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Fort Lauderdale Extreme Rainfall and Flooding Event
A review of the historic rainfall and flooding event that occurred around Fort Lauderdale beginning April 12, 2023.
Event Overview
During the afternoon and evening of April 12th, 2023, prolific amounts of rain fell across the southeast coast of Florida, including the cities of Fort Lauderdale, Hollywood, and Dania Beach. Showers and thunderstorms repeatedly training over this urban corridor brought multiple hours with rainfall rates of 3-6 inches/hour, and 12-hour amounts exceeding 20 inches. Flash flooding crippled the area, leaving people stranded in inundated vehicles and homes, while also shutting down a major airport, and leading to a significant recovery effort. Follow along as we walk through the factors that lead to this historic weather event, the timeline in which it occurred, and the aftermath left in its wake.
Meteorological Setup
Synoptic Conditions
Synoptic - Mid to Upper Levels: 500 mb and 300 mb analysis maps at 11AM show a closed upper-level low centered over the TX-LA border, with a subtropical jet stream extending into the Eastern Gulf of Mexico.
The left exit region of the jet encompassed South Florida, supporting large scale upward motion in the area. Divergent flow, noted in the purple hatched area, was evident at both the 500 mb and 300 mb levels over South Florida. With W/SW flow over the area, there was very little advection of cool air aloft, allowing for nearly moist adiabatic lapse rates in the mid to upper levels.
Synoptic - 850 mb: 850 mb analysis at 11AM shows moist E/SE flow across South Florida. Note that this wind direction is perpendicular to the winds aloft, implying enhanced hodograph arcing and reduced cloud-layer mean winds!
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Synoptic - Surface: Surface analysis maps issued on 4/12 at 7AM and 2PM show a warm front slowly lifting north from the Florida Straits up into South Florida.
As the front continues to lift north throughout the day, large-scale ascent, as well as moisture advection (dewpoints in the 70s) will occur across South Florida.
Mesoscale Environment Conditions:
Mesoscale - Forecast Sounding: The 20Z RAP area-averaged sounding showed significant potential for slow moving, heavy precipitation supercells and multicells.
Looking at the winds, there is sharp veering throughout the column, with Sfc-6km wind shear of 37 knots, favorable for rotating thunderstorms. The slow-moving storm potential is noted when looking at the 1km and 6km wind barbs, which are nearly opposite. This opposing steering flow is reflected in the Cloud Layer Mean Winds, which show southerly around 10 knots.
Swipe to the left to see the tall/skinny CAPE profile, low LCLs, and high precipitable water (PW) values highlighted. These features/values all indicate the potential for heavy precipitation.
Timeline
April 11th (Previous Day)
NWS Miami issued a Flood Watch on April 11th for a majority of the Miami metropolitan area due to previous rainfall and anticipated heavy rainfall. This was in effect through April 12th.
Morning of April 12 (8-11AM EDT / 12-15Z)
Scattered showers had occurred through much of the overnight period and early morning hours.
At 9AM, NWS Miami sent additional messaging on the increasing threat and confidence of flooding along the urban corridor during the afternoon and evening.
Morning of April 12: Radar (8-11AM EDT / 12-15Z)
This radar loop, from 8-11AM, shows scattered activity rapidly becoming more organized south of Fort Lauderdale (KFLL), in association with the northward progression of the warm front.
Early Afternoon (11AM-2:39PM / 15-1839Z)
At 1130AM EDT, the Weather Prediction Center (WPC) issued a Mesoscale Discussion regarding the potential for localized flash flooding across the Miami Metro.
Mesoanalysis data began showing a pronounced bulls-eye of deep moist convergence developing near Fort Lauderdale (KFLL).
Early Afternoon: Radar (11AM-2:39PM / 15-1839Z)
From 11AM to 239PM, a wide swath of heavy precipitation with embedded supercells, slowly moved north across the area. Rainfall amounts of 3 to 5 inches were observed during this time over a large area of the metro, most of it falling in a 2 hour window. These loops show the radar reflectivity (left) and accumulated precipitation (right) during this time frame.
