Walla Walla, WA Weather

Key Messages

- Drier conditions as we head into the later overnight hours, with a ridge aloft promoting drier conditions to continue through Saturday.

- Wind advisories continue through tonight and through the morning. Freezing temperatures possible Friday night into Saturday.

- Wetter, cooler conditions through next week with the next weather system bringing another round of rain across the region.

Discussion

As the low pressure system located across California and Nevada continues to move towards the east, conditions will continue to dry out of the area headed into the overnight hours. Previous precipitation from the system has brought wetting rains across portions of the Foothills of the Blues, Northern Blue Mountains, Eastern Mountains, Grande Ronde Valley, and parts of the John Day Basin. Surface observations have recorded up to a quarter of an inch of rain in most places, with locations further east up to a half an inch. Current radar displays rain continuing to lighten up across the eastern portion of the CWA and will dry out over the next few hours. Wind advisories persist over the Kittitas, Gorge, and North Central ORegon with tight pressure gradients continuing to bring gusts up to 40-45 mph.

Guidance is in good agreement that a low amplitude ridge aloft will dry out the region through Saturday (80-90% chance), leaving clear and dry conditions with light winds. This results in effective radiation cooling in the overnight hours, that will drop temps below freezing in much of the area. Given that, a Freeze Watch has been issued for the remaining forecast zones that are eligible and will most likely (70-90% chance) result in a season ending freeze. If freezing temps verify Friday night into Saturday, the Freeze Warning products for our area will be discontinued for each verified forecast zone until sometime in the Spring of 2027.

Guidance is in good agreement that our next weather potential will be from a developing shortwave over the Gulf of Alaska that will drift down into the PacNW by next week. As far as strength and impacts go, ensembles are split into how it wants to evolve the system. By Monday, 44% of clusters (which are heavily Canadian and European models) brings a more elongated trough with a slight negative axis over the PacNW, while the 38% brings a slower shortwave and delays the impacts until Tuesday. The differences in clusters becomes greater by Tuesday with 49% promoting a stronger/wetter shortwave that are primarily GFS models, while 28% promotes a weaker/drier shortwave that is primarily EURO solutions. Plenty of time to monitor for impacts with this evolving system, but not currently seeing any significant QPF amounts at this time.

Aviation

VFR conditions with most precipitation moving out of the TAF sites. Expecting drier conditions through the overnight hours as the prevailing weather system moves out the region. Might see some lower decks develop at RDM, BDN, and ALW with a small chance (5-15%) that we'll see MVFR conditions in the later overnight hours. Gusty and breezy winds continue for most of the sites, but will see winds decrease as e head into the late morning to early afternoon hours.

Pdt Watches

WA...Wind Advisory until 11 AM PDT this morning for WAZ024-026. Freeze Watch from this evening through Saturday morning for WAZ024-027>029. OR...Wind Advisory until 11 AM PDT this morning for ORZ041-510. Freeze Watch from this evening through Saturday morning for ORZ041-044-507.