textproduct: Seattle/Tacoma

SYNOPSIS

Cool and cloudy conditions will continue through Friday as onshore flow persists. A weakening cool front will bring chances for light rains to the coastal and mountain regions Thursday with only slight chances across the lowlands. Improving conditions are expected Friday afternoon through the weekend with decreasing cloud cover and temperatures returning to near normal. Dry weather and seasonable temperatures will continue into early next week.

SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/

Considerable cloud cover persists early this afternoon across much of Western WA, though clearing has begin pushing into the coastal regions. Patchy breaks in the clouds have allowed for some filtered sunshine across the lowlands with temperatures climbing into the 60s as of 1pm. Continued mostly cloudy skies with a few spotty breaks in the cloud deck are likely through the remainder of the afternoon and early evening before clouds redevelop overnight.

On Thursday, a shortwave pushing into British Columbia will drag a weakening cool front into Western WA, with light rain chances spreading into the coast and mountain terrain during the day, and just slight chances (20% or less) across the Seattle urban corridor. Otherwise, continued cloudy and cool conditions are expected.

By Friday, heights will begin to climb considerably as ridging builds into the central and western US. This will allow for an earlier afternoon clearing trend and encourage afternoon highs to climb closer to seasonal normals.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Increasing heights over the weekend in response to strengthening ridging in the Western and Central US will allow for temperatures to return to near normal early July values. Meanwhile, morning stratus across the low-lands will tend to thin and be less persistent than observed over the past week. Dry conditions and continued seasonable temperatures will continue into early next week.

AVIATION

The northwesterly flow from an upper level trough continues through the TAF period. Generally VFR conditions prevail this afternoon through MVFR persists near KPWT and will persist at least a few more hours. Stratus deck will return overnight with widespread MVFR conditions expected. Light rain showers will move into western WA Thursday with best chances affecting KCLM and KHQM and continued cloudy conditions. Periods of MVFR conditions are once again expected during the morning hours, particularly from 12z-18z. South to southwest winds 5 to 10 kt will continue through the period, with a few gusts of 15 to 20 knots possible this afternoon.

KSEA...VFR conditions are expected this afternoon with SCT-BKN cloud decks between 4-6kft AGL. MVFR conditions are expected to return overnight with ceilings generally in the 2-3kft range. Cloudy conditions expected for Thursday with slight chances for shower activity in the afternoon and evening. Generally light winds of 5 to 10 knots out of the south expected through the period.

MARINE

Broad high pressure offshore and low pressure inland will continue today, maintaining onshore flow with steep seas over the outer coastal waters. A frontal system will cross area waters on Thursday, weakening the onshore flow and bringing an end to the steep seas over the outer coastal waters. Thereafter, a low pressure system will deepen over the Gulf of Alaska, maintaining onshore flow over the Pacific Northwest. This will result in periods of diurnally driven westerly pushes through the Strait of Juan de Fuca over the next week.

A westerly push this evening through the Strait of Juan de Fuca will generate Small Craft winds through the central and east Strait. A frontal system Thursday will limit winds over area waters on Thursday. Additional westerly pushes are favored to occur Friday and Saturday evenings, and likely once again on Monday and Tuesday. A weak frontal system will also bring gusty winds to the southern coastal waters Sunday, with potential for SCA winds (60-70% chance of gusts over 30 kt).

Steep seas will calm tonight as waves subside, lowering to 3 to 5 feet on Thursday. Seas will gradually build to 6 to 9 feet on Sunday and Monday, then slowly subside on Tuesday.

FIRE WEATHER

Little in the way of fire weather concerns in the week ahead. Upper level troughing maintaining cool and cloudy conditions with high relative humidity values and a slight chance for showers along the coast and mountains on Thursday. Drier, sunnier, and more seasonable temperatures will begin Friday continuing into early next week. Low level onshore flow will moderate daytime minimum RH values and bring in good RH recovery each night.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 6 PM this evening to 2 AM PDT Thursday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 6 PM PDT this evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.