textproduct: Pendleton

KEY MESSAGES

- Light snow and rain showers continue in the mountain regions Tonight. Drying conditions develop Thursday morning through the weekend.

- High running rivers continue

DISCUSSION

The balance of this afternoon will bring the most breezy/windy conditions of the forecast heading through the weekend. As of 2 PM, METARS and other mesonet locations on the lower slopes and areas into the Columbia basin were showing between 30 and 40 mph gusts, however this was not widespread. The gusty winds are in response to a frontal system Late Today and Tonight that will will push the nose of a Pacific surface high pressure across into the Inland Northwest, bringing lowered snow levels and colder morning temperatures to the region. Additional snowfall across the Washington Cascade crest/Eastern Upper Slopes can reach 6-10 inches at the peaks in Kittitas county. However the broader area of the upper slopes below about 4500 ft MSL will only see potential for up to 2 inches of snow at the most; all of which will be melting on contact on roads through the Snoqualmie Pass and the I-90 corridor. Based on the LAMP guidance trend, these wind gusts should trend up a few more knots through the evening as the post cold frontal momentum transfer influences low level mixing after sunset. Breezy conditions behind the front late this evening will wane to 5 to 15 knots range by the overnight hours. Just about the entire forecast area is expected to be around freezing or colder, based on NBM mean forecasts. Frost probabilities are high enough for areas to widespread frost across portions of the Lower Columbia Basin as well as the Kittitas and Yakima Valleys, and Eastern Columbia river Gorge. These are areas to first be eligible for routine frost and freeze headlines as we heading into the middle of April. The next semblance of a fetch of AR moisture is noted in the EC/GFS IVT by late Sunday into Monday. This one appears to be weaker and more of a southern track than the last atmospheric river. In the meantime expect dry conditions area wide Thursday through Saturday with some 50% probabilities for mountain rain/snow showers returning by Sunday. Russell/71

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

VFR conditions are expected through Thursday. Gusty winds continue to liner in a few locations but should decrease overnight, with all sites 10 kts or less by morning. Winds should then be 10 kts or less through the remainder of the period.

FIRE WEATHER

Overall fire weather risk though the week is low. That said drier, warmer conditions Friday and Saturday will lead to low relative humidity across the central Oregon , Eastern Slopes of the Oregon Cascades and into the John Day/Ochoco Highlands each afternoon. Winds may gusts up to around the 20 mph threshold and make the fire risk more elevated for any areas of dry and fire carrying fuels especially Saturday afternoon. Russell/71

HYDROLOGY

Rivers continue to run high through this period however the break in the more persistent rainfall will bring a reprieve to the minor flooding conditions along The Yakima and Naches Rivers. The Naches River at Naches is forecast to fall below flood stage This Evening, however the most recent measured stage was slightly over the latest forecast hydrographs, hence uncertainty in the river timing to fall below minor flood stage extend into late evening. Russell/71

Preliminary Point Temps/PoPs

PDT 30 52 29 59 / 10 0 0 0 ALW 33 52 33 60 / 20 0 0 0 PSC 32 57 29 62 / 10 0 0 0 YKM 28 53 30 58 / 10 0 0 0 HRI 32 56 28 61 / 0 0 0 0 ELN 27 49 27 54 / 20 0 0 0 RDM 20 53 23 67 / 0 0 0 0 LGD 27 49 26 61 / 30 0 0 0 GCD 25 51 28 67 / 10 0 0 0 DLS 34 58 33 62 / 20 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

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