Unsettled weather conditions prevailed across Puerto Rico through the first week of September as a retrograding upper level trough lingered in the region. The instability of the trough, diurnal heating, and low level moisture combined to generate widespread showers and thunderstorms across the region.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SJU wrote it up.
Unsettled weather conditions prevailed across Puerto Rico through the first week of September as a retrograding upper level trough lingered in the region. The instability of the trough, diurnal heating, and low level moisture combined to generate widespread showers and thunderstorms across the region. Each day, accumulations ranged from 2 to 3 inches, with maximum amounts up to 5 inches in some areas. This led to several reports of mudslides, lightning, and gusty winds.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Juan, PR wrote its last area forecast discussion before the first event at Sep 5, 4:52 PM AST, 1 hour 41 minutes earlier.
Area Forecast Discussion National Weather Service San Juan PR 452 PM AST Thu Sep 5 2024 .SYNOPSIS... Above-normal hot heat indices are expected to persist throughout the forecast period, primarily due to the combination of above- normal air temperatures and abundant tropical moisture. Afternoon showers and thunderstorms are expected again tomorrow, particularly across the interior and western sectors of Puerto Rico. Our next tropical wave, which is expected to bring periods of showers and thunderstorms, will significantly increase the threat of flooding from Sunday through at least early Tuesday. && .SHORT TERM...Tonight through Saturday... During the morning, isolated showers began to drift across all the islands. As the afternoon progressed, convective activity intensified, with localized thunderstorms producing between 2 and 3 inches of rain according to radar estimates. Maximum accumulations were observed in municipalities in the interior, western, southwestern Puerto Rico, and the metro area. A few Flood Advisories were issued for municipalities such as Cabo Rojo, Hormigueros, Gurabo, Guayanilla, Maricao, Peñuelas, Ponce, Sabana Grande, Yauco, Bayamón, and Guaynabo. As expected, it was another hot day across the islands, with heat indices surpassing 110 degrees in lower elevations. In St. Croix, the warning was validated with a maximum heat index of 118 degrees Fahrenheit. Warm-to-hot conditions are likely to continue throughout most of this period, with temperatures potentially reaching into the upper 90s and heat indices remaining elevated. Residents and visitors should take precautions to stay hydrated by drinking plenty of water, wearing light and breathable clothing, and avoiding prolonged exposure to the sun, especially during peak heat hours. The short-term forecast remains on track. For the next few hours, expect rain activity to gradually decrease, allowing for a quieter night period. However, additional passing showers driven by the trade winds cannot be ruled out. On Friday, moisture levels will remain around normal values but will still be sufficient to trigger rain activity. Additionally, instability will prevail across the region due to the influence of a retrograding TUTT low moving from the Central Atlantic toward the U.S. Virgin Islands. This feature will create favorable conditions aloft for the development of showers and thunderstorms, especially across the interior and western sectors of Puerto Rico during the early afternoon and extending until sunset. As a result, an elevated risk of flooding, frequent lightning, and strong gusty winds are some of the anticipated risks for tomorrow. && .LONG TERM...Sunday through Thursday... .PREV DISCUSSION... /issued 510 AM AST Thu Sep 5 2024/ A tropical wave will bring periods of showers and thunderstorms across the region on Sunday and possibly Monday. The wave's trailing moisture could persist through at least Tuesday. This weather pattern may increase the threat of flooding during the first half of the upcoming week. As we move into the peak of the hurricane season, model guidance suggests a frontal boundary across North America; this frontal boundary, with its associated surface lows, will move across the northwestern Atlantic early next week. Additionally, the latest model solutions suggest a surface low pressure developing near the Bahamas Islands, promoting an east-southeast to southerly wind flow across the Northeast Caribbean during the second part of the following workweek. This wind flow may pool abundant tropical moisture from the southeast Caribbean over or near Puerto Rico and the U.S. Virgin Islands, increasing the threat of flooding rains. Additionally, the abundant tropical moisture, combined with the above-normal sea surface temperatures around the islands and the above-normal maximum and minimum air temperatures, may promote the extension of hot heat indices throughout the long term, especially in areas where rain activity does not form and even more if the winds turn from the south. && .AVIATION... (18Z TAFs) Brief MVFR conditions could be present from now to 05/23Z due to TSRA and SHRA near the TAF sites. Therefore, aircrafts can expect, lower ceiling and oclurred vision around the mountain sections. Improving conditions will lead VFR conditions from 05/23Z to 06/14Z with increasing winds from the E at 12 knots with