A boundary stalled over the area. Warm and humid conditions led to an unstable atmosphere while an upper-level trough passed through the area. The forcing from the boundary front combined with the instability to trigger thunderstorms. Stronger shear from the upper-level trough caused some thunderstorms to produce gusty winds.

Marine Thunderstorm Wind in CHESAPEAKE BAY SANDY PT TO N BEACH MD, ATLANTIC NORTH
From 19-JUL-16 22:11:00 to 19-JUL-16 22:16:00 (EST-5)
Location: TOLLY POINT (TOL)
Magnitude: 40.00 MG
Reported by: Buoy

Wind gusts of 40 knots were reported at Tolly Point.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 22:40:00 to 19-JUL-16 22:40:00 (EST-5)
Location: PEPCO (PEPCO)
Magnitude: 50.00 EG
Reported by: Unknown

Wind gusts up to 50 knots were estimated based on thunderstorm wind damage nearby.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 23:40:00 to 19-JUL-16 23:50:00 (EST-5)
Location: UPPER POTOMAC BUOY (44061)
Magnitude: 37.00 MG
Reported by: Buoy

A wind gust of 37 knots was reported. at the Upper Potomac Buoy.

Marine Hail in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 22:04:00 to 19-JUL-16 22:09:00 (EST-5)
Location: NATIONALS PARK (WSHNP)
Magnitude: 1.00 
Reported by: Public

Quarter sized hail was reported.

Marine Hail in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 22:08:00 to 19-JUL-16 22:08:00 (EST-5)
Location: NATIONALS PARK (WSHNP)
Magnitude: 0.88 
Reported by: Public

Nickel sized hail was reported.

Marine Thunderstorm Wind in CHESAPEAKE BAY POOLES IS TO SANDY PT MD, ATLANTIC NORTH
From 20-JUL-16 00:40:00 to 20-JUL-16 00:40:00 (EST-5)
Location: SANDY POINT (SPT)
Magnitude: 34.00 EG
Reported by: Buoy

Wind gusts in excess of 30 knots were reported at the Annapolis Buoy.

Marine Thunderstorm Wind in CHESAPEAKE BAY POOLES IS TO SANDY PT MD, ATLANTIC NORTH
From 19-JUL-16 23:40:00 to 19-JUL-16 23:40:00 (EST-5)
Location: PATAPSCO BUOY (44043)
Magnitude: 34.00 EG
Reported by: Buoy

Wind gust in excess of 30 knots was reported at the Patapsco Buoy.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 21:55:00 to 19-JUL-16 21:59:00 (EST-5)
Location: GEORGE WASHINGTON UNIVERSITY (GWUNI)
Magnitude: 40.00 MG
Reported by: Mesonet

Wind gusts up to 40 knots were reported.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 21:59:00 to 19-JUL-16 21:59:00 (EST-5)
Location: GEORGE WASHINGTON UNIVERSITY (GWUNI)
Magnitude: 45.00 MG
Reported by: Mesonet

Wind gusts up to 45 knots were reported at the Ellipse.

Marine Thunderstorm Wind in TIDAL POTOMAC KEY BRIDGE TO INDIAN HD MD, ATLANTIC NORTH
From 19-JUL-16 22:04:00 to 19-JUL-16 22:09:00 (EST-5)
Location: (DCA)REAGAN NATIONAL AIRPORT
Magnitude: 34.00 EG
Reported by: ASOS

Wind gusts in excess of 30 knots were reported at Reagan National.

Marine Thunderstorm Wind in CHESAPEAKE BAY SANDY PT TO N BEACH MD, ATLANTIC NORTH
From 19-JUL-16 22:10:00 to 19-JUL-16 22:49:00 (EST-5)
Location: GREENBERRY POINT (GBY)
Magnitude: 40.00 MG
Reported by: Buoy

Wind gusts of 40 knots were reported at Greenbury Point.