textproduct: Pendleton

KEY MESSAGES

- Shower and Thunderstorm chances peak Thursday but continue through Friday.

- Breezy to Windy on Friday.

- Drier for the weekend onward.

DISCUSSION

An upper low and trough over the Pacific Northwest was moving southward into California and Nevada.

The main low will be south of the region on Wednesday, but the broader cyclonic flow will remain over the region on Wednesday, as weak ridging tries to build over the area. While most of the region will remain dry, there could be some showers and thunderstorms, mainly over the mountains.

The upper low will begin to move northeastward Thursday into Friday and decent shortwave energy will move across the energy on Thursday. This energy, coupled with instability from the low will bring thunderstorm chances. The Storm Prediction Center has placed much of our area in Marginal Risk for severe thunderstorms on Thursday. Convective potential will have to be monitored on Friday as well. Thursday will also be quite warm with high temperatures in the lower 90s across the Columbia Basin and Yakima Valleys and mid to upper 80s across much of the lower elevation areas. Friday's high temperatures will be 10 to 15 degrees cooler, on average than on Thursday.

On Thursday, CAPE values are over 2000 J/kg and LI values are lower than -3 degrees Celsius in areas. However, there is also some convective inhibition and ultimately till it be too cloudy in areas remains to be seen. ECMWF EFI puts CAPE values in the 80th to 90th percentile.

Additionally, on Friday, there will be an area of gusty winds across the Kittitas Valley, Yakima Valley, Columbia Basin, Cascade Gaps and Foothills of the Blue Mountains. It is possible that wind headlines may be needed for a portions of this region as well.

Finally, it looks like there will be more zonal flow moving in for the weekend bringing drier weather. A weak upper low moves through Sunday night, but at this time, it appears to be dry, but will need to see if it remains that way.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

VFR conditions currently across all sites, which will stay the course through the period. Light showers are continuing to move west across the Basin and will linger through the evening. Breezy 15-25kt winds currently for KDLS/KRDM/KBDN and dissipates late this evening with 4-6kft ceilings lifting early Wednesday morning. 75

Preliminary Point Temps/PoPs

PDT 45 79 51 86 / 40 0 0 20 ALW 49 81 57 88 / 30 0 10 20 PSC 47 86 55 93 / 20 0 0 10 YKM 49 88 57 93 / 0 0 0 10 HRI 46 83 54 90 / 30 0 0 10 ELN 47 83 55 89 / 0 0 0 20 RDM 38 77 44 80 / 70 10 40 80 LGD 45 79 49 85 / 60 20 20 40 GCD 39 79 45 81 / 80 30 50 80 DLS 52 86 59 90 / 10 0 0 30

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.