Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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854 FXUS66 KPDT 072111 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 211 PM PDT Fri Jun 7 2024 .SHORT TERM...Today through Sunday... Bottom Line Up Front (BLUF) 1. Thunderstorms over south central OR and along the eastern mountains Saturday and Sunday. 2. Warmer than average temperatures through the short term with hottest day Saturday. 3. Winds increase again Sunday. Hi-res models are in decent agreement with the upper level synoptic patter through Saturday. An upper level ridge is in place over the region and will begin to flatten slightly as the leading edge of an upper level trough makes its way towards the PacNW. Mid level moisture will enhance as the southwesterly flow intensifies ahead of the the upper level trough. This synoptic set up will lead to thunderstorm probabilities across the eastern mountain steadily increasing in probabilities each day. The SPC has a general thunderstorm outlook over the southern portion of the CWA both today and Saturday then it switches to along the eastern mountains on Sunday. Model derived soundings across the eastern mountains, MUCAPE values will be 200-300 J/kg through Deschutes county with lapse rates of 7.9 C/km, lifted index of -2, PWATs of 07 inches and bulk shear neat 20 kts. While these ingredients are present, confidence in thunderstorm chances are low of Deschutes County with less than 15%. As the upper level trough continues to push onshore, thunderstorm ingredients are projected to increase as well as begin to move along the Ochoco-John Day Highlands. Model derives sounding again show MUCAPE of 250-350 J/kg, lapse rates of 8 C/km, lifted index of -2 to -3, PWATs of 0.85 inches and bulk shear nearing 25- 35kts. This increases thunderstorm probabilities to 20% Saturday. Lastly, thunderstorm probabilities increase Sunday to 25-30% and shift along the entire eastern mountains and highlands. MUCAPE increase to 400 J/kg and even higher values of 600 J/kg through the Wallowa mountains with lapse rates cresting 9 C/km, lifted index of - 4, PWATs nearing 0.9 inches and bulk shear of 35 kts. Confidence in these storms becoming severe is low, less than 5%. With the upper level ridge in place over the region through Saturday and the incoming frontal boundary and upper level trough, temperatures are going to remain above average through the short term period. Models show the upper level trough to be mostly dry and cooler, only dropping the temperatures as few degrees Sunday. EFI is signaling above average temperatures for much of OR today increasing across portions of WA Saturday and leveling back to near normal on Sunday. Over 50% of the raw ensembles show that today much of the region will be in the upper 80s with some isolated 90s in the Basins, mid elevations like central and north central OR will be in the upper 80s and the higher terrains will be in the mid 60s. Saturday, the hottest day of the period, 80% of the raw ensembles are showing the majority of the region to be in the upper 80s to low 90s, mid level terrains in the mid to upper 80s and the higher terrains in the upper 60s. Models then show the trough axis to be onshore Sunday which will push a frontal boundary across the Cascades allowing some cooler air to rush into the area. Temperatures will only cool by a few degrees with over 60% of the raw ensembles showing temperatures in the mid to upper 80s through the Basins, upper 70s to low 80s along the lower and mid elevations and low 60s along the higher elevation. There is an enhanced heat risk on Saturday of portions of the Basin where HeatRisk guidance is signaling moderate risk, so be mindful if outside and remember to drink plenty of fluids. Lastly, with the upper level trough pushing across the Cascades, model derived pressure gradient tool shows that there is a slight tightening of the surface gradients along the Cascades. Due to this, ensembles are picking up on increased winds, especially through our wind prone areas. There is over a 55% chance the Simcoe Highlands and portions of the Gorge seeing winds of 25 mph or greater, 50-70% through the lower Kittitas Valley and less than 25% along the foothills of the Blues. Bennese/90 .LONG TERM...Monday 12Z(Monday) to Saturday 06Z(Friday night)... Key Messages: 1. Cooling period during this week. 2. Breezy to locally windy conditions throughout this week. As the transient ridge exits eastward Monday, the PacNW enters a zonal pattern Tuesday through Wednesday. A short-lived ridge will build in Thursday followed on Friday by a trough moving into the PacNW. This trough is driven by the upper low centered over the BC coast, bringing a cooling period across the region this week. This would result in seasonable temperatures through the weekend (>60% confidence). Precip could occur along the crest of Cascades Friday once the trough moves over the PacNW (20-30% confidence). Otherwise, there will be no significant weather impacts for the extended period. There is a high chance for windy conditions at Yakima Valley, Simcoe Highlands, and Kittitas Valley during this period at 25-35 mph (>70%). The wind gusts could exceed up to 40 mph mainly in the Kittitas Valley and Simcoe Highlands, but confidence is low (<20%). The surface pressure gradient remains strong as this progressive pattern persists. Breezy winds will be across for the remaining PacNW at around 17-25 mph (>50% confidence). Feaster/97 && .AVIATION...18Z TAFS...All sites remain in VFR for this TAF period with clear skies. Winds will be light as SWLY flow aloft continues over the PacNW. Feaster/97 && .PRELIMINARY POINT TEMPS/POPS... PDT 56 87 59 82 / 0 0 0 20 ALW 57 90 61 84 / 0 0 0 20 PSC 57 92 63 88 / 0 0 0 10 YKM 56 89 59 86 / 0 0 0 10 HRI 57 92 62 88 / 0 0 0 10 ELN 55 88 60 82 / 0 0 0 10 RDM 53 85 56 80 / 0 0 20 10 LGD 54 84 58 77 / 0 0 10 30 GCD 56 89 57 80 / 0 10 30 50 DLS 62 89 63 84 / 0 0 0 10 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...90 LONG TERM....97 AVIATION...97