Wildfire in Washington, August 5 to 31, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
449 PM PDT SUN AUG 5 2007

.SYNOPSIS...A WEAK TROUGH OF LOW PRESSURE WILL RESIDE OVER THE
PACIFIC NORTHWEST THROUGH MONDAY. TEMPERATURES WILL BE ABOUT
AVERAGE FOR EARLY AUGUST. THERE WILL ALSO BE A SLIGHT CHANCE FOR
THUNDERSTORMS MAINLY OVER THE MOUNTAINS THROUGH THIS EVENING AND
AGAIN ON MONDAY.

&&

.UPDATE... DID A QUICK UPDATE THIS AFTERNOON TO ADD THUNDERSTORMS
TO THE CAMAS PRAIRIE AREA THIS EVENING. SHOWERS AND THUNDERSTORMS
HAVE DEVELOPED ACROSS JUST SOUTH OF LA GRANDE OREGON AND ARE
MOVING TO THE NORTHEAST. IF THE SHOWERS/THUNDERSTORMS CONTINUE
ALONG THIS TRACK THEY WOULD MOVE RIGHT INTO THE CAMAS PRAIRIE AREA
STARTING AROUND 5:45 PDT. HAVE ALSO INCREASED AREAL COVERAGE OF
THUNDERSTORMS ACROSS THE CASCADES TO SCATTERED. LOOKING AT
SEATTLES RADAR DECENT SHOWERS HAVE DEVELOPED RIGHT ALONG THE
CREST...JUST TO THE WEST OF LEAVENWORTH.

&&

.PREV DISCUSSION... /ISSUED 217 PM PDT SUN AUG 5 2007/

DISCUSSION... TONIGHT THROUGH TUESDAY NIGHT...A POSITIVELY TILTED
TROUGH WITH ITS AXIS OVER THE INLAND NORTHWEST IS EVIDENT ON WATER
VAPOR IMAGERY THIS AFTERNOON. ONE SPEED MAX INDICATED BY THE
DARKENING OF THE IMAGE IS SEEN DIVING INTO THE BASE OF THE TROUGH
JUST OFF THE OREGON COAST WHILE A SECOND ONE IS RIDING THE EAST
SIDE OF THE TROUGH THROUGH NORTHERN CALIFORNIA AND EASTERN OREGON.
AS THESE FEATURES ROTATE THROUGH THE TROUGH THEY WILL OFFER SOME
SYNOPTIC FORCING OVER OUR FORECAST AREA. THE VISIBLE SATELLITE
PICTURE SHOWS A GROWING CUMULUS FIELD OVER THE NORTHERN MOUNTAINS
AND AS FAR SOUTH AS THE WATERVILLE PLATEAU. CONVECTION IS FIRING
OVER SOUTHEAST IDAHO AND SPREADING NORTHEAST. THE NORTHERN EXTENT
OF THE CONVECTION THIS AFTERNOON IS CENTRAL IDAHO...REMAINING
SOUTH OF OUR FORECAST AREA. CIRRUS BLOW OFF FROM THE CONVECTION IS
BEGINNING TO INFILTRATE THE SOUTHEAST ZONES BUT VERY DRY LOWER
LEVELS WITH DEWPOINTS IN THE THIRTIES SHOULD KEEP THE ACTIVITY TO
OUR SOUTH TONIGHT. A MINOR SHORTWAVE TROUGH WILL SWING EAST ACROSS
THE NORTHERN PORTION OF THE FORECAST AREA TONIGHT. THE COMBINATION
OF THIS DIFFERENTIAL VORTICITY ADVECTION ALONG WITH SOME UNCAPPED
CAPE AND SURFACE BASED INSTABILITY ACROSS THE AREA WILL SUPPORT AT
LEAST A SLIGHT CHANCE OF THUNDER FOR OUR MOUNTAIN ZONES WITH THE
BEST CHANCE ACROSS THE NORTHERN CASCADES WHERE THE DEEPER MOISTURE
WILL BE.

