textproduct: Seattle/Tacoma

SYNOPSIS

An upper level ridge will build offshore today and tonight then move inland Tuesday and Wednesday. Thermally induced surface trough developing over the area tonight will remain in place through at least Wednesday night creating northerly flow in the lower levels. This will pull some smoke over Western Washington. The ridge will shift eastward later Thursday into Friday. Increasing low level onshore flow at the end of the week with cooler temperatures and less smoke.

SHORT TERM /TODAY THROUGH WEDNESDAY/

Hazy skies this morning; satellite imagery shows smoke aloft from the fires in Eastern Washington moving across Western Washington. Chilly morning for the first week of August with Bremerton and Olympia in the 40s. Most of the remainder of the area in the lower to mid 50s.

Upper level ridge building over Western Washington today with the ridge axis offshore. Northerly flow aloft last night pulled some upper level smoke down over the area ( you could see it at sunset ) but with the flow aloft becoming more northwesterly with the ridge building smoke in the upper levels will be kept at a minimum. Patchy low clouds and fog will dissipate early with sunny skies. Highs warming into the 70s and lower 80s.

Upper level ridge continuing to build tonight and Tuesday with the ridge axis drifting towards the Pacific Northwest. Thermally induced surface trough developing along the coast tonight turning the low level flow northeasterly. This will most likely pull low level smoke from the fires in Eastern Washington into Western Washington by Tuesday morning. Smoke will remain over the area during the day. The transition to offshore flow in the lower levels warming high temperatures into the 80s and lower 90s. Lows Monday night in the 50s. HeatRisk moving into the moderate category for most locations away from the immediate coast.

Upper level ridge axis moving over Western Washington later Tuesday night into Wednesday with the thermally induced surface trough over the area. Low level northeasterly flow will keep low level smoke moving into Western Washington. Highs in the 80s to mid 90s. Lows in the mid 50s to lower 60s, cool enough to prevent most of the area from major HeatRisk.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Models showing good consistency for the latter half of the week into the weekend. Upper level ridge axis over the area Wednesday night moving east Thursday and Friday. Thermally induced surface trough moves over the interior Thursday. Afternoon seabreezes developing along the coast cooling high temperatures into the lower to mid 70s. One more hot day over the interior with highs similar to Wednesday, 80s to mid 90s. Moderate HeatRisk with a 20-40 percent chance of major HeatRisk Central and Southern Puget Sound and Cascade foothills.

Increasing low level onshore flow Thursday night into Friday with the ridge axis well to the east and the thermal induced trough moving east of the Cascades. Low level onshore flow will bring cooler temperatures and also push the low level smoke out of the region. Highs in the mid 70s to mid 80s inland and upper 60s along the coast. Lows in the 50s and lower 60s.

Weak upper level trough settling over the area for the weekend with varying degrees of low level onshore flow. Morning clouds each day will give way to afternoon sunshine. Highs in the 70s and lower 80s. Lows in the 50s. Felton

AVIATION

Northwest flow aloft throughout the TAF period as an upper-ridge axis sits offshore. Low-level flow has switched northerly - ushering in drier air and leading to mostly clear skies (VFR) this morning. VFR remaining throughout the day Monday into Tuesday as well. Elevated smoke from region fires today. Smoke will become more surface based on Tuesday and bring the chance for visibility restrictions. As to how much visibility will decrease, it is uncertain at this time.

KSEA...VFR throughout the TAF period. Elevated smoke will increase today before becoming more surface-based into Tuesday. Can't rule out the chance for vis restrictions. NE surface winds 6-8 kt this morning, increasing out of the N-NW this afternoon 8-12 kt with gusts near 20 kt. Winds out of the NE 5-8 kt overnight into Tuesday.

MARINE

A strong surface high pressure will continue to remain offshore throughout midweek as a thermally induced low pressure expands northward along the interior coast. Winds over the waters will continue to generally remain under small craft advisory levels. The exception being, with the aforementioned presence of the thermal trough over Western Washington, this could allow winds over the outer coastal waters to approach low end advisory levels this afternoon briefly and also, Tuesday afternoon mainly in the southern inner coaster water zone.

The surface trough will move eastward Thursday and Thursday night for increased onshore flow across the region, along with potential headlines for westerlies in the Strait of Juan De Fuca.

Coastal seas generally 4 to 6 feet through the first half of the week. Seas look to gradually increase 6 to 8 feet during the second half of the week.

Mazurkiewicz

FIRE WEATHER

No changes as far as fire weather is concerned. Warming trend beginning today peaking Thursday. Very low daytime RH values throughout the CWA Tuesday through Thursday. The Cascades, Cascade valleys, the adjacent lowlands of the Chehalis River Valley and the south Puget Sound area will be of particular concern. Minimum RH values each of those afternoons are expected to slip into the teens. Wednesday and Thursday will be of particular concern as minimum RH values could get as low as the low teens to upper single digits. No significant winds or instability expected during this time frame, so Red Flag criteria will most likely not be met. Even without a red flag warning, with RHs this low, any wind will contribute to fire spread and as such, maximum caution is emphasized. Friday and beyond will see a much more significant rebound in daytime RH values with low level onshore flow. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.