Wildfire in Washington, August 19 to 20, 2005

AREA FORECAST DISCUSSION...UPDATED SHORT TERM AND AVIATION...
NATIONAL WEATHER SERVICE PENDLETON OR
1054 PM PDT THU AUG 18 2005

.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT...AN UPPER LEVEL SHORT
WAVE HAS EXITED EASTERN OREGON AND IS MOVING EASTWARD ACROSS IDAHO
AND MONTANA. AN UPPER LEVEL HIGH PRESSURE RIDGE IS BUILDING JUST
OFFSHORE AND ALONG THE COAST AND WILL MOVE INLAND AND BUILD OVER THE
PACIFIC NORTHWEST FRIDAY THROUGH SATURDAY. SUBSIDENCE ASSOCIATED
WITH THE RIDGE WILL KEEP DRY CONDITIONS OVER THE REGION WITH A
WARMING TREND STARTING FRIDAY AND CONTINUING SATURDAY. SOME ELEVATED
INSTABILITY ASSOCIATED WITH INCREASING MID LEVEL MOISTURE MAY MOVE
NORTH FROM CALIFORNIA INTO SOUTH CENTRAL AND CENTRAL OREGON LATE
SATURDAY NIGHT...BUT THE INITIAL LEADING EDGE OF THE MID LEVEL
MOISTURE THAT WILL MOVE INTO CENTRAL OREGON LATE SATURDAY NIGHT
LOOKS TO BE LIMITED...SO EXPECT CONVECTION THAT COULD LEAD TO A
SLIGHT CHANCE OF THUNDERSTORMS WILL BE DELAYED UNTIL SUNDAY
MORNING.  POLAN

.AVIATION...VFR CONDITIONS AND LIGHT AND VARIABLE WINDS WILL OCCUR
ACROSS THE AREA FOR THE REMAINDER OF TONIGHT THROUGH FRIDAY EVENING
AS AN UPPER LEVEL HIGH PRESSURE RIDGE BUILDS OVER THE PACIFIC
NORTHWEST. SEE THE LATEST TAFS AND TWEBS FOR DETAILS.  POLAN

&&

.PREVIOUS DISCUSSIONS...(ISSUED AT 155 PM PDT THU AUG 18 2005)

.LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT...A TROUGH OF LOW
PRESSURE WILL BEGIN TO MIGRATE TOWARD THE PACIFIC NORTHWEST DURING
THE AFTERNOON SUNDAY. AHEAD OF THIS TROUGH SOUTH TO SOUTHWEST FLOW
AT MID AND UPPER-LEVELS WILL BEGIN TO DRAW MONSOONAL MOISTURE FROM
UNDERNEATH A FOUR-CORNERS HIGH AND DEPOSIT IT OVER CENTRAL AND
NORTHEAST OREGON. THIS MOISTURE...COMBINED WITH INTENSE SURFACE
HEATING AND A WEAK DISTURBANCE ALOFT...WILL GENERATE CONVECTION OVER
CENTRAL AND EASTERN MOUNTAIN AREAS. THE DISTRIBUTION AND DEPTH OF
CONVECTION IS HARD TO PINPOINT AT THIS TIME...BUT AT LEAST ISOLATED
THUNDERSTORM DEVELOPMENT SEEMS PROBABLE. MONSOONAL MOISTURE ALONG
WITH INSTABILITY WILL LINGER OVER EASTERN AREAS OVERNIGHT SUNDAY
INTO MONDAY WITH CONVECTION CONTINUING. BY MONDAY AFTERNOON THE
OFF-SHORE TROUGH WILL BEGIN TO MIGRATE ONSHORE INTO THE PACIFIC
NORTHWEST. LATEST ECMWF HINTS AT A MORE ZONAL SYSTEM WITH THE LOW
CENTER IN NORTHERN WASHINGTON AND SOUTHERN BRITISH COLUMBIA...WHILE
TH GFS DEPICTS A DEEPER...MORE INTENSE SYSTEM. FAVORED THE MORE
NORTHERN AND ZONAL SYSTEM DEPICTION. AFTER A HOT DAY SUNDAY
TEMPERATURES WILL BACK DOWN TO MORE NORMAL LEVELS EARLY IN THE
WEEK.  CANTIN

&&

.FIRE WEATHER...AS HIGH PRESSURE BUILDS ACROSS THE PACIFIC
NORTHWEST...WARMER AND DRIER CONDITIONS WILL PREVAIL. ONE CONCERN
FOR NOW WILL BE THE CHANGE IN PATTERN SUNDAY AND MONDAY...AS THE
POTENTIAL FOR THUNDERSTORMS MAY RETURN ACROSS CENTRAL AND EASTERN
OREGON.  PALMER

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  52  89  55  96 /   0   0   0   0
ALW  56  89  60  96 /   0   0   0   0
PSC  48  92  51  98 /   0   0   0   0
YKM  48  89  50  95 /   0   0   0   0
HRI  47  91  50  97 /   0   0   0   0
ELN  45  90  49  96 /   0   0   0   0
RDM  41  88  45  94 /   0   0   0   0
LGD  43  87  46  93 /   0   0   0   0
5J0  43  89  47  94 /   0   0   0   0
DLS  55  94  58  98 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

TI:GGY
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
99/96/99

HAZARDOUS WEATHER OUTLOOK...UPDATED...
NATIONAL WEATHER SERVICE PENDLETON OR
1043 PM PDT THU AUG 18 2005

WAZ024>030-ORZ041>050-191200-
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-
FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-BLUE MOUNTAINS-
JOHN DAY BASIN-OCHOCO-JOHN DAY HIGHLANDS-GRANDE RONDE VALLEY-
WALLOWA COUNTY-
1043 PM PDT THU AUG 18 2005

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

.DAY ONE...TONIGHT

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

MOSTLY CLEAR SKIES AND DRY CONDITIONS WILL OCCUR TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS SUNDAY AND SUNDAY
NIGHT IN THE MOUNTAINS OF CENTRAL AND NORTHEAST OREGON AND THE BLUE
MOUNTAINS IN SOUTHEAST WASHINGTON. THE MOUNTAINS OF CENTRAL AND
NORTHEAST OREGON AND SOUTHEAST WASHINGTON WILL HAVE A SLIGHT CHANCE
OF SHOWERS AND THUNDERSTORMS MONDAY AND MONDAY NIGHT. A SLIGHT
CHANCE OF SHOWERS IS FORECAST FOR THE WASHINGTON CASCADES AND THE
MOUNTAINS OF NORTHEAST OREGON AND SOUTHEAST WASHINGTON TUESDAY.
OTHERWISE...DRY CONDITIONS WILL PREVAIL THROUGH THE MIDDLE OF NEXT
WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.

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

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

WEATHER.GOV/PENDLETON

AND SELECT GRAPHICAL HAZARDS.