My uncertainty last night with today’s forecast is manifest this morning, as we have an area of showers that is almost stationary and is oriented along the upper air jet flow vorticity at 300mb. This feature could be persistent today and the NAM model (often wrong lately) has been correct with this forecast so far. Indeed, the NAM predicts even heavier showers for the afternoon today.
Some areas today won’t see much if any rain, but if you’re currently getting some rain, this area of rain may be persistent and slow to move.
After a string of almost perfect weekend weather this summer, today’s less than stellar weather is nature’s way of moving things toward the mean.
Building cumulonimbus with altostratus late Thursday
A blocking pattern is causing high pressure near Nova Scotia to maintain an easterly flow of moisture, resulting in considerable cloudiness, cool temperatures and an ongoing chance of showers on Saturday.
This high pressure system is expected to build down over us later on Saturday, allowing a more northerly flow of drier air. Clearing skies late Saturday should remain with us through Sunday.
The NAM has a much greater chance of showers during the day on Saturday than the GFS, but it has a tendency to overstate precipitation lately. Neither model has done very well with this blocking pattern over the past week and I have lower confidence in this forecast, especially for Saturday.
Sat 8/23: Mostly cloudy, a chance of widely scattered showers but mostly dry. Brightening skies late in the afternoon. High 77.
Sun 8/24: Sunny and warmer. Some fair weather clouds develop in the afternoon. High 83.
