015
FXUS66 KOTX 150559
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
948 PM PST SAT DEC 14 2024
SYNOPSIS
SUNSHINE IS EXPECTED ACROSS MUCH OF CENTRAL AND EASTERN
WASHINGTON ON SUNDAY, BUT THE SUN WON'T LAST LONG. ON MONDAY A
SWATH OF LIGHT SNOW WILL SPREAD ACROSS THE INLAND NORTHWEST.
TUESDAY THROUGH THE WEEKEND WILL FEATURE TEMPERATURES IN THE 30S
AND 40S WITH PRECIPITATION MAINLY CONFINED TO THE MOUNTAINOUS
TERRAIN.
DISCUSSION
TONIGHT THROUGH SUNDAY NIGHT: TEMPERATURES HAVE WARMED INTO THE
UPPER 30S TO UPPER 40S, WITH SOME LOW 50S ACROSS PORTIONS OF THE
PALOUSE AND LC VALLEY. OTHER THAN THE SOUTH TO SOUTHWEST WINDS
AROUND 10 MPH, IT HAS TURNED OUT TO BE QUITE A NICE DAY WITH SOME
LOCATIONS SEEING SUN BEFORE THE HIGH CLOUDS MOVED IN.
THE TROUGH AXIS IS MOVING INTO WESTERN WA AND OR THIS AFTERNOON.
AS IT DOES, IT WILL PUSH A COLD FRONT ACROSS CENTRAL WA, AND INTO
EASTERN WA AND NORTH ID LATER TONIGHT. SNOW WILL BEGIN TO
ACCUMULATE ONCE AGAIN AT STEVENS PASS. THERE IS A 70% CHANCE OF
SEEING 4 INCHES, AND A 35% CHANCE OF SEEING 6 INCHES FROM SUNSET
TO JUST BEFORE SUNRISE. A WINTER WEATHER ADVISORY IS IN EFFECT
UNTIL 6AM. AS THE COLD FRONT MOVES THROUGH TONIGHT, SNOW LEVELS
WILL LOWER. THERE IS MOISTURE MOVING INTO SOUTHEAST WA AND
PORTIONS OF CENTRAL AND THE SOUTHERN ID PANHANDLE, AND AS IT
INTERACTS WITH THE FRONT, WE WILL SEE AN INCREASED CHANCE OF
PRECIPITATION. SOME OF THE MODELS WANT TO BRING THE PRECIP CHANCES
FURTHER WEST INTO PARTS OF THE EASTERN COLUMBIA BASIN. HAVE CUT IT
OFF TO ALONG AND EAST OF HIGHWAY 395 AND I90. THERE IS A 30%
CHANCE OF LIGHT RAIN THIS EVENING IN THE SPOKANE AREA, BUT IT
WOULD BE FAIRY BRIEF. IF PRECIP HOLDS TILL 1 OR 2AM ACROSS THE
PALOUSE (IT SHOULD BE EXITING TO THE EAST), THEY COULD SEE BRIEF
SNOW. LOOKOUT PASS WILL SEE SNOW THIS EVENING AND OVERNIGHT. THERE
IS A 80% CHANCE OF 2 INCHES AND A 45% CHANCE OF 4 INCHES.
SUNDAY A SHORTWAVE RIDGE WILL MOVE INTO THE REGION. MANY COULD SEE
THE SUN! THE BEST CHANCE OF SEEING THE LARGE ORB IN THE SKY WILL
BE ACROSS CENTRAL WA. AS YOU HEAD INTO EASTERN WA TOWARD THE ID
BORDER, THERE WILL BE AN INCREASE IN CLOUDS, BUT WILL SEE SOME
FILTERED SUNSHINE. THE NORTH ID PANHANDLE WILL HAVE THE MOST CLOUD
COVER BECAUSE OF THE EXITING TROUGH, BUT THERE COULD BE SOME BRIEF
BREAKS.
SUNDAY NIGHT WE WILL SEE AN INCREASE IN CLOUDS AHEAD OF THE NEXT
TROUGH TO MOVE INTO THE PAC NW. GIVEN THE ORIENTATION OF THE
TROUGH, WE WILL SEE UPSLOPE FLOW INTO THE CASCADES OVERNIGHT WITH
LIGHT SNOW ACCUMULATIONS. CURRENTLY HAVE ABOUT A HALF INCH IN THE
VALLEYS OF THE CASCADES, WITH SIMILAR OR SLIGHTLY HIGHER AMOUNTS
IN THE MOUNTAINS. /NISBET
MONDAY AND MONDAY NIGHT: A ROBUST LOW PRESSURE SYSTEM WILL MOVE
INTO THE AREA, WITH MORE WIDESPREAD SNOW FOR THE START OF THE NEW
WORK WEEK, THOUGH RAIN WILL BE MIXED IN FOR SOME AREAS. LOW
PRESSURE CURRENTLY SPIRALING SOUTH OF THE ALEUTIANS WILL BE MOVING
TOWARD THE AREA, APPROACHING THE COAST BY EARLY MONDAY. THE
LEADING WARM FRONT LIFTS INTO THE AREA THROUGH THE MORNING, WITH
THE TRAILING OCCLUDING FRONT COMING ON ITS HEELS IN THE AFTERNOON.
