Tonight is one of those situations where our mesoscale models can really help out the forecast…at least that’s my plan as I’ve done some minor “outpatient” surgery to the forecast for the next few days. That’s as opposed to the “open-heart” surgery we do on a day like…for example…Tuesday, December 29th at 3:30pm. Not that I’m still bitter about that day, but let’s move on…
The point is that the general plan the next few days has been for a major marine push tonight, coupled with a cold airmass (for August) moving in overhead the rest of the week.
1. The airmass appears to be mainly dry through at least Saturday/Sunday. It’s a cold trough but just really dry. Models just aren’t generating much of any precip. Other than a possible afternoon shower either tomorrow or Sunday, I think the next real chance for rain isn’t until Monday as a somewhat organized system slides in on a northwesterly jet.
2. The 2nd change goes with the image above. The mesoscale models show that we don’t get a solid layer of clouds tonight inland, or along the coast for that matter! The mixing of drier air above appears to totally disrupt the stratified marine layer. Due to that, it’s quite possible a good chunk of the metro area starts sunny tomorrow and just gets a few puffy cumulus clouds in the afternoon. Combine that with a gusty northwest wind and it should be a nice refreshing late August day. Definitely not a gloomy “marine-layer” day…no chance for drizzle, just a sprinkle from one of those clouds in the afternoon…maybe. The image above is our RPM model around 8am. In the animation (you can’t see that part) you actually see the low clouds peel down off the coast as the drier air moves south after midnight.
Friday should be a bit cloudier, but even then just lots of higher clouds. Saturday as the cold trough sinks over us we start clear…which means a very cold start, probably the coldest so far this late summer season. Then we get pop-up afternoon clouds with maybe a mountain shower.
So…not a gloomy forecast at all, just some real “September Weather” for the last few days of August. It’ll be time to try and get a roof on the chicken coop and kids treehouse this weekend since the walls are all finished.
Chief Meteorologist Mark Nelsen