Maryland Weather: Storms again threaten Minotaur launch - Weather forecast: Meteorology and climate conditions in the Baltimore region from reporter Frank Roylance

More showers and thunderstorms are forecast for the Eastern Shore Friday and Saturday nights, which will be the last opportunities for what could be weeks for the launch of a 69-foot Minotaur rocket from the NASA Wallops Flight Facility.

NASA The launch, only the fourth attempt to put satellites in orbit from Virginia, could be visible for hundreds of miles if skies are clear. Two attempts this week have been scrubbed due to bad weather.

UPDATE at 4 p.m.: Launch window will open early, at 7:35 p.m., in an effort to get the rocket off before bad weather moves in. There is a 50 percent chance of another scrub. Earlier post resumes below.

If the rocket doesn't get off during tonight's 8-11 p.m. launch window, the launch team will regroup for another attempt on Saturday night. After that, NASA will need to reconfigure the facility to support Monday's planned launch of the space shuttle Atlantis from Cape Canaveral in Florida. Atlantis and its crew of seven astronauts are headed for an 11-day mission to repair and upgrade the Hubble Space Telescope.

Keith Koehler, spokesman for Wallops, said that once Atlantis has landed, the Wallops tracking station will be needed again to support another Florida launch. He wasn't sure which that was. The only one I could find that's coming up on the NASA launch schedule in Florida is the Lunar Reconnaissance Orbiter and the Lunar Crater Observing and Sensing Satellite, set for a tandem launch on June 2. The two spacecraft are being sent to the moon to scout potential landing sites, and search for water near the north and south lunar poles.

There's another shuttle launch - Endeavour - scheduled for June 13. How Wallops will slip the Minotaur 1 and its Air Force TacSat-3 satellite into the mix will depend on when Atlantis actually launches and when it returns.

Our forecast for the next two nights looks about the same as last night's. Ditto for the Virginia Shore. That means a threat of showers and thunderstorms as solar heating stirs up all this humidity and kicks off convection. Bad weather has already scrubbed two Minotaur launch attempts on Tuesday and Thursday nights. Last night, the launch pad had to be cleared because of nearby lightning. And heavy rains swept the rocket as it stood on the pad just before the game was called at around 10 p.m.

The forecasters out at Sterling say these storms are continuing to track along with the jet stream, one after the other, as they have all week. The next batch should reach Central Maryland this NOAA evening. They could come in waves, with some locations being smacked by repeated showers and storms through the night.

Saturday will bring more of the same and some storms will have the potential to become severe, with damaging winds and large hail a possibility, especially east of the Blue Ridge.

By Sunday, however, the front that has served as a railroad track for these storms will push farther south, and we will finally begin to enjoy cooler, drier air from the north and west. Incredibly, the forecast calls for "partly" and "mostly" sunny weather here from Sunday through Wednesday. Highs will be seasonable, and comfortable, in the upper 60s and low 70s.

That would end what will likely become nine straight days of rainfall at BWI. Streamflow across the state is shown in the map below. Green dots show streams that have returned to normal levels for this time of year. Blue are above normal. Black are still at record highs.

So far, the total has come to 3.88 inches. I got my calculation of Thursday's total wrong the other day. Here's the official toll so far:

May 1: 0.02 inch USGS