I have noticed today and yesterday that the forecast here, and other places I check frequently, both predicted westerly winds almost all day long. Yesterday afternoon the winds turned south east prolly @ 10mph+ similar to how they do in the summer and today they turned east earlier in the day but have remained light. Is there a particular reason why winds are so difficult to predict along the coast? I also forget why the SE winds pick up in the summer I know it has to do something with the land warming up or something, can anyone provide an explanation?
Without any research whatsoever I'm going to guess that in the summer, the sun heats the land causing warm air to rise (causing an area of low pressure over the beach). Then the cold air over the ocean rushes in to replace it. Thus causing an onshore breeze.
Land warms faster than water. Air warms, expands, rises, lowers pressure.
Water absorbs the heat and the air does warm as fast, and the pressure stays higher.
Winds follow pressure, so the winds move onshore.
In the morning they are equal, as the land hasn't heated up yet.
Sea breeze usually hits late afternoon, sometimes much earlier when the temp/pressue difference is greater (you'll notice it can go onshore as early as 10-11 am in the summer.
That's what's nice about early fall...the land doesn't heat up as quick, and the ocean is at it's warmest of the year...so you can get offshores all day long.
Good timing on your question... The Swellinfo wind data has just been updated, literally within the past 20 minutes. The land/sea breezes should be more accurate now (not perfect) for the 0-3 day forecast. This data will be in the text forecasts, timeline forecasts, and on the nearshore wind maps. Official blog update coming later today.
Yeah, wind forecasts the past two days have been pretty off. (not just here - NWS has had it wrong, too) I've noticed over the years that forecasters simply cannot seem to nail the wind predictions in spring. Probably just too many variables. When you have a 20 degree difference between the land and water temps like the past two days, you're going to get a sea breeze.