Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Seattle Washington
840 am PST Thursday Mar 5 2015
Synopsis...an upper ridge and high pressure will give dry weather
through the weekend. Weather systems moving into British Columbia
will brush the area with some clouds at times. Fronts should reach
western Washington next Tuesday through Thursday.
Short term...a frontal system moving into b.C. Is sending high
clouds over western Washington. An upper ridge will build a bit over the pacnw
Friday and then shift just offshore over the weekend. There will be
high clouds at times but otherwise fair dry mild weather for western Washington
will extend through the weekend. Looking at the sea level pressure
analysis...there is a 1028 mb surface high that is centered along
the Washington b.C. Border this morning. After the weather system over b.C.
Today departs the high will build north into b.C. Friday and Sat.
Long term...the upper ridge should continue to protect western Washington from
weather systems into early next week. The ridge will break down or
shift away from the area and the westerlies should start to affect
the area again Tuesday and Wednesday. The 12z GFS has the tail end of a cold
front reaching western Washington around daybreak Tuesday followed by a warm
front later Tuesday that extends out to a southern stream system that kicks
out through the area Wednesday and Thursday.
Hydrology...flooding is unlikely for the next 7 days.
Aviation...westerly flow aloft will continue today and tonight as
upper level high pressure builds. A weak system moving across
southern British Columbia will bring high clouds into western
Washington at times. Air mass is stable and dry in the lower and middle
levels. At the surface winds are light.
Ksea...light southerly wind today will become light northerly
tonight. High clouds at times with VFR conditions. Chb
Marine...surface high pressure over the Pacific northwest will
result in weak pressure gradients and light winds through the
weekend. Weak onshore flow may develop Sunday night. A front may
reach the waters by Monday. Chb
You can see an illustrated version of this forecast discussion at