textproduct: Pendleton

KEY MESSAGES

- Slight chance of showers each day through Tuesday, mainly over the mountains

- Gradually warming to near or above normal through this week

DISCUSSION

Water vapor imagery shows a deep closed low downstream over the Canadian Prairies. Meanwhile, a couple weak shortwaves embedded within northerly flow aloft on the west side of the aforementioned low are sliding south over the Pacific Northwest. Predominantly clear to partly skies are present across the lower elevations, while the mountains have seen scattered to numerous cumulus develop. A few isolated showers are evident within the cumulus field, mainly over Wallowa County. Anticipating convection will remain shallow today given the lack of vertical extent of CAPE profiles in forecast soundings (EL around 12-18 kft) from HREF and REFS NWP guidance.

Looking ahead, flow aloft will turn more northwesterly by Monday and Tuesday, with a couple shortwaves and weak diurnally driven instability (CAPE of 500 J/kg or less per latest CAMs) providing impetus for another round of isolated to scattered showers, mainly over the mountains.

Wednesday through the remainder of the week, ensemble cluster analysis shows 500-hPa heights rising to near or above normal over the Pacific Northwest and vicinity. Roughly 80-90 percent of members place dry conditions region-wide, though all ensemble clusters now show hints of a trough or closed low moving over southern Canada or the Northern Tier sometime between late Thursday and late Friday. Confidence in the feature providing significant precipitation to the forecast area is low (10-20 percent).

By next weekend, uncertainty in the 500-hPa height field burgeons as ensemble guidance struggles to resolve the evolution of an upper-level closed low and upper-level ridge in the vicinity of the Pacific Northwest. Based on the 00Z ensemble runs, roughly 55 percent of members keep the region warm and dry under a ridge, while the remaining members place the low in a position that would provide precipitation and cooler temperatures. 86

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

VFR conditions will persist through the period. The only exception will be KBDN, which is expected to lower to MVFR conditions around 12Z due to nearby prescribed fire smoke reducing visibilities to around 3SM and ceilings of 7kft. KRDM/KBDN will see breezy winds beginning 20-21Z with gusts of 15-20kts. 20-25kt gusts will also be possible for KDLS after 17Z.Otherwise, the remaining sites will see CIGs of 25kft to skc and winds below 10kts.

Preliminary Point Temps/PoPs

PDT 39 65 41 67 / 0 10 0 0 ALW 42 65 45 67 / 0 30 10 10 PSC 40 71 43 72 / 10 0 0 0 YKM 39 69 41 71 / 10 0 0 0 HRI 40 69 43 69 / 0 0 0 0 ELN 36 63 40 62 / 10 10 0 0 RDM 29 61 30 65 / 10 0 0 0 LGD 32 58 35 64 / 0 50 10 10 GCD 31 58 33 64 / 10 40 10 10 DLS 42 68 44 67 / 10 10 0 0

PDT WATCHES/WARNINGS/ADVISORIES

WA...None. OR...None.