In Seatac this morning, the weather is partly sunny and cool. It looks like today may be a pleasant day. There are a few L1 cumulus clouds around, but I did need sunglasses this morning, which I had to find in my car, as I haven’t used them for several days.
The National Weather Service (NWS) in Seattle forecasts a mostly sunny day today with a high temperature of 72 F and a 6 mph west-southwest wind. This evening will be mostly cloudy with a low temperature of 59 F and west winds becoming calm by late evening.
The visible satellite imagery shows clearer skies than we’ve seen at this hour over the last few days.
The enhanced infrared satellite imagery shows no thick clouds over the state. This image has been excluded from today’s post.
The water vapor satellite imagery shows uniform moisture over the state today. This image has been excluded from today’s post.
The 12Z upper air sounding from UIL shows a less mixed and slightly drier sounding this morning, with moisture remaining in the boundary layer below around 900 mb. There was only 0.81 inches of precipitable water present in the column this morning and no Convective Available Potential Energy (CAPE). There was no strong thermal inversion near the surface, and the 0-3 km average lapse rate was 4.4 C/km.
The deep-layer shear was 20 kts (speed changes), and the low-level shear was 9 kts (directional changes).
The surface observations (from the SPC Mesoscale Analysis Map) show still winds across the state today, and mostly clear skies. There are no major boundaries present over the state in this graphic.
The surface pressure map shows no strong pressure gradients over the state this morning, and none are expected to develop in the next six hours, according to the RAP.
Synoptically speaking, the 300 mb NAM chart (from Unisys) shows that the upper-level low has weakened, though there is a weak jetstreak moving through the area.
The 500 mb NAM chart shows no significant vorticity advection over the state today. This chart has been excluded from today’s post.
The 700 mb NAM chart shows no rapidly-rising air over the state today. This chart has been excluded from today’s post.
The 850 mb NAM shows only weak Cold Air Advection (CAA) today, so perhaps we are about done with that.
Overall, I expect a pleasant day today. I am getting ready to go for a run, and will enjoy this weather before the rain hits tomorrow.
Thank you for reading my forecast.
The upper air soundings and mesoscale analysis plots are from the Storm Prediction Center website.
The forecasted upper air soundings are from TwisterData.com.
The surface observation and upper level charts are from Unisys Weather.
The satellite data is from NASA – MSFC