Dry weather will prevail for much of today with low level northeasterly flow. Light rain showers will spread north into the area late this afternoon and tonight as a front moves into western washington then dissipates on thursday. A weak upper level trough will give seasonable temperatures but a chance of afternoon and evening showers to the mountains friday and saturday. A system may bring a chance of rain to the area late sunday into monday.
A split flow pattern is developing across the eastern pacific and western north america, and the atmosphere starting to show signs of predictability issues.
All is okay with the forecast today through thursday. High pressure over british columbia combined with a frontal system approaching the area from the southwest is giving northeasterly offshore pressure gradients this morning, and conditions are dry across the region. A northwest to southeast (negative tilt) frontal system stretching from the central oregon offshore waters southeastward into the northern california coastal waters will lift northeastward today. Light precipitation ahead of the main frontal band will begin moving into the far southern portions of the forecast area from about hoquiam to olympia and southward during the late afternoon hours. Given the strength of the offshore flow and the initial dryness of the air mass, i would not be surprised if the models are a bit too aggressive and fast in bringing the rain shield northward into the area during the late afternoon hours. Pops will be held down over a majority of the forecast area for today as just mid and high level moisture increase from the south later today. Highs will generally be around the 60 degree mark, a few degrees warmer than normal for late march.
Tonight the front moves northward into the area and produces some light precipitation, mainly from about everett or so southward. The front will be weakening as it moves away from its parent low and into the preexisting dry air mass, so precipitation amounts will generally range from 0.1 to 0.25 inches. Lows tonight will be held into the upper 30s to mid 40s for the most part with the increase in cloud cover and moisture.
The air mass will destabilize and dry somewhat on thursday as the front moves northward and dissipates. Models appear to be on track in keeping most of the shower chances over the mountains on thursday with daytime heating. Low chances of showers cannot be ruled out over portions of the lowlands as showers get steered north and northwestward in sse flow aloft. Showers will dissipate thu night as the air mass stabilizes with the loss of insolation. Highs on thu will be around 60 once again and lows thu night will be in the 30s to lower 40s with better radiational cooling.
Friday is where the forecast starts to get tricky. The ecmwf and nam solutions are insistent that the northern stream will dominate across our area with high pressure aloft dropping southeastward along the canadian rockies. This results in easterly flow aloft and a stabilizing air mass across the area with at best an isolated mountain shower. The gfs, canadian, and experimental fv3-gfs solutions keep more southern stream influence on our area with an upper level low just off the mouth of the columbia river instead of over the southwestern oregon waters. this results in an increased threat instability showers over the mountains on friday afternoon and evening. Forecasts at this point will represent a mean of the model solutions and will likely need to be adjusted later as things come into better focus. nonetheless, lows will again be in the 30s to lower 40s and highs will be around the 60 degree mark with springtime firmly in place. Albrecht
The dry ecmwf solution results in only an isolated mountain shower on saturday while the gfs continues to show more mountain convection with an upper low closer to the area. Sunday the ecmwf shows a passing upper trough giving convective showers to the northern mountains while the gfs is drier with a system approaching from the southwest. Monday and tuesday is mostly dry in the ecmwf while it is showery in the gfs. At this time, a middle ground approach was made to compose the forecast. Albrecht
Flooding is not expected over the next 7 days.
Wa...none. Pz...small craft advisory from 5 am early this morning to 5 pm pdt this afternoon for coastal waters from point grenville to cape shoalwater 10 to 60 nm.
small craft advisory from 5 am to 11 am pdt this morning for coastal waters from point grenville to cape shoalwater out 10 nm.
small craft advisory from 5 am early this morning to 2 pm pdt this afternoon for coastal waters from cape flattery to james island 10 to 60 nm-coastal waters from cape flattery to james island out 10 nm-coastal waters from james island to point grenville 10 to 60 nm-west entrance u.s. Waters strait of juan de fuca.
Offshore flow will continue to develop today as a result of a low pressure system well to the southwest. Small craft winds on wednesday for the much of the coastal waters as well as the west entrance to the strait of juan de fuca. Southerly winds and light showers will spread north late this afternoon through tonight as a weak front moves into the area. Offshore winds are expected again later thursday through the weekend. -wolcott-
Light flow aloft becoming southeasterly this afternoon and tonight. System moving up from the south later today and tonight. Increasing mid and high level clouds this afternoon with ceilings lowering down into the 3500-4500 foot range tonight into thursday morning.
Ksea...increasing high clouds this afternoon. Mid level deck arriving early evening with ceilings lowering down to near 4500 feet around 06z with rain. Northerly wind 8 to 12 knots becoming southerly 6 to 10 knots 00z-03z. Felton