Strong low pressure over the eastern Gulf of Mexico resulted in a slow-moving pre-frontal trough focusing heavy convective rainfall over portions of the middle and upper Florida Keys.  One EF0 tornado was observed on Big Pine Key in association with a small supercell which evolved in advance of the passing squall line. In additional, strong winds associated with a convectively-induced mesoscale low pressure system over the middle and upper Florida Keys resulted in moderate to major coastal flooding near the shores of Barnes and Card Sounds.

Flood in MONROE, FLORIDA
From 15-NOV-23 12:00:00 to 15-NOV-23 17:00:00 (EST-5)
Location: MARATHON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rainfall estimated by radar of 5 to 8 inches produced extensive poor drainage area flooding across Marathon and Key Colony Beach, with some streets with one to two feet depth of water.  Several motor vehicles stalled due to flooding.

Thunderstorm Wind in MONROE, FLORIDA
From 16-NOV-23 03:10:00 to 16-NOV-23 03:10:00 (EST-5)
Location: OCEAN REEF
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

A northeast wind gust of 57 knots was measured at the Ocean Reef Club Airport.

Flood in MONROE, FLORIDA
From 15-NOV-23 19:30:00 to 15-NOV-23 23:00:00 (EST-5)
Location: TAVERNIER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Florida DOT and Monroe County Law Enforcement reported flooding of US-1 near Mile Marker 91 in Tavernier.  Northbound lanes were nearly impassible for about one hour.  Later rainfall estimates from CoCoRAHS observers reported approximately 7 to 10 inches of rainfall by the following morning.

Coastal Flood in MONROE/UPPER KEYS, FLORIDA
From 15-NOV-23 22:00:00 to 16-NOV-23 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Coastal Flooding observed by Monroe County law enforcement, fire rescue, and Florida DOT over Card Sound Road west of the 3-way stop to just east of Card Sound Bridge, as well as for about a half mile west of Card Sound Bridge, reaching 6 to 12 inches of depth and requiring temporary closure.  Coastal flooding was also observed 1 to 2 feet deep in the Manatee Bay subdivision, and was about 6 to 12 inches deep over an exposed area of northbound U.S. 1 near Barnes Sound due to wave action.

Tornado in MONROE, FLORIDA
From 15-NOV-23 06:27:00 to 15-NOV-23 06:28:00 (EST-5)
Location: BIG COPPIT IS
Tornado F-scale: EF0
Property damage: 1.50K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A brief tornado initially developed over the
southeast edge of the Eden Pines subdivision, located over the
central portion of (the island of) Big Pine Key around 6:27 AM EST.
The relatively narrow tornado moved quickly north-northwest in
the general area framed by Lantana Lane, Buttonwood and Oleander
Drives. EF-0 damage was observed via the survey included vinyl
siding torn off a portion of a home, a couple downed and snapped
buttonwood trees, and a twisted fence.  Maximum winds of 75 mph were estimated in this portion of the Eden Pines subdivision.  The directional deposition
despite relatively low volume of debris strongly suggested a
tornadic circulation at the surface along a short and narrow path.
A resident heard a distinct audible rushing sound almost
immediately before tornado passage, notable due to the lack of any
observed wind damage off the path within the residential
subdivision. The timing of the original observation of wind
damage corresponded with the passage of a supercell on a northwest
path across central Big Pine Key and into Pine Channel.