Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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767 FXUS66 KPDT 121726 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1026 AM PDT Wed Jun 12 2024 Updated Aviation Discussion .AVIATION...18Z TAFs...VFR conditions will prevail through the period. Winds will be light, less than 12kts, through the period. Except at site DLS where winds will be 12-17kts with gusts up to 25kts through early this evening. Lawhorn/82 && .PREV DISCUSSION... /issued 326 AM PDT Wed Jun 12 2024/ .SHORT TERM...Today through Friday night...Near-seasonal temperatures and mostly clear skies will prevail today under dry zonal flow. Surface winds will be significantly lighter than Tuesday, with typical diurnally driven onshore winds through the Cascade gaps. Thursday, the 500-mb pattern will become more amplified as an anomalously deep upper-level closed low approaches in the Northeast Pacific and an upper-level ridge builds over the Rockies. Flow aloft will turn southwesterly in response, and although the upper-level ridge axis will be east of our CWA, above-normal afternoon high temperatures are forecast area-wide. While chances are very low (<5% chance), an afternoon shower cannot be completely ruled out across the Blue Mountains. By late Thursday afternoon and evening, onshore-directed pressure gradients will increase as a mid-level shortwave and attendant dry cold front propagate onshore. Additionally, a robust LLJ of 30-45 kts is advertised through the Columbia River Gorge (CRG) and Kittitas Valley (KV) as well as across the Lower Columbia Basin and foothills of the Blue Mountains. Forecast soundings suggest favorable profiles for gusty winds reaching the surface, so while confidence is not high (<60% chance), brief advisory-level wind gusts appear possible through the CRG/KV. Friday, breezy to windy onshore winds will continue as the parent upper low tracks towards the PacNW. Aside from "chance" (25-54%) to locally "likely" (55-74%) PoPs along the WA Cascade crest, dry conditions are expected. Temperatures will be near seasonal normals on Friday. Plunkett/86 .LONG TERM...Saturday through Wednesday...Models begin the period in pretty good agreement with an upper level trough near the coast, but they begin to diverge on its impact and persistence over the area through the remainder of the period. WPC cluster analysis shows the majority (80-85%) sticking with a troughy pattern while one member (which varies) shows a few periods of zonal flow. Ensembles favor a more troughy pattern as well. Given consistency, confidence is high (80-85%) we`ll see an upper level trough move over the Pacific Northwest over the weekend, but confidence decreases to moderate (50- 60%) on its longevity. At this time, we`re only expecting convection over the mountains with the lower elevations remaining relatively dry. Cooler temperatures are expected beneath the trough averaging 5-10 degrees below normal. The chance (40-60%) of a wetting rain (0.1 of an inch or more) remains confined to the Cascades over the weekend, but does increase to a moderate chance (30-40%) over the mountains of Northeast Oregon Monday. Earle/81 && .PRELIMINARY POINT TEMPS/POPS... PDT 76 46 82 53 / 0 0 0 0 ALW 79 48 86 56 / 0 0 0 0 PSC 81 51 87 57 / 0 0 0 0 YKM 81 45 84 49 / 0 0 0 0 HRI 81 48 87 56 / 0 0 0 0 ELN 76 46 82 50 / 0 0 0 0 RDM 77 43 81 43 / 0 0 0 0 LGD 75 45 84 50 / 0 0 0 0 GCD 80 47 89 49 / 0 0 0 0 DLS 79 50 84 53 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...86 LONG TERM....81 AVIATION...82