textproduct: Portland

SYNOPSIS

The region remains underneath a pattern favoring hot and dry conditions but improvement is already slowly underway in regards to lingering smoke/haze across the region - a trend which accelerates later today into tonight. High temperatures for most inland valley locations peak in the upper 80s to mid-90s through Friday leading to Moderate HeatRisk impacts. Temperatures moderate over the weekend with renewed onshore flow keeping smoke pinned east of the Cascade crests. Near normal summertime weather conditions are anticipated Monday through the middle next week.

DISCUSSION...Tonight through Wednesday

Weak onshore flow has begun to take hold early this morning as the ridge of high pressure, which up until late yesterday(Wed) had supported easterly flow near the surface, is finally beginning to progress. We've already seen smoke/haze improvement along the coast, through the coastal gaps, and along the western Columbia River into the northern Portland/Vancouver metro. Still, as we go through today it'll take some time to completely flush the wildfire smoke from the region with a more noticeable improvement for many of the inland valleys arriving this evening. While the thick smoke and haze tempered high temperatures from truly realizing their potential yesterday, ensemble 850 mb temps of around 20-22C are expected to present again today, and with the smoke gradually dispersing, more sunshine could lead to slightly warmer temperatures inland with highs in the low to mid 90s.

Given the expected temperatures this afternoon, a Heat Advisory remains in effect across the inland valleys through this evening highlighting the increased risk of heat-related illnesses. In areas with Air Quality Advisories in effect, it is recommended to keep windows and door shut to prevent smoke from going indoors. Something as simple as a large box fan with a damp towel draped over the front of it can provide effective cooling given the dry airmass in place today if you're seeking some alternative means of relief.

Friday and into the weekend, the axis of the broad upper-level ridge feature progresses further east of OR/WA, while more zonal flow develops over western Oregon and southwestern Washington. However, at least on Friday and Saturday confidence is high there'll be enough influence from the high pressure ridge aloft and a slight increase in upper-level heights to keep high temperatures in the upper 80s to low 90s - warmest the former day. Fortunately, any lingering wildfire smoke should be completely flushed from west of the Cascade crests assuming no additional new starts locally. Onshore northwesterly flow is expected to strengthen further the second half of the weekend into early next week helping temperatures moderate back close to normal with high confidence in maximum temperatures returning to the low to mid 80s range Sunday/Monday through the middle of the week. Areas with good coastal marine influence can expect a daily dance between morning low clouds and afternoon sunshine. If you're searching for any rainfall chances headed through the middle to end of next week you're likely out of luck as there are no signs of any appreciable precipitation for western Oregon and southwestern Washington headed into the middle of August. -99/DH

AVIATION...Through 12Z Fri

Current satellite imagery and surface observations depict areas of low stratus and IFR/LIFR conditions along the coast, with a mix of MVFR to VFR VIS inland due to lingering smoke/haze. For inland terminals, increasing NW flow as the day progresses will keep working to slowly flush smoke out the region leading to the return of prevailing VFR conditions, although for truly significant improvement it'll likely take until the 00-06z Friday. Until this point most sites maintain a 30-40% chance for MVFR VIS. Along the coast, LIFR/IFR stratus is expected to persist until 17-20z before a window of potential improvement to MVFR/VFR during the afternoon hours, most likely near KAST, before stratus rebuilds 02-05z for the evening. Winds stay fairly light, only gusting up to 5-12 knots this afternoon before decreasing overnight.

KPDX AND APPROACHES...VIS continues to fluctuate between 5-6SM early this morning with only limited improvement until 00z, after which point VFR conditions will be heavily favored. Up until then, expect occasional MVFR conditions. Expect northwesterly winds around 3-10 kt, strongest in the afternoon. -99/10

MARINE

High pressure at the surface over the eastern Pacific keeps northerly winds in place the remainder of the week through the weekend and into next week as well. Confidence is moderate to high both seas and winds remain below Small Craft criteria through today and Friday. However, winds increase later on Saturday with the NBM projecting a 40-70% chance for gusts above 21 knots into the evening hours. Similar probabilities are present during the afternoon/evening hours into early next week so Small Craft Advisories may be needed yet again, mainly across the outer waters. Seas hold around 4-7 feet at 7-8 seconds over the next 5-7 days. -99

PQR WATCHES/WARNINGS/ADVISORIES

OR...Heat Advisory until 11 PM PDT this evening for ORZ108>118. WA...Heat Advisory until 11 PM PDT this evening for WAZ204>208. PZ...None.