Rain chances for Opening Day at Oriole Park at Camden Yards may be increasing, but there is still some uncertainty on how significantly a moist system from the Gulf of Mexico could affect the region.
Even so, rain could start to clear in time for the 3:05 p.m. Friday first pitch.
The National Weather Service is forecasting 60 percent chances of rain Friday, up slightly from 50 percent chances in earlier forecasts.
Forecasts call for what is known as a "Miller A type low" moving up from the Gulf of Mexico, though there is some uncertainty as to the track and timing of the system, according to the weather service's forecast discussion.
That type of system develops near the southeast coast and moves toward the Atlantic, either moving out to sea or up the East Coast, said Kevin Witt, a meteorologist in the weather service's Baltimore/Washington forecast office in Sterling, Va.
"In this case, the low is going to follow along the coast and then move out to sea when it gets to New Jersey," Witt said. About half an inch of rain is possible across Virginia and Maryland from late Thursday through Friday.
The calculation of 50-60 percent odds comes from a look at various forecasting models that show different expectations for the system's track. As Friday draws closer, the rain likelihood typically increases or decreases as the forecast becomes clearer.
AccuWeather.com is meanwhile calling for periods of rain Friday, but clearing by the evening. The Weather Channel is calling for 70 percent chances of rain.
Regardless of the precipitation, temperatures are expected to remain below normal late in the week. Highs are expected in the lower 50s Friday.
No worries about the weather for the Orioles' season opener Tuesday, essentially a spring training extension just an hour's drive from the team's home in Sarasota, Fla. Dry air is moving into the Tampa Bay area as the Orioles take on the Rays, according to the weather service's Tampa Bay forecast office. But regardless, the teams will start the 2013 season under the dome of Tropicana Field.