A combo satellite that carries instruments to precisely measure ocean winds on Earth and approaching geomagnetic storms from the Sun will ride a refurbished U.S. Titan 2 missile into orbit Sunday from California, weather permitting.

The Coriolis spacecraft, a joint endeavor between the U.S. Air Force and Navy, remains scheduled for liftoff from Vandenberg Air Force Base's Space Launch Complex 4-West at 1418 GMT (9:18 a.m. EST; 6:18 a.m. PST). The day's launch window extends for 15 minutes.

Early weather forecasts call for an 80 percent chance that winds, clouds and rain will scrub the launch. A backup launch opportunity is available on Monday, but meteorologists are predicting similar conditions.

"We've planned hard, we've trained hard, we've taken great pains in the processing cycle to make sure we do everything right and we are go for launch," Lt. Col. Clint Crosier, 2nd Space Launch Squadron commander at Vandenberg, said in an interview Thursday.

"My biggest concern right now is simply weather. I feel very comfortable that across the community we are green and go for all of our capabilities and requirements. The weather is the one issue that could potentially hold us up. But we don't have any hardware anomalies or anything like that in process that are going to cause any trouble, at least not at this point."

After an hour-long ascent, the Titan 2 rocket is expected to deploy the 1,798-pound satellite into the targeted Sun-synchronous orbit around Earth's poles with a high point of 447 nautical miles, low point of 150 nautical miles and inclination of 98.7 degrees to the equator. Coriolis will later maneuver itself into a circular orbit about 450 miles up.

This Titan 2 stood in an underground silo at Davis-Monthan Air Force Base in Arizona from 1967 to 1982, topped with a 9.6 megaton nuclear warhead, as part of the U.S. Intercontinental Ballistic Missile arsenal. During the Titan ICBM deactivation, the two-stage booster was converted by Lockheed Martin to serve as a space launch vehicle.

"That is the neat thing about the Titan 2s is they have done previous duty as war birds as ICBMs, they have led a dual life," Capt. Dan Wetmore, the Air Force launch controller for Sunday's mission, said in an interview. "It is in a kinder, gentler phase of its life now."

The Coriolis craft, made by Spectrum Astro, serves as the orbiting platform for the Navy's Windsat microwave polarimetric radiometer and the Air Force's Solar Mass Ejection Imager.

The Windsat payload aims to gather wind speed and direction measurements at or near the surface of Earth's seas. Such information promises to benefit the Navy's planning of operations and improve weather forecasting.

"We are very, very interested in wind direction and wind speed, not only from a safety of operations standpoint but from the tactical exploitation of the atmosphere -- what direction do you steam the battle group to launch, which direction do you have your underway replenishments in, which areas do you avoid. So this is an operational sensor," Navy Capt. Bob Clark, manager of meteorological and oceanographic programs, said in an interview Thursday.

The Solar Mass Ejection Imager will provide an early warning of coronal mass ejections from the Sun that impact Earth, disrupting communications and power grids. Mission officials say the system should give one to three days notice to prepare for impending geomagnetic storms by tracking the ejections as they head for our home planet.

"What this sensor is designed to do is to sense, earlier than we presently can sense, solar emissions from the Sun which are electromagnetic pulses which do affect military and civilian operations," Clark said.

Coriolis will embark on its three-year mission if there's a break in the expected bad weather along the central coastline of California.

"We got an 'up' check on all systems as far as readiness for launch. The only thing we're watching right now is the developments of weather into Sunday morning. There's a lot of different things to worry about -- wind direction, wind shear, rain, rain rates, the amount of electricity in the atmosphere," Clark said.

Sunday's weather forecast calls for broken clouds at 2,000 feet with 7/8ths sky coverage and tops at 8,500 feet and complete overcast decks from 10,000 to 18,000 feet and 20,000 to 26,000 feet, five miles of visibility, northwesterly winds from 290 to 340 degrees at 15 gusting to 20 knots, a temperature of 50 to 54 degrees F and light rain.

Lt. Paul Lucyk, the launch weather officer, gave this overview on Thursday:

"High pressure continues to build in off the coast and is the dominant feature for the Vandenberg area. Over the next few days, winds will be primarily onshore, from the northwest. Expect low clouds and fog in the mornings with early afternoon sun throughout the forecast period. The onshore winds will moderate the temperatures and keep them in the low 50's at night and upper 50's to near 60 during the day. Upper level winds for the launch will be out of the south-southwest, reaching a maximum near 30 knots between 30,000 and 35,000 feet."

In the event of a one-day launch delay, Lucyk predicts: "Weather conditions will remain similar for a 24 hour scrub, as high pressure continues to dominate the Central Coast on Tuesday. Upper level winds Tuesday morning are forecast to be predominately from the west-southwest, reaching a maximum of about 20 knots near 30,000 feet."

The specific concerns on Sunday -- prompting the 80 percent chance of violating the launch weather rules -- are high winds as measured at the 102-foot level, precipitation above 4,000 feet, thick cloud layers and cumulus cloud avoidance.

On Monday, the percentage remains 80 'no go' due to the 102-foot level winds, cumulus avoidance and thick cloud layers.