890 FXUS66 KPDT 111008 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 308 AM PDT Fri Apr 11 2025 .SHORT TERM...Friday through Monday Morning... 1) Dry conditions for most of the period 2) Chance of widespread below freezing min temps Sun AM A trough is currently bringing isolated showers at the Cascades and along the Foothill of the Blue Mountains. Precip will move away as we head into the overnight hours before popping up again Friday evening along the Mountain areas. Precip will dry out and skies will clear out by Saturday evening as ridging begins to push over the PacNW region. Overnight Sunday, effective radiation cooling coupled with upper northwest winds will drop minimum temperatures in the low to mid 30s across the region. Confidence is high (70-90% chance) that temperatures will fall at or below freezing heading into Sunday morning for most of the region. Although many parts of the region will eligible for freeze warnings starting April 15th, no warnings or highlights will be issued for this particular day. As we get closer to the ridge axis heading over the region, temperatures will begin a warming trend heading through the short term into the long term. By Saturday afternoon, a trough will enter the region, tightening the pressure gradient and increasing the winds 25-35 knots across large swaths of the CWA. NBM is giving the Basin and the Foothills 40-60% chances of wind gusts greater than 25 mph Saturday afternoon with 60-80% chances in the higher elevations around the Kittitas Valley/Ellensburg area. No wind highlights are expected with this system with low confidence at this time (20-30% confidence). .LONG TERM...Monday through Friday...Weather conditions through the extended forecast will for the most part be warm and dry with light winds. That said, the beginning of the work week may see another round of near to just below freezing morning temperatures in the lower elevations. Ensemble guidance is in great agreement that upper level ridging will sit over the PacNW through much of next week, producing dry conditions with passing bands of cirrus. The upper ridge overhead will also promote warming temperatures, with the trend continuing through the end of the work week. That said, at the start of this warming trend, members from the ECMWF, GFS, and Canadian ensemble suites are split on how low temperatures will be Monday morning. Overall, the dry conditions (PWATS of 0.35" or lower) with a lack of any cloud cover present in all three ensemble suites will result in great radiative cooling across the lower elevations, leading to another morning of near to below freezing temperatures (confidence 50-60%). At this time, freeze warnings are not being considered as many of the forecast zones in the Lower Columbia Basin, including the Yakima/Kittitas valleys and the eastern Gorge are not eligible until the morning of April 15th. While upper level ridging will persist through much of extended forecast, it is worth mentioning that ensemble cluster solutions do indicate that a shortwave trough passage Tuesday into early Wednesday will result in the ridge flattening. Nearly 80% of the cluster members favor no precipitation during this shortwave passage, but the remaining members do favor very light precipitation across the Cascade crest and portions of the northern Blues. Wednesday and Thursday, ensemble cluster solutions all favor the upper level ridge rebounding in some form, however there is disagreement in placement of the ridge axis and amplitude of the ridge that persists through the end of the week. That said, there is mod-high confidence (60-80%) that a warming trend with dry conditions will persist through this period. By Friday, there is good agreement that the ridge axis will shift east of the PacNW, but disagreement on whether the Cascade crest will continue to see dry conditions (~65% of members) or if very light showers will return under a southwest flow aloft. Lawhorn/82 && AVIATION...06Z TAFS...VFR conditions current at all sites, which will stay the course through the period. A cold front passage has attribute to breezy winds of between 15-25kts for KDLS/KPDT and lowered ceilings of SCT-BKN040-060 across all sites. There is a 30% chance of light rain at KPDT/KALW this evening, with a low probability (15%) of conditions dropping to MVFR due to reduced ceilings of 3kft or below. 75 && .PRELIMINARY POINT TEMPS/POPS... PDT 62 38 57 33 / 0 10 0 0 ALW 62 40 56 35 / 0 10 10 0 PSC 67 39 62 33 / 0 0 0 0 YKM 63 36 59 32 / 0 0 0 0 HRI 66 38 62 33 / 0 0 0 0 ELN 59 36 54 31 / 0 0 0 0 RDM 63 30 57 26 / 0 0 0 0 LGD 60 35 51 29 / 10 20 10 0 GCD 62 35 52 29 / 20 40 0 0 DLS 63 38 59 36 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...95 LONG TERM....82 AVIATION...75