Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
890 FXUS66 KPDT 031818 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1118 AM PDT Thu Jul 3 2025 .AVIATION...18Z TAFs...VFR conditions are forecast through the day for all sites. Overnight into early Friday, a low-pressure system is anticipated to move onshore and produce scattered to numerous showers across central and eastern Oregon with some potential (30% chance) for thunderstorms for RDM/BDN. Chances of showers and thunderstorms for other sites are low (<30%) through 15Z with low (30%) chances of showers for ALW/PDT beginning 15Z. Winds will be locally breezy today. Plunkett/86 && .PREV DISCUSSION... /issued 952 PM PDT Wed Jul 2 2025/ UPDATE... Winds have decreased across the region and will continue to slowly do so. Latest radar imagery also showed that all shower and thunderstorm activity is now south and east of the area...in Idaho and should remain there before moving further away or dissipating. With winds decreasing, and temperatures also decreasing, humidities will slowly rise. Therefore, the red flag warning was allowed to expire. Also, the wind advisory for the Kittitas Valley was cancelled early as winds, while breezy have dropped below advisory criteria. .PREV DISCUSSION... /issued 613 PM PDT Wed Jul 2 2025/ .UPDATE...Northwest winds have bounced around advisory levels through the Kittitas Valley for much of the afternoon. While winds are anticipated to be near their peak, confidence is high (80%) that criteria will be periodically met through much of the valley for the next few hours so have issued a Wind Advisory. Expecting sustained winds of 25-35 mph accompanied by gusts of 40-50 mph will shift to area ridgetops (such as Ryegrass Summit along I-90) after sunset. Plunkett/86 .PREV DISCUSSION... /issued 402 PM PDT Wed Jul 2 2025/ .SHORT TERM...Today through Friday...With the ridge up north moving further eastward, the PacNW will enter a troughing pattern through this term. Today, Temperatures will be mainly in the 80s and 90s with RHs remaining in the teens. Due to the latest observations showing RH values lowering to the single digits and breezy to windy conditions for Columbia Basin, Kittitas Valley, and central OR, a Red Flag Warning has been issued through late this evening for those areas. In addition to that, thunderstorms continue over the eastern mountains this afternoon through evening. The CAMs have CAPE values slightly modest (500-800 J/Kg) with decreased PWATs (<0.75 inches). Given the low moisture level, the severity of these storms may not be very high but, slightly moderate enough to induce CG lightning and small hail based on current satellite and radar imagery. Outflow winds will also become breezy as well (50% confidence). Confidence increases for the winds with the dry microburst parameters showing an inverted-V sounding, downdraft CAPE (DCAPE) above 1000 and steep lapse rates (>8.0 C/km). By tonight, convective activity should begin moving out of our area, though may leave some lingering showers behind. The Cascade gaps will continue having breezy to locally windy conditions from the strong surface pressure gradients. There is a 30-50% prob for gusts reaching to 45 mph or higher over the Gorge and Kittitas Valley. Winds have been close to wind advisory criteria for Kittitas Valley since the gusts are borderline between 35-45 mph. Winds will start decreasing later on this evening. Tomorrow will be relatively quiet through the afternoon before evening showers arrive across the eastern mountains with slight chances (<30%) of thunderstorms through Friday morning. Instability is there but CAPE values remains modest (under 800 J/Kg) including low moisture, so chances on severity will be unlikely as well. Light showers could develop over the Columbia Basin and valley zones Friday evening, however confidence is low (<15%) at this time given the latest HREF and other guidance showing limited spread of precip. Temperatures will decline to the 70s and 80s across the forecast area. RHs will gradually recover a bit to the 20s with portions of the Yakima Valley, north central OR, and upper part of the Lower Basin having pockets of RHs in the teens for tomorrow, but will improve Friday. Breezy winds at 15-25 mph continue to impact the Cascade gaps with a 40% prob for gusts to reach 30 mph at the Gorge and Kittitas Valley through Friday. Friday night, convective activity will then move to the Wallowas, but mostly out of our area with winds becoming light again. Critical fire conditions might not be anticipated at this time. Feaster/97 && .LONG TERM...Saturday through Wednesday...This long term is characterized by long-lasting warm and dry conditions. Temperatures will steadily return to the 80s and higher into next week with RHs dropping again to the 20s and teens. Tuesday and Wednesday will be our warmest and driest days of this term with temps in the low 100s around the Columbia Basin and valley zones, leaving everywhere else in the high 90s. Moderate HeatRisk will start off Monday over portions of the Columbia Basin before extending across the forecast area Tuesday and Wednesday with pockets of Major HeatRisk over the Columbia Basin, which could warrant Heat Advisories. Winds will be relatively light for most locations with occasional breezes at the Cascade gaps. Feaster/97 && .PRELIMINARY POINT TEMPS/POPS... PDT 87 59 81 57 / 0 0 30 10 ALW 87 62 80 60 / 0 0 30 10 PSC 89 59 84 59 / 0 0 20 0 YKM 88 58 83 58 / 0 0 10 0 HRI 89 59 83 59 / 0 0 20 0 ELN 84 57 83 56 / 0 0 10 0 RDM 83 50 76 43 / 0 30 40 10 LGD 84 57 74 51 / 0 10 50 20 GCD 87 54 77 48 / 0 30 70 30 DLS 85 60 81 57 / 0 10 20 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...97 LONG TERM....97 AVIATION...86