HAZARDOUS WEATHER OUTLOOK
Issue Date: 545 AM PST THU DEC 24 2009
Expiration: 545 AM PST FRI DEC 25 2009

Expires:200912251345;;
FLUS46 KPQR 241344
HWOPQR
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PORTLAND OR
544 AM PST THU DEC 24 2009
ORZ005>008-WAZ022-039-251345-
LOWER COLUMBIA-GREATER PORTLAND METRO AREA-
CENTRAL WILLAMETTE VALLEY-SOUTH WILLAMETTE VALLEY-I-
5 CORRIDOR IN COWLITZ COUNTY-GREATER VANCOUVER AREA-
544 AM PST THU DEC 24 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
OREGON AND SOUTHWEST WASHINGTON.
.DAY ONE...TODAY AND TONIGHT
AREAS OF DENSE FREEZING FOG WILL AFFECT THE AREA THIS MORNING.
.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED.
$$

AIR STAGNATION ADVISORY
Issue Date: 417 AM PST THU DEC 24 2009
Expiration: 600 PM PST SAT DEC 26 2009

...AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST
SATURDAY...
...DENSE FOG ADVISORY REMAINS IN EFFECT UNTIL 10 AM PST THIS
MORNING FOR THE CENTRAL AND SOUTH WILLAMETTE VALLEY...
AN AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST
SATURDAY. A DENSE FOG ADVISORY REMAINS IN EFFECT UNTIL 10 AM PST
THIS MORNING.
* IMPACTS...AREAS OF DENSE FOG ARE EXPECTED TO REDUCE VISIBILITIES
  TO ONE QUARTER OF A MILE OR LESS AT TIMES THE MORNING. FREEZING
  TEMPERATURES WILL ALLOW THE FOG TO FREEZE TO SURFACES MAKING
  THEM SLIPPERY.
* TIMING...THROUGH 10 AM THURSDAY.
OFFSHORE FLOW OVER THE REGION WILL STRENGTHEN OVERNIGHT AND
CONTINUE FOR THE REST OF THE WEEK INTO THE COMING WEEKEND.
HOWEVER...STRONG LOW LEVEL INVERSIONS WILL KEEP AREAS BELOW
1500 FEET FROM MIXING WELL. THIS WILL LEAD TO AIR QUALITY THAT
WILL GRADUALLY BECOME MORE POOR WITH TIME.
* AREAS AFFECTED...THE WIND SHELTERED LOWLANDS OF THE CENTRAL
  AND SOUTHERN WILLAMETTE VALLEY.
* TIMING...NOW THROUGH SATURDAY.
* AIR QUALITY...EXPECT SLOWLY DEGRADING AIR QUALITY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
AN AIR STAGNATION ADVISORY IS ISSUED WHEN LOCALLY ESTABLISHED
CRITICAL VALUES OF TRANSPORT WINDS...MIXING HEIGHT...AND
VENTILATION ARE EXPECTED TO PERSIST FOR AT LEAST 72 HOURS. THIS
PRODUCT WILL BE UPDATED AT LEAST EVERY 24 HOURS WHEN CONDITIONS
EXIST OR ARE EXPECTED TO CONTINUE.
A DENSE FOG ADVISORY MEANS VISIBILITIES WILL FREQUENTLY BE
REDUCED TO LESS THAN ONE QUARTER MILE. IF DRIVING...SLOW DOWN...
USE YOUR HEADLIGHTS...AND LEAVE PLENTY OF DISTANCE AHEAD OF YOU.
&&
$$

DENSE FOG ADVISORY
Issue Date: 1105 PM PST WED DEC 23 2009
Expiration: 1000 AM PST THU DEC 24 2009

...DENSE FOG ADVISORY IN EFFECT UNTIL 10 AM PST THURSDAY...
...AIR STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST
SATURDAY...
THE NATIONAL WEATHER SERVICE IN PORTLAND HAS ISSUED A DENSE FOG
ADVISORY...WHICH IS IN EFFECT UNTIL 10 AM PST THURSDAY. AN AIR
STAGNATION ADVISORY REMAINS IN EFFECT UNTIL 6 PM PST SATURDAY.
* IMPACTS...DENSE FOG WILL INCREASE IN AREA OVERNIGHT.
VISIBILITIES ARE EXPECTED TO LOWER TO ONE QUARTER OF A MILE OR
LESS AT TIMES. FREEZING TEMPERATURES WILL ALLOW THE FOG TO FREEZE
TO SURFACES MAKING THEM SLIPPERY.
* TIMING...THROUGH 10 AM THURSDAY.
OFFSHORE FLOW OVER THE REGION WILL STRENGTHEN OVERNIGHT AND
CONTINUE FOR THE REST OF THE WEEK INTO THE COMING WEEKEND.
HOWEVER...STRONG LOW LEVEL INVERSIONS WILL KEEP AREAS BELOW
1500 FEET FROM MIXING WELL. THIS WILL LEAD TO AIR QUALITY THAT
WILL GRADUALLY BECOME MORE POOR WITH TIME.
* AREAS AFFECTED...THE WIND SHELTERED LOWLANDS OF THE CENTRAL
AND SOUTHERN WILLAMETTE VALLEY.
* TIMING...NOW THROUGH SATURDAY.
* AIR QUALITY...EXPECT SLOWLY DEGRADING AIR QUALITY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
AN AIR STAGNATION ADVISORY IS ISSUED WHEN LOCALLY ESTABLISHED
CRITICAL VALUES OF TRANSPORT WINDS...MIXING HEIGHT...AND
VENTILATION ARE EXPECTED TO PERSIST FOR AT LEAST 72 HOURS. THIS
PRODUCT WILL BE UPDATED AT LEAST EVERY 24 HOURS WHEN CONDITIONS
EXIST OR ARE EXPECTED TO CONTINUE.
A DENSE FOG ADVISORY MEANS VISIBILITIES WILL FREQUENTLY BE
REDUCED TO LESS THAN ONE QUARTER MILE. IF DRIVING...SLOW DOWN...
USE YOUR HEADLIGHTS...AND LEAVE PLENTY OF DISTANCE AHEAD OF YOU.
$$