textproduct: Pendleton

KEY MESSAGES

1. Dry and warm conditions will persist through Thursday *Heat Advisory Issued*

2. Elevated Fire Weather concerns return Wednesday and Thursday

3. Pattern shift Thursday will bring cooler temperatures and mountain rain

DISCUSSION

Current satellite show mostly clear skies across the region today. Northwest flow has ushered in some slightly cooler air for today allowing for temperatures to be a bit cooler than past days. NBM has temperatures in the mid to upper 80s across much of the region with a few isolated locations in the Basin hitting 90 degrees with 70-90% NBM raw ensembles probabilities for the Basin, foothills and Gorge and 60-80% for central and north central OR.

After today, models show the axis of the ridge to begin to move over the region bringing back the increased temperatures. NBM shows temperatures Monday to be 5 degrees warmer than Sunday with temperatures returning to the 90s in the Basin and upper 80s along the foothills and central OR with 80-90% probabilities. OVernight lows into Tuesday will also be elevated with areas in the gorge seeing lows in the upper 50s to low 60s with raw ensembles showing agreement of 80-90%. With no real overnight relief from the heat an Heat Advisory has been issued for the Gorge as daytime temperatures coupled with no recoveries overnight has the area reaching a major HeatRisk of 3 of 4. The Basin, foothills of the Blues and central OR are all HeatRisk of 2 of 4 while the remaining areas are 1 of 4. HeatRisk of 2 of 4 will remain for the aforementioned areas through Wednesday.

With the continued dry and warm conditions over the past few weeks, the RHs have remained critical with little to very little overnight recoveries. With that said, the incoming system Wednesday and Thursday will cause elevated fire weather concerns due to critical RHs and winds. As of now the NBM shows RHs across some isolated pockets of RFW criteria Wednesday with RHs in the low to mid teens and sustained winds of 10-20 mph. Thursday however, NBM in-house calculations show there to be widespread RFW criteria overlap through the Kittitas/Yakima Valleys, the Columbia River Basin of OR and WA with some isolated pockets in north central OR as well. With RHs at 15% and winds at 20 mph, calculations using the two points of information, NBM WSUP Viewer is already showing 30-50% probabilities of areas reaching this criteria with some packets already showing 60-70%. Will continue to monitor as the day comes closer.

Thursday morning, models show an upper level system moving into the region from the northwest. Clusters show some variance between the models with mostly amplitude and timing. Regardless, models show the system to bring with it mountain rain and cooler temperatures. Rain amounts will be low with only 25-30% of the NBM raw ensembles showing 0.01 inches of rain Thursday before becoming widespread and only 15-20% of the raw ensembles showing 0.01 inches across the region Friday. Thursday NBM raw ensembles show 80-90% probabilities of temperatures above 80 degrees decreasing to 60-80% probabilities of temperatures above 70 degrees Friday.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

VFR conditions to prevail through the period. Winds at site DLS will gust to around 20kts through the afternoon. Otherwise, winds will be light with diurnal wind shifts through the period. Lawhorn/82

FIRE WEATHER

Continued dry and warm conditions will affect the region. Wednesday winds will begin to increase just enough for some pockets of critical fire weather. Thursday is the primary day of concerns as winds are expected to be sustained winds of 15-25 with RHs in the low to mid teens. In-house calculations show 30-50% probabilities over the vast majority of zones WA690 Kittitas/Yakima Valleys), WA691 and OR691 (Columbia Basin of WA & OR) meeting criteria. Will continue to monitor as the day come closer but can say with 50-70% confidence Wednesday and Thursday will be elevated fire days.

Preliminary Point Temps/PoPs

PDT 52 88 53 91 / 0 0 0 0 ALW 58 89 58 92 / 0 0 0 0 PSC 57 92 56 94 / 0 0 0 0 YKM 57 91 59 93 / 0 0 0 0 HRI 55 91 55 93 / 0 0 0 0 ELN 54 87 56 89 / 0 0 0 0 RDM 46 88 50 90 / 0 0 0 0 LGD 48 85 50 89 / 0 0 0 0 GCD 46 89 48 93 / 0 0 0 0 DLS 59 93 62 96 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Heat Advisory from 11 AM Monday to 11 PM PDT Tuesday for WAZ024. OR...Heat Advisory from 11 AM Monday to 11 PM PDT Tuesday for ORZ041.