textproduct: Seattle/Tacoma

SYNOPSIS

Near-seasonal temperatures throughout the weekend with reoccurring spells of morning clouds and afternoon sun. Upper ridging will build back into the Pacific Northwest early next week for warmer, dry conditions through much of the upcoming week.

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/

Widespread southwest flow over the region as broad upper- troughing positions over the NE PAC along with a high center present over the Four Corners region. Diurnal heating has eroded marine stratus from this morning however, it'll redevelop overnight into early Saturday morning as low-level onshore flow increase this evening. Min temperatures are forecast to range between the upper 40s to mid 50s, around average for early July.

As alluded to, expect a grey start to the day on Saturday for most areas as the marine layer expands across western Washington. It'll gradually decrease in coverage into the afternoon in typical fashion, giving way to scattered mid-high level cloud coverage. Upper-troughing offshore will progress on Saturday as well, bringing the return of 30-40% PoPs, mainly in the North Cascades and the Olympics. The upper-trough will lift north into BC on Sunday as the threat for mountain showers end. But, another round of morning clouds is in the offing. Seasonal temperatures are expected during this time highs in the lower to upper 70s and overnight lows in the upper 40s to mid 50s.

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LONG TERM /MONDAY THROUGH FRIDAY/

A warming trend continues into Monday and Tuesday with southwesterly flow aloft and relatively high upper level heights. The temperature forecast has trended higher, now with a 65-85% chance of high temperatures at or above 80F from Seattle metro southward on Monday, and more widespread 75-90% odds of highs above 80F over much of the interior lowlands including the Cascade foothills and valleys on Tuesday. There remains a range of potential outcomes Wednesday through late next week resulting a higher degree of uncertainty with respect to the temperature forecast. Some scenarios could play out with high temperatures Thursday in the low 90s, while others could be in the low 70s. Confidence remains better for continued dry conditions through the entire extended period. The overall message at this time remains to expect increased risk of Moderate (orange)HeatRisk through the early part of next week, followed by a potentially extended period of warm and dry weather.

AVIATION

Mostly VFR observed this afternoon as marine stratus has all but eroded. VFR is favored to remain this evening however, marine stratus is slated to redevelop overnight into Saturday morning. Areas of MVFR ceilings are favored with possible IFR particularly along the coast (30-50% chance for KHQM). Any lingering MVFR/IFR cigs should lift by 18-21z Saturday.

KSEA...VFR ceilings this afternoon throughout the evening. The NBM is indicating a 15-25% chance of MVFR ceilings developing between 09z-12z Saturday. If manifest, a return to VFR by 18z is favored by current guidance. NW winds briefly this evening before backing towards the SW by 06z. SW winds into Saturday as well between 5-10 kt.

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MARINE

A weak frontal system is crossing the waters this evening, bringing increased low-level onshore flow. As a result, a Small Craft Advisory is in effect this evening into Saturday morning for central/eastern Strait of Juan de Fuca. High pressure will rebuild Sunday into Monday and remain in place into midweek. Diurnally driven increases in westerlies can be expected in the Strait of Juan de Fuca each the next several days.

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FIRE WEATHER

The current onshore pattern will continue through the weekend which will lead to continued excellent nightly RH recoveries. 30-40% chance of rain showers exist into Saturday, mainly for the Olympics and northern Cascades but the chance for wetting rain appears less than 10%. Rainfall amounts during this period would generally total less than 0.10". A ridge of high pressure rebuilds into the region Monday and Tuesday. While the onshore pattern will largely remain in place, warmer daytime temperatures and clear skies will likely lead to RH values dipping into the 20-40% percent range, with the lowest values in the south interior and Cascades Valleys. This will allow fine fuels to continue to dry with elevated fire weather conditions. Some modest cooling is slated to arrive by the middle of next week, but may well be short-lived.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 3 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.