Wildfire in Washington, August 18 to 21, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1048 PM PDT FRI AUG 17 2007

.SYNOPSIS...PACIFIC LOW PRESSURE WILL MOVE INTO THE INLAND
NORTHWEST FOR THE WEEKEND...USHERING IN COOLER AND WETTER WEATHER.
A MORE WESTERLY PATTERN WILL SET UP FOR MUCH OF NEXT WEEK...WITH
MORE SEASONAL TEMPERATURES AND THE THREAT OF MOUNTAIN SHOWERS.

&&

DISCUSSION...
TONIGHT THROUGH MONDAY...STILL LOOKS LIKE A SIGNIFICANT COOL
TROUGH DUE TO SWING THROUGH THE AREA OVER THE WEEKEND.
UNFORTUNATELY THE COMPUTER MODELS ALL HAVE DIFFERENT DETAILS WHICH
PLAYS HAVOC WITH CONFIDENCE ON THE EXACT TIMING AND LOCATION OF
PRECIPITATION.

SATELLITE SHOWS ONE LOW ROTATING JUST OFF VANCOUVER ISLAND. THIS
LOW IS IN ITS DECAYING STAGES AND WILL DIE AND SLOWLY DRIFT TO
THE NORTH...REMAINING OFFSHORE AND NOT HAVING A BIG IMPACT ON OUR
WEATHER. THE NEXT SHORT WAVE THAT WILL DROP INTO THE LONG WAVE
TROUGH TO TAKE THE PLACE OF THE DYING WAVE IS ACTUALLY YESTERDAYS
SHORT WAVE WHICH HAS ROTATED AROUND IN THE TROUGH AND IS CURRENTLY
SEEN ON THE WATER VAPOR IMAGE WEST OF THE QUEEN CHARLOTTE ISLANDS
NEAR 52/140.  THIS WAVE WILL REACH THE BOTTOM OF THE TROUGH TONIGHT
AND BEGIN TO EJECT TO THE NORTHEAST ON SATURDAY MORNING. THE
DYNAMICS FROM THIS WAVE SWING THROUGH OUR AREA ON SATURDAY WITH
THE STRONGEST LIFT OVER THE NORTH CASCADES. MOISTURE IS NOT
PLENTIFUL WITH THIS WAVE AND AS SUCH I ONLY HAVE LOW POPS
CONCENTRATED ACROSS THE NORTHERN MOUNTAINS. MAIN EFFECT OF THIS
WAVE WILL BE THE WESTERLY WINDS ON SATURDAY AFTERNOON. THEY DONT
LOOK QUITE AS STRONG AS PREVIOUS MODEL RUNS BUT THEY SHOULD STILL
BE GOOD ENOUGH FOR 15 GUST 25 MPH TYPE WINDS. THE NAM MODEL ISNT
AS EXCITED ABOUT THIS WAVE AND THUS HAS SOMEWHAT WEAKER WINDS.
TEMPERATURES WILL BE ABOUT THE SAME AS TODAY.

THE MODEL DIFFERENCES COME INTO PLAY FOR SUNDAY AND MONDAY. AFTER
SATURDAYS WAVE SWINGS THROUGH A SECOND SHORT WAVE QUICKLY FOLLOWS
ITS HEELS. THIS IS THE WELL-DEFINED SYSTEM THATS CURRENTLY NEAR
50N/150W WITH A DECENT CLOUD SHIELD AHEAD OF IT. THIS KICKS THE
ENTIRE TROUGH ONSHORE RATHER THAN JUST SPIN BY US LIKE ITS
PREDECESSORS. THE GFS IS THE FASTEST OF ALL THE MODELS AND IS THE
MOST DISORGANIZED. IT ACTUALLY PUTS DOWN VERY LITTLE RAIN OVER
WESTERN WA...BUT INSTEAD CHOOSES TO INTENSIFY THE FRONT FOR A
BRIEF TIME OVER SOUTHEAST WA ON SUNDAY MORNING BEFORE IT AGAIN
DIES OUT. THIS SOLUTION HAS BEEN FAIRLY CONSISTENT IN THE GFS BUT
I HAVE A HARD TIME BUYING INTO IT COMPLETELY. THE CONSENSUS OF THE
NAM AND THE FOREIGN MODELS /UKMENT...CANADIAN...ECMWF/ FAVORS A
SLIGHTLY SLOWER AND MORE CONSOLIDATED SOLUTION. THE RESULT IS A
MORE CLIMATOLOGICALLY TYPICAL SCENARIO WHERE THE MAIN PRECIP
SHIELD MOVES ONSHORE OVER NW OREGON SUNDAY MORNING AND SWEEPS
ACROSS MY CWA BEFORE DYING OVER WESTERN MONTANA BY MONDAY MORNING.
EVEN SO IVE STILL KEPT MY FORECAST FOR SUNDAY FAIRLY GENERAL IN
TERMS OF TIMING AND LOCATION. IF THE GFS TURNS OUT TO BE RIGHT
MOST OF MY FORECAST AREA WONT SEE ANY RAIN. FOR NOW I HAVE AT
LEAST A CHANCE OF RAIN EVERYWHERE WITH LIKELY WORDING FOR THE
USUAL MOUNTAINOUS AREAS.