SNOW WILL BE INCREASING OVER THE CASCADES AND CENTRAL WASHINGTON
EARLY IN MORNING, EXPANDING ACROSS THE REMAINDER OF WA AND ID IN
THE LATE MORNING TO EARLY AFTERNOON. PRECIPITATION CHANCES REMAIN
HIGH ACROSS THE EASTERN THIRD OF WA AND ID THROUGH EVENING, BUT
WILL BEGIN TO WANE IN THE LEE OF THE CASCADES/CENTRAL WA. THEN
OVERNIGHT THE BEST POTENTIAL RETREATS TO THE CASCADE CREST AND
SOUTHEAST WA TO THE CENTRAL PANHANDLE.
* TEMPERATURES, PRECIPITATION-TYPE AND SNOW AMOUNTS: TEMPERATURES
WILL BE WARMING A BIT THROUGH THE DAY, PUSHING JUST A LITTLE BIT
ABOVE FREEZING ACROSS THE COLUMBIA BASIN INTO THE SPOKANE/CDA
AREA AND PALOUSE AND TO THE MIDDLE TO UPPER 30S IN THE L-C
VALLEY. SO A CHANCE OF RAIN/SNOW MIX WILL BE IN THE DEEPER
COLUMBIA BASIN AND L-C VALLEY IN THE MORNING, EXPANDING OVER
MORE OF THE COLUMBIA BASIN/MOSES LAKE AREA AND PALOUSE IN THE
AFTERNOON. SOME MIX IS ALSO POSSIBLE IN THE LOWER ELEVATIONS
AROUND THE SPOKANE/CDA AREA LIKE THE DOWNTOWN AND SPOKANE VALLEY
AREAS. ON AVERAGE 24-HOUR SNOW AMOUNTS IN THE LOWLANDS ARE
FORECAST TO BETWEEN 1-2 INCHES, WITH LOCAL AMOUNTS TO 3 INCHES.
THOSE HIGHER AMOUNTS ARE MORE LIKELY OVER SOUTHEAST SPOKANE
COUNTY AND THE HIGHER PALOUSE. AREAS THAT SEE A RAIN/SNOW MIX
ARE FORECAST TO SEE LESS THAN 1 INCH OF SNOW. FOR EXAMPLE THE
WEST PLAINS OF SPOKANE COULD SEE 2 OR SO INCHES, WHILE AREAS
TOWARD THE VALLEY COULD SEE ONLY A 0.5 INCHES. MOUNTAINS ARE
FORECAST TO PICK 2-4 INCHES WITH LOCAL AMOUNTS TO 5 AROUND
STEVENS PASS. ENSEMBLES ONLY SHOW ABOUT A 10% CHANCE OF SEEING
GREATER THAN 6 INCHES NEAR STEVENS PASS. PRECISE NUMBERS ARE APT
TO BE FINE-TUNED, BUT IMPACTS ARE POSSIBLE TO THE MONDAY
COMMUTES.
TUESDAY TO SATURDAY: THE INLAND NW WILL REMAIN IN A PROGRESSIVE
PATTERN, WITH A SERIES OF FRONTAL WAVES MOVING THROUGH THE AREA.
HOWEVER THE WAVES BEGIN TO TRACK FURTHER NORTH AND MILDER AIR IS
PROJECTED TO COME TO THE AREA. MODELS SLOWLY WARM UP TUESDAY, THEN
A LITTLE MORE INTO THE MIDDLE TO LATTER PART OF NEXT WEEK. STILL
THERE IS MODEST UNCERTAINTY IN THE PRECISE TEMPERATURES HEADING
INTO WEDNESDAY AS THEY SHOW AS MUCH OF A 10 DEGREES SPREAD IN THE
25-75 PERCENTILES. THIS IS OWING TO THE DIFFERENCES IN TIME OF THE
PASSING WAVES. HOWEVER THAT SPREAD STARTS TO SHRINK THEREAFTER.
AS FOR PRECIPITATION, A CHANCE FOR SNOW LINGERS TUESDAY, WITH THE
SNOW MIXING WITH RAIN IN THE AFTERNOON IN THE LOWLANDS. THE
PRECIPITATION POTENTIAL CONTINUES ON WEDNESDAY, WITH A LOWLAND
RAIN/SNOW MIX POTENTIALLY CHANGING TO RAIN THAT DEPENDS ON WHERE
PRECISE TEMPERATURES LAY AS MODELS START TO COME INTO BETTER
AGREEMENT; AS OF SNOW 60% OF THE MODELS SHOW TEMPERATURES WARMING
ENOUGH TO BECOME ALL RAIN IN MANY AREAS ACROSS THE BASIN. HOWEVER
IN THE MOUNTAIN ZONES, THE PRECIPITATION IS MORE LIKELY TO REMAIN
ALL SNOW. SNOW AMOUNTS, HOWEVER, ARE NOT THAT HIGH. THE POTENTIAL
FOR MORE 2 OR MORE INCHES IS LARGELY AROUND THE CASCADES, AND THE
NORTHERN MOUNTAIN ZONES CLOSER TO THE CANADIAN BORDER. THE THREAT
OF PRECIPITATION RETREATS TO THE MOUNTAINS THURSDAY AND FRIDAY,
THEN EXPANDS OUT AGAIN TOWARD NEXT SATURDAY WITH MOUNTAIN SNOW AND
A LOWLAND RAIN/SNOW MIX. WINDS WILL BE BE SLIGHTLY BREEZY AROUND
WEDNESDAY, WITH GUSTS AROUND 15-20 MPH IN THE UNSHELTERED AREAS.
