High pressure was located over the Atlantic Ocean and an upper trough of low pressure moved into the Ohio Valley.  Flow between the exiting high and approaching low pressure caused onshore flow to develop that led to dense fog across the Mid Atlantic.

Dense Fog in ORANGE, VIRGINIA
From 25-DEC-12 01:15:00 to 25-DEC-12 10:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was reported around a quarter mile at Orange airport.

Dense Fog in CULPEPER, VIRGINIA
From 25-DEC-12 03:35:00 to 25-DEC-12 10:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was reported around a quarter mile at Culpeper airport.

Dense Fog in PRINCE WILLIAM, VIRGINIA
From 25-DEC-12 04:15:00 to 25-DEC-12 09:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was reported around a quarter mile at Manassas airport.

Dense Fog in SOUTHERN FAUQUIER, VIRGINIA
From 25-DEC-12 03:15:00 to 25-DEC-12 10:30:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was reported around a quarter mile at Warrenton-Fauquier airport.

Dense Fog in ROCKINGHAM, VIRGINIA
From 25-DEC-12 05:30:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was reported around a quarter mile at Shenandoah airport.

Dense Fog in AUGUSTA, VIRGINIA
From 25-DEC-12 05:30:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was estimated around a quarter mile at Shenandoah airport.

Dense Fog in SHENANDOAH, VIRGINIA
From 25-DEC-12 03:30:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Shenandoah, Winchester and Luray airport.

Dense Fog in NORTHERN FAUQUIER, VIRGINIA
From 24-DEC-12 21:06:00 to 25-DEC-12 09:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Dulles International airport.

Dense Fog in WARREN, VIRGINIA
From 25-DEC-12 04:35:00 to 25-DEC-12 13:35:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Luray airport.

Dense Fog in STAFFORD, VIRGINIA
From 25-DEC-12 07:35:00 to 25-DEC-12 09:35:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was reported around a quarter mile at Stafford airport.

Dense Fog in RAPPAHANNOCK, VIRGINIA
From 25-DEC-12 01:53:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Charlottesville airport.

Dense Fog in PAGE, VIRGINIA
From 25-DEC-12 04:35:00 to 25-DEC-12 13:35:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was reported around a quarter mile at Luray airport.

Dense Fog in LOUDOUN, VIRGINIA
From 24-DEC-12 21:06:00 to 25-DEC-12 09:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was reported around a quarter mile at Dulles International and Leesburg airport.

Dense Fog in FREDERICK, VIRGINIA
From 25-DEC-12 01:35:00 to 25-DEC-12 12:10:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was reported around a quarter mile at Winchester airport.

Dense Fog in CLARKE, VIRGINIA
From 25-DEC-12 01:35:00 to 25-DEC-12 12:10:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Visibility was estimated around a quarter mile at Winchester airport.

Dense Fog in ALBEMARLE, VIRGINIA
From 25-DEC-12 01:53:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was reported around a quarter mile at Charlottesville airport.

Dense Fog in NELSON, VIRGINIA
From 25-DEC-12 01:53:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Charlottesville and Lynchburg airport.

Dense Fog in GREENE, VIRGINIA
From 25-DEC-12 01:53:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Charlottesville airport.

Dense Fog in MADISON, VIRGINIA
From 25-DEC-12 01:53:00 to 25-DEC-12 11:50:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Visibility was estimated around a quarter mile at Charlottesville airport.