The anticipated flash flood threat was materializing...
Early Afternoon: MRMS (239PM / 1839Z)
With 3 to 5 inches of rainfall, and additional rain anticipated, two Flash Flood Warnings (green box) were issued across a large area of the metro, including one that covered Fort Lauderdale, at 2:39 PM.
MRMS guidance (CREST Max Unit Streamflow, and QPE:FFG Max Ratio) was a very useful tool in this situation, as it clearly depicted areas of flash flood concern.
Mid Afternoon: Radar (2:39-3:37PM / 1839-1937Z)
Supercell storm modes become more discrete, and continue to slowly move across the Fort Lauderdale area. This radar reflectivity loop does a great job of showing how much slower the supercells were moving north compared to the stratiform and multicell precipitation areas.
By 3:37PM, additional rainfall amounts of 2 to 3 inches had fallen during the past ~1 hour, totaling 4 to 7 inches over several hours. A Considerable-Tagged Flash Flood Warning was issued, centered over the Fort Lauderdale area (thick green outline at end of loops).
Mid Afternoon: MRMS (2:39-3:37PM / 1839-1937Z)
MRMS products/guidance continued to show the increasing flash flood threat across the area, supporting the considerable FFW.
Mid Afternoon: TORFF (2:56-3:38PM / 1856-1938Z)
One of the supercells moving toward the Fort Lauderdale metro area showed potential for tornado development and a tornado warning was issued. A brief tornado debris signature (TDS) was visible on radar around 3:30pm.
This was a TORFF situation, where you have a tornado warning and a flash flood warning for the same area at the same time. The advised actions for people to take during these events are conflicting (tornado - get to the lowest interior room, flash flood - get to high ground). This is a communication dilemma the NWS is actively working on.
See Impacts & Aftermath for more on this event!
Mid-Late Afternoon: Radar (3:37-5:15PM / 1937Z-2115Z)
During the mid to late afternoon, a localized and significant flash flood threat was beginning to unfold near Fort Lauderdale as storms with heavy precipitation began to stall and/or train over the area.
During a ~2hr period, over 9 inches of rain fell at the Fort Lauderdale - Hollywood International Airport (FLL), including over 6 inches during the 4-5PM hour!
4:01PM - With the heavy rainfall, NWS Miami sent out a call for reports.
Mid-Late Afternoon: MRMS (3:37-5:15PM / 1937Z-2115Z)
As one would think, with rainfall totals of 8-11 inches from 1-5PM, MRMS FLASH guidance highlighted the area of concern very well, and reports of significant flooding began to emerge...
Mid-Late Afternoon: Reports (3:37-5:15PM / 1937Z-2115Z)
One of the first reports of flooding was from Fort Lauderdale - Hollywood International Airport (FLL), which halted all inbound and outbound activity due to the conditions at 4:15PM.
Videos from the area around the time showed notable flooding taking place along the perimeter of the airport, and in the 'Arrivals' area of the airport.
Late Afternoon: Reports (5:00-5:15PM / 2100Z-2115Z)
As we moved past the top of the 5PM hour, additional reports came in showing conditions worsening across portions of the Fort Lauderdale area.
At FLL, roadways entering and exiting the airport became impassable, with several vehicles becoming stuck and inundated. FLL advised the public to avoid the area.
In downtown Fort Lauderdale, roads were also becoming inundated.
Early Evening: Radar (5:15-6:21PM / 2115Z-2221Z)
Nearly stationary storms remained over the Fort Lauderdale area for much of this time period, with another 1-3 inches of rainfall. As a majority of the rainfall finally moved north, in the same direction as the background wind field, training-convection along the coast developed into another supercell structure, just south of the hardest hit area...
3-hour observed rainfall totals from FLL approached 12 inches(!!!), with daily totals to this point of 7-14 inches across the area.
