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Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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857 FXUS66 KPDT 282325 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 424 PM PDT Fri Jun 28 2024 Updated aviation discussion .SHORT TERM...Tonight through Sunday night...A weak and dry westerly flow aloft has brought another day of seasonal temperatures. Winds are considerably less, temperatures are a few degrees warmer, and the relative humidity is about the same or a little lower than this time yesterday. Overall, it has been a tranquil weather day and tonight will be quiet and mild. No major weather concerns are anticipated this weekend, although it will be breezy to locally windy on Sunday which raises minor concerns for fire weather. Tomorrow, the westerly flow will back to the southwest as a shortwave trough develops off the eastern Pacific. The trough will move onshore Saturday night and across WA/OR on Sunday. This will help to destabilize the atmosphere, and there will be enough upper level support and moisture to bring a chance of mountain showers and a slight chance of t-storms Saturday night and Sunday. The PoPs were increased slightly Saturday night over the Blues and Wallowas to around 30%, primarily due to the support of the left exit region of an 80kt jet. NBM shows a 15% probability of thunder, and CAPEs from the NBM and CAMs average around 150 J/kg so will keep the slight chance of t-storms in the forecast. There will be an uptick in winds Saturday, starting in the late afternoon as the inverted surface thermal trough shifts eastward and an onshore flow increases. Sunday`s winds will be stronger due to a more pronounced marine push. Forecast soundings near Puget Sound show the marine layer as deep as 800 mb, so confidence is high that cooler air will seep through the Cascade gaps and induce winds in the Kittitas Valley, the eastern CR Gorge, Sisters, and other wind exposed areas in the eastern valleys. The most likely wind gusts will be 25-35 mph with a 20% probability of 35-40 mph gusts. RHs will not be critically low--mostly in the 20s to mid 30s--therefore red flag conditions are not expected (70% confidence). Showers and t-storms will mainly develop over ID with a 20-30% chance of convection in Wallowa County Sunday afternoon. Wister/85 .LONG TERM...Seasonable temperatures and gusty winds will continue through Monday as the transient trough exits the PacNW. With the upper ridge sweeping across the region Tuesday onward, dry conditions persist with no chance of precip across the region. Temperatures will be above normal starting Tuesday with the ridge building over the PacNW. Through late Monday, gusty winds at 25-35 mph will occur around the Cascade gaps (>70% confidence). This is due to the tightening surface pressure gradient left behind from the passing trough. Probability remains low to moderate (30-50%) for wind gusts exceeding 40 mph. No Red Flag conditions have been forecasted, but the combination of increased winds and low relative humidity in the teens to lower 20s will raise concerns for areas of elevated fire weather potential, including 4th of July. Tuesday onward, winds will decrease as the upper ridge builds over the forecast area. Breezy conditions will continue with occasional wind gusts at around 15-25 mph through the remaining extended period. Feaster/97 && .AVIATION...00Z TAFS...All sites remain VFR for this period with an increase of high clouds overnight becoming mostly cloudy Saturday SCT100-150 and BKN-OVC150-200. Winds will remain light under 10 kts but will begin to see increasing westerly winds at DLS, RDM and BDN to 10-15kts in the afternoon. && .PRELIMINARY POINT TEMPS/POPS... PDT 55 82 57 82 / 0 10 10 0 ALW 58 87 60 87 / 0 10 10 0 PSC 60 88 62 90 / 0 10 0 0 YKM 57 87 55 85 / 0 10 0 0 HRI 57 87 60 88 / 0 10 10 0 ELN 57 85 56 80 / 10 10 0 0 RDM 48 80 48 80 / 0 10 0 0 LGD 52 84 54 79 / 0 10 30 10 GCD 51 86 52 81 / 0 10 20 10 DLS 59 85 60 82 / 0 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...85 LONG TERM....97 AVIATION...97