KCEC Day 8

The (Feb 21st 00z) GFS has the upper level and surface lows stacked right off the coast of Oregon at the start of the forecast period. The low should weaken and ride northward along the coast. Precipitation in association should be ongoing at this point and be sustained by instability and forcing introduced by weak coat-tails shortwave pushing through. The shortwave is followed by slight ridging in advance of the next, more powerful storm system that will impact the area over the weekend. So, toward the end of the period, precipitation should diminish and then stop, making way to partly cloudy skies and subsidence. Winds should be initially strong with a decent gradient at the beginning but eventually weaken after the sun rises. The very beginning of the forecast period should see the strongest winds, possibly approaching a two-minute average of 15-20kts. The most recent GFS MOS(6z) has stepped up winds in the early period, contrasting it with the much lower estimation from the Eta MOS. We'll see some cold air advection after 12z or so and that will keep temperatures down, but not too far considering the wind will be off the water. The forecast period temperature minimum should come at the very end of the period with clear skies and light winds, plus some good radiational cooling with the ground being fairly wet from earlier rains will get the temperature down into the lower 40's.. The maximum temperature will not do much to surpass 50ºF. Rainfall amounts are hard to predict considering it will come from a shared storm from the day before. A half of an inch would not be out of the question.

Cianca.