Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
268 FXUS66 KPDT 020418 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 918 PM PDT Tue Jul 1 2025 .UPDATE... Made some minor adjustments to the forecast mainly for pops based on the current radar and latest model guidance. The heat advisory has expired and the red flag warning for today across central Oregon has also expired. && .AVIATION... 06Z TAFS...VFR conditions are expected through the TAF period. Any thunderstorms from earlier have all but dissipated and any thunderstorms Wednesday afternoon look to remain east of the TAF sites. WInds will once again be the main concern. DLS will remain breezy through the period with gusts in the 25 to 30 kt range and possibly even to 35 kts. All other sites will generally be 10 kts or less overnight and then in the 20 to 25 kt range on Wednesday afternoon/early evening. && .PREV DISCUSSION... /issued 451 PM PDT Tue Jul 1 2025/ SHORT TERM...Today through Thursday...The PacNW will be in between the ridging to the north and the cutoff low moving across California. The Heat Advisory continues through this evening for the Basin, Gorge, Yakima/Kittitas Valleys, Simcoe Highlands and north central Oregon, given the upper ridge keeping our today`s temperatures in the low 100s for these areas. The remaining forecast area will be in the 90s, though RHs will mainly be in the teens across the forecast area. And with the Columbia Basin and Kittitas Valley being drier and warmer than other locations, this will elevate critical fire conditions for those specific areas as well heading into Wednesday. With elevated CAPE values (>500 J/Kg), PWATs of 0.80-1 inches and low lapse rates of 6.5-7.0 C/km, we are also looking at thunderstorms this afternoon into this evening with abundant lightning over central OR, John Day Highlands, and John Day Basin, thanks to the upstream intensification influenced from the cutoff low. This allows the Red Flag Warning for Zone OR700 through the evening as well due to abundant lightning from these storms. In addition to that, breezy outflow winds (15-25 mph) will be induced across the Cascade Gaps from the strong surface pressure gradients. However, there is a 30-60% probability of wind gusts exceeding to 30- 35 mph around the Gorge and Kittitas Valley. With persistent warm temps (<90 degrees) and low RHs (<20%), Red Flag Warning has been issued for Wednesday from 2pm to 9pm PDT for the Columbia Basin. Thunderstorms will develop over the eastern mountains Wednesday late morning into evening with the CAMs showing CAPE values becoming slightly modest (500-800 J/Kg) along with decreased PWATs (<0.75 inches). Even though the moisture level remains low, dry lightning can be still be threatening to potential new or ongoing fires. However, these storms should move further eastward out of our area by tomorrow night. Breezy to windy conditions will continue throughout the day tomorrow across the Cascade gaps from the strengthening surface pressure gradients. The raw ensembles suggest a 30-50% prob for gusts exceeding to 40 mph over the Gorge and Kittitas Valley. Winds will begin decreasing later in the evening. Thursday morning should be relatively quiet until evening showers arrive. Temperatures will decrease to the 70s and 80s across the forecast area with RHs gradually recover a bit to the 20s. However, portions of the Yakima Valley, north central OR, and upper part of the Lower Basin may have pockets of low RHs in the teens. But, no critical fire conditions will be anticipated at this time. The Cascade gaps will have breezy winds at 15-25 mph with a 30-40% prob for gusts to reach 30 mph at Kittitas Valley. Feaster/97 LONG TERM...Friday through Tuesday...Light showers will arrive Friday late morning into evening at the eastern mountains with slight chances (<30%) of afternoon thunderstorms. Weak instability (300-800 J/Kg) and low moisture level (<0.10 inches) may inhibit the storms from becoming severe, but CG lightning could be the main threat. Late Friday evening into night, precip activity should be out of the area. Although the Gorge will be gusting at 25-35 mph in the afternoon, the remaining locations will have light winds with occasional breezes. Saturday could have morning showers over the Wallowas but, chances are low (<20%). Starting Saturday afternoon onwards, the weather will be warm and dry with slight breezy winds. Feaster/97 AVIATION...00Z TAFs...VFR conditions are expected to be present for all sites through the majority of the valid period. The notable exception will be at KRDM/KBDN through roughly 04Z due to ongoing VCTS. Sub-VFR conditions may develop should a heavier shower or TS track overhead; nearby observations at KS21 suggest localized IFR conditions are occurring within the more intense thunderstorms. Moreover, gusty and erratic winds may occur with these cells; so far, surface observations indicate sustained outflow of 15-30 mph with gusts of 30-45 mph. Looking ahead to tonight, confidence is low (<30%) in elevated showers developing over PSC/ALW/PDT/DLS, so have excluded mention in the TAF. Otherwise, westerly winds will ramp up later Wednesday morning and afternoon. Plunkett/86 && .PRELIMINARY POINT TEMPS/POPS... PDT 66 93 58 87 / 10 20 10 0 ALW 70 93 62 86 / 10 20 10 0 PSC 67 96 59 89 / 0 10 0 0 YKM 66 94 57 87 / 0 0 0 0 HRI 69 96 60 89 / 10 10 0 0 ELN 65 88 57 82 / 0 0 0 0 RDM 56 88 46 82 / 30 10 0 0 LGD 63 90 54 84 / 10 20 20 10 GCD 60 91 52 86 / 20 20 20 10 DLS 66 86 60 83 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning from 2 PM to 9 PM PDT Wednesday for ORZ691. WA...Red Flag Warning from 2 PM to 9 PM PDT Wednesday for WAZ690-691. && $$ SHORT TERM...97 LONG TERM....97 AVIATION...77