textproduct: Pendleton

DISCUSSION

Current radar and satellite imagery shows light band of precip moving through portions of the Foothills-Northern Blue Mountains of OR extending across the Northern Blues and OR Cascades.

With an incoming shortwave trough, precip activity will continue through this weekend with the help from a weak atmospheric river (100-200 kg m/s). Storm Total QPF amounts from this morning through early Monday morning (09Z Sat to 12Z Mon) for the lower elevations will continue exceeding 0.05 inch or more (>50% probability) with 0.35 inch or higher for the eastern OR mountains (Northwest Blues and portions of Wallowa County) and OR Cascades (50-70% prob). The QPF amounts had slightly trend downward for the Lower slopes of WA Cascades to 0.05-0.10 inch with East Slopes of WA Cascades exceeding 0.20 inch or more (25-40% confidence). Snow accumulations also have trend slightly downward ranging from 1 to 4 inches for the Northwest Blues, East Slopes of WA Cascades, but 6 to 12 inches for the mountain area in Wallowa County today through early Monday morning. Snow levels will be drop at 2.5 kft or below for Yakima/Kittitas Valleys with above 3 kft for the remaining forecast area through this weekend.

Monday through early Thursday morning, heavy snow accumulations will persist across the mountain areas within a 72-hr period (12Z Monday through 12Z Thursday). Snow levels will drop to 2.5-3.5 kft Monday and then further to 1.5-2.5 kft Tuesday through Wednesday. Winter Weather Advisories may be considered with WA/OR Cascades (mainly the East slopes of WA Cascades and crest of OR Cascades) seeing a 3-day Storm Total Snow exceeding 5 inches or more (>50% confidence) and 8 inches or more for the Northwest Blues (20-40% confidence). For now, Monday will be the first day to be monitored for snow concerns. Tuesday as well but being 4+ days out, confidence will remain low (<30%) at this time. Feaster/97

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

VFR to MVFR conditions will initially set, with the exception of YKM that is sitting at IFR/LIFR due to dense fog in the area. Fog will lift going through the morning hours and is expected to briefly lift to VFR through 04Z. Chances of rain generally increase going through the afternoon through early evening hours and will stop at most sites going through the overnight hours. Visibilities in many sites will drop to IFR to near LIFR conditions. Not expecting conditions to improve by 18Z tomorrow for many sites, but will monitor for guidance changes.

Preliminary Point Temps/PoPs

PDT 36 46 34 47 / 80 30 20 70 ALW 37 47 37 48 / 90 50 30 80 PSC 36 49 35 50 / 60 20 10 60 YKM 33 46 32 43 / 30 10 10 50 HRI 36 49 35 48 / 70 20 20 60 ELN 30 41 29 39 / 20 10 10 50 RDM 28 48 29 44 / 40 10 20 50 LGD 36 51 33 47 / 80 50 30 80 GCD 34 51 33 47 / 50 20 20 70 DLS 38 48 38 45 / 70 20 20 70

PDT WATCHES/WARNINGS/ADVISORIES

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