textproduct: Pendleton

KEY MESSAGES

- Return of showers and isolated thunderstorms to the eastern mountains Today

- Breezy to gusty winds developing across the area Tonight into Friday morning, with strongest winds through the Cascade gaps

- Moderate-high confidence (65-80%) in freezing morning temperatures across lower elevation area Saturday

DISCUSSION

An upper trough and a cold front will move across the region later Today and Tonight, with limited weather impacts from winds, rains and convection. A limited convective threat today as CAPEs over the eastern mountains broadly 100-200 J/kg and higher elevated 400 J/kg pose an isolated lightning risk. Initially, the REFs is trending toward an initial warm advection induced swath of showers supported by the REFS mean lighting fields of 0.02-0.05 flashes/ sq KM/5 mins. This feature is focused across the John Day Basin at 8 am, and advecting across Pendleton/Walla Walla toward the Tri-Cities between about 9 and 11 am. The time window for best rain accumulations is between about 3 and 12z Friday (8 pm This evening - 5 am Tomorrow) when 3 hour probability matched means show areas in excess of a quarter inch every 3 hours across the Foothills Blues Mountains eastward into Wallowa county. The HREF 24 hr PMMs are at about 0.75 to 1 inch QPF across these areas and at least widespread wetting rain over the entirely of the eastern mountains.

A wind advisory remains in effect across the Kittitas and Eastern Columbia river Gorge zones for increasing wind This Evening through much of the overnight as the post frontal pressure isallobaric pressure rises cause channeling effects leading to NBMs probabilities for gusts in excess of 40 mph averaging 50 to 80 percent, particularly around The Dalles and Ellensburg.

Lastly, cold temperatures will return on the backside of this exiting weather system Friday night into Saturday morning, bringing potential for growing season ending sub freezing temperatures across the lower elevations of the Kittitas/Yakima valley, Blue Mt foothills and the Columbia Basin.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

VFR conditions expected through the period. A system passing to the south will bring rain shower impacts to sites RDM/BDN through 00Z, PSC through 02Z, and sites PDT/ALW through 08-09Z tonight. BKN-OVC CIGS are expected to lower after sunset at sites PDT/ALW this evening, but should remain AOA 4kft AGL. A cold front passage will bring breezy conditions to sites DLS/PDT/RDM/BDN/YKM. At site DLS, winds will increase to 15-25kts with gusts up to 40kts after 22Z. Sites RDM/BDN will see winds increase to 12-15kts with gusts to around 20kts between 00Z-13Z. Site YKM winds will increase to 12-15kts with gusts to around 23kts between 03Z-15Z. Short-term model guidance is indicating low level wind shear impacts up to 2kft AGL between 03Z-15Z tonight at site YKM, but confidence is low-moderate(30-40%) in persistent wind shear impacts over the site. Lawhorn/82

Preliminary Point Temps/PoPs

PDT 58 36 56 27 / 80 70 0 0 ALW 59 40 57 32 / 80 80 0 0 PSC 62 38 64 29 / 70 50 0 0 YKM 67 39 64 31 / 0 0 0 0 HRI 59 39 61 30 / 70 50 0 0 ELN 66 33 57 26 / 0 0 0 0 RDM 60 25 51 19 / 60 10 0 0 LGD 66 37 53 25 / 70 100 20 0 GCD 65 36 53 25 / 80 90 20 0 DLS 69 43 62 34 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory from 7 PM this evening to 11 AM PDT Friday for WAZ024-026. OR...Wind Advisory from 7 PM this evening to 11 AM PDT Friday for ORZ041.