587 FXUS66 KOTX 140808 AFDOTXArea Forecast Discussion National Weather Service Spokane WA 108 AM PDT Sun Sep 14 2025
.KEY MESSAGES...
- Cooler today with widespread rain. Highest totals across southeast Washington and southern Idaho Panhandle. Isolated afternoon thunderstorms.
- Warm and dry Tuesday and Wednesday.
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.SYNOPSIS... A weather system arrives today bringing cooler temperatures, breezy west to southwest winds, and widespread precipitaiton. High pressure rebuilds Tuesday and Wednesday with a brief return of warmer and drier conditions.
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.DISCUSSION... Sunday and Monday: An upper-level trough and an associated old front will move across the Inland Northwest today. Water vapor imagery and model consensus depict the trough to become negatively tilted as it tracks onshore. Deep southerly flow ahead of the system is advecting ample moisture into the Inland Northwest, with precipitable water values exceeding 0.80 inches Sunday morning. Models have come into much better agreement for the base of the trough to travel across northern Oregon, providing sufficient lift for widespread precipitation this morning into the early afternoon. This will transition to scattered convective showers this afternoon and evening, with showers lingering over the Idaho Panhandle into Monday morning.
While models have trended wetter, considerable spread remains in National Blend of Models (NBM) QPF. The 25th-75th percentile range is 0.05-0.50 inches for northeast Washington and north Idaho. Lower totals, from 0-0.15 inches, are expected in the lee of the Cascades due to downsloping effects off the Cascades. The highest totals are favored across southeast Washington and the southern Idaho Panhandle, closer to the base of the trough, with a 25th-75th percentile range of 0.10-0.90 inches. CAMs indicate the greatest instability and steepest lapse rates will also be focused in these southern areas, with the NBM giving a 15-20% chance of thunderstorms this afternoon. Instability decreases farther northward, with less confidence (5-15% chance) in thunderstorms Sunday afternoon.
Southwesterly winds will increase with the morning precipitation, with sustained speeds of 10-20 mph and gusts of 20-30 mph.
Monday night through Friday: High confidence exists in an upper-level ridge building over the region late Monday, becoming centered over the area Tuesday and persisting through Wednesday. A thermally- induced surface pressure trough is expected to develop west of the Cascades, supporting breezy easterly winds across central Washington into Tuesday. The thermal trough will shift east of the Cascades by Wednesday, allowing winds to return to a west/southwesterly direction.
Forecast confidence decreases late in the week. Ensembles agree on another upper-level trough affecting the region but show significant spread in its track and strength. This will be the next period to monitor for breezy winds as the ridge breaks down, however, forecast uncertainty remains too high for specifics at this time. /vmt
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.AVIATION... 06Z TAFS: Clouds will increase tonight ahead of an approaching cold front, with VFR conditions expected through the night. Precipitation looks to begin around 12Z around MWH and spread to the northeast through the morning. Models currently have precipitation beginning at KPUW/KLWS/KGEG/KSFF/KCOE between 14Z-17Z. Ceilings will initially be VFR at the onset of precipitation, then begin to lower through the morning. There is a 40-50% chance for MVFR ceilings at KGEG/KSFF between 18-22Z and at KCOE between 20-00Z with steadier showers. Winds will pick up from the southwest with the onset of precipitation with gusts 15-25kts. Models show afternoon convective showers developing in the afternoon that brings a 10-20% chance of thunderstorms across southeast Washington and the southern Idaho Panhandle that includes KPUW/KLWS, but the probability is too low at this moment to include it in the TAF.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions before 12Z. Moderate confidence in MVFR conditions with rain at KGEG/KSFF/KCOE and low confidence at KPUW/KLWS with rain. Low confidence in thunderstorms at TAF sites Sunday afternoon and evening.
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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:/weather.gov/otx/avndashboard
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.Preliminary Point Temps/PoPs... Spokane 68 50 72 50 82 52 / 80 40 10 0 0 0 Coeur d`Alene 69 52 69 50 82 54 / 70 60 20 0 0 0 Pullman 64 46 67 45 78 49 / 80 60 10 0 0 0 Lewiston 72 55 74 53 83 57 / 80 60 10 0 0 0 Colville 72 43 74 41 82 42 / 70 50 20 0 0 0 Sandpoint 70 47 67 46 80 48 / 60 70 50 0 0 0 Kellogg 68 51 63 50 80 55 / 60 70 40 0 0 0 Moses Lake 73 47 75 49 83 50 / 70 20 0 0 0 0 Wenatchee 73 52 77 56 81 58 / 60 20 0 0 0 0 Omak 73 50 80 53 84 55 / 60 40 0 0 0 0
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.OTX WATCHES/WARNINGS/ADVISORIES... WA...Air Quality Alert until noon PDT Monday for Central Chelan County-Northeast Mountains-Okanogan Highlands-Wenatchee Area-Western Chelan County. ID...None.
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NWS OTX Office Area Forecast Discussion