772
FXUS66 KOTX 082336
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
330 PM PST SUN NOV 8 2009
SYNOPSIS
THE ACTIVE WEATHER PATTERN WILL CONTINUE OVER THE INLAND NORTHWEST
THROUGH THE MIDDLE OF THE WEEK. LINGERING VALLEY RAIN AND
MOUNTAIN SNOW SHOWERS WILL CONTINUE INTO THIS EVENING...THEN A
BREAK IN THE PRECIPITATION IS EXPECTED MONDAY...BEFORE ANOTHER
MOIST STORM SYSTEM ARRIVES LATE IN THE DAY. MORE PACIFIC STORM
SYSTEMS ARE EXPECTED EVERY 24 TO 36 HOURS THROUGH THE NEW WORK
WEEK.
DISCUSSION
TONIGHT AND MONDAY...A WEAK WARM FRONT IS PASSING THROUGH THE
FORECAST AREA FROM SOUTH TO NORTH THIS AFTERNOON...WITH MOST OF
THE PRECIPITATION FROM THIS LIFTING MECHANISM FALLING OVER THE
EASTERN HALF OF THE AREA WHERE THE MOIST ISENTROPIC ASCENT IS
AUGMENTED BY UPSLOPE FLOW ABOVE THE RISING TERRAIN OF THE EASTERN
BASIN AND PANHANDLE HIGH TERRAIN. THIS IS A SLOW MOVING FRONT WITH
REGIONAL RADAR AND SATELLITE SUGGESTING MORE MOISTURE UPSTREAM
WHICH WILL ENHANCE OVER THE EASTERN THIRD OF THE FORECAST AREA
INTO THIS EVENING. THE WARM FRONT WILL GRADUALLY LIFT OUT OF THE
FORECAST AREA TO THE NORTHEAST OVERNIGHT TONIGHT...ALLOWING
PRECIPITATION TO TAPER OFF LATER THIS EVENING...TO ONLY LINGERING
MOUNTAIN SNOW SHOWERS BY MIDNIGHT OR SO. HOWEVER...THE RECENT
PRECIPITATION WILL SET THE STAGE FOR A VERY MOIST AIR MASS BY DAWN
WITH THE PROSPECT FOR SIGNIFICANT FOG AND STRATUS FIELDS OVER THE
REGION AND CHOKING THE VALLEYS FOR THE MONDAY MORNING COMMUTE PERIOD.
FORTUNATELY THE MOIST AIR MASS AND EXPECTED RESIDUAL CLOUD COVER
WILL HELP KEEP MOST POPULATED LOCATIONS AT LEAST SLIGHTLY ABOVE
FREEZING OVERNIGHT.
FOR MONDAY THE GFS AND NAM MODELS ARE IN REASONABLE AGREEMENT AND
PLAUSIBLE AGAINST SATELLITE EXTRAPOLATION IN ESTABLISHING A SHORT
WAVE RIDGE OVER THE REGION AHEAD OF THE NEXT FRONTAL SYSTEM
VISIBLE OFF THE COAST NEAR 130W. THIS COLD FRONT WILL MOVE INTO
THE WESTERN ZONES DURING THE DAY MONDAY BRINGING MORE LIGHT
MOUNTAIN SNOW AND VALLEY RAIN TO THE CASCADES BY AFTERNOON...AND
SPREADING OUT OVER THE BASIN LATE IN THE DAY. SOUTHWEST FLOW AHEAD
OF THIS FRONT WILL ALLOW MONDAY'S HIGH TEMPERATURES TO ACHIEVE
SLIGHTLY HIGHER MAXIMUM TEMPS TOMORROW THAN TODAY. /FUGAZZI
