textproduct: Pendleton

DISCUSSION

Current satellite and radar imagery show the frontal system moving across our forecast area with increased cloud coverage. With the help of this system, fog has been lifted for the Foothills-Northern Blue Mountains of OR and portions of Kittitas Valley (Ryegrass Summit and Manastash Ridge). Fog will be less likely (<20%) to return through overnight hours for most locations, but could last through overnight for the upper parts of the WA Cascades.

Precip activity will continue through Monday with today's ridge breakdown and Sunday's shortwave. StormTotalQPF amounts will exceed to 0.60 inches for the lower elevation and 1 inch or more for the mountain areas. The NBM Probability of 24 hr Precipitation suggested a 20-40% prob of 0.60 inch or more, but 50-70% prob for 1 inch or more for OR Cascades and Northwest Blue Mountains. The WA Cascades may see precip of 0.70 inch (20-40% prob), but chances then decreases past that. With Naches River elevated to Action Stage, this could also potentially raise other river levels.

Light mountain snow might accumulate up to 1 inch or more over the WA/OR Cascades and southern parts of Wallowa County Sunday through early Monday morning (30-70% prob). Snow levels will drop from 5 kft Sunday to 2.9-3.7 kft Monday. Portions of the eastern mountains (Grande Ronde Valley, Southern Blue Mountains- OR, and John Day Highlands) and Northwest Blues will remain seeing less than 0.5 inch. In addition to the frontal system, breezy to windy winds (Gusts of 20-30 mph) will develop late Sunday morning into early Monday morning across Deschutes County through eastern OR mountains (50% confidence). NBM suggest a 20-40% prob for gust exceeding 25 mph.

With the trough arriving to the PacNW, dry conditions will return for most of our forecast area Tuesday through Thursday. However, a plume of moisture may develop Tuesday overnight through early Thursday morning for the Deschutes County and eastern OR mountains. This could bring light rain, but confidence is low for right now (<30%). Feaster/97

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Rain chances ramp up to above 90% across the BDN and RDM areas before 12z while rain chances increase to 80% at most of the other terminals through early afternoon Sunday. As for local impacts, the ceilings will be reduces, but the guidance does not point to LIFR or worse conditions. Model ensemble probabilistic stats suggest capping the chances for sub 1,000 ft ceilings to at 50% and chances for sub 500 ft cigs are even lower. The DLS terminal might be the outlier with about a 40 to 50 % chance for ceilings below 500ft. Likewise YKM might will be improving over the course of the night. Russell/71

Preliminary Point Temps/PoPs

PDT 42 52 36 49 / 70 90 80 20 ALW 45 51 38 49 / 80 90 90 40 PSC 41 49 36 55 / 60 90 60 10 YKM 37 46 31 49 / 50 70 30 0 HRI 42 50 37 53 / 60 90 70 20 ELN 34 41 30 44 / 60 60 40 10 RDM 38 49 27 47 / 60 90 40 0 LGD 41 48 35 45 / 80 100 90 50 GCD 42 50 33 44 / 60 90 80 20 DLS 43 49 38 52 / 90 90 60 20

PDT WATCHES/WARNINGS/ADVISORIES

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