textproduct: Seattle/Tacoma

SYNOPSIS

A dry and warm airmass associated with a strong upper level ridge will settle over western Washington through Monday. Temperatures peaking in the 80s and 90s will bring widespread Moderate HeatRisk to the region today and again Monday. Offshore flow will bring lower relative humidities and elevated fire danger. The ridge will weaken on Tuesday, resulting in increased onshore flow and seasonable temperatures through the rest of the week.

SHORT TERM /TODAY THROUGH TUESDAY/

Infrared satellite imagery depicts high level cirrus clouds advecting in from British Columbia. Winds have remained light overnight with offshore flow along the coast. A strong upper level ridge remains anchored offshore, bringing hot and dry conditions through Monday. Temperatures will climb into the 80s and 90s today and Monday during peak heating hours as a thermal trough moves in, hottest into the mid 90s in interior southwest Washington. Widespread Moderate HeatRisk is expected both Sunday and Monday. Record temperatures will likely be broken today and again on Monday along the I-5 corridor, particularly in Seattle and Olympia. Little to no overnight relief is expected with temperatures only briefly dropping into the 50s and 60s for lows both tonight and Monday night. Record warm low temperatures are also likely to be broken in Seattle and Olympia as temperatures along I-5 from Everett to Olympia may only drop to 65 degrees overnight tonight and Monday night. Know the signs of heat related illnesses and take precautions to stay safe from the heat! Vulnerable populations and those who do not have access to air conditioning are especially susceptible to heat. The only exception to the heat on Monday will be when the thermal trough will shifts eastward Sunday night into Monday, bringing a reprieve from the heat for the coast with highs in the 70s.

The upper level ridge flattens late Monday into Tuesday, allowing for a brief break from the heat. Tuesday's highs will be much closer to normal for this time of the year as onshore flow ensues with zonal flow aloft. Confidence is low but with onshore flow, a Puget Sound Convergence Zone could set up late in the day Tuesday. Have kept 10-20% chances for rain (mainly drizzle) from the NBM in the forecast for east of Puget Sound for Tuesday evening into early Wednesday morning.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Onshore flow continues throughout the week with zonal flow aloft and near normal to slightly warmer than normal temperatures. The upper level ridge may amplify slightly again by mid to late week, with forecast highs generally in the 70s to low 80s. We could see a return to temperatures in the low to mid 80s along the I-5 corridor depending on how amplified the upper level ridge gets. Chances for precipitation are very low (less than 10%) mid to late in the week given the persistent dry and stable airmass.

AVIATION

High pressure and offshore flow will lead to dry and stable conditions across western Washington. VFR conditions will prevail. 33

KSEA...VFR today with high clouds. N winds gusting to 10-15 kt this afternoon and evening. 33

MARINE

Offshore flow today with a thermal trough along the coast. The thermal trough will shift east of the Cascades on Monday with a return to onshore flow. Expect strong winds with possible gales through the strait of Juan de Fuca Monday night and Tuesday. Onshore flow prevails through the rest of the week with strongest winds and highest seas over the outer coastal waters. Highest winds through the strait will be during the afternoon and evening hours each day. 33

FIRE WEATHER

Dry conditions and much warmer than normal temperatures over the next two days will bring elevated fire weather concerns through Monday. A persistent upper level ridge remains over the area with offshore flow today. Widespread high temperatures in the 80s and 90s are expected today and Monday with low relative humidity values. The lowest minimum relative humidity values are expected over the southwest Interior where humidities may drop to 15 to 20 percent both this afternoon and again on Monday afternoon. Even though fine fuels have not reached critical thresholds, this rapid drying will create elevated fire concerns especially for dry grassy/shrubby areas, as well as piles of dead fuels. Offshore flow today into Monday will prevent good relative humidity recoveries overnight. Relative humidities improve with the return of onshore flow Tuesday. Low level onshore flow and seasonable temperatures throughout the week will ease fire weather concerns.

CLIMATE

SeaTac is forecast to reach 87-89 degrees today, June 14, which would break the current record of 86 degrees set back in 1988. NBM probabilities for highs of 90 degrees or warmer at SeaTac today are at 3%. SeaTac is forecast to reach 89-91 degrees on Monday, June 15, which would break the current record of 88 degrees set back in 1963. While it is not the most likely outcome, two consecutive days of 90 degrees or warmer cannot be completed ruled out. This is very rare at SeaTac during the first half of June; the last time that occurred is June 6-7, 2003. In addition, record warm low temperatures are also likely to be broken in Seattle over the next two nights. Monday's low temperature forecast is 62 degrees in Seattle, which would break the daily record warm low for June 15 of 55 degrees set back in 1970. Tuesday's forecast low of 61 would break the record warm low for June 16 of 54 degrees set back in 1973.

Olympia is also likely to break record high temperatures today, June 14 and Monday, June 15. The forecast high today is 93 and the forecast high on Monday is 94 degrees. This would break two daily record highs, as the current record high for June 14 is 88 degrees set back in 1999, and the current record high for June 15 is 88 degrees set back in 1963. Record warm low temperatures are also likely to be broken in Olympia over the next two nights. Monday's low temperature forecast is 61 degrees in Olympia, which would break the daily record warm low for June 15 of 55 degrees set back in 1954. Tuesday's forecast low of 58 would break the record warm low for June 16 of 56 degrees set back in 1964.

Even Hoquiam is likely to break a record high temperature today, June 14. The current forecast suggests Hoquiam will peak near 83 degrees on Sunday, which would break the current record high of 79 degrees set back in 1988.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Heat Advisory from 11 AM this morning to 5 AM PDT Tuesday for City of Seattle-Downtown Everett / Marysville Area- Eastern Kitsap County-Eastern Strait of Juan de Fuca- Eastside-Foothills and Valleys of Central King County- Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Snohomish and Northern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Foothills and Valleys of the North Cascades- Foothills of the Western and Southern Olympic Peninsula- Island County-Lake Crescent Area Including US 101-Lower Chehalis River Valley-Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties-Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County- Middle Chehalis River Valley-Northern Hood Canal-Olympia and Southern Puget Sound-Port Townsend Area-San Juan County-Shoreline / Lynnwood / South Everett Area-Southern Hood Canal-Willapa and Black Hills.

PZ...None.