textproduct: Pendleton

KEY MESSAGES

1. Very low chances of showers and thunderstorms this afternoon and evening

2. Temperatures today and Wednesday will remain above seasonal normal through Wednesday

3. An upper level low approaching the region will bring increased winds Wednesday increasing fire weather concerns.

DISCUSSION

Current satellite shows a cumulus field developing over the Elkhorns and Blues as well as over the Eagle Caps down into the Wallowa Valley. Ground observations are showing no rainfall associated with these cells at this time.

NBM raw ensembles shows a 5-15% chance of thunderstorms and showers over the eastern mountains and Wallowas this afternoon and this evening. Looking at RAP forecast soundings, there is between 500-650 J/kg of MUCAPE, LIs of -2 to -3, lapse rates of 9-10 C/km and bulk shear nearing 15-20 knots. This is enough instability and lift that we cannot rule out the possibility of a shower or thunderstorm forming over the area. Wednesday models and NBM raw ensembles show a bit more instability in the region decreasing the chances of showers and thunderstorms to under 10%.

Models show the ridge of high pressure remaining over the region through Wednesday ahead of the next system. Looking at in house calculations, temperatures are expected to be anywhere from 5 to 10 degrees above seasonal average today, increasing to near 15 degrees today and Wednesday. Looking at HeatRisk probabilities, tomorrow (Wednesday) will be the peak with 70-80% probabilities of areas reaching Moderate HeatRisk (level 2 of 4) across the Columbia Basin and Central OR. There is also a low to medium risk of areas in the Columbia Basin seeing Major HeatRisk (level 3 of 4) with 20-40% probabilities. Moderate HeatRisk affects those who are sensitive to heat, especially those without cooling/hydration, while Major HeatRisk affects anyone without cooling/hydration.

Models on Wednesday show the leading edge of the upper level low beginning to make its way onshore. As the low begins to traverse east, the leading edge over the Cascades Wednesday will bring a tightening of the surface pressure gradients. Winds will be increased through the Columbia River Gorge, Kittitas Valley and along portion of the Simcoe Highlands and foothills of the southern Blues. NBM raw ensembles shows 70-80% probabilities that winds will be 20-25 mph with gusts to near 30-35 mph. The increase in the winds will also raise some fire weather concerns on Wednesday. With that, a special weather statement has been issued for isolated areas within the aforementioned places for critical fire weather between 1100-2000 (8PM) Wednesday due to winds and low relative humidity. While not widespread, this will affect a few of the fires already on the landscape as well as any new fire that may occur in these areas.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

VFR conditions to prevail through the period. Very low confidence (10-15%) in smoke impacts to sites. Winds at sites DLS/RDM/BDN will be 10-15kts with gusts up to 25kts this afternoon. Winds will be light tonight, then increase at sites DLS/PDT to 12-17kts with gusts to around 25kts after 18Z. Lawhorn/82

FIRE WEATHER

Hot and dry conditions will prevail through Wednesday with elevated fire weather concerns. Wednesday will see an increase in winds as an upper level low makes its way onshore. Sustained winds will be between 20-25 mph with winds gusts between 30-35 mph. Coupled with areas of low relative humidity, a special weather statement has been issued between 1100-2000 (8PM) Wednesday for localized critical fire weather concerns. While not widespread, this will affect a few of the fires already on the landscape as well as any new fire that may occur in these areas.

Preliminary Point Temps/PoPs

PDT 57 93 56 85 / 0 0 0 0 ALW 65 94 63 87 / 0 0 0 0 PSC 62 96 61 90 / 0 0 0 0 YKM 63 96 60 88 / 0 0 0 0 HRI 64 95 62 88 / 0 0 0 0 ELN 61 91 56 80 / 0 0 0 0 RDM 51 91 49 85 / 0 0 0 0 LGD 58 97 56 90 / 20 0 0 0 GCD 58 96 57 92 / 10 0 0 0 DLS 65 89 63 83 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until noon PDT Wednesday for WAZ026-028>030- 522-523. OR...Air Quality Alert until noon PDT Wednesday for ORZ044-502-503- 507.