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 FXUS66 KOTX 231149
 AFDOTX
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SPOKANE WA
 350 AM PST MON NOV 23 2009
 
 .SYNOPSIS...
 WEAK HIGH PRESSURE OVER THE REGION WILL PROMOTE DRY BUT MOSTLY
 CLOUDY CONDITIONS TODAY. A WEAK PACIFIC WARM FRONT WILL BRING A
 POSSIBILITY OF VERY LIGHT PRECIPITATION TONIGHT...WITH GENERALLY
 DRY BUT CLOUDY WEATHER RETURNING TUESDAY AND THROUGH THANKSGIVING.
 ON FRIDAY A COLD FRONT WILL PASS THROUGH WITH ANOTHER REASONABLE
 CHANCE OF MOUNTAIN SNOW AND VALLEY RAIN OR SNOW. CONDITIONS WILL
 REMAIN CLOUDY AND UNSETTLED INTO NEXT WEEKEND.
 
 &&
 
 .DISCUSSION...
 TODAY THROUGH TUESDAY...AFTER YESTERDAY`S TROUGH
 PASSAGE...SATELLITE INDICATES A WEAK UPPER LEVEL RIDGE BUILDING
 OVER THE FORECAST AREA TODAY AHEAD OF THE NEXT STORM SYSTEM WHICH
 IS APPROACHING THE PACIFIC COAST. IT WILL TAKE MUCH OF THE DAY FOR
 THIS NEXT WAVE TO REACH THE FORECAST AREA...THUS A MAINLY DRY BUT
 VARIABLY CLOUDY DAY IS ON TAP FOR THE INLAND NORTHWEST. THE MOIST
 LOW LEVEL AIR MASS FROM YESTERDAYS PRECIPITATION WILL PROMOTE
 AREAS OF MORNING LOW CLOUDS AND PATCHY FOG ACROSS THE EASTERN
 BASIN...WITH DENSE MID AND HIGH CLOUDS ELSEWHERE. HIGH
 TEMPERATURES WILL CREST AT ABOUT SEASONAL NORMALS TODAY WITH
 DECREASING WINDS. 
 
 MODEL AGREEMENT IS REASONABLE WITH THE EVOLUTION OF THE INCOMING
 STORM SYSTEM. MOST OF THE DYNAMIC ENERGY ASSOCIATED WITH THE
 PARENT TROUGH WILL SWING NORTH INTO BRITISH COLUMBIA...HOWEVER A
 STRONG AND FAVORABLY DIRECTED FETCH OF PACIFIC MOISTURE WILL
 ENHANCE ALONG A WEAK WARM FRONT TONIGHT AND LIKELY PRODUCE SOME
 LIGHT PRECIPITATION ACROSS THE NORTHERN AND EASTERN ZONES.
 PRECIPITATION TYPE WILL BE MOUNTAIN SNOW...BUT OVER THE VALLEYS
 AND BASIN P-TYPE WILL BE MORE AMBIGUOUS. A NIGH TIME PASSAGE AND
 WET BULB COOLING AS THE AIR MASS MOISTENS UP ARGUES FOR LIGHT
 SNOW...HOWEVER THE MAGNITUDE OF THE PRECIPITABLE WATER FETCH
 SUGGEST A LOW LEVEL AIR MASS TOO WARM FOR SNOW. EITHER THE MODEL
 FETCH MAGNITUDE IS BEING OVER FORECAST...OR THE PRECIPITATION OVER
 THE BASIN AND THE LOWER NORTHERN VALLEYS WILL BE EITHER RAIN OR A
 NON-ACCUMULATING MIX OF RAIN AND A FEW SOPPING WET SNOW FLAKES
 WHICH WILL MELT UPON CONTACT WITH THE GROUND. THE AMSU
 PRECIPITABLE WATER SATELLITE SUGGEST THE MODELS ARE INITIALIZING
 THE MAGNITUDE OF THIS FETCH WELL...THUS WILL BET ON THE LATTER
 REASONING AND EXPECT MOUNTAIN SNOW AND VALLEY/BASIN RAIN OR NON-
 ACCUMULATING MIX WITH THIS NEXT WAVE. IN ANY EVENT AMOUNTS WILL BE
 LIGHT...AND PRETTY MUCH PASS OUT OF THE REGION BY TUESDAY MORNING.
 
 ON TUESDAY THE RIDGE BUILDS BACK WITH SURFACE HIGH PRESSURE
 BECOMING ESTABLISHED OVER THE REGION ONCE AGAIN FOR ANOTHER DRY
 BUT MOSTLY CLOUDY AND SEASONABLY COOL DAY. /FUGAZZI
 
