textproduct: Pendleton

KEY MESSAGES

1. Dry and cooler temperatures over the weekend

2. Pattern shift at the beginning of the week will bring seasonal temperatures

3. Chances of precipitation and Thunderstorms Wednesday and Thursday

DISCUSSION

Current nighttime satellite is showing mostly cloudy skies over the region. this will keep overnight temperatures a bit warmer than previous nights. NBM shows overnight lows to be in the low to mid 30s along the foothills, through the Basin ans adjacent valleys, the Gorge and central OR with a few isolated locations seeing low 40s. The cold prone areas around Three Rivers and Seneca will see temperatures remain below freezing.

Hi-Res models show a weak southwest flow has settled over the region as the upper level ridge moved east and the upper level low moves down the coast and is by B.C. currently. This flow regime will keep the region under dry conditions with near normal to slightly above normal temperatures. In house calculations show temperatures to be 2- 6 degrees above seasonal normal in some locations along the foothills of the Blues, the Basin and the Gorge. NBM shows temperatures to be in the low to mid 60s for much of the region with a few areas along the eastern mountains and John Day Basin seeing low 70s through Wednesday.

By Monday models show the upper level low to be shifting south off the coast of Oregon and bringing a sharper southwest flow over the region. Models are in firm agreement that a closed low will form and traverse towards the coast of California and stretch as far north as Oregon. Clusters differ slightly in the amplitude of the low, but are in agreement with it shifting south and undercutting the region by Tuesday and Wednesday. The variance in the amplitude will determine the amount of rainfall expected as models show the potential for wrap around moisture making its way into the region from the east. NBM raw ensembles show a a low chance (20%) of precipitation reaching the eastern portion of the CWA by Wednesday night. Highest chances of rain will be Thursday as models show more moisture influx available. Many of the raw ensembles show the timing of the precipitation to be after 5 AM Thursday with 40-50% probabilities of wetting rain (0.1-0.2 inches).

Not only will the leading edge of the upper level low bring precipitation, but warm air advection will bring some instability to the region as well as early as Wednesday night. NBM shows there to be a 15% chance of thunders along the eastern mountains and 15-20% chances of afternoon thunderstorms Thursday.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

VFR conditions will persist through the forecast period. Winds will be generally diurnally/terrain driven and below 10 kts. CIGs will be primarily 18kft and above.

Preliminary Point Temps/PoPs

PDT 62 36 63 37 / 0 0 0 0 ALW 63 39 63 41 / 0 0 0 0 PSC 65 35 68 34 / 0 0 0 0 YKM 63 39 69 38 / 0 0 0 0 HRI 63 35 65 33 / 0 0 0 0 ELN 60 33 65 36 / 0 0 0 0 RDM 59 28 60 25 / 10 10 0 0 LGD 69 36 68 37 / 0 0 0 0 GCD 71 37 71 38 / 0 0 0 0 DLS 66 42 70 41 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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