textproduct: Pendleton

KEY MESSAGES

1.Dry and warm through the weekend becoming hot Monday *Heat Advisories Issued*

2. Breezy to windy across the region through Wednesday

3. Isolated fire weather concerns today becoming widespread Tuesday

DISCUSSION

Current night time satellite shows little to no clouds over the region this morning. The ridge remains overhead allowing for the clear skies to continue through the forecast period. Clear skies and warming temperatures will continue through the beginning of next week with the hottest day being Monday. High temperatures across the lower Columbia Basin, Central Oregon, Columbia Gorge, Blue Mountain foothills, and the Yakima/Kittitas Valleys will reach into the upper 80s to low 90s today, and in the mid-to upper 90s on Monday. Monday morning lows are expected to drop into the mid-50s and lead to widespread moderate HeatRisk (2) across the area. There are also isolated areas of major HeatRisk (3 or 4) through the Columbia Gorge and the Yakima Valley with 80-90% probabilities of temperatures. Due to higher overnight lows and the high temperatures Monday, a Heat Advisory has been issued from 10 AM to 10 PM Monday for the Columbia Gorge, Central Oregon, and the Yakima/Kittitas Valleys. Temperatures will remain warm through the week, however, overnight lows will decrease and the HeatRisk will settle to near normal.

Models show that Monday and upper level shortwave will ripple over the crest of the upper level ridge. This will bring increased chances of breezy conditions to the mountain gaps and highland zones Monday. In house calculations using the GFS and SREF shows the tightening of the pressure gradient across the Cascades to be anywhere from 10-15 mb in difference. This will lead to areas seeing wind gusts as high as 50 mph, especially along the Simcoes, the Gorge, north central OR and along the foothills of the southern and northern Blues. NBM ensembles show nearly a 90% probability of these areas seeing near wind advisory criteria on Tuesday.

With the increase in temperatures and winds, isolated areas through the region will see increased chances of fire weather through Monday and even higher on Tuesday. NBM shows daytime minimum RHs to be dipping into the low to mid teens. Red Flag Warnings may be possible, especially Tuesday and winds remain elevated and RHs remain low. However, clusters so show some variances within the models and depending on how quick the shortwave presents itself could affect the possible RFW. If the shortwave comes in quick, then criteria will decrease, but if it comes in slower, widespread fire weather will be possible. Confidence in the need of RFWs is 40-60% and will continue to monitor the situation as the event draws near.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

VFR conditions currently at most sites, with MVFR visibilities observed at KPDT due to smoke from a nearby wildfire. This should improve slowly as winds shift more from the northeast later in the afternoon. Elsewhere, VFR conditions will persist through the period as clear skies stay overhead. Breezy winds for KRDM/KBDN this afternoon as gusts of 15-20kts out of the north are expected, subsiding in the evening. 75

FIRE WEATHER

Update 1042: A Fire Weather Watch has been issued for WA/OR691 for Tuesday between 1000 and 2300 related to low RH and high winds. Confidence has increased to 60% related to critical RH values, which prompted the issuance of the watch.

Previous 0313 Discussion: WA/OR691, OR700, OR704, and OR705 are the areas of concern for the potential of fire weather. These areas fuels are receptive and if a fire ignites, spread could be quick with higher sustained winds and low RHs. Confidence in the high winds is high at 79-80% and RHs are slightly less confident with only 50%. Will continue to monitor the situation as the event draws near.

Preliminary Point Temps/PoPs

PDT 87 53 92 61 / 0 0 0 0 ALW 87 58 92 65 / 0 0 0 0 PSC 91 57 97 63 / 0 0 0 0 YKM 91 61 99 63 / 0 0 0 0 HRI 90 56 95 64 / 0 0 0 0 ELN 87 59 94 63 / 0 0 0 0 RDM 86 49 91 55 / 0 0 0 0 LGD 84 49 89 54 / 0 0 0 0 GCD 86 47 91 52 / 0 0 0 0 DLS 93 64 99 69 / 0 0 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...Heat Advisory from 10 AM to 10 PM PDT Monday for WAZ024-026- 027. Fire Weather Watch from Tuesday morning through Tuesday evening for WAZ691. OR...Heat Advisory from 10 AM to 10 PM PDT Monday for ORZ041-511. Fire Weather Watch from Tuesday morning through Tuesday evening for ORZ691.