textproduct: Portland

SYNOPSIS

A steady warming trend will continue through the weekend as high pressure strengthens across the region. Inland temperatures will rise into the 80s this weekend, then into the upper 80s to mid 90s early next week. Hot and dry weather is expected to persist through at least midweek, with increasing heat impacts possible across the interior lowlands.

DISCUSSION...Tonight through Friday

A synoptic scale pattern shift continues through the weekend and into next week. High pressure over The Great Basin will continue to strengthen resulting in a warming and drying trend across the CWA through at least the middle of next week. While high pressure will build in the mid and upper levels of the atmosphere, onshore (north/northwest) flow will persist near the surface and provide some temperature mitigation, or in simpler terms: Onshore flow will help to keep the region slightly cooler. Even with onshore flow, inland temperatures will warm day by day, while coastal areas remain noticeably cooler, but still experience a warming trend even with the persistent onshore flow.

Sunday, most inland locations are expected to reach the mid 80s to low 90s. Along the coast, highs will remain relatively cooler, with daytime highs in the mid 60s to mid 70s. Higher elevations will will see daytime highs in the upper 70s to upper

Monday through Wednesday, The Great Basin ridge is expected to peak in strength. This is resulting in high confidence in Monday's forecast, with interior lowland highs in the upper 80s to low 90s. The coast will have highs in the mid 60s to mid 70s, with higher elevations having highs in the upper 70s to upper 80s. Tuesday and Wednesday, uncertainty grows significantly. The majority of the uncertainty can be tied to two features within the eastern Pacific. The first id a low off the California coast, which could drive some monsoonal moisture into the region. The second feature is what tropical moisture remains from Tropical Storm Elida, which is currently centered near 19.45 N/-123.57 W, which places it southwest of the Baja Peninsula. TS Elida, is forecasted to weaken through the early part of next week as it continues to push northward into the central and northeastern Pacific. So, with all that in mind, even modest increases in cloud cover or moisture could easily influence afternoon temperatures and is reflected in ensemble guidance as well as WPC 500 mb clusters, which show a fairly even spread between the four different clusters through the middle of next week.

Despite that uncertainty, the overall message remains the same: Tuesday and Wednesday still appear likely to be the hottest days of the period for many inland locations. Probabilistic guidance continues to support a moderate to high chance of 90-degree temperatures across much of the interior lowlands, with the higher odds on Tuesday and Wednesday. There is also a meaningful chance (20-30% chance on Monday, 30-50% chance on Tuesday and Wednesday) that some of the traditionally warmer valleys push into the mid 90s. With several consecutive hot afternoons and only limited overnight cooling, Moderate HeatRisk appears increasingly likely for portions of the interior lowlands, especially for those without effective cooling or for anyone spending extended time outdoors. There is also a lower-end chance (15-35%) for pockets of Major HeatRisk if temperatures end up on the warmer side of the forecast envelope.

By Thursday and Friday, guidance still favors a slight easing of the heat as the two, aforementioned systems, combined broader upper-level low coming from the Gulf of Alaska, will help to push The Great Basin high eastward. Even with a pattern change for the latter part of next week, daytime highs look to remain a few degrees above normal for late July. /42

AVIATION

Southwest to westerly flow aloft continues through the TAF period as an upper low moves through British Columbia. Predominately VFR conditions across the airspace. Another marine push is expected tonight into tomorrow morning. MVFR/IFR cigs expected to form along the coast again, initially near KAST by 04-06z Sun, spreading south to KONP by 08-12z Sun. Additionally, there's a 35-45% chance of MVFR ceilings developing between 10-14z Sun inland stretching from the Portland metro to KSLE, including KPDX and KTTD. Any lowered flight conditions are expected to improve to VFR by 18-21z Sun. Expect north to northwest winds to 8-12 kts inland, up to 15 kts along the coast with gusts up to 20-25 kts. Winds decrease less than 8 kts by 06-09z Sun.

KPDX AND APPROACHES...Predominately VFR conditions through the TAF period. There is a 30-45% chance of MVFR CIGs 12-18z Sun. Northwest winds around 8-12 kt with occasional gusts up to 20 kt, decreasing after 04-06z Sun. -03

MARINE

A typical summertime pattern will continue through early next week with persistent north to northwest winds over the coastal waters. Winds will be strongest during the afternoon and evening hours each day, especially through weekend for the waters south of Cape Falcon. Expect wind gusts up to 25 kt over the central and southern waters this weekend, with seas becoming steep on Sunday due to a fresh northwest swell around 6-7 ft at 7-8 seconds. By Sunday afternoon, these gusty winds and steep seas will expand into the waters north of Cape Falcon. Between the increasing winds and steepening seas, conditions will become hazardous to small craft. As such, Small Craft Advisories are in effect from Saturday afternoon through late Sunday.

Winds decrease below 20 kts early Monday morning, with seas becoming less steep through the day Monday as the swell decreases. Benign conditions expected Tuesday into late next week.

PQR WATCHES/WARNINGS/ADVISORIES

OR...None. WA...None. PZ...Small Craft Advisory from 2 PM Sunday to 2 AM PDT Monday for PZZ251-271.

Small Craft Advisory from 5 PM this afternoon to 2 AM PDT Monday for PZZ252-272-273.

Small Craft Advisory until 2 AM PDT Monday for PZZ253.