gusty winds and sea breeze variation. && .MARINE... A surface high pressure across the Atlantic Ocean will promote gentle to moderate easterly winds over the next few days. Wave height will range between 2 and 4 feet across the Caribbean and between 3 and 5 feet across the Atlantic Waters. A tropical wave will cross the Lesser Antilles around Saturday, with its axis moving across the local region around Sunday, deteriorating marine conditions. Thunderstorms affecting the coastal waters of western Puerto Rico are expected each afternoon, and should increase with the next tropical wave. && .BEACH FORECAST... The risk of rip currents are expected to remain moderate across the north-central and northwestern beaches of Puerto Rico, while a low risk elsewhere. During the next few days, a moderate risk is anticipated to continue across the whole northern coast of Puerto Rico, and a low risk elsewhere. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && SHORT TERM...YZR/DS LONG TERM....CAM AVIATION...LIS/DS PUBLIC...MMC
Hazardous Weather Outlook National Weather Service San Juan PR 426 AM AST Thu Sep 5 2024 AMZ711>745-PRZ001>013-060830- San Juan and Vicinity-Northeast-Southeast-Eastern Interior- North Central-Central Interior-Ponce and Vicinity-Northwest- Western Interior-Mayaguez and Vicinity-Southwest-Culebra-Vieques- The nearshore and off shore Atlantic and Caribbean Coastal Waters- 426 AM AST Thu Sep 5 2024 This Hazardous Weather Outlook is for portions of Puerto Rico. .DAY ONE...Today and Tonight .Lightning...Isolated to scattered thunderstorms possible across the islands. Be aware of thunderstorms in your area and be prepared to take shelter. .Excessive Rainfall...Flooding of urban areas, roads, small streams, and washes. Isolated flash floods possible. .Excessive Heat...This level of heat affects most individuals sensitive to heat, especially those without effective cooling and/or adequate hydration. Impacts possible in some health systems and in heat-sensitive industries. .Rip Currents...Life-threatening rip currents are possible in the surf zone particularly along the north and eastern beaches of Puerto Rico and Culebra. .DAYS TWO THROUGH SEVEN...Friday through Wednesday There is a risk of thunderstorms and urban and small stream flooding each day. A moderate risk of rip currents will continue along the northern and eastern coast of Puerto Rico through the weekend. Afternoon activity may result in strong thunderstorms each day. A tropical wave could bring unsettled weather conditions by early next week. .SPOTTER INFORMATION STATEMENT... Spotter activation is encouraged. Please relay any information about flooding, winds, waves, and rip currents to the National Weather Service in San Juan. AMZ716-726-VIZ001-002-060830- St. Thomas St. John adjacent Islands-St Croix- Nearshore Atlantic and adjacent Caribbean Coastal Waters- 426 AM AST Thu Sep 5 2024 This Hazardous Weather Outlook is for portions of USVI. .DAY ONE...Today and Tonight .Lightning...Isolated to scattered thunderstorms possible across the islands. Be aware of thunderstorms in your area and be prepared to take shelter. .Excessive Heat...This level of heat affects anyone without effective cooling and/or adequate hydration. Impacts likely in some health systems, heat-sensitive industries and infrastructure. .Rip Currents...Life-threatening rip currents are possible in the surf zone particularly St. Croix. .DAYS TWO THROUGH SEVEN...Friday through Wednesday There is a risk of thunderstorms and urban and small stream flooding each day. A moderate risk of rip currents will continue along the northern and eastern coast of St Croix through most of the period. Afternoon activity may result in strong thunderstorms each day. A tropical wave could bring unsettled weather conditions by early next week. .SPOTTER INFORMATION STATEMENT... Spotter activation is encouraged. Please relay any information about flooding, winds, waves, and rip currents to the National Weather Service in San Juan.
The San Juan radar (TJUA), 70 km away, was scanning. The volume nearest the first event began at 22:34 UTC.
2 lightning, 1 debris flow, 1 thunderstorm wind. Local standard time, as filed.
The mayor of Adjuntas through social media reported a landslide affecting PR-123 making the road impassable.
Lightning struck the roof of a house in Residencial Fray Bartolome de las Casas in Santurce. Damage to the roof was visible from inside the house, with paint surrounding the area stripped away and small debris visible on the living room. The house was left without electrical power. Paramedics visited the scene, but everyone was ok.
Lightning struck the outside wall of a house in Urbanizacion Mirador del Sol in Cabo Rojo. Damage was visible from outside the house, with paint and some cement surrounding the areas (entry and exit points were visible and showed damage) stripped away. Small debris was visible in the garden and driveway.
NWS Employee and local emergency managers reported a fallen tree affecting road PR-416 near km 6.8 in Bo. Lagunas of Aguada, or near Jose Gonzalez Ruiz elementary school. The road was impassable at the time of the event.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2024Every state in 2024This day in weather historyWarnings in Puerto Rico, September 2024
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1216716, 1216711, 1216713, 1216715.