FXUS66 KPDT 090531 AAA
AFDPDT
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
930 PM PST TUE DEC 8 2009
UPDATED AVIATION DISCUSSION.
.UPDATE...HIGH PRESSURE CONTINUES TO BUILD OVER THE AREA TONIGHT.
PRESSURE READINGS ARE UP ABOUT 10 MB FROM LAST NIGHT AT THIS TIME.
COLD AIR CONTINUES TO MOVE INTO THE AREA FROM THE CANADIAN ROCKIES.
TEMPERATURES ARE RUNNING SIMILAR TO OR SLIGHTLY COLDER THAN LAST
NIGHT. DEW POINT TEMPERATURES ARE A FEW DEGREES LOWER. BELIEVE THAT
TONIGHT WILL BE SLIGHTLY COLDER THAN LAST NIGHT...PERHAPS A DEGREE
OR TWO. SKIES ARE MAINLY CLEAR BUT SOME MID AND HIGH LEVEL CLOUDS
ARE MOVING THROUGH SOUTHERN CANADA AND NORTHERN WASHINGTON AND WILL
BEGIN MOVING INTO THE AREA LATER TONIGHT. BELIEVE THAT THE CLOUDS
ARE TOO HIGH AND TOO THIN TO HAVE MUCH IMPACT ON TEMPERATURES BUT
HAVE INCREASED CLOUD COVER IN THE NORTH AND EAST TO PARTLY CLOUDY.
ANOTHER LOW STRATUS DECK IS TRYING TO FORM AROUND BEND IN CENTRAL
OREGON. THIS WOULD SEEM LIKELY TO KEEP TEMPERATURES UP BUT SIMILAR
STRATUS DECKS THE LAST TWO NIGHTS HAVEN'T HAD MUCH EFFECT ON
TEMPERATURES SO EXPECT THAT WILL BE THE CASE TONIGHT. DID ADJUST A
FEW TEMPERATURES BUT MAINLY LEFT CURRENT FORECAST AS IS. HAVE BUMPED
WINDS UP THROUGH THE GRANDE RONDE VALLEY TO 10 TO 15 MPH TO MATCH
OBSERVATIONS AND WHAT HAPPENED LAST NIGHT. UPDATE OUT SOON. PERRY
&&
.AVIATION...06Z TAFS...VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24
HOURS. CURRENT CLEAR TO MOSTLY CLEAR SKIES WILL SEE SOME SCATTERED
MID LEVEL CLOUDS ABOVE 8000 FT AGL MOVE IN TO THE NORTH AND EAST
AREAS AND AROUND BEND LATER TONIGHT THROUGH TOMORROW MORNING.
TOMORROW AFTERNOON AND EVENING WILL HAVE CLEAR SKIES. WINDS WILL
REMAIN UNDER 10 KTS AT ALL LOCATIONS. PERRY
&&
.PREV DISCUSSION... /ISSUED 215 PM PST TUE DEC 8 2009/
SHORT TERM...TONIGHT THROUGH FRIDAY. MAINLY CLEAR SKIES TONIGHT
WITH VERY COLD TEMPERATURES. LOWS WILL BE SIMILAR TO LAST NIGHT WITH
MOST AREAS BELOW ZERO AND THE COLDEST LOCATIONS 10 TO 20 BELOW ZERO.
SATELLITE SHOWS A LITTLE CIRRUS MOVING THROUGH AT TIMES BUT SHOULD
HAVE NO IMPACT ON TEMPERATURES. THE PACIFIC NORTHWEST WILL REMAIN
UNDER A COLD NORTHERLY FLOW ALOFT THROUGH FRIDAY. IT WILL REMAIN DRY
WITH CLEAR TO PARTLY CLOUDY SKIES. THE AIRMASS WILL BE WARMING
SLOWLY THROUGH THE PERIOD SO EXPECT TEMPERATURES TO START INCREASING
A FEW DEGREES EACH DAY. EVEN WITH THE GRADUAL WARMING TREND
TEMPERATURES WILL STILL BE 10-15 DEGREES BELOW NORMAL BY FRIDAY.
LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...THE LATEST MODEL RUNS
HAVE BEEN TRENDING COOLER AND DRIER DURING THE LONG TERM
PERIOD...ESPECIALLY THE ECMWF. AS A RESULT...DO NOT EXPECT
TEMPERATURES TO RETURN TO NEAR NORMAL VALUES UNTIL AT LEAST TUESDAY.
THAT SAID...ANY PRECIPITATION THAT DOES FALL OVER THE WEEKEND WILL
LIKELY BE IN THE FORM OF SNOW. HOWEVER...SINCE THE ECMWF TRACKS THE
NEXT PACIFIC STORM SYSTEM MUCH FARTHER SOUTH THAN PREVIOUS RUNS OR
THE GFS...CONFIDENCE IS LOW THAT THERE WILL BE SIGNIFICANT SNOWFALL
ON SATURDAY OR SUNDAY.
ON MONDAY THE MODELS COME BACK INTO AGREEMENT AND BUILD A RIDGE OF
HIGH PRESSURE OVER THE REGION...WHICH WILL ADVECT WARM AIR INTO THE
AREA. THIS WARM AIR IS FORECAST TO RIDE OVER THE COLDER AIR AT THE
SURFACE...FAVORING A WINTRY MIX INCLUDING SLEET AND/OR FREEZING RAIN
ON MONDAY NIGHT. THEN ON TUESDAY A FAIRLY STRONG FRONTAL SYSTEM WILL
APPROACH THE REGION...FINALLY MIXING OUT THE COLD AIR...ALLOWING
FREEZING PRECIPITATION TO CHANGE OVER TO RAIN IN THE COLUMBIA BASIN
AND SURROUNDING VALLEYS. 82
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT -1 17 6 20 / 0 0 0 0
ALW 6 20 11 21 / 0 0 0 0
PSC -1 22 7 22 / 0 0 0 0
YKM -4 19 2 20 / 0 0 0 0
HRI -3 19 5 22 / 0 0 0 0
ELN -4 18 2 21 / 0 0 0 0
RDM -11 16 -5 23 / 0 0 0 0
LGD -1 16 2 20 / 0 0 0 0
GCD -3 17 1 22 / 0 0 0 0
DLS 2 18 8 22 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&
THREAT INDEX
WEDNESDAY : GREEN
THURSDAY : GREEN
FRIDAY : GREEN
GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
$$
83/82/83