THE TROUGH AXIS AND ASSOCIATED COLD POOL ALOFT SHIFTS EAST
OVERNIGHT. THERE IS SOME WEAK UPPER LEVEL SUPPORT AND THE BEST
AVAILABLE MOISTURE APPEARS TO BE OVER THE NE BLUES SO HAVE LIMITED
CONVECTION TO THIS AREA OVERNIGHT. ON MONDAY THE TROUGH SWINGS
THROUGH THE EASTERN PORTION OF THE FORECAST AREA WITH THE COLD POOL
REMAINING OVERHEAD. THERE IS SOME SYNOPTIC FORCING DEPICTED IN DIF-Q
FIELDS. WHILE THE BEST FORCING IS ACROSS OUR EXTREME SOUTHEAST ZONES
THERE IS POTENTIAL INSTABILITY ACROSS MUCH OF THE FORECAST AREA
ALONG WITH AT LEAST MODEST AMOUNTS OF MOISTURE FOR ALL BUT THE LOWER
BASIN. THIS WILL SUPPORT A SLIGHT CHANCE OF THUNDER ACROSS MUCH OF
THE REGION INCLUDING THE CASCADES WHERE BOUNDARY LAYER MOISTURE WILL
BE ABUNDANT. ON TUESDAY THE UPPER LEVEL TROUGH LIFTS OUT OF THE
REGION. MORE STABLE NORTHWEST FLOW ALOFT WILL TRANSITION TO MORE
ZONAL FLOW. TEMPERATURES WILL REMAIN CLOSE TO SEASONAL NORMALS
THROUGH THIS FORECAST PERIOD. /KELCH

WEDNESDAY THROUGH SUNDAY...LONG RANGE MODELS IN GOOD AGREEMENT
THROUGH FRIDAY...THEN BEGIN TO SHOW SOME DIFFERENCES OVER THE
WEEKEND. A STRONG UPPER RIDGE WILL CONTINUE TO BE ESTABLISHED NEAR
150W...WITH A WEAK DOWNSTREAM TROUGH OVER THE INLAND NW THROUGH AT
LEAST FRIDAY. A FEW VERY WEAK SHORT WAVES ARE PROGGED TO MOVE
THROUGH...WHICH SHOULD BRING BRIEF INCREASES IN MID AND HIGH
CLOUDS AT TIMES BUT NO PRECIPITATION. TEMPERATURES THROUGH FRIDAY
WILL REMAIN NEAR SEASONAL AVERAGES. THEN OVER THE WEEKEND THE PAST
COUPLE GFS MODEL RUNS TRACK THE NEXT IN A SERIES OF SHORT WAVES
DOWN THE BACK SIDE OF THE RIDGE OFF THE COAST...THEN DEVELOPING A
LARGE CUTOFF LOW. THIS SCENARIO ACTS TO BUILD THE RIDGE AHEAD OF
IT OVER THE INLAND NW WHICH WOULD RESULT IN A WARMING TREND.
HOWEVER...THE ENSEMBLE MEAN SHOWS NO CUTOFF LOW...AND NEITHER DOES
THE ECMWF MODEL AND UKMET MODEL. THESE SOLUTIONS KEEP A NEAR
PERSISTENT PATTERN WITH THE RIDGE PERSISTING NEAR 150W AND
ADDITIONAL WEAK SHORT WAVES PASSING THROUGH THE AREA. THUS...WILL
HAVE TO WITH HPC ON THIS FORECAST...AND GO WITH A MORE
CLIMATOLOGICAL FORECAST WITH NEAR NORMAL TEMPS AND DRY CONDITIONS.
JW

AVIATION...
VFR CONDITIONS EXPECTED AT ALL TAF SITES THROUGH 00Z/07TH.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS IN THE MTNS EARLY
THIS EVENING WILL LEAD TO LOCAL MVFR CONDITIONS...BUT THIS
ACTIVITY WILL STAY AWAY FROM THE TERMINALS. THIS PATTERN WILL OCCUR
AGAIN MONDAY AFTERNOON AND EVENING...BUT WITH THE CHANCE OF ANY
SHOWER OR THUNDERSTORM IMPACTING THE TERMINALS LOW. JW

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        59  85  59  84  57  83 /  10  20  10  10  10  10
COEUR DALENE  57  85  55  85  54  83 /  10  20  10  10  10  10
PULLMAN        48  83  52  83  52  84 /  10  20  20  10  10  10
LEWISTON       62  89  62  90  62  90 /  10  20  20  10  10  10
COLVILLE       51  88  55  89  54  88 /  10  20  10  10  10  10
SANDPOINT      53  82  52  82  55  77 /  10  20  10  10  10  10
KELLOGG        60  82  54  83  53  84 /  10  20  20  10  10  10
MOSES LAKE     60  91  60  89  61  89 /  10  10  10   0   0   0
WENATCHEE      66  91  65  88  64  86 /  10  10  10   0   0   0
OMAK           62  91  62  90  61  89 /  10  10  10   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...RED FLAG WARNING FROM 4 AM TO 6 PM PDT MONDAY FOR NORTHEAST BLUE
     MOUNTAINS.

&&