* WHAT. Temperatures in the mid 30s will result in frost formation. * WHERE. Adams, Cumberland, Dauphin, Lancaster, and York Counties. * WHEN. From 3 AM to 9 AM EDT Friday. * IMPACTS. Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.

* WHAT. Temperatures as low as 35 will result in frost formation. * WHERE. Portions of central and northern Maryland, and central and northern Virginia. * WHEN. From 3 AM to 9 AM EDT Friday. * IMPACTS. Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered.

Elevated fire conditions are expected due to dry conditions and gusty winds. Relative humidity values around 30 percent are expected, along with sustained northwesterly winds of 15 to 20 mph and gusts of 25 to 30 mph. This will result in the rapid drying of fine fuels. Residents and visitors are urged to exercise caution if handling open flames or equipment that create sparks. Also, dispose of cigarette butts, matches, and other flammable items in appropriate containers. Keep vehicles off of dry grass and obey local burn bans. Most dry grasses, dead leaves, and other tree litter could easily ignite and spread fire quickly. For more information about wildfire danger, burn restrictions, and wildfire prevention and education, please visit your state's forestry or environmental protection website.

* WHAT. North winds 15 to 25 kt with gusts up to 30 kt and waves 2 to 4 ft. * WHERE. Chesapeake Bay main channel north of Smith Point VA, Tidal Potomac from Cobb Island MD to Smith Point VA, Chester River to Queenstown MD, Eastern Bay, Choptank River to Cambridge MD and the Little Choptank River, Patuxent River to Broomes Island MD, and Tangier Sound and the inland waters surrounding Bloodsworth Island. * WHEN. Until 6 AM EDT Friday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Northwest winds 15 to 20 kt with gusts up to 30 kt. * WHERE. Tidal Potomac River from Key Bridge to Cobb Island MD, and Patapsco River including Baltimore Harbor. * WHEN. Until 6 PM EDT this evening. * IMPACTS. Conditions will be hazardous to small craft.

A combination of dry and windy conditions will create an elevated risk of wildfire spread across mainly southern Pennsylvania today. Relative humidity values dip to the 30 to 40 percent range this afternoon accompanied by wind gusts out of the northwest between 15 and 25 MPH. The higher gusts will be along and to the southeast of I-81. Residents are urged to exercise caution if handling any potential ignition sources, such as machinery, cigarettes, or matches. If dry grasses and tree litter begin to burn, the fire will have the potential to spread rapidly. For more information about wildfire danger and wildfire prevention and education, please visit the Pennsylvania Department of Conservation and Natural Resources website at http://dcnr.pa.gov/Communities/Wildfire.