textproduct: Pendleton

DISCUSSION....DISCUSSION

Mountain snow showers continue through the Washington Cascades with a Winter Storm Warning still in effect through midnight tonight. Prepare for some winter weather driving going through the Washington passes as snow/wintry mix will continue over the next few hours. Elsewhere, dry conditions prevail with light and locally breezy winds across the region. Our next round of unsettled weather comes through tomorrow as a low pressure pushes from the Gulf of Alaska, bringing southwest flow aloft into the region. Snow levels will increase near Central Oregon and the Blue Mountains to 4500 to 5500 feet going through tomorrow morning, with the Washington Cascades and Kittitas Valley nearing 2500 to 3500 feet (>80% chance). Snow rates will increase across the mountain regions Sunday morning through the rest of the day with the OR and WA Cascades nearing 2 to 5 inches an hour by the mid to late morning hours. Will more than likely consider Winter Weather Advisory tonight with 24-hour accumulations for both regions falling between 4 and 8 inches. In the lower valleys, we'll continue to see periods of light rain showers over the next few days, becoming more light to moderate heading into the midweek with 3-hour QPF amounts between a tenth and a quarter of an inch (60-80% chance).

Going through Christmas Eve and Christmas Day, we'll see what will be the best chances of snow flurries for parts of Central OR and parts of the Foothills of the Blues with prob chances of seeing measurable snow (>0.1 inches) go up to 5 to 15 percent (higher end probabilities are in Central Oregon area). Although chances and confidence remain low for snow Wednesday and Thursday, winter weather conditions persist if traveling through mountain passes as light to moderate snow continues. A dryer pattern is currently forecasted to emerge by next week with zonal flow transitioning into a weak ridge will give the lower Columbia Basin a break with clearer conditions. Temps remain somewhat stable through the week with highs in the low to mid 40s in most populated areas with lows dropping below or near freezing overnight.

AVIATION...00Z TAFs

VFR conditions are expected through the first half of the TAF period. After 08Z for BDN/RDM there is a 30% probability that these two sites will see CIGs and VSBY decrease to MVFR due to RASN. However, temperatures will play a roll in whether the precipitation falls as rain or snow or a combination of the two, therefor we cannot rule out the possibility of BDN/RDM seeing sub- MVFR. All other sites except PDT have a 30% probability of MVFR after 13Z due to CIGs and VSBY as low as 2500ft and 4SM due to RA and BR. PDT/ALW have a 30% prob of seeing sub-MVFR after 17Z dues to -RA BR. Winds will mainly be 10 kts or less. However, there could be some gusts to around 20 kts through the morning before they decrease to 10 kts or less. 90

PRELIMINARY POINT TEMPS/POPS

PDT 32 43 33 50 / 10 60 70 10 ALW 35 44 36 51 / 10 60 80 20 PSC 33 43 32 48 / 0 40 50 0 YKM 28 40 26 43 / 0 20 40 10 HRI 32 42 32 49 / 10 50 60 0 ELN 24 35 23 37 / 20 30 60 20 RDM 27 45 27 47 / 50 80 60 0 LGD 27 41 32 43 / 30 90 90 30 GCD 30 46 30 45 / 60 100 70 20 DLS 35 42 35 46 / 10 50 90 30

PDT WATCHES/WARNINGS/ADVISORIES

OR...None. WA...Winter Storm Warning until midnight PST tonight for WAZ522.