If you're hoping for at least one good outdoor day this weekend, it looks like Saturday will be your best bet. The next coastal storm in this autumn's continuing parade is fixing to spin on up the East Coast, and we're likely to fall under its rain shield as early as Sunday afternoon.

Saturday, however, looks great for a hike or a roll up the bike trail. High pressure centered in the Ohio Valley is building across the region today (Friday) and will bring us more sunshine Saturday, with a high in the upper 50s.

The relatively mild temperatures are the work of bright sunshine, and something called "downsloping." Winds out of the west or northwest flow across the Appalachians and slide down the eastern slope. And as they descend, the air is compressed, which warms it up. The average highs at BWI at this time of year are in the mid-50s.

By Sunday, however, clouds will be on the increase, with the chance of showers rising in the afternoon as a low-pressure system forming over the Gulf moves off the Southeast coast. The computer models disagree, of course, on the timing, and on how close the low will come to the shore. And, as it does with winter storms, that storm track will determine just how much precipitation we see.

Whatever we get, it's likely to arrive late Sunday into Monday. We may get a brief look at the sun again on Tuesday, but there's more rain likely at mid-week as the next cold front slides by. From this distance, Thanksgiving Day is looking like a gray one, too, with a 40 percent chance of rain.

(SUN PHOTO/Jerry Jackson/2007)