474 FXUS66 KPDT 061809 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1009 AM PST Sun Nov 6 2022 .Updated Aviation Discussion. AVIATION...18Z TAFs..VFR conditions are forecast to continue through the morning. By late this afternoon through the evening, conditions are expected to degrade to MVFR as lowering ceilings and -RA impacts most terminals, with -SN at BDN/RDM and possibly a mix at YKM. HREF probabilities indicate low chances of IFR conditions (<10%) at all terminals except BDN/RDM later this afternoon and evening as the band of precipitation goes through. IFR probabilities are 20-30% for BDN/RDM this evening. Confidence is also lower than average on the onset of MVFR conditions and this timing may have to be adjusted in subsequent issuances. Winds are forecast to be around 10 kts or less through the period, except for BDN/RDM/ALW which will see some gusts to around 25-35 kts at BDN/RDM and 20 kts at ALW today. Plunkett/86 && MORNING UPDATE...Main concern for today continues to be snow across the Cascades, with precip eventually spreading eastward later today as the flow aloft shifts more SW. Webcams around the OR Cascades are showing a respite in snow showers, while snow continues to fall across the WA Cascade crests. Expecting snow to resume later today in the OR Cascades as the flow makes its SW shift, supporting more moisture influx into the area, where snow will spill over a bit more into the foothills, but still looking like the bulk of this system's snow will impact primarily the crests and mountain passes rather than the foothills. Latest Hi- res guidance has a band of precip sweeping across the rest of the forecast area east of the Cascades beginning around 5 PM, however current radar does show light showers in the WA Basin running ahead of the precip falling over the Cascades. Expect snow levels to run around 3500 to 4500 ft east of the Cascades for much of the day. Any precip east of the Cascades and foothills looks to be on the lighter end - less than a tenth of an inch. Made some minor tweaks, otherwise most of the morning forecast package remains intact. Evans/74 PREV DISCUSSION... /issued 326 AM PST Sun Nov 6 2022/ SHORT TERM...Today through Tuesday...Current radar imagery is showing that the current precipitation is in Wa moving to the Northeast. The short term models HRRR/SREF/NAM12 and RAP are in strong agreement that the low will continue to dig south and a little eastward through the day bringing the moisture over the Cascades later this morning and moving farther east by the afternoon. Snow levels are expected to drop to as the system digs in bringing cold air in behind it. As the system moves over the Cascades, expect snowy conditions, especially in the the mountain passes. The ECMWF EFI forecast of 0.88 for Sunday into Monday is signaling above average snowfall over the Cascades and some higher terrains. Showers are expected in the Basin with a chance (30-50%) of showers elsewhere. A Winter Weather Advisory is in affect for both the Or and Wa Cascades until 4 pm today. Please check road conditions through the passes before traveling. The HRRR/SREF/NAM and Rap models continue to forecast the low traversing farther south through the period, it will deepen and the moisture is then shifted out of the region. The deepening of the low will allow for cold air to move in over the region bringing cold temperatures. The NBM is showing highs today will be in the low 50s in the Gorge and Basin, 40s for the foothills and Central Or and 30s for the higher terrains. The ECMWF EFI is again signaling a below average temperatures through the short term, mostly in the higher terrains and Central Or. Again, the NBM is showing temperatures will decrease by about 5 degrees each day through Wednesday when high temperatures will bottom out in the 20s for the higher terrains and 30s elsewhere. Bennese/90 LONG TERM...Wednesday through Saturday...A large trough will be making its way onshore in California beginning Wednesday and then will progress north and east across the Great Basin on Thursday and end up in the northern plains on Friday as ridging returns to the west. The models are in very good agreement through about Friday, with only minor timing differences on the low as it ejects northeastward. By Saturday, there is another low off the Pacific Northwest coast and there are model differences that develop with respect to this feature. As far as sensible weather goes, it is going to be unseasonably cold through the week, with high temperatures generally in the mid to upper 30s...at best. There is some disagreement win the models as to how high the temperatures will be, with the ECMWF generally warmer. Regardless, these temperatures are 15 to 20 degrees colder than normal. Overnight lows will be in the teens and 20s which are also about 10 to 20 degrees below normal. As the axis of the trough crosses the region on Wednesday, there could be some snow showers, mainly over the mountains, but after that the balance of the forecast looks dry. The ECMWF EFI shows the anomalous cold well. Beginning Wednesday There is a large swath of values -0.7 to -0.7 over the entire region with some embedded -0.8 to -0.9 Thursday and Friday are quite similar, with perhaps some slight moderation by Saturday. Low temperatures don't show up as extreme until Thursday when there is a large swath of -0.8 to -0.9 from the Columbia Basin in Washington northward. By Friday and Saturday, most of the area is indicated in -0.7 to 0.8. Examining the ensemble clusters toward the end of the period, while certainly not definitive, there is some support for the ECMWF solution over the other models on Saturday, but there is not great agreement between the clusters either. However, the cluster phase space shows that the ECMWF ensembles are most cluster together compared to the other models and are also more clustered around the deterministic run, which would lend additional credence to the ECMWF solution during this time. && .PRELIMINARY POINT TEMPS/POPS... PDT 51 30 46 22 / 20 70 10 20 ALW 51 33 48 25 / 20 70 20 10 PSC 53 36 48 30 / 50 60 10 20 YKM 45 25 40 22 / 70 50 20 30 HRI 55 33 50 27 / 40 60 10 20 ELN 42 24 38 22 / 80 60 20 30 RDM 46 22 43 21 / 50 80 20 30 LGD 41 29 41 20 / 10 70 20 10 GCD 47 25 43 22 / 10 80 10 10 DLS 48 33 49 32 / 80 50 30 30 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory until 10 PM PST this evening for ORZ509. WA...Winter Weather Advisory until 4 PM PST this afternoon for WAZ520. && $$ MORNING UPDATE...74 SHORT TERM...90 LONG TERM....77 AVIATION...86