Early Evening: MRMS (5:15-6:21PM / 2115Z-2221Z)
With confirmed flooding, continued rainfall, and more on the way, Flash Flood Warning products were updated with stronger wording at 6:21. A second considerable-tagged Flash Flood Warning was issued south of the already ongoing one. MRMS FLASH guidance began maxing out over the area.
Early Evening: Reports (5:15-6:21PM / 2115Z-2221Z)
The reports of flooding continued to increase in numbers, and severity, as rush hour traffic commenced.
FLL's runways and roads remained closed, while roads around Fort Lauderdale were also starting to close due to flooding and the influx of traffic. Nearby communities, such as Hollywood, Dania Beach, and Edgewater also began having reports of flooding and road closures.
The severity of the flooding was leaving people and vehicles stranded across the area.
Mid Evening: Radar (6:21-7:58PM / 2221Z-2358Z)
As the evening continued, the rain would not let up, as additional slow-moving heavy precipitation storms developed/propagated across the Fort Lauderdale area.
It was becoming evident this was going to be an extreme and historic rainfall/flooding event for South Florida, as rainfall totals began to exceed 15 inches in the area...
Mid Evening: FFE! (6:21-7:58PM / 2221Z-2358Z)
So, with the continued deluge of rainfall in areas that were already seeing considerable flooding, and nightfall quickly approaching, NWS Miami issued a Flash Flood Emergency for the Fort Lauderdale area at 7:58pm.
This was the first FFE ever issued for the Miami-Fort Lauderdale-West Palm Beach metropolitan area. The auto-tweet was shared widely across Twitter with over 180,000 impressions.
WPC issued a mesoscale precipitation discussion update regarding life threatening flash flooding near Fort Lauderdale.
Mid Evening: MRMS (6:21-7:58PM / 2221Z-2358Z)
By the time of the FFE issuance, the MRMS Average Recurrence Interval Maximum was starting to exceed 150. This means these rainfall amounts had a 0.67% chance of occurring in the area in any given year.
Mid Evening: Reports (6:21-7:58PM / 2221Z-2358Z)
As the catastrophic flooding worsened through the evening, so did the number of stranded motorists, with an influx of calls to emergency officials for high-water rescues. City of Fort Lauderdale officials started requesting that residents stay off the roads.
FLL sent another update, re-iterating the closures, and images of the inundated runways started to spread on social media.
Late Evening: Radar (7:58-10:03PM/2358Z-0203Z)
While most convective activity across South Florida dropped off, a persistent cell lingered over the already devasted Fort Lauderdale area.
This was an unfortunate ‘perfect storm’ type setup, where this cell was likely sitting along the slowly northward-moving warm front, and was pinned by the subtle coastal surface trough just to its east (see graphic below).
Annotated Surface Analysis at 8PM (00z). A coastal surface trough is shown by the black dashed line. The warm front and surface low are shown in red. The yellow star is KFLL.
Late Evening: MRMS (7:58-10:03PM/2358Z-0203Z)
By 10pm, the 12-hour rainfall totals for the Fort Lauderdale area ranged from an astonishing 20 to 25 inches, with most of that falling in a 6-hour period!
MRMS guidance was now showing an ARI of over 200 (0.5% chance in any given year) across the area, while Maximum CREST Unit Streamflow and QPE:FFG Ratios were at the top of their scales.
Late Evening: Reports (7:58-10:03PM/2358Z-0203Z)
Reports, pictures, and videos of impacts continued to come in as the sun set and flooding worsened across the area.
Flooded roads were becoming filled with stuck or abandoned vehicles, and now homes were starting to experience flooding. Power outages were also starting to trickle in, making any travel or rescue efforts that much more difficult and dangerous.
8PM - Flooding at FLL, courtesy of @WPBF_BROOKE
Late Evening: TORFFE (9:16-9:55PM/0116Z-0155Z)
As the slow-moving storms propagated along the coast and over the Fort Lauderdale area, there was a period where one showed tornado-producing potential, and a Tornado Warning was issued by NWS Miami. A brief tornado debris signature was visible on radar around 9:40pm-9:50pm.
