textproduct: Pendleton

KEY MESSAGES

- Below-normal temperatures today, then warming to near or above normal Wednesday and Thursday.

- Low-medium (20-50%) chance of widespread advisory-level winds through the Cascade gaps Thursday, with locally higher (60-85%) chances for wind-prone portions of north-central Oregon and the Kittitas Valley.

- Friday into Monday brings showers and potential convective precipitation.

DISCUSSION

The upper-level low-pressure system that brought cool temperatures and widespread precipitation to the region over the holiday weekend is ejecting eastward over the ID/MT Rockies, with a dry northwesterly flow aloft in its wake. Meanwhile, water vapor imagery reveals an upper-level ridge of high pressure in the northeast Pacific extending into British Columbia. Farther south, the remnants of Marie are tracking northward towards another area of low pressure that is located off the central California coast. Satellite shows mostly clear skies across the forecast area early this afternoon, aside from a fair weather cumulus field that is developing over the Blue Mountains. Temperatures will be a few degrees below normal today, with predominantly light winds.

Looking ahead, ensemble NWP guidance is in excellent agreement that the remnants of Marie will merge with the low off the California coast and retrograde through the week. Heights will rise over the forecast area as the ridge slides east tomorrow, resulting in near- normal or above-normal afternoon high temperatures. The ridge will be suppressed Thursday as a shortwave trough dives south across British Columbia, resulting in strengthening zonal flow aloft.

Westerly winds will increase in strength on Thursday, and may result in wind headlines. The NBM indicates a low-medium (20-50%) chance of advisory-level wind gusts (45 mph or greater) through the Cascade gaps, with locally higher (60-85%) chances for wind-prone portions of north-central Oregon and the Kittitas Valley.

Aside from the winds, anticipating another day of near-normal to above-normal high temperatures Thursday, and a slight chance (15- 25%) chance of showers across the Blue Mountains and their foothills Thursday afternoon into Thursday night.

Leading into Friday shows the trough entering the Pacific NW region traveling east through the region up throughout the weekend, bringing showers and chance for convective precipitation for the Blue Mountain region. Conditions from Friday into Sunday show chance Showers, potential convection and near normal temperatures. While the model clusters, NAM, and GFS are in agreement of when the trough will arrive they are split on the NS position of the trough upon arrival, with the favored position being near the Washington Oregon Border (49.6% confidence). Chances for precipitation greater than a tenth of an inch range from 30% - 62% with a slight chances of thunder at 11%.

Monday the clusters show drier and warmer conditions along with a weak ridge pattern (67% confidence) with low confidence in the trough lingering, potentially deepening, bringing more showers and lower temperatures to Western Oregon (33% confidence).

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

VFR conditions prevail throughout the TAF period with clear and dry conditions. Winds remain light and variable in nature with most sustained winds less than 12 knots throughout the next 24-hours. Otherwise, no CIG or VIS issues expected.

Preliminary Point Temps/PoPs

PDT 47 84 51 83 / 0 0 0 0 ALW 52 84 58 83 / 0 0 0 0 PSC 50 86 54 87 / 0 0 0 0 YKM 53 84 56 83 / 0 0 0 0 HRI 49 86 54 86 / 0 0 0 0 ELN 49 82 55 75 / 0 0 0 0 RDM 41 87 45 83 / 0 0 0 0 LGD 46 84 50 84 / 0 0 0 0 GCD 47 87 51 85 / 0 0 0 0 DLS 56 87 58 82 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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