Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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458 FXUS66 KPDT 220514 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1014 PM PDT Sat Sep 21 2024 Updated Aviation Discussion .SHORT TERM...Today through Monday... Bottom Line Up Front 1. Windy through the Grande Ronde Valley through early evening 2. Quiet weather with near normal temperatures Current observations show the most interesting thing happening across the region is the windy conditions moving through the Grande Ronde Valley. Surface models show a tightening of the surface pressure gradients along the area which is leading to the enhancement of the winds through the area. Latest obs show sustained winds of 20 mph with gusts to 26 mph. Winds will begin to settle later in the afternoon around 5 PM as the leading edge shifts slightly eastward and surface gradients ease. Models are in firm agreement with an upper level flat ridge over the forecast area today and through the remainder of the forecast period. Monday morning a very weak disturbance will pass by along the leading edge of the ridge bringing slight chances of light rain over the Snoqualmie Pass area with 20% of raw ensembles showing 0.01 inches of rain. After the quick pass, things will resettle under the ridge. Conditions across the area will remain benign through the forecast period. EFI shows temperatures to be at or near normal with 83% of the raw ensembles putting the PDT area in the upper 60s to low 70s, 70% showing the Basin and surrounding area seeing low to mid 70s, central OR in the low 70s and the higher terrains in the low to mid 60s and cooler at the crests. As the ridge continues to settle in, temperatures will steadily increase with over 62% of the raw ensembles putting much of the lower elevations in the upper 70s to low 80s with 60s along the higher terrains. Bennese/90 .LONG TERM...Tuesday through Saturday...Ensemble guidance is in fairly good agreement on the long term synoptic pattern, showing a persistent pattern starting around the midweek onward, which may make for some precip chances across the forecast area, especially for our high mountain zones. Cooler air may also be on the way as we start to head toward October. Tuesday will be dominated by strong ridging, which could push high temps across some of our population centers into the upper 80s and even low 90s, which would be a good 15 to 20 degrees above average for the time of year. Confidence on getting that warm is on the lower end (20%), but models are in good agreement on an awfully strong ridge with high pressure centered just to our south. This ridge could also yield some localized unstable conditions for the few remaining wildfire incidents in the area as well with thermal troughing in place. The pattern then changes Wednesday onward as ensembles bring in a broad trough with SW winds aloft through the PacNW. Much of the moisture transport associated with this system looks to lie to our northwest, isolating the highest PoPs more toward the WA Cascades, but certainly could see chances spread more to the southeast should this trough track just a bit more southward. Once this trough moves through, models show persistent SW flow through the region, which will make for at least slight chance PoPs across our high mountain zones - both the Cascades and the Blues - potentially spreading into the lower elevations should an embedded shortwave track through. By next weekend, ensembles start to diverge on their solutions, but some members do suggest that the center of the upper-level low driving this SW flow could start to inch toward our area, which would make not only for more widespread PoPs, but for an influx of colder air as well. Evans/74 .AVIATION...06z TAFs...VFR conditions to prevail through the period. High level sct-bkn cigs will impact sites through tomorrow evening. Winds will be light, less than 12kts, and terrain driven through the period. Except, site DLS will see northwest winds 12-15kts with gusts to around 21kts develop after 22Z. Lawhorn/82 && .PRELIMINARY POINT TEMPS/POPS... PDT 45 78 49 77 / 0 0 0 0 ALW 47 80 53 80 / 0 0 0 0 PSC 49 81 55 81 / 0 0 0 0 YKM 46 80 50 82 / 0 0 0 0 HRI 47 81 53 82 / 0 0 0 0 ELN 48 79 54 83 / 0 10 0 0 RDM 39 79 45 79 / 0 0 0 0 LGD 42 77 46 76 / 0 0 0 0 GCD 41 78 45 78 / 0 0 0 0 DLS 50 83 57 85 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...90 LONG TERM....74 AVIATION...82