Similar to the earlier tornado event in the day, this was a TORFFE situation, which results in very complicated messaging.
See Impacts & Aftermath for more on this event!
Night: Radar (10PM-12AM/02Z-04Z)
By midnight, the rainfall aspect of this historic event was finally coming to an end, while the flooding and impacts were only just beginning.
Night: MRMS (10PM-12AM/02Z-04Z)
Following the unprecedented rainfall, radar precipitation estimates and MRMS FLASH products were all maxed out.
Night: Reports (10PM-12AM/02Z-04Z)
Catastrophic flooding continued to devastate the area, with ongoing high water rescues from homes and vehicles, and power outages complicating matters.
By midnight, several announcements were made due to the impacts of flooding, including: - FLL to remain closed until at least noon on Thursday (the following day). - City of Fort Lauderdale activated their Emergency Operations Center, and was in the process of issuing a local state of emergency. All city facilities were closed on Thursday. - Broward County also closed most facilities, as well as all schools on Thursday.
Impacts & Aftermath
The atmospheric setup on April 12th, 2023 produced an extreme amount of rainfall in a relatively short amount of time resulting in catastrophic flash flooding with long-lasting implications and a long recovery for the hardest-hit communities ahead. The event did result in a few minor injuries, but thankfully there were no fatalities. Preliminary damage assessments shortly after the event suggest that damages could exceed over 100 million dollars. Critical facilities (both public and private infrastructure) with a wide range of community services were affected on various levels:
- Emergency services
- Medical care
- Childcare
- Recreation
- Government function
- Mass transit
- Utilities
On April 25th, 2023, Governor DeSantis issued a Major Disaster Declaration for Broward County due to the historic flooding that occurred in southeastern Broward County. On April 28th, 2023, President Biden approved the Major Disaster Declaration for Broward County.
Rainfall Amounts and Analysis
The rainfall amounts that were observed during this event were unprecedented for the area, especially in the time frame in which they occurred. There is a dense network of precipitation observations in the area, which allowed for detailed rainfall analysis.
Here are the maximum observed rainfall amounts for specific time periods on April 12th at WeatherStem site FWSN FLL, which is located at Fort Lauderdale-Hollywood International Airport:
- 1hr Max - 6.15" (4PM-5PM)
- 3hr Max - 11.74" (3PM-6PM)
- 6hr Max - 19.98" (4PM-10PM)
- 12hr Max - 25.74" (11AM-11PM)
- Daily Total - 25.91" (12AM-12AM)
Two interactive maps, and static versions of those maps, can be found below. These show preliminary rainfall analysis, as well as 12-hr rainfall amount annual exceedance probabilities for the same area.
April 12th Rainfall Analysis (in inches, based on preliminary rainfall data) The area in white received at least 20 inches of rain.
12hr Rainfall Annual Exceedance Probabilities April 12th, 2023. For example, areas within the pink (<1/1,000) contour received 12-hr rainfall amounts that have a less than 0.1% chance of occurring in any given year.
Preliminary rainfall reports and analysis for April 12th, 2023 (Left) 12-Hr Annual Exceedance Probabilities on April 12th, 2023 (Right, same data as interactive map above)
Flash Flood Impacts and Aftermath:
Historic and catastrophic flash flooding took place across the greater Fort Lauderdale area as over 15-25 inches of rainfall occurred in a short period of time. This led to devastating impacts in the area, with weeks to months of recovery needed. Below are just a handful of reports, pictures, and videos on these impacts:
- More than 12 hours after rainfall had ended, NWS Miami attempted to conduct a survey on the flooding. Below are the notes from the survey, with a caveat that many of the hardest-hit neighborhoods were still mostly inaccessible due to the deep-standing water.
- Near FLL, including Edgewater just to the north, was where the deepest standing water was surveyed. There was a high water mark of 3.3 feet on a building near Floyd Hull Stadium, with widespread 2-3ft high water marks across the area. To the north of this area, near downtown Fort Lauderdale, high water marks of 1-2ft were found.