 TUESDAY NIGHT THROUGH THURSDAY...THE INLAND NW BRIEFLY TRANSITIONS
 TO A DRIER PATTERN AS A WARM FRONT LIFTS THROUGH AND A SHORT-WAVE
 RIDGE BUILDS IN. WEAK BUT MOIST ISENTROPIC ASCENT WILL PROVIDE
 MID/HIGHER CLOUDS FOR MUCH OF THE REGION AND RISK FOR PRECIP OVER
 THE CASCADES AND NORTHERN MTN ZONES THROUGH WEDNESDAY. A NEAR
 ISOTHERMAL PROFILE IN THE SFC-800 MB LAYER SUPPORTS EITHER RAIN OR
 WET SNOW OR A MIX. EITHER WAY PRECIP AMOUNTS LOOK LIGHT. THE MID
 AND HIGHER CLOUDS AND PRECIP RISK RETREAT TO THE CANADIAN BORDER
 AND CASCADES BY WEDNESDAY NIGHT...AS THE SHORT-WAVE RIDGE
 CONTINUES TO BUILD. AT MOST OTHER TIMES OF THE YEAR THE BUILDING
 RIDGE WOULD SUPPORT WARMING TEMPERATURES. YET THE RIDGING WILL
 FAVOR STRATUS/FOG IN THE VALLEYS...INHIBITING TEMPERATURES FROM
 WARMING. THUS CONFIDENCE IN PRECISE NUMBERS IS LOW. ATTM VALUES 
 LAY SLIGHTLY ABOVE NORMAL. HOWEVER STRATUS/FOG IS MORE PERSISTENT
 ...VALUES COULD BE LOWER. IN FACT IT IS POSSIBLE MOUNTAINS WILL
 SEE WARMER TEMPERATURES THAN THE VALLEYS...ESPECIALLY AWAY FROM
 THE SOUTHEAST CWA. THE SOUTHEAST CWA WILL BE MOST APT TO MIX OUT
 WITH A SOUTHEAST WIND...AND SO SEE BETTER WARMING.
 
 THURSDAY NIGHT INTO FRIDAY...THE PRECIPITATION RISK INCREASES AND 
 EXPANDS EAST FROM THE CASCADES INTO IDAHO AS THE NEXT COLD FRONT
 PASSES. RIGHT NOW IT DOES NOT LOOK LIKE A SIGNIFICANT SNOW
 PRODUCER...BUT RATHER A RAIN OR A RAIN/SNOW MIX THREAT WITH 
 PRECIPITATION TIED MORE TO THE FRONT. THE SYSTEM BEGINS TO MOVE
 EAST FRIDAY NIGHT INTO SATURDAY. THE NW FLOW BEHIND IT PUSHES THE
 PRIMARY PRECIPITATION CHANCES TO THE ID PANHANDLE AND FAR SE
 ZONES. THEREAFTER MODEL CONSISTENCY FALTERS. CURRENT RUNS SUGGEST
 A WARM FRONT SKIMS BY AND A SHORT-WAVE RIDGE BUILDS IN SATURDAY
 NIGHT INTO SUNDAY...SUPPORTING SOME LOW PRECIP RISK OVER THE FAR
 NRN AND ERN MOUNTAINS. YET PREVIOUS RUNS WERE A BIT WETTER. UNTIL
 BETTER AGREEMENT IS ESTABLISHED SOME LOW-GRADE POPS ARE WARRANTED
 ...THOUGH AT THIS POINT THEY REMAIN BELOW CLIMO. /JCOTE
 
 
 &&
 
 .AVIATION...
 A SHORTWAVE RIDGE WILL MOVE OVERHEAD TODAY RESULTING IN WEAKENING 
 WINDS AND LARGELY VFR CONDITIONS AREA WIDE. MAIN FORECAST CHALLENGE 
 IN THE SHORT TERM WILL BE WHETHER OR NOT LOW STRATUS WILL DEVELOP 
 ALONG THE KGEG-KCOE CORRIDOR. BETWEEN THE 12Z KOTX SOUNDING 
 DISPLAYING A SHALLOW MOIST LAYER APPROX 800FT AGL...WINDS BACKING TO 
 A MORE FAVORABLE SW UPSLOPE FLOW...AND THE 06Z NAM MODEL SUGGESTING 
 A SLIGHT INCREASE IN THE 925-850MB RH THIS MORNING...BELIEVE THERE 
 IS A 50:50 CHANCE OF STRATUS DEVELOPING BRIEFLY AT KGEG-KCOE. OTHER 
 THAN THAT...A WEAK WARM FRONT WILL MOVE INTO NORTHERN WA AND THE ID 
 PANHANDLE TONIGHT RESULTING IN RAIN AND SNOW SHOWERS. HOWEVER...SOME 
 UNCERTAINTY EXISTS ON WHETHER OR NOT PRECIP...AND SUBSEQUENT MVFR 
 CIGS...WILL REACH THE KGEG-KCOE CORRIDOR LATE TONIGHT. /NEUMAN
 
 
 
 &&
 
 .PRELIMINARY POINT TEMPS/POPS...
 SPOKANE        38  33  39  31  41  31 /  10  50  10  10   0   0 
 COEUR D`ALENE  38  33  39  31  41  31 /  10  50  10  10   0   0 
 PULLMAN        39  34  41  29  43  32 /  10  50  30   0   0   0 
 LEWISTON       45  34  45  34  45  34 /  10  30  20   0   0   0 
 COLVILLE       39  34  40  29  40  27 /  30  70  10  20  20  10 
 SANDPOINT      37  30  35  27  36  26 /  20  60  10  20  20  10 
 KELLOGG        34  28  37  28  40  29 /  20  60  30  10  10   0 
 MOSES LAKE     43  28  44  31  44  30 /  10  10  10   0   0   0 
 WENATCHEE      42  31  43  32  43  32 /  10  20  10  10  10   0 
 OMAK           40  27  43  29  43  29 /  50  60  10  20  10  10 
 
 &&
 
 .OTX WATCHES/WARNINGS/ADVISORIES...
 ID...NONE.
 WA...NONE.
 &&
 
 $$
 
 
 
 
 
 
 
 

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Spokane Weather Forecast Office
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Spokane, Washington 99224

Tel: (509) 244-0110