MONDAY NIGHT THROUGH WEDNESDAY NIGHT...THE REGION WILL BE AFFECTED
BY TWO WEATHER SYSTEMS WITH A BRIEF BREAK ON TUESDAY. THE FIRST
SYSTEM WILL SPREAD WARM FRONTAL PRECIPITATION ACROSS THE FORECAST
AREA MONDAY NIGHT. MOIST ISENTROPIC UPGLIDE WILL BE ENHANCED BY
SYNOPTIC ASCENT FROM THE NOSE OF A 100KT JET DIRECTED SOUTHWEST TO
NORTHEAST ACROSS THE FORECAST AREA. THE MOST FAVORABLE AREA FOR
PRECIPITATION WILL SHIFT FROM THE WESTERN ZONES TO THE NORTHEAST
ZONES OVERNIGHT. WARM AIR ADVECTION WILL KEEP SNOW LEVELS ABOVE 4000
FT THROUGHOUT THE BULK OF THE PRECIPITATION. VALLEYS SHOULD SEE ALL
RAIN FOR THIS EVENT. COLD AIR ADVECTION ON TUESDAY WILL SHUT OFF
PRECIP ACROSS THE BASIN WITH MAINLY OROGRAPHIC SHOWERS LINGERING
OVER THE FAVORED TERRAIN. A SECOND STRONGER FRONTAL SYSTEM WILL
START TO AFFECT THE INLAND NORTHWEST BY TUESDAY NIGHT. STRONG
ISENTROPIC UPGLIDE WILL SPREAD OVERRUNNING PRECIPITATION FROM THE
CASCADES AND NORTHERN MOUNTAINS OVERNIGHT TUESDAY...REACHING THE
REMAINDER OF THE FORECAST AREA ON WEDNESDAY. UPPER JET DYNAMICS WILL
ONCE AGAIN ENHANCE SYNOPTIC LIFT WITH THE NORTHEAST ZONES AGAIN
FAVORABLY LOCATED IN THE LEFT FRONT QUAD. ONCE THE COLD FRONT SWEEPS
THROUGH WEDNESDAY NIGHT...SNOW LEVELS WILL DROP TO 2000-2500 FT.
THERE IS THE POTENTIAL FOR SNOWFALL ACCUMULATION IN THE NORTHEAST
VALLEYS. THIS SYSTEM WILL BE MONITORED CLOSELY FOR POSSIBLE WINTER
HIGHLIGHTS. TEMPERATURES WILL TREND NEAR SEASONAL NORMALS. /KELCH
THURSDAY THROUGH SUNDAY...VERY DYNAMIC PERIOD WITH JET STREAM
REMAINING IN CLOSE PROXIMITY AND GENERALLY TO THE SOUTH OF THE
FORECAST AREA MOST OF THE TIME DURING THIS FORECAST INTERVAL...MEANING
SENSIBLE WEATHER WILL BE HEAVILY INFLUENCED BY SHORTWAVE ACTIVITY
RUNNING NEAR THE JET THROUGH THIS TIME INTERVAL. SHORTWAVE/LOW
PRESSURE SYSTEM CONTAINING QUITE THE CONDITIONALLY UNSTABLE
AIR MASS TO BE EXPECTED ON THE NORTH SIDE OF THE JET KEEPS
THURSDAY/THURSDAY NIGHT SOMEWHAT UNSETTLED ALONG ITS WAY OF OF
EXIT...PRIMARILY THE IDAHO PANHANDLE BUT WRAP AROUND MOISTURE AND
FORCING COULD KEEP SHOWER ACTIVITY UP ALONG WASHINGTON NORTHEAST
MOUNTAINS AND OVER TO THE EAST SLOPES OF THE NORTHERN CASCADES.
