Pullman, WA Weather

Key Messages

- Dry weather continues through Wednesday with mild afternoon temperatures.

- Medium to high confidence for rain across far eastern Washington and north Idaho Thursday afternoon through Friday morning.

- Breezy to gusty west to northwest winds across central Washington and southeast Washington Thursday night through Friday afternoon.

Synopsis

Dry weather is expected through Wednesday, with variable cloud cover and mild temperatures. Precipitation chances increase on Thursday across far eastern Washington and north Idaho Thursday afternoon through early Friday morning. This comes with stronger west to northwest winds across central and southeast Washington through Friday afternoon. There is very low confidence in the weather forecast for the weekend.

Discussion

Tuesday night through Wednesday: Weather will be warm and dry through Wednesday as subtle ridging continues over the Pacific Northwest. Temperatures on Wednesday will be similar to Tuesday, but with lighter winds as the north-south pressure gradient decreases.

Thursday through Monday: Changes in the weather pattern arrive Thursday as the closed low over California begins to eject northeastward and a frontal system with a trailing shortwave approaches from the west. While the frontal system looks mostly dry, moisture and precipitation associated with the upper-level low moving into far eastern Washington and north Idaho will bring a 30- 70% chance of rain across far eastern Washington. The highest chances for Washington are across southeast Washington, including the Palouse, the L-C Valley, and the Blue mountains. Across north Idaho, there is a 60-80% chance for rain, with the highest confidence across Shoshone County and the southern Panhandle. Additionally, winds will be breezy to gusty from the northwest to west with the cold front. With the KPDX-KGPI increasing to +12-17 mb Friday morning, there is high confidence for wind gusts greater than 30 mph across central Washington and southeast Washington (60- 90% chance). Chances for gusts greater than 30 mph have decreased across the Spokane area, with now only a 10-20% chance. Blowing dust is not anticipated to be a significant hazard given the lack of dust generation during recent comparable wind events.

By the weekend, confidence in the weather pattern significantly decreases regarding the strength and track of the next approaching weather system. Ensemble analysis continues to reveal considerable variance. Ensemble membership has significantly decreased on the idea of an upper-level low influencing the Inland Northwest, with only 20% showing this scenario now. 37% of ensembles suggest the upper-level low to remain offshore, leaving the Inland Northwest under subtle ridging and most of the precipitation west of the Cascades. The last 43% do not have this low near the PNW at all and keep the entire region under some form of ridging. So, 80% of global ensembles now favor a drier and warmer weekend for the Inland Northwest. The NBM still maintains a 30-40% chance of rain over central Washington to northeast Washington and a 10-15% chance across southeast Washington and the central and southern Idaho Panhandle. This uncertainty is further increased by a 9-12 degreeF spread in the the 25th-75th percentile temperature solutions in the NBM across the Inland Northwest. AI ensembles still provide little consensus, as the GEFS AI ensemble favors the cooler and wetter solution (which is the opposite of the physics-based models) while the ECMWF AIFS ensemble indicates only subtle mean troughing, highlighting the uncertainty for the weekend. /vmt

Aviation

00Z TAFS: Mid and high clouds will continue to stream across the region under southwest flow aloft. This will promote VFR conditions through the period with ceilings well above 10k ft AGL. Light wind are expected through Wednesday.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions. JW

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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:/www.weather.gov/otx/avndashboard