A stalled frontal boundary acted as the triggering point for an initial line of showers and thunderstorms, with many of the storms becoming severe with strong moisture advection combining with diurnal heating and leading to an unstable air mass. The remnants of Tropical System Bill moved through the Mid-Atlantic overnight, continuing the severe threat late into the early part of the overnight hours.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 20-JUN-15 19:20:00 to 20-JUN-15 20:20:00 (EST-5)
Location: LYLES-CROUCH ACADEMY ALEXANDRIA
Magnitude: 54.00 MG
Reported by: Buoy

Upper Tidal Potomac Buoy 44061 reported gusts between 31 and 54 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC INDIAN HD TO COBB IS MD, ATLANTIC NORTH
From 20-JUN-15 20:00:00 to 20-JUN-15 20:10:00 (EST-5)
Location: CUCKOLD CREEK
Magnitude: 54.00 MG
Reported by: Mesonet

CCK reported gusts of 36 to 54 knots.

Marine Thunderstorm Wind in PATAPSCO RIVER INCLUDING BALTIMORE HARBOR, ATLANTIC NORTH
From 20-JUN-15 20:12:00 to 20-JUN-15 21:30:00 (EST-5)
Location: RIVIERA BEACH
Magnitude: 40.00 MG
Reported by: Mesonet

FSKM2 reported gusts between 32 and 40 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY SANDY PT TO N BEACH MD, ATLANTIC NORTH
From 20-JUN-15 21:30:00 to 20-JUN-15 21:30:00 (EST-5)
Location: KENT ISLAND
Magnitude: 34.00 EG
Reported by: Mesonet

KNT reported gusts between 31 and 34 knots.

Marine Thunderstorm Wind in TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH ISLAND, ATLANTIC NORTH
From 20-JUN-15 22:27:00 to 20-JUN-15 22:27:00 (EST-5)
Location: BISHOPS HEAD
Magnitude: 41.00 MG
Reported by: Mesonet

BHD reported gusts of 41 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 20-JUN-15 19:19:00 to 20-JUN-15 19:19:00 (EST-5)
Location: WASHINGTON NATIONALS PARK
Magnitude: 34.00 EG
Reported by: Mesonet

PEPCO reported gusts between 31 and 34 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY N BEACH TO DRUM PT MD, ATLANTIC NORTH
From 20-JUN-15 20:42:00 to 20-JUN-15 20:48:00 (EST-5)
Location: COVE POINT
Magnitude: 36.00 MG
Reported by: Mesonet

COVM2 reported gusts between 32 and 36- knots.

Marine Thunderstorm Wind in CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER, ATLANTIC NORTH
From 20-JUN-15 20:55:00 to 20-JUN-15 20:55:00 (EST-5)
Location: HORN POINT
Magnitude: 42.00 MG
Reported by: Mesonet

BWH reported gusts of 42 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY SANDY PT TO N BEACH MD, ATLANTIC NORTH
From 20-JUN-15 21:07:00 to 20-JUN-15 21:17:00 (EST-5)
Location: TOLLY POINT
Magnitude: 35.00 MG
Reported by: Mesonet

TOL reported gusts between 31 and 35 knots.

Marine Thunderstorm Wind in CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER, ATLANTIC NORTH
From 20-JUN-15 21:12:00 to 20-JUN-15 21:12:00 (EST-5)
Location: CAMBRIDGE
Magnitude: 34.00 MG
Reported by: Mesonet

CAMM2 reported gusts of 34 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY SANDY PT TO N BEACH MD, ATLANTIC NORTH
From 20-JUN-15 21:18:00 to 20-JUN-15 21:18:00 (EST-5)
Location: STEVENSVILLE
Magnitude: 43.00 MG
Reported by: AWOS

KW29 reported gusts of 43 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 20-JUN-15 21:20:00 to 20-JUN-15 21:30:00 (EST-5)
Location: LYLES-CROUCH ACADEMY ALEXANDRIA
Magnitude: 49.00 MG
Reported by: Buoy

Upper Tidal Potomac Buoy 44061 reported gusts between 35 and 49 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY N BEACH TO DRUM PT MD, ATLANTIC NORTH
From 20-JUN-15 22:00:00 to 20-JUN-15 22:30:00 (EST-5)
Location: MID BAY BUOY
Magnitude: 45.00 MG
Reported by: Buoy

Goose Reef Buoy 44062 reported gusts between 35 and 45 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY DRUM PT TO SMITH PT VA, ATLANTIC NORTH
From 20-JUN-15 22:00:00 to 20-JUN-15 22:05:00 (EST-5)
Location: POINT LOOKOUT
Magnitude: 39.00 MG
Reported by: Mesonet

PTL reported gusts between 34 and 39 knots.