/SOLVEIG
AVIATION
06Z TAFS: COLD FRONT IS CURRENTLY PASSING THROUGH THE CASCADES AND
WILL PUSH THE WIDESPREAD STRATIFORM PRECIPITATION OVER EXTREME SE WA
AND NC ID (INCLUDING PUW AND LWS)EAST OF THESE SITES OVER THE NEXT
FEW HOURS. BRIEF MVFR CIGS ARE POSSIBLE AT THESE SITES, BUT FAR FROM
LIKELY. WHAT HAPPENS AS THE COLD FRONT MOVES IN IS TOUGHER TO
FIGURE. MANY OF THE HREF MODEL MEMBERS SUGGEST THAT AS THE HIGH
CLOUDS PUSH INTO MT TONIGHT, THAT WE WILL SEE LOW CLOUDS (IFR/MVFR)
FORMING BETWEEN PUW AND GEG AND EXTENDING EAST INTO NORTH ID. IF
THESE CLOUDS IN FACT FORM, THE LOW LEVEL S-SW WINDS COULD PUSH THESE
INTO GEG-SFF-COE SOMETIME AFTER 12Z, BUT WHETHER THEY MAKE IT THIS
FAR ISN'T CERTAIN. ADDING SLIGHTLY TO THE CHANCES WILL BE A WEAK
DISTURBANCE MOVING IN FROM THE SW AROUND THIS TIME WHICH MAY RESULT
IN SOME LIGHT SNOW SHOWERS. BY AFTERNOON AND EVENING WE THINK ALL
SITES SHOULD SEE VFR CONDITIONS, HOWEVER SOME LOW CLOUDS IN THE
VALLEYS NORTH AND EAST OF SPOKANE COULD PERSIST OF THE COLD FRONT
PASSAGE TONIGHT DOESN'T MIX THEM OUT. THE NEXT SYSTEM WILL MOVE OVER
THE AREA LATE IN THE PERIOD BRINGING INCREASING HIGH CLOUDS, BUT ANY
CHANCE OF PRECIPITATION (LIKELY SNOW) WILL HOLD OFF UNTIL AFTER
06Z.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: REDEVELOPMENT OF
STRATUS TOWARDS SUNRISE SUNDAY MORNING BETWEEN PULLMAN, SPOKANE, AND
COEUR D'ALENE IS MODERATE HOWEVER WHETHER OR NOT THIS MOVES INTO GEG-
SFF-COE IS FAR LESS CERTAIN. IF IT DOES MOVE IN AND AFFECT THESE
LOCATIONS IT COULD PERSIST INTO THE AFTERNOON RESULTING IN IFR/MVFR
CONDITIONS. FX
-----------------------
CONFIDENCE DESCRIPTORS:
LOW - LESS THAN A 30 PERCENT CHANCE
MODERATE - 30 TO 70 PERCENT CHANCE
HIGH - GREATER THAN A 70 PERCENT CHANCE
FOR ADDITIONAL PROBABILISTIC INFORMATION FOR NWS SPOKANE AIRPORTS,
PLEASE REFER TO THE AVIATION DASHBOARD ON OUR WEBPAGE:
HTTPS:/WWW.WEATHER.GOV/OTX/AVNDASHBOARD
PRELIMINARY POINT TEMPS/POPS
SPOKANE 30 36 28 34 29 36 / 30 0 10 90 60 30
COEUR D'ALENE 30 36 27 34 29 37 / 40 10 0 90 70 30
PULLMAN 29 36 27 33 29 35 / 70 0 10 90 70 30
LEWISTON 34 44 32 38 32 41 / 80 0 0 70 50 20
COLVILLE 24 35 23 32 22 35 / 10 0 20 90 50 30
SANDPOINT 30 34 27 33 28 35 / 30 30 10 90 70 40
KELLOGG 31 34 28 34 31 37 / 90 30 10 90 80 60
MOSES LAKE 28 39 30 35 29 36 / 10 0 20 90 30 20
WENATCHEE 28 37 30 33 27 34 / 0 0 40 90 30 30
OMAK 27 36 26 33 26 34 / 0 0 30 80 20 20
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...WINTER WEATHER ADVISORY UNTIL 6 AM PST SUNDAY FOR WESTERN CHELAN
COUNTY.
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