SHORTWAVE RIDGING ENTERING IN THE WAKE OF THE EARLIER MENTIONED
EXITING WEATHER SYSTEM ALLOWS WARMING AND IMPROVING TREND FRIDAY
INTO PART OF FRIDAY NIGHT PERHAPS UNTIL MOISTURE PLUME/SUBTROPICAL
MOISTURE TAP ALIGNED AHEAD OF INCOMING COLD FRONT/LOW PRESSURE
SYSTEM ALLOWS STABLE STRATIFORM OVERRUNNING RAIN/SNOWFALL TO SWEEP
FROM WEST TO EAST SATURDAY NIGHT INTO SUNDAY. THE LOW LEVEL FLOW
AHEAD OF THIS INCOMING WET FRONTAL ZONE HAS ENOUGH LOW LEVEL
SOUTH/SOUTHEAST FLOW TO WORK AGAINST ANY LOWER LEVEL COLD AIR THAT
THE FRONT IS EXPECTED TO OVERRUN AND WILL LIKELY RESULT IN NOISY
SNOW LEVELS THAT RISE OVER MOST LOCATIONS FROM WENATCHEE TO COEUR
D' ALENE AND POINTS SOUTH TO PERHAPS GO WITH SNOW CHANGING TO ALL
RAIN WORDING THERE...BUT UP NORTH COLD AIR IS MORE STUBBORN TO
MODIFY VIA THIS SOUTH/SOUTHEAST FLOW AND WILL BE HARDER TO PIN
DOWN A HOMOGENEOUS SNOW LEVEL. LATER SUNDAY AS MORE OF EASTERN
WASHINGTON AND NORTHERN IDAHO IS BEHIND THE COLD FRONT A
TRANSITION TO INSTABILITY SHOWERS OF LESSER INTENSITY AND COVERAGE
COUPLED WITH A DROP IN SNOW LEVEL IS EXPECTED. FORECAST
TEMPERATURE WISE THE EXPECTATION IS THAT WITH SHORTWAVE RIDGING
AND LACK OF SENSIBLE WEATHER WILL ALLOW WARMING FOR FRIDAY...WITH
THE EARLIER DISCUSSED WARM AIR ADVECTION AHEAD OF THE WEEKEND
WEATHER SYSTEM TO SHOW ADDITIONAL WARMING SATURDAY OVER ALL BUT
PERHAPS THE NORTHERN THIRD OF THE FORECAST AREA DUE TO THE EARLIER
DISCUSSED STUBBORNNESS OF COOLER AIR MASSES TO MODIFY IN THIS
MANNER GIVEN THEIR LOCATION. /PELATTI
AVIATION
A WARM FRONT WILL BRING MAINLY MVFR CEILINGS IN RAIN TO THE
KGEG/KSFF/KCOE AND KPUW TAF SITES THROUGH 03Z THIS EVENING...WITH
WIDESPREAD MOUNTAIN OBSCURATIONS IN CLOUDS AND PRECIPITATION OVER
THE IDAHO PANHANDLE THROUGH TONIGHT. THE MOIST LOW LEVEL AIR MASS
MAY ALLOW AREAS OF FOG AND LOCAL IFR STRATUS CEILINGS IN THE VALLEYS
NORTH AND WEST OF THE COLUMBIA BASIN LATE TONIGHT THROUGH 18Z
MONDAY. THE KGEG AREA TAF SITES AND KEAT WILL BE MOST AT RISK FOR
OCCASIONAL LOW MVFR OR IFR CEILINGS DURING THE MORNING HOURS. THE
NEXT STORM SYSTEM WILL SPREAD THICKENING CLOUDS AND PRECIPITATION
FROM WEST TO EAST LATE MONDAY AFTERNOON.
PRELIMINARY POINT TEMPS/POPS
SPOKANE 33 45 36 46 32 43 / 50 20 50 30 10 50
COEUR D'ALENE 33 45 34 45 32 43 / 60 10 60 40 20 60
PULLMAN 31 52 35 48 33 46 / 30 10 40 20 10 50
LEWISTON 35 53 40 52 38 50 / 10 10 20 20 10 40
COLVILLE 35 48 33 46 30 44 / 50 20 60 30 20 60
SANDPOINT 34 44 34 42 32 40 / 70 20 60 50 20 60
KELLOGG 34 40 34 41 33 39 / 60 10 50 70 30 60
MOSES LAKE 30 48 33 50 31 47 / 10 30 70 0 10 30
WENATCHEE 36 46 35 47 34 45 / 10 50 80 10 10 40
OMAK 34 48 30 46 25 44 / 20 50 90 0 20 40
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...NONE.
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