Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
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084 FXUS66 KPDT 010941 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 241 AM PDT Mon Jul 1 2024 .SHORT TERM...Today through Wednesday...Nighttime and water vapor satellite imagery show a shortwave trough dropping into the PacNW tonight, though radar returns show little to no shower activity. The shortwave passing over the region today will bring slight chances (15-20%) of isolated showers to the WA Cascade crest and the Wallowa mountains. An tightened cross Cascade pressure gradient will be reinforced by the shortwave passage this afternoon, with winds of 20-30mph and gusts generally up to 40mph in the Cascade gaps and portions of the OR Columbia Basin, with 15-20mph winds and gusts between 25-30mph elsewhere in the lower elevations. While there is a lack of jet support between 700mb-850mb, NBM probabilities of peak wind gusts meeting or exceeding 45mph are between 50-80% in the aforementioned areas, suggesting gusts will mostly be localized and infrequent with low confidence (20%) in widespread and frequent gusts exceeding 45mph. Fire weather concerns will remain elevated today with the breezy winds, but a marine layer up to 850mb is expected to spill through the Cascade gaps, keeping RHs above critical red flag thresholds (confidence 75-85%). Tuesday through Wednesday, upper level ridging will be amplifying across the eastern Pacific with persistent northwest flow aloft. While conditions will mostly be quiet during this period, an inverted thermal trough extending into southeastern OR Tuesday will promote another afternoon/evening of a strengthening cross Cascade pressure gradient. Winds 20-30mph and gusts up to 40mph through the Cascade gaps into far western portions of the OR Columbia Basin (confidence 70-80%). Wednesday, while breezy winds will develop through the Cascade gaps once again, sustained winds will generally be between 15-25mph and gusts up to 35mph (confidence 60-70%). While fire weather concerns will remain elevated through Wednesday, the aforementioned marine layer west of the Cascades will linger through Wednesday evening and continue to support marine pushes through the Cascade gaps each day, precluding the need of any fire weather headlines (confidence 60-70%). Lawhorn/82 .LONG TERM...Thursday through Monday...The extended period is characterized by an upper-level ridge across the region with above normal temperatures and breezy winds. Starting Friday, temperatures will be in the low 100s around the Columbia Basin and 90s across the rest of the forecast area. Confidence increases with EFI values greater than 0.90 showing an extreme event. Through Sunday, the heat could be problematic with the HeatRisk product showing moderate categories over most of the forecast area with a few small patches of major categories in some portions of the Columbia Basin. That said, heat advisory may be considered for Friday through the weekend. Models and ensembles are in great agreement with this week`s pattern, despite having 20% or less total members favoring a trough for Friday through Saturday and zonal for the rest of this period. Through Monday, breezy conditions will occur with occasional wind gusts between 15-25 mph around the Cascade Gaps and Lower Columbia Basin. However, the combination of increased northwesterly winds and low relative humidity in the teens to lower 20s could raise concerns for areas of elevated fire weather potential. And for 4th of July, winds will be light but critically low relative humidity will develop later in the afternoon. Feaster/97 && .AVIATION...Previous Discussion...06Z TAFs...VFR conditions will prevail through the period. Breezy conditions will remain the primary focus with winds gusting to near 20 to 25+ kts with the exception of PSC which will remain below 10 kts. CIGs are mostly high giving way to clear skies. Bennese/90 && .PRELIMINARY POINT TEMPS/POPS... PDT 83 54 82 51 / 0 0 0 0 ALW 86 57 85 55 / 0 0 0 0 PSC 89 59 88 56 / 0 0 0 0 YKM 85 53 86 53 / 0 0 0 0 HRI 88 57 87 55 / 0 0 0 0 ELN 78 53 78 53 / 0 0 0 0 RDM 80 46 81 44 / 0 0 0 0 LGD 78 49 79 47 / 0 0 0 0 GCD 80 47 82 46 / 0 0 0 0 DLS 83 56 80 55 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...82 LONG TERM....97 AVIATION...90