textproduct: Pendleton

DISCUSSION

Current satellite shows no returns over the region with nighttime satellite showing mostly high clouds in the area that are quickly moving southward. Northwest flow aloft is advecting cooler air into the region tonight which will bring overnight temperatures into the teens to low 20s in most areas with only the Basin, foothills and the Gorge seeing temperatures in the upper 20s.

Models show the weak shortwave that came through last night to be mostly out of the region leaving northwest flow aloft. As stated above, this will bring below average temperatures to the region overnight and through tomorrow. By Sunday morning, the leading edge of the upper level ridge will begin moving over the region. Models are in form agreement and show the high pressure will dominate the region through the mid-week with steadily increasing temperatures. However, climate shows that the Basin and foothills will remain slightly below normal seasonal temperatures while elsewhere will see slightly above average. 100% of all raw ensembles show that all locations will be below 40 degrees Sunday, everywhere except central OR on Monday while steadily increasing to the eastern mountains Tuesday and Wednesday. Temperatures will be steady in the upper 30s to low 40s for most locations through Wednesday with 40-60% of the ensembles having central OR in the upper 40s to low 50s by Wednesday.

Pattern recognition couple with the cold pooling from the northwest flow aloft, points to the typical winter set up for fog to form. While HREF and other guidance suggests low potential for fog Sunday (10-30% chances) we can not rule out the potential for fog to form in the prone areas through the week and with cooler temperatures, chances of freezing fog is likely. However, timing on if and when fog will develop is low/moderate at best (30-50% confidence)

By Thursday models show an upper level low sweeping southward of the region and breaking down the ridge. Southwesterly flow aloft will bring in warm air advection and moisture back to the region. Models show that temperatures will steadily increase Thursday through the weekend bring the area back into 5-10 degrees above seasonal average. Raw ensembles show the vast majority of the region to begin seeing temperature in the upper 30s to low 40s by the weekend. 90

PRELIMINARY POINT TEMPS/POPS

PDT 37 24 36 22 / 10 0 0 0 ALW 36 26 35 25 / 0 0 0 0 PSC 37 23 36 22 / 0 0 0 0 YKM 36 23 36 21 / 0 0 0 0 HRI 37 24 35 22 / 0 0 0 0 ELN 31 21 32 21 / 0 10 0 0 RDM 40 21 43 20 / 0 0 0 0 LGD 36 23 39 26 / 0 0 0 0 GCD 38 23 43 25 / 0 0 0 0 DLS 41 29 38 27 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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