textproduct: Pendleton

KEY MESSAGES

1. Continued dry and warm conditions through the week *Excessive Heat Watch in Effect*

2. Isolated to scattered thunderstorms Wednesday and Thursday

3. Hot, dry and windy conditions return Friday

DISCUSSION

Current radar is showing a few echos across the central portion of the region. Ground observations show mostly a trace with a few isolated locations in central OR showing 0.02-0.03 inches of rain. Satellite shows clouds over much of the region with heavy smoke near the surface. The smoke has kept the temperatures across the region 5- 7 degrees below the original forecast. Temperatures are sitting in the upper 70s instead of the mid 80s.

Models show the upper level ridge to remain overhead through Thursday keeping the region under dry and warm conditions. Temperatures will steadily increase and there is 70-80% chance of seeing major HeatRisk Tuesday through Thursday with highest probabilities being Wednesday. If the smoke lifts, NBM shows temperatures to reach between 100-105 in the Columbia Basin ands the Gorge with isolated areas along the foothills seeing upper 90s to 100 degrees. That coupled with the high overnight temperatures in the upper 60s to low 70s will cause heat related impacts to occur. Confidence in the HeatRisk is high (70-90%).

By Wednesday, models are in decent agreement and show a slight pattern shift with the upper level ridge shifting towards the Four Corners and advecting some monsoonal moisture up into the region. Clusters show the main difference to be mainly with the amplitude of the ridge. NBM raw ensembles show Wednesday to have 40% chance of thunderstorms through Deschutes and Grant counties after 2 PM. Looking at soundings show CAPE values over 400-500 J/kg, lapse rates 9-10 C/km, effective bulk shear of 25-30 kts and LIs of -4 and PWATs of 0.05-1.0 inches. NBM QPF continues to show these storms to be more on the drier side with less than 10% chance of a wetting rain. Cannot rule out isolated dry thunderstorms mixed with wet thunderstorms and with the fuels as ready as they are, not a lot is needed to ignite a fire. This pattern is similar to the pattern from last week and therefore a Red Flag Warning has been issued for abundant lightning over central OR and the eastern mountains 11 AM Wednesday to 11 PM Wednesday.

Thursday models show a dry upper level low beginning to push into the region shifting the upper level high of to the east. In house calculations show the pressure gradients along the Cascades tightening which will bring elevated winds to the Cascade Gaps as well as portions of the southern Blues and central OR. NBM raw ensembles shows the region with the highest probabilities for 20 mph sustained winds is through the Gorge and foothills of the southern Blues at 70-90%. 15 mph sustained winds expected through the Kittitas Valley and through portions of central OR with 60-80% probabilities. With the continued dry and warm conditions, relative humidities will remain low and coupled with the winds elevated fire weather concerns for Friday and Saturday.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

VFR conditions prevail at DLS/RDM/BDN/YKM over the next 24-hours. Lingering smoke from local wildfires poses a chance for smoke to inhibit any site, especially during sunset, sunrise, and the general early morning hours. Currently, smoke is impacting PDT/ALW/PSC with MVFR to IFR conditions, and will likely linger through the late afternoon/early evening hours today. We will continue to see smoke impacts at TAF sites through at least Wednesday. Otherwise, small chance of showers passing through PSC/ALW/PDT (though not strong enough to clean out the smoke) over the next few hours as light returns is advertised across the Colombia Basin.

FIRE WEATHER

There are two periods of concern for fire weather. The first is with the potential for thunderstorms on Wednesday through central OR and the eastern mountains. There is a 10-30% chance of isolated to scattered thunderstorms through the aforementioned portion of the CWA. These thunderstorms are expected to bring gusty outflow winds of 25-35 mph as well as abundant lightning. With that, a Red Flag Warning has been issued for OR zones 698, 700 and 705.

Preliminary Point Temps/PoPs

PDT 62 96 66 100 / 10 0 0 0 ALW 67 99 71 102 / 10 0 0 0 PSC 65 100 68 103 / 10 0 0 0 YKM 68 99 70 102 / 0 0 0 0 HRI 66 99 70 103 / 10 0 0 0 ELN 65 97 68 99 / 0 0 0 0 RDM 58 93 62 95 / 10 10 10 30 LGD 62 97 66 99 / 0 0 10 0 GCD 59 95 63 97 / 0 0 10 10 DLS 69 101 73 104 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Heat Advisory from 11 AM Tuesday to 9 PM PDT Thursday for WAZ024-027>029. Air Quality Alert until 9 AM PDT Wednesday for WAZ028>030. OR...Heat Advisory from 11 AM Tuesday to 9 PM PDT Thursday for ORZ041-044-507. Air Quality Alert until 4 PM PDT Wednesday for ORZ044-049-050- 502-503-505>509-511. Red Flag Warning from 11 AM to 11 PM PDT Wednesday for ORZ698- 700-705.