TEMPERATURES ARE GOING TO BE RATHER COOL ON SUNDAY. EVEN THE GFS
WITH ITS FASTER SOLUTION AND PARTIAL AFTERNOON CLEARING STILL
KEEPS TEMPS 10 DEGREES BELOW NORMAL FOR MID-AUGUST. THE NAM IS
EVEN COOLER WITH THE BULK OF THE RAIN IN THE AFTERNOON...AND IF IT
VERIFIES THEN TEMPERATURES WOULD BE EVEN COOLER THAN MY CURRENT
FORECAST...WITH SOME LOCATIONS POSSIBLY NOT REACHING 60 DEGREES. I
STILL DONT SEE MUCH CHANCE OF THUNDER WITH THIS SYSTEM. DYNAMICS ARE
PLENTY STRONG BUT LAPSE RATES ARE VERY STABLE.

MONDAY POSES ANOTHER DILEMMA. THE FASTER GFS IS READY TO BARREL THE
NEXT SYSTEM INTO OUR AREA. THE REMAINDER OF THE MODELS HAVE A
WEAKER AND SLOWER SYSTEM. AT THIS POINT HAVE JUST KEPT WITH LOW
POPS AND SLIGHTLY WARMER TEMPERATURES. THE FLOW IS RATHER ZONAL
WITH THIS SYSTEM SO THE PRECIP /IF ANY/ SHOULD BE CONFINED TO THE
CASCADES AND ID PANHANDLE MOUNTAINS. RJ

MONDAY NIGHT THROUGH FRIDAY...THE MAIN CHANGE TO THE EXTENDED
FORECAST PERIODS OVERALL TREND OF WARMING AND NO SIGNIFICANT
WEATHER OCCURS IN THE FIRST PERIOD FOR MONDAY NIGHT. WHILE RUN TO
RUN CONTINUITY IS NOT GOOD FOR THIS TIME FRAME...A SOLUTION
INVOLVING ANOTHER VIGOROUS SHORT WAVE PASSAGE IN THE WAKE OF THIS
WEEKENDS STRONG TROUGH PASSAGE IS SUPPORTED BY THE
GFS...ECMWF...AND CANADIAN MODELS. TOUGH TO IGNORE THIS
CONSISTENCY AND STAY WITH THE PREVIOUS DRY ZONAL FLOW FORECAST
ESPECIALLY GIVEN THE RATHER WELL DIRECTED FETCH OF UP TO 1 INCH OF
PRECIPITABLE WATER AVAILABLE TO FOCUS INTO SHOWERS WITH THIS SHORT
WAVE. THUS MONDAY NIGHT HAVE INCREASED POPS TO CHANCE CATEGORY FOR
THE EASTERN TIER OF ZONES. IN THE WEST AND DEEP BASIN...THE
OVERALL ZONAL NATURE OF THIS TRANSIENT WAVE WILL LIKELY PRODUCE A
RAIN SHADOW WITH SIGNIFICANT PRECIPITATION FOCUSED OVER THE
OROGRAPHICALLY FAVORABLE EASTERN ZONES. FOR TUESDAY THROUGH FRIDAY
THERE IS LOOSE MODEL TO MODEL AGREEMENT FEATURING FLAT ZONAL FLOW
OR WEAK RIDGING WITH THE POLAR STORM TRACK NORTH OF THE FORECAST
AREA. THUS CONFIDENCE IS IMPROVING...BUT STILL GUARDED...FOR A
GENERALLY DRY FORECAST FOR THE REMAINDER OF THE EXTENDED PERIOD
WITH A SLOW WARM UP BACK TO CLIMATOLOGICAL NORMALS BY MID
WEEK...AND THEN ONLY A SLIGHT INCREASE IN HIGH TEMPERATURES EACH
DAY BEYOND WITH CONTINUED WESTERLY FLOW ALOFT PREVENTING ANY
DRAMATIC WARM-UPS IN THE OUTER PERIODS OF THE EXTENDED. /FUGAZZI

&&

AVIATION...
VFR CONDITIONS EXPECTED AT ALL TAF SITES THROUGH 06Z SUNDAY. MAIN
AVIATION CONCERNS WILL REVOLVE AROUND LOCAL MVFR VISIBILITIES FROM
SMOKE NEAR THE CASCADES AND OVER THE VALLEYS OF THE NORTH IDAHO
PANHANDLE. OTHERWISE LOOK FOR AN INCREASING CLOUD TREND THROUGH
THIS PERIOD AS THE UPPER LEVEL TROF SHIFTS TOWARD THE COAST. FX

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        53  79  55  69  50  73 /   0  10  20  50  20  20
COEUR DALENE  51  80  55  69  50  73 /   0  10  20  50  20  20
PULLMAN        45  80  47  70  43  71 /   0   0  20  40  20  20
LEWISTON       57  86  57  78  54  79 /   0   0  10  40  20  20
COLVILLE       48  82  47  74  44  78 /   0  10  30  50  20  20
SANDPOINT      45  80  52  68  45  76 /   0  10  20  50  30  20
KELLOGG        54  82  52  68  48  71 /   0  10  20  50  30  20
MOSES LAKE     53  80  54  78  52  78 /   0  10  20  40  10  10
WENATCHEE      59  79  59  76  57  80 /   0  10  20  40  10  10
OMAK           51  82  56  75  55  81 /   0  10  30  40  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&