Marine Thunderstorm Wind in TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH ISLAND, ATLANTIC NORTH
From 20-JUN-15 23:04:00 to 20-JUN-15 23:39:00 (EST-5)
Location: CRISFIELD
Magnitude: 37.00 MG
Reported by: Mesonet

CRS reported gusts of 31 and 37 knots.

Marine Thunderstorm Wind in TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH ISLAND, ATLANTIC NORTH
From 20-JUN-15 23:19:00 to 20-JUN-15 23:19:00 (EST-5)
Location: RACCOON POINT
Magnitude: 34.00 EG
Reported by: Mesonet

RAC reported gusts between 33 and 34 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC INDIAN HD TO COBB IS MD, ATLANTIC NORTH
From 20-JUN-15 18:44:00 to 20-JUN-15 18:44:00 (EST-5)
Location: QUANTICO
Magnitude: 34.00 EG
Reported by: ASOS

KNYG reported gusts between 32 and 34 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 20-JUN-15 19:17:00 to 20-JUN-15 19:17:00 (EST-5)
Location: (DCA)REAGAN NATIONAL AIRPORT
Magnitude: 34.00 EG
Reported by: ASOS

KDCA reported gusts between 33 and 34 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC INDIAN HD TO COBB IS MD, ATLANTIC NORTH
From 20-JUN-15 19:23:00 to 20-JUN-15 20:00:00 (EST-5)
Location: QUANTICO
Magnitude: 54.00 MG
Reported by: ASOS

KNYG reported gusts between 37 and 54 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC INDIAN HD TO COBB IS MD, ATLANTIC NORTH
From 20-JUN-15 19:54:00 to 20-JUN-15 19:54:00 (EST-5)
Location: COLONIAL BEACH
Magnitude: 38.00 MG
Reported by: Mesonet

CLNLB reported gusts of 38 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC INDIAN HD TO COBB IS MD, ATLANTIC NORTH
From 20-JUN-15 20:04:00 to 20-JUN-15 20:24:00 (EST-5)
Location: COBB POINT
Magnitude: 46.00 MG
Reported by: Mesonet

COB reported gusts between 33 to 46 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC INDIAN HD TO COBB IS MD, ATLANTIC NORTH
From 20-JUN-15 20:04:00 to 20-JUN-15 20:09:00 (EST-5)
Location: POTOMAC LIGHT
Magnitude: 48.00 MG
Reported by: Mesonet

LT3 reported gusts between 33 to 48 knots.

Marine Thunderstorm Wind in PATAPSCO RIVER INCLUDING BALTIMORE HARBOR, ATLANTIC NORTH
From 20-JUN-15 20:05:00 to 20-JUN-15 20:20:00 (EST-5)
Location: MARYLAND SCIENCE CENTER
Magnitude: 36.00 MG
Reported by: Mesonet

BLMRE reported gusts of 36 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY N BEACH TO DRUM PT MD, ATLANTIC NORTH
From 20-JUN-15 20:20:00 to 20-JUN-15 21:00:00 (EST-5)
Location: MID BAY BUOY
Magnitude: 52.00 MG
Reported by: Mesonet

Goose Reef Buoy 44062 reported gusts between 33 and 51 knots.

Marine Thunderstorm Wind in TIDAL POTOMAC COBB IS MD TO SMITH PT VA, ATLANTIC NORTH
From 20-JUN-15 20:24:00 to 20-JUN-15 20:30:00 (EST-5)
Location: PINEY POINT
Magnitude: 34.00 MG
Reported by: Mesonet

PPTM2 reported gusts between 33 and 34 knots.

Marine Thunderstorm Wind in CHESAPEAKE BAY DRUM PT TO SMITH PT VA, ATLANTIC NORTH
From 20-JUN-15 20:39:00 to 20-JUN-15 20:39:00 (EST-5)
Location: PATUXENT RIVER ASOS
Magnitude: 39.00 MG
Reported by: ASOS

KNHK reported gusts of 39 knots.