVELS WILL REMAIN WEDNESDAY NIGHT WITH THE POTENTIAL FOR
FLOODING AS THE BIGGEST THREAT FOR OUR AREA. MORE DETAILS CAN BE
FOUND IN THE HYDROLOGY SECTION. SNOW LEVELS WILL LOWER ON THURSDAY
AND PRECIPITATION WILL CHANGE BACK TO SNOW OVER THE MOUNTAINS AFTER
THE PASSAGE OF A COLD FRONT. PRECIPITATION WILL TAPER OFF ON FRIDAY
AS HIGH PRESSURE AT THE SURFACE AND ALOFT STRENGTHENS OVER THE
PACIFIC NW. MOST OF THE FORECAST AREA WILL BE DRY...ALTHOUGH A FEW
LIGHT SHOWERS ARE POSSIBLE ALONG THE WASHINGTON CASCADES THIS
WEEKEND. CONFIDENCE IN THE EXTENDED FORECAST IS HIGH...AS MEDIUM
RANGE MODELS ARE IN GENERAL AGREEMENT. JOHNSON
&&
.AVIATION...12Z TAFS. A WARM FRONT IS SPREADING PRECIPITATION ACROSS
THE REGION THIS MORNING. PRECIPITATION WILL FALL IN THE FORM OF
RAIN AT ALL TAF SITES EXCEPT IN KYKM WHERE -FZRA IS EXPECTED WITH A
MIXTURE OF LIGHT SNOW. CIGS AND VSBYS WILL FLUCTUATE FROM VFR TO
MVFR WITH LOCALLY IFR CONDITIONS THROUGH 00Z/7TH WITH CONDITIONS
IMPROVING AFTERWARD. WINDS 10-25G35KT CAN BE EXPECTED THIS
AFTERNOON AND EVENING...EXCEPT AT KYKM WHERE WINDS LESS THAN 10KT
ARE FORECAST. JOHNSON
&&
.HYDROLOGY...WITH THE SNOW LEVELS RISING TO AROUND 7000 FEET FOR
WEDNESDAY AND WEDNESDAY NIGHT AND SIGNIFICANT RAIN EXPECTED...WE
WILL SEE RAPID RISES ON STREAMS AND RIVERS ALONG THE EAST SLOPES OF
THE WASHINGTON CASCADES AND ALONG THE WEST FACING SLOPES OF THE BLUE
MOUNTAINS. FOR TUESDAY THROUGH THURSDAY...THE EAST SLOPES OF THE
WASHINGTON CASCADES...6 TO 7 INCHES OF RAIN CAN BE EXPECTED NEAR THE
CREST WITH LESSER AMOUNTS EASTWARD...WITH ONE-QUARTER TO ONE-HALF
INCH EXPECTED IN THE YAKIMA VALLEY. ALONG THE BLUE MOUNTAINS...3
INCHES OF RAIN IS EXPECTED IN THAT PERIOD. GUIDANCE SHOWS THE THE
WALLA WALLA AND UMATILLA RIVERS RISING TO FLOOD STAGE WEDNESDAY
NIGHT AND EARLY THURSDAY. THE MAINSTEM YAKIMA AND NACHES RIVERS
WILL SEE RAPID RISES...BUT ARE NOT EXPECTED TO REACH FLOOD STAGE.
NUMEROUS SMALL STREAMS ACROSS CENTRAL/SOUTHEAST WASHINGTON AND
NORTHEAST OREGON WILL SEE RAPID RISES AND WE WILL MONITOR FOR
POSSIBLE ADVISORIES OR WARNINGS. ML
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 47 40 50 41 / 80 20 30 50
ALW 46 39 50 40 / 90 30 40 50
PSC 36 37 49 39 / 60 20 30 40
YKM 31 33 43 33 / 70 20 30 40
HRI 47 40 50 39 / 70 20 30 40
ELN 43 35 41 33 / 70 40 40 50
RDM 49 36 52 35 / 60 20 30 30
LGD 40 37 45 39 / 90 40 60 50
GCD 43 37 48 37 / 90 40 50 40
DLS 45 42 50 40 / 70 30 50 50
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WARNING UNTIL 3 PM PST THIS AFTERNOON FOR ORZ502.
WA...WINTER STORM WARNING UNTIL 3 PM PST THIS AFTERNOON FOR WAZ030.
FREEZING RAIN ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR WAZ027-
028.
&&
$$
TI:YYY
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
94/85/85
