Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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109 FXUS66 KPDT 111114 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 413 AM PDT Sat May 11 2024 Updated aviation discussion .SHORT TERM...Today through Monday night...Clear skies allowed for a perfect view of the Auroras this evening as we continue to be dominated by the upper level ridge. Temperatures today will be roughly 5 degrees warmer across the forecast area with dry conditions continuing. Models show the ridge to continue to strengthen over the forecast region through today keeping the area dry. EFI shows the majority of the area to be above climatological normal today with 70-90% of the raw ensembles showing the Columbia and lower Columbia Basin, Yakima Valley and portions of the Gorge to be above 85 degrees with some isolated low 90s. The foothills, central and north central OR will see the upper 70s to low 80s with isolated mid 80s and the higher terrains will see the upper 60s. Sunday and continuing through Monday, models show the upper level ridge flattening as an upper level shortwave makes its way into the area. By Monday the shortwave will have moved the ridge eastward and will bring northwesterly flow back to the region. Even with this shortwave crossing the area, models and ensembles show this shortwave to be mostly dry. Ensembles show a less than 20% probability of light rain over the highest peaks of the WA Cascades. The main noticeable change that the shortwave will bring is the cooler temperatures by Monday and increased winds both days. EFI continues to show the region to be above average temperatures with 80-90% of the raw ensembles showing the entirety of the Basin, Yakima Valley, and the foothills of the Blues seeing temperatures in the upper 80s with a few isolated 90s, mid elevations in the upper 70s to low 80s and upper elevations still in the upper 60s. By Monday the EFI has backed off and modulated towards near normal temperatures for the majority of the area. Less than 60% of the raw ensembles show the Basin in the mid 80s. However, over 80% of the raw ensembles have the region in the upper 70s to low 80s, mid elevations in the upper 70s and the higher terrains in the 50s. Lastly, as the shortwave makes its way across the Cascades, models show the low level pressure gradients tightening along the Cascades. This will bring increased winds on Sunday through the Cascade Gaps with 70% probabilities the Gorge, Simcoe Highlands and both Yakima and Kittitas Valleys will see sustained winds to 20 mph. By Monday the models show the gradients tightening even more as the shortwave passes the Cascades and winds will increase even more. Monday shows an increase to 80% probabilities the aforementioned areas will see sustained winds to 25 plus mph with 50-80% probabilities of gusts to 40 mph. Quick note: If you are outside enjoying the warmth, please be mindful and wear sunscreen, drink plenty of fluids and remember that the rivers will be fast flowing and still dangerously cold. Bennese/90 .LONG TERM...Tuesday through Saturday...Ensemble and deterministic models start out in showing good agreement with a building ridge Tuesday following Monday`s trough passage but they continue to differ from Wednesday onward. However, they are agreeing that the advertised persistent ridging pattern does not hold and that a trough over western Canada will become the dominant weather feature at some point late in the week. Thus timing of said trough remains in question amongst the models at this point. ECMWF is fastest at breaking down the ridge by bringing a trough through western Canada on Wednesday that clips the region. This is followed by a secondary shortwave that drives the trough further south over the region late Thursday and Friday. Meanwhile, the GFS does maintain a flat ridge pattern over the region through the week but does bring a trough into the region on Friday which closely matches with the timing and position of the second shortwave in the ECMWF solution. Both models then drive this trough east and out of the forecast area on Saturday leaving a verily dry westerly flow over the forecast area. So, forecast will reflect the model agreement on Tuesday by being dry and warm. This will be followed by the effects of a westerly flow as indicated by a few showers along the Cascade crest Wednesday through Sunday while mainly dry across the rest of the forecast area but with a low degree of confidence. NBM high temperature variations continue to show a large range of due to the model uncertainty but overall maintaining a little above normal. No model solutions indicate any significant event through the extended other than some breezy to windy conditions associated with the trough passage over the Thursday through Friday period. && .AVIATION...06Z TAFs...Clear skies for all sites for the next 24 hours. Light winds will increase midday with some sustained AOA 10kts and gusts AOA 20kts mainly at DLS, RDM and BDN. Wind decrease around sunset becoming light again overnight. && .PRELIMINARY POINT TEMPS/POPS... PDT 83 54 83 53 / 0 0 0 0 ALW 85 59 85 58 / 0 0 0 0 PSC 91 58 89 57 / 0 0 0 0 YKM 90 51 88 50 / 0 0 0 0 HRI 89 56 88 56 / 0 0 0 0 ELN 86 54 84 52 / 0 0 0 0 RDM 82 47 80 43 / 0 0 0 0 LGD 80 51 80 48 / 0 0 0 0 GCD 80 49 81 46 / 0 0 0 0 DLS 88 58 84 55 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...90 LONG TERM....91 AVIATION...85