Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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016 FXUS66 KPDT 271106 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 406 AM PDT Fri Sep 27 2024 SHORT TERM...Today through Sunday Night... Key Messages: 1. Breezy winds linger today across the east slopes. 2. Widespread breezy winds late Saturday through Sunday. 3. Drying conditions through the weekend, warmer through Saturday. Current radar and infrared satellite imagery shows light returns along the Washington Cascade crest with dry conditions and mostly clear skies elsewhere across the region. This is in response to a weak shortwave and associated cold front clipping northern Washington. High pressure, centered over the Desert Southwest, will continue to strengthen and infiltrate into the Interior Northwest, leading to drying conditions over the Washington Cascades through the morning as the shortwave also departs to our northeast. The weak cold front associated with the exiting shortwave will pass through from northwest to southeast and allow a pressure gradient to develop over the Kittitas Valley. This will keep winds elevated through the day today as sustained northwest winds of 15-20 mph and gusts of up to 25 mph are expected to peak during the late morning and early afternoon. Transient ridging will occur late Friday into Saturday as winds dissipate, skies stay mostly clear, and conditions stay dry. However, another upper level shortwave will approach the Washington coast Saturday afternoon to allow for increased cloud cover overnight and breezy conditions to return across the Kittitas Valley, Gorge, and portions of the Basin. The GFS, NAM, and SREF all suggest a pressure gradient of 6-9 mb setting up between Everett (KPAE) and Pasco (KPSC) after 5 PM Saturday and extending into Sunday afternoon. These values relate to sustained northwest winds of 25-30 mph and gusts of up to 40 mph over the Kittitas Valley. Sustained west winds through the Gorge and portions of the Blue Mountain foothills are expected to reach between 20-25 mph with gusts of up to 35 mph. There is high confidence (80-90%) in these elevated winds, as the NBM advertises a 75-95% chance of sustained winds of 25 mph or greater over the Kittitas Valley, a 65-85% chance through the Gorge, and a 45-65% chance along the Blue Mountain foothills. The NBM also suggest a 55-85% chance of gusts reaching 40 mph or greater across the Kittitas Valley, a 35-55% chance through the Gorge, and a 20-40% chance along the Blue Mountain foothills. Chances stay low (25%) in winds reaching advisory criteria as the NBM showcases a 20-30% chance of sustained winds of 30 mph or greater and gusts of 45 mph or greater over the Kittitas Valley and Gorge, dropping to a 10% chance through the Blue Mountain foothills. Zonal flow aloft from the west today will attribute to continued warming and drying as high temperatures bump up 3 to 7 degrees from Thursday as highs break into the low 80s across lower elevations of the Basin. Temperatures will increase another 1 to 3 degrees on Saturday before a significant drop of 7 to 10 degrees is expected on Sunday associated with the passing shortwave. Conditions will continue to dry through the weekend with Sunday afternoons humidities dropping into the low 20s to mid-teens across Central Oregon and the John-Day Basin. Luckily, these dry humidities are not expected to coincide with breezy winds over our Gorge and eastern slopes of the Cascade zones. Thus, there are currently no fire weather concerns during this timeframe. 75 LONG TERM...Monday through Friday... Through Wednesday, the PacNW will enter a quiet weather pattern as the upper builds over. Light winds will be less than 12 mph Monday (>70% confidence). Slight chance of showers (15-30%) could occur Tuesday through Wednesday morning at the crest of WA Cascades due to the orographic lifting from the cold front off British Columbia area. Models are in good agreement with the arrival of the front. Breezy conditions will develop up to 25 mph Tuesday into Wednesday morning at the Kittitas and Yakima Valley, eastern CR Gorge and Simcoe Highlands (50-80% probability). The PacNW will then enter another ridge Thursday with light winds remaining throughout the day. Friday, the upper trough moves inland of the PacNW with the associated cold front. This could increase chances for precip due to the orographic lifting, but chances are low (<30%). Friday afternoon into evening, breezy winds will also return at 15-25 mph at the Cascade Gaps including central OR (50-70% probability). Though, models begin to differ where the GFS show the trough over the region with the cold front sooner than ECWMF with Canadian favoring dry conditions. Given the timing differences and uncertainties, showers could happen depending on how this trough behaves (<30% confidence). Feaster/97 AVIATION...12Z TAFS...VFR conditions prevail through the TAF period. Mid to high (FEW-BKN at 120-250) clouds will continue for the next 24 hours. Winds will be less then 12 kts for all sites. Feaster/97 && .PRELIMINARY POINT TEMPS/POPS... PDT 77 47 78 48 / 0 0 0 0 ALW 79 51 80 53 / 0 0 0 0 PSC 79 51 80 52 / 0 0 0 0 YKM 77 47 79 44 / 0 0 0 0 HRI 80 50 80 51 / 0 0 0 0 ELN 73 45 77 46 / 0 0 0 10 RDM 78 43 82 42 / 0 0 0 0 LGD 80 48 88 48 / 0 0 0 0 GCD 83 51 90 45 / 0 0 0 0 DLS 79 51 82 52 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...75 LONG TERM....97 AVIATION...97