textproduct: Pendleton

KEY MESSAGES

- Chances of isolated to scattered thunderstorms tomorrow through midweek. Some dynamics a bit uncertain with models struggling with the offshore low.

- Climatologically normal dryness through the region with light to slightly elevated winds through the week.

DISCUSSION

Satellite shows a trail of mid to upper level clouds over the Eastern Mountains with light returns on radar. Conditions will continue to clear out overnight with the absence of a lifting mechanism to streamline precipitation through the early morning hours. Through the next few days, guidance is having trouble (namely the ECMWF vs GFS vs GEPS ensemble members) how the low pressure system will behave through its life-cycle, giving less confidence with the forecast this week. The European model solutions like to be more aggressive with pushing the low pressure system on-shore, bringing wetter and cooler conditions. The GFS, on the other hand, brings the opposite solution of keeping the low mostly off-shore and not allow the forcing mechanism to initiate more widespread rain showers and isolated thunderstorms.

Looking at LREF clusters, 64% of the members (which are notably skewed towards the European model) bring the low pressure system closer to shore by Tuesday through Wednesday afternoon, initiating slight chances (10-30%) of thunderstorms across Central Oregon and the Southern Blues. Fire weather concerns can manifest with the potential of some dry thunderstorms developing. Current PWAT values in the thunderstorm development region hover between 0.8-1.4 inches, developing mostly wetter thunderstorms (40-70% confidence) with isolated areas of dry storms possible. Model guidance completely diverges by late Thursday afternoon with only 41% of clusters already bringing the low on-shore, bringing a cooler and wetter pattern while the remaining keep the system off- shore.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

VFR conditions are forecast at all sites for the next 24 hours. There is low confidence (30% or less) in smoke from area wildfires affecting CIGs/VSBYs at BDN/RDM such that sub-VFR conditions are observed.

Winds will be predominantly diurnally/terrain-driven, gusty during the afternoon and evening hours today, especially at DLS/RDM/BDN.

An area of high-based showers may develop overnight into Tuesday across eastern Oregon and south-central to southeast Washington, but confidence is low (10% or less) in any showers producing measurable precipitation at TAF sites, so left mention out of the 00Z TAFs. There is a slight chance (20%) of isolated showers and thunderstorms developing between 21Z Tue and 00Z Wed in the vicinity of BDN/RDM.

Preliminary Point Temps/PoPs

PDT 62 93 62 94 / 0 0 10 10 ALW 66 95 66 96 / 0 0 10 10 PSC 62 97 63 98 / 0 0 0 10 YKM 62 98 64 97 / 0 0 0 10 HRI 64 97 66 97 / 0 0 10 10 ELN 59 95 62 93 / 0 0 0 10 RDM 56 92 57 90 / 0 0 40 20 LGD 63 91 61 93 / 0 20 20 10 GCD 61 92 59 92 / 0 20 40 10 DLS 63 97 66 96 / 0 0 10 10

PDT WATCHES/WARNINGS/ADVISORIES

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