textproduct: Pendleton

KEY MESSAGES

1. Dry and warmer conditions through Sunday

2. A trough will bring increased chances of precipitation Monday through midweek

DISCUSSION

Current satellite shows mostly clear skies across the region. Temperatures today will remain 5-10 degrees below seasonal normal according to in house comparison. West to north-west flow aloft is what is keeping temperatures on the cooler side. NBM shows temperatures today to be in the low to mid 50s across much of the region with higher terrains seeing highs in the upper 30s to low 40s and NBM raw ensembles show 60-80% agreement.

Deterministic models are in firm agreement with the weak upper level ridge moving over the region beginning late Thursday evening into Friday. Southwest flow aloft will bring in continued dry conditions and increasingly warmer temperatures. In house seasonal temperature comparison shows that temperatures will increase to nearly 15 degrees above seasonal averages for much of the southern and portions of the eastern region. Temperatures in the Basin, adjacent valleys and the foothills will remain at or slightly above normal. 90% of the NBM raw ensembles shows central or and portions of the eastern mountains seeing temperatures in the mid to upper 60s, 60- 80% show the foothills, Gorge, La Grande area and even Wallowa Valley will see temperatures in the upper 50s to low 60s. Elsewhere will see temperatures in the low 50s. Temperatures will remain in the mid to upper 60s through Sunday ahead of the next system (70-90% confidence)

Beginning Sunday models begin to diverge a bit with clusters showing the main deviance between the models being that of the timing of the system. The ECMWF has precipitation coming in as early as Sunday night where the GFS and Canadian models do not have precipitation reaching the Cascades until after 5 AM Monday. Regardless of this deviation, all models do show increased chances of precipitation steadily moving across the region through midweek. 24 hour NBM raw ensembles show probabilities of rain for Sunday are low, below 40% probabilities of 0.01 in the Cascades. As we shift to Monday however, 24 hour ensembles show probabilities of 60-70% for up to 0.01-0.05 inches of rain for the Cascades and 40-60% for the Northern Blue Mountains. Tuesday and Wednesday ensembles show 30-50% probabilities of the lower elevations of the Basin, adjacent valley and the foothills seeing 0.01-0.05 inches of rain.

Snow levels will steadily come down as the trough makes its way across the region. Monday snow levels are above 2500 feet and NBM ensembles show 50-60% probabilities of snow accumulating between 0.5- 1 inch for the WA Cascades and these amounts with be above 3500 feet for the OR Cascades. Tuesday the Cascades will continue seeing very light snowfall while the Northern Blues will see 40% probabilities of 0.05 inches Tuesday and Wednesday and 50-60% for the Cascades. Thursday appears to be the peak as of now with 60-70% probabilities of 2-3 inches for both the Cascades and the Northern Blues. 90

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

VFR conditions currently at all sites, which will stay the course through the period. Surface high pressure will keep skies clear and winds light (below 10kts). 75

Preliminary Point Temps/PoPs

PDT 29 60 36 63 / 0 0 0 0 ALW 33 61 41 62 / 0 0 0 0 PSC 30 63 37 67 / 0 0 0 0 YKM 30 59 36 64 / 0 0 0 0 HRI 29 62 36 66 / 0 0 0 0 ELN 27 55 33 57 / 0 0 0 0 RDM 22 68 31 65 / 0 0 0 0 LGD 27 62 34 65 / 0 0 0 0 GCD 28 66 35 67 / 0 0 0 0 DLS 33 63 39 65 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.