- In Dania Beach, several streets, parks, and open areas had deep standing water of 1-2 feet, with high water marks reflecting these values observed on a few structures.
- In Hollywood, areas of deep-standing water were noted near TY Park west of I-95, where 1-2 feet of water still covered streets in some neighborhoods.
- 600 residents were displaced by the flood, with many being rescued from their homes by local officials.
- Over 1,000 homes sustained 'Major' damage, with another 200+ sustaining 'Minor' damage.
- 22,000 residents were without power late Wednesday night during the peak of the event, with the hardest hit areas remaining without it for days.
- Port Everglades, which supplies 100% of the fuel for the area (~13 million gallons per day), suffered a 50% reduction in distribution due to submerged fuel pumps, with interruptions lasting over 10 days. This led to a fuel 'shortage' across the area, with most gas stations having to close for days at a time, and incredibly long lines for those that did have fuel.
- Fort Lauderdale - Hollywood International Airport was closed for nearly 40 hours (4PM Wednesday to 9AM Friday). Over 1,000 flights were canceled, impacting over 60,000 passengers.
- Nearly one thousand calls were made to local towing companies for abandoned/stranded vehicles in flooded water, with the number of vehicle insurance claims across the area in the thousands.
- The city of Fort Lauderdale's facilities were a "complete loss" which included not only the building but the city's vehicles and equipment/records that were present inside.
A series of videos showing flooding around the Fort Lauderdale area from Wednesday night through Thursday morning Videos courtesy of Twitter users: @fortlauderdalebeach, @wpbf_angela, and @CodeWithAgni
A series of videos showing flooding and rescues around the Fort Lauderdale area from Wednesday night through Thursday morning Videos courtesy of Twitter users: @FTLRPIO, @BrowardSheriff, and @WPLGLocal10
A series of videos showing flooding and abandoned cars around the Fort Lauderdale area on Thursday. Videos courtesy of Twitter users: @xTranquil, @dylanhubermantv, and @johncardillo.
A series of videos showing abandoned vehicles and flooded areas around Fort Lauderdale on Thursday morning. Videos courtesy of WPLG.
Aerial footage of FLL on Thursday morning. Video courtesy of WSVN.
Aerial photos of FLL on Thursday, April 13th
Images around the Fort Lauderdale area on April 12th and 13th.
Additional images around the Fort Lauderdale area on April 12th and 13th.
Tornado Impacts and Aftermath:
Although the excessive rainfall and resultant flash flooding were the biggest hazards experienced during this event. Atmospheric conditions also resulted in the development of two EF-0 tornadoes that occurred across portions of southern Broward County.
Dania Beach Tornado
A tornado briefly touched down south of Fort Lauderdale - Hollywood International Airport before moving due west for a little over half a mile. The EF-0 was rated on the higher end of the scale due to damage observed in a mobile home community east of I-95. A tornado damage signature (bottom right corner of image below) was also observed on KAMX with this tornado.
Dania Beach Tornado Path, Warning Polygon, Radar Image, and Damage
Sheridan Beach Tornado
Minimal damage was observed in a very small spatial area. A weak tornado damage signature (bottom left corner on image below) was observed on KAMX at 3:29 pm in the exact location damage was found.
Sheridan Tornado Path, Warning Polygon, Radar Image, and Damage
Additional Impact and Aftermath Resources
- City of Fort Lauderdale Flood Recovery Updates Webpage
- City of Fort Lauderdale ArcGIS Hazard Reports
- Broward County’s “Document The Floods” Webpage
- FL Executive Order 23-65 (State of Florida declares Broward County State Of Emergency)
- Broward County Declaration of Local State of Emergency (April 13th)
Social Media & Communication
From April 11th to April 13th, NWS Miami reached 2,391,534 people on Twitter, with an additional reach of 19,598 people on Facebook. Utilizing social media as an avenue for important information dissemination, NWS Miami was able to provide real-time content while the event was unfolding.
