282 FXUS66 KPDT 252022 AFDPDTArea Forecast Discussion National Weather Service Pendleton OR 122 PM PDT Thu Sep 25 2025
.DISCUSSION... The key impacts during the next seven days will largely be confined to the next 6-12 hours as Red Flag conditions affect a large chunk of southeast WA and portions of central/northeast OR. A cold front, extending south from a surface low over northeast WA, will move across the CWA this afternoon, resulting in a tight pressure gradient across the Cascades. Gusty west winds have developed in response to this gradient, with gusts exceeding 35 mph at times in the Kittitas Valley and Columbia River Gorge. Gusts will top out in the 45-55 mph range in the Kittitas Valley this afternoon and evening; thus, the Wind Advisory will remain in effect. RH values will drop to 10-20% across much of the CWA this afternoon, as downsloping and mid-level dry air tend to "overachieve" relative to numerical guidance.
The dry cold front will traverse the area during the daytime hours, moving east of the CWA by sunset. The 12z REFS/HRRR indicates a fair amount of vertically integrated smoke emanating southeast from the Labor Mountain wildfire across the Tri-Cities into the Blue Mountains this evening. Winds will be slow to diminish in the Cascade gaps this evening, eventually becoming light area wide as the surface anticyclone nudges into the area. Cooler air will settle over southeast WA/northeast OR for tomorrow with high temperatures much closer to climatology.
Generally pleasant weather is expected through most of the weekend with temperatures running a few degrees above normal both Saturday and Sunday. Highs will top out in the mid 70s to lower 80s with overnight lows in the mid 40s to lower 50s (mid/upper 30s in the higher elevations of central and northeast OR). An upper-level trough will begin to deepen over the Gulf of Alaska this weekend, resulting in increasing southwesterly flow aloft by Sunday. The pressure gradient will tighten somewhat on Sunday ahead of the next cold front, potentially increasing southwest winds across central OR Sunday afternoon. At this time, critical fire weather conditions are not anticipated with both wind and RH currently forecast to remain in check. That said, this is something to watch.
There are some synoptic scale differences in the various global ensemble clusters early next week with the GEFS favoring a deeper trough, the GEPS highlighting a faster trough, and the EPS trending toward a slower system. Regardless of these timing and amplitude differences, sensible weather doesn`t look to differ much with similar QPF suggested by all three clusters. The probability for a wetting rain early next week falls in the 70-90% range for most areas with some of the Columbia Basin areas more in the 40-70% window. Rainfall probabilities for 0.25" to 0.5" are generally at or above 60% for the Cascade peaks and from central OR through the Blue Mountains. Temperatures during this early week precipitation event will be near to slightly below normal with drier conditions settling over the region by the latter half of the week. /MJ
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.AVIATION... 18z TAFs...VFR conditions currently prevail area-wide and are expected to continue over the next 24-hrs. A dry cold front is starting to work into northwest WA that will eventually enter and cross the area late this afternoon. Ahead of the front, breezy W-NW winds are anticipated with some terminals starting to see winds increase, such as KPDT. These increasing winds late morning-early afternoon could be attributable to strong cross-Cascade pressure differences that is sharpening. These breezes will then be maintained as the front moves through promoting breezy winds through the evening hours. Winds should start subsiding 3-9 UTC tonight with light winds prevailing the remainder of tonight. Otherwise, increasing high clouds are expected this evening-overnight.
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.PRELIMINARY POINT TEMPS/POPS... PDT 46 72 46 80 / 0 0 0 0 ALW 50 72 51 80 / 0 0 0 0 PSC 46 74 45 78 / 0 0 0 0 YKM 45 74 48 79 / 0 0 0 0 HRI 47 74 45 79 / 0 0 0 0 ELN 44 72 44 78 / 0 0 0 0 RDM 36 73 38 83 / 0 0 0 0 LGD 41 71 42 81 / 0 0 0 0 GCD 40 72 43 85 / 0 0 0 0 DLS 49 78 51 83 / 0 0 0 0
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.PDT WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 11 PM PDT this evening for ORZ691-701-703.
WA...Red Flag Warning until 11 PM PDT this evening for WAZ690-691-695.
Wind Advisory until 2 AM PDT Friday for WAZ026.
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DISCUSSION...MJ AVIATION...80
NWS PDT Office Area Forecast Discussion