textproduct: Pendleton

KEY MESSAGES

- Moderate to Major HeatRisk This Afternoon and Evening

- Windy Tuesday

- Critical Fire Weather conditions Tuesday Afternoon and Evening

DISCUSSION

Mid level ridging is beginning to break down into what will be a more zonal pattern heading into the overnight and Tuesday, transitioning to NW flow by Wednesday morning across the Interior NW. That will allow an increase in the gap winds staring Tonight and result in breezy to windy conditions over the entire forecast area on Tuesday. Based on probabilities for wind gusts in excess of 40 mph, the Kittitas valley has about a 90% chance for exceedance of 40 mph lending to high confidence to high end advisory criteria, and perhaps pushing the limits of high wind criteria (40 mph sustained winds and/or 58 mph gusts). We will hedge on a wind advisory over high wind here as the NBM members area at around 34% for late afternoon sustained winds at 34 kts (39 mph) peaking in the late afternoon.

Heat risk is at its highest This Afternoon and will wane after Today as the thermal trough breaks eastward and the temperatures are unable to warm up as much on Tuesday due to mixing of the boundary layer. Still elevated or Level 2 HeatRisk will create conditions that affect those more at risk to heat illnesses and do not have access to cooling or hydration. A couple of cooler days on Wednesday and Thursday dipping into a widespread level 1 HeatRisk will be followed by warming temps again Friday, however not as intense as Today.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

VFR conditions currently across all sites, which will stay the course through the period. Winds will stay light and below 10kts for all sites over the majority of the day, with DLS becoming 10-15kts late this afternoon. Cloud cover increases with a 25kft ceiling late in the period as the system approaches. Winds will also increase for most sites early Tuesday morning, with gusts between 20-30kts expected. 75

FIRE WEATHER

The Fire Weather Watches have been upgraded to Red Flag Warnings for the Fire Zones WA691/OR691 valid Tuesday 10 AM through 11 PM. Combined probabilities for low RH and wind of 25% and 30 mph gusts are in the 80 to 90th percentile, resulting in high confidence in the risk for rapid fire spreading of any starts Tuesday afternoon and evening.

Preliminary Point Temps/PoPs

PDT 62 88 51 84 / 0 0 0 0 ALW 66 90 55 84 / 0 0 0 0 PSC 64 94 55 88 / 0 0 0 0 YKM 62 90 54 89 / 0 0 0 0 HRI 67 90 55 87 / 0 0 0 0 ELN 62 81 52 82 / 0 0 0 0 RDM 54 89 47 87 / 0 0 0 0 LGD 55 88 49 81 / 0 0 0 0 GCD 53 91 48 85 / 0 0 0 0 DLS 69 86 57 85 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Heat Advisory until 10 PM PDT this evening for WAZ024-026-027. Red Flag Warning from 10 AM to 11 PM PDT Tuesday for WAZ691. Wind Advisory from 10 AM to 11 PM PDT Tuesday for WAZ024-026- 521. OR...Heat Advisory until 10 PM PDT this evening for ORZ041-511. Red Flag Warning from 10 AM to 11 PM PDT Tuesday for ORZ691.