Aside from providing real-time alerts and warnings, additional content was shared that highlighted both the severity of the situation but also echoed partner's posts about both life-saving actions during the event and recovery actions during the aftermath of the event. This brief recap on the communication from NWS Miami highlights the information shared before, during, and after this historic event.
With forecasted rainfall totals trending higher, NWS Miami collaborated with the Weather Prediction Center to issue a Flood Watch on the morning of April 11th. The locations included as part of the Flood Watch were: Coastal/Metro Miami-Dade and Broward Counties. In conjunction with sharing the product via the weather.gov webpage and various alert pathways, a message was also shared to Social Media shortly after 11am highlighting the issuance of the Flood Watch.
Continued messaging of the increasing risk of significant flooding continued through April 11th and into the early to mid morning hours of April 12th. To illustrate the increasing risk of flooding across vulnerable areas, A combination of rainfall forecasts, a picture of a rain-gauge, and a meso-graphic were used to convey information to the general public.
As heavy rainfall continued to train over the same areas during the late morning to early afternoon hours of April 12th, an increasing flood threat began to materialize across portions of Broward County. A call for flooding reports was put out to the public as conditions continued to worsen.
After several hours of heavy rainfall over the same saturated areas, reports both from NWS Miami partners and social media began to increase in both number of reports and severity of the reports. With nightfall quickly approaching and a continued deluge of rainfall over the area that was already experiencing Flash Flooding, NWS Miami issued a Flash Flood Emergency, the first FFE ever issued for the Miami-Fort Lauderdale-West Palm Beach metro. The auto-tweet was shared widely across Twitter with over 180,000 impressions.
With heavy rainfall still falling in the Flash Flood Emergency and conditions remaining hazardous across portions of Broward County, NWS Miami began to retweet social media reports from the hardest affected areas and important real-time information from NWS partners.
While retweeting information from partners, NWS Miami also provided several tweets that highlighted real time conditions that were ongoing, the meteorological setup that was ongoing, and an easy to understand break-down of the current hazards at hand.
With the eventual cessation of heavy rainfall over the hardest hit areas, but still severely flooded communities, NWS Miami transitions the Flash Flood Emergency to a Flood Warning during the early morning hours of April 13th.
With the continued extension of the Flood Warning across Fort Lauderdale and Dania Beach as flood waters were slow to drain, NWS Miami continued to share important information and updates about residual flooding. Partner posts were amplified by the NWS Miami social media account to help spread critical information.
Additional Notes
Noteworthy radar loops from this historic day:
KAMX reflectivity loop centered on KFLL for the entire duration of the historic rainfall event. (8AM-1159PM on April 12th) During multiple periods throughout this event, storm motions across the area were quite chaotic, especially when individual storms strengthened and took on supercell characteristics.
KAMX reflectivity loop centered on a slow-moving, deviant motion supercell from 12PM-9PM. Despite southerly background winds, this long-lasting storm over the Atlantic waters became nearly stationary as it gained strength and took on supercell characteristics, before eventually drifting slightly south and dissipating.
KBYX reflectivity loop centered on a long-lasting, deviant motion supercell from 7AM-4PM. Despite southerly background winds, this storm over Florida Bay (between the Keys and South FL) moved nearly due east as it took on supercell characteristics.
NWS Product Timeline
Below is a link to a detailed timeline that examines the NWS products that were issued before, during, and in the aftermath of the Fort Lauderdale Flood, as well as the two confirmed EF-0 tornadoes that were observed. A Flash Flood Emergency was issued, which was the first for the Miami-Fort Lauderdale-West Palm Beach Metro Area, and only the second time that NWS Miami has issued that product (The only other instance was Collier County for Hurricane Irma in 2017). From 9:48pm to 10:15pm on April 12th, a Tornado Warning and Flash Flood Emergency were both in effect for Fort Lauderdale and Dania Beach.