textproduct: Pendleton

KEY MESSAGES

- Fire Weather Watches for WA690, WA691, and OR691 for the Columbia Basin & Yakima/Kittitas Valley region Thursday for wind and low RH.

- Hot, dry conditions with breezy winds through Thursday, with stronger locally windy conditions developing Thursday.

- Cooler, wetter pattern forecasted to develop Friday and into the weekend.

DISCUSSION

Current satellite shows dry and mostly clear conditions prevailing through the overnight thanks to weak over-head ridging. The ridge pattern will end by Wednesday (>90% chance) and introduce a more zonal flow aloft, allowing for some isolated thunderstorms to develop across the Washington Cascade crest (10-20% chance). Dry air will stay in place through much of Thursday with breezy winds developing during the day, with stronger locally windy conditions developing Thursday. Confidence is currently medium (40-60% chance) that Red Flag Warning conditions will develop across the Columbia Basin and Yakima/Kittitas region Thursday, thus a Fire Weather Watch has been issued for WA690, WA691, and OR691.

Friday will see a more cooler, wetter pattern develop Friday and through the weekend, as an area of broad troughing dips down from the coast of Alaska and British Colombia and eventually through the Pacific Northwest (70-90% chance). Guidance is in good agreement that the pattern will turn cooler and wetter by Friday (70-90% chance) bringing a relief to the heat and dry air. While the attention is currently on winds and low RH for fire weather, we will have to pay close attention for fire weather from abundant lightning. As the shortwave/trough slides to the east, NBM guidance advertises 15-25% chances of thunder developing across Central Oregon through the Blue Mountain/Eastern Mountain region. Current NBM guidance shows some storms producing 0.05" inches through 0.15" in a six-hour period, while some are forecasting less for dry thunderstorms. Exact timing/amplitude of the system is a bit unknown and could change the outcome of the QPF amounts. Will keep monitoring if RFW will be needed for any impacted fire weather zones.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

VFR conditions prevail through the period with no CIG or VIS issues expected. Main concern will be breezy 20-30 knot gusts developing in the late morning into the afternoon hours for DLS, BDN, and RDM. Winds will be elevated through much of the afternoon, with winds weakening to 10-20 knot gusts by the very late afternoon into the early evening.

Preliminary Point Temps/PoPs

PDT 92 60 85 53 / 0 0 0 30 ALW 93 64 87 58 / 0 0 0 20 PSC 96 62 90 56 / 0 0 0 20 YKM 95 61 88 56 / 10 10 0 30 HRI 95 63 88 55 / 0 0 0 20 ELN 91 60 82 51 / 20 10 0 30 RDM 88 49 82 47 / 0 10 0 40 LGD 89 56 85 53 / 0 0 0 40 GCD 91 53 86 50 / 0 0 0 50 DLS 95 63 83 58 / 0 0 0 50

PDT WATCHES/WARNINGS/ADVISORIES

WA...Fire Weather Watch from Thursday afternoon through Thursday evening for WAZ690-691. OR...Fire Weather Watch from Thursday afternoon through Thursday evening for ORZ691.