074
FXUS66 KOTX 271803
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1103 AM PDT SUN SEP 27 2026
KEY MESSAGES
- AREAS OF FROST MONDAY MORNING OVER EASTERN WASHINGTON AND
IDAHO PANHANDLE MOUNTAIN VALLEYS AND UPPER COLUMBIA BASIN, AS
WELL THE OUTLYING AREAS AROUND THE SPOKANE AREA.
- MILD AND DRY PATTERN THIS WEEK, EXCEPT FOR RAIN NEAR THE CASCADE CREST
AND CHANCE OF RAIN NORTH IDAHO PANHANDLE ON TUESDAY
SYNOPSIS
CHILLY FALL LIKE OVERNIGHT TEMPERATURES WILL RESULT IN AREAS OF
FROST FOR MONDAY MORNING AGAIN OVER NORTHEAST WASHINGTON AND THE
IDAHO PANHANDLE AS WELL AS THE UPPER COLUMBIA BASIN. MOISTURE
OFF THE PACIFIC WILL BRING RAIN TO THE CASCADE CREST ON TUESDAY,
BUT REMAINING MOSTLY DRY EAST OF THE CASCADES. TEMPERATURES
WILL MODERATE BACK TO NEAR NORMAL NEXT WEEK. SEASONAL
TEMPERATURES THEN CONTINUE THROUGH THE REST OF THE WORK WEEK.
DISCUSSION
TODAY THROUGH MONDAY: A DRY AIR MASS WILL REMAIN OVER THE INLAND
NW THROUGH SUNDAY NIGHT WITH PRECIPITABLE WATER VALUES RANGING
FROM NEAR 40-70 PERCENT OF NORMAL. THIS COMBINED WITH LIGHT
WINDS WILL PROMOTE STRONG RADIATIONAL COOLING WITH AREAS OF
FROST. ANOTHER FROST ADVISORY HAS BEEN ISSUED FROM 12 AM TO 9 AM
PDT MONDAY FOR AREAS STILL WITHIN THEIR CLIMATOLOGICAL GROWING
SEASON WHERE AREAS OF FROST ARE FORECAST. THIS INCLUDES THE
UPPER COLUMBIA BASIN, MOSES LAKE AREA, AND OUTLYING AREAS AROUND
THE SPOKANE AND COEUR D'ALENE AREA. FOR HIGH TEMPERATURES
GRADUAL WARMING IS EXPECTED FOR MONDAY AS SOUTHWEST FLOW
DEVELOPS AHEAD OF THE NEXT SYSTEM. HIGH TEMPERATURES ON MONDAY
WILL BE RIGHT NEAR NORMAL VALUES WITH READINGS IN THE MID 60S TO
LOW 70S.
MONDAY NIGHT AND TUESDAY: A WEAK ATMOSPHERIC RIVER TAKES AIM AT
THE REGION WITH AN INCREASE IN MOISTURE AS PRECIPITABLE WATER
INCREASES TO 150-200 PERCENT OF NORMAL. YET WITH THE STRONG
WESTERLY FLOW AND DRY AIR MASS TO START, PRECIPITATION WILL HAVE A
HARD TIME REACHING THE GROUND OTHER THAN POTENTIAL SPRINKLES, AND
A CHANCE FOR LIGHT RAIN OVER THE NORTHERN MOUNTAINS. UPSLOPE FLOW
INTO THE CASCADE CREST WILL LEAD TO WET CONDITIONS WITH AROUND
0.50-1.00 INCH OF RAIN, WITH LIGHT RAIN SPILLING OVER THE CREST
INTO THE UPPER REACHES OF THE METHOW VALLEY, LAKE CHELAN, AND LAKE
WENATCHEE.
WEDNESDAY THROUGH SATURDAY: FOLLOWING TUESDAY'S INFLUX OF CLOUDS
AND AREAS OF LIGHT RAIN OR SPRINKLES, THE WEATHER LOOKS VERY
QUIET FOR THE REST OF THE WEEK. A MILD WEST-SOUTHWEST FLOW
PATTERN OCCURS FOR THE REST OF THE WEEK WITH WEAK RIDGING BRINGING
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES. ABOUT 25 PERCENT OF
THE MODEL CLUSTERS SHOW THE STRONGER RIDGE BUILDING IN SOONER, BY
FRIDAY, WHICH WOULD RESULT IN A MORE RAPID WARMING TREND BY
SATURDAY IF REALIZED. JW
AVIATION
18Z TAFS: BROKEN TO OVERCAST CIRRUS WILL BE PRESENT THROUGH
MUCH OF THE DAY. CEILINGS WITH LOWER BETWEEN 12-15K FT AGL AT
TIMES, ESPECIALLY AROUND LEWISTON AND PULLMAN AS A SHORTWAVE
PASSES SOUTH OF THE REGION.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HIGH CONFIDENCE
FOR VFR CONDITIONS AT ALL TAF SITES. THERE IS A SMALL RISK FOR
SPRINKLES AROUND KLWS FROM THE THICKER MIDLEVEL CLOUDS. THIS
COMES WITH LOW CONFIDENCE AND WAS LEFT OUT OF THE FORECAST AT
THIS TIME. JW
-----------------------
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 63 39 68 45 68 47 / 0 0 0 0 0 0
COEUR D'ALENE 63 35 66 43 65 47 / 0 0 0 0 10 10
PULLMAN 63 38 66 42 68 45 / 0 0 0 0 0 0
LEWISTON 66 46 71 46 75 53 / 0 0 0 0 0 0
COLVILLE 66 28 69 41 67 36 / 0 0 0 0 10 0
SANDPOINT 62 31 64 41 61 41 / 0 0 0 0 10 20
KELLOGG 63 36 64 42 63 47 / 0 0 0 0 10 30
MOSES LAKE 68 35 71 46 72 45 / 0 0 0 0 0 0
WENATCHEE 67 46 71 50 69 51 / 0 0 0 0 10 10
OMAK 68 36 70 48 68 42 / 0 0 0 0 0 0
OTX WATCHES/WARNINGS/ADVISORIES
WA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PDT MONDAY FOR
MOSES LAKE AREA-SPOKANE AREA-UPPER COLUMBIA BASIN.
ID...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PDT MONDAY FOR
COEUR D'ALENE AREA.
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