Locally and diurnally induced shower and thunderstorm activity developed over interior and southwestern portions of Puerto Rico during the afternoon hours.
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.
Locally and diurnally induced shower and thunderstorm activity developed over interior and southwestern portions of Puerto Rico during the afternoon hours.
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 Aug 18, 10:40 AM AST, 4 hours 52 minutes earlier.
Area Forecast Discussion National Weather Service San Juan PR 1040 AM AST Sat Aug 18 2018 .UPDATE...Relative quiet morning for Puerto Rico and the U.S. Virgin Islands. TSJU radar shows a few passing showers mainly over the coastal areas due to left over moisture from the previous tropical wave. GOES-16 imagery shows the mid to upper level clouds moving to the WNW, while the low level clouds are moving to the east, there are CU clouds building to the south of the local office as a result of daytime heating. The rest of the day drier air will continue to filter in from the east, which should limit shower activity for portions of the U.S. Virgin Islands and eastern areas of Puerto Rico. Due to local and diurnal effect an isolated shower can not be ruled out. Scattered showers and isolated thunderstorms are possible over portions of interior and western Puerto Rico due to lingering moisture and locally and diurnal effects. Daytime high temperatures will range from upper 80s to lower 90s near the coastal areas, and upper 70s to lower 80s in higher elevations. Winds will be out of the east at 10 to 15 kts with higher gusts possible. && .AVIATION...VRF conditions are expected to continue until 18/16Z. Iso/sct SHRA/VCTS could cause MVFR conds over portions of western Puerto Rico and terminals TJBQ & TJMZ through 18/22Z. Sfc winds out of the east at 10 to 15 kts. && .MARINE...Seas will range from 3 to 5 feet across the outer waters and 2 to 4 feet over the protected waters. Winds will be out of the east at 10 to 15 kts with higher gusts possible. && .PREV DISCUSSION... /issued 513 AM AST Sat Aug 18 2018/ SYNOPSIS... Shower activity should diminish across the local islands as a dry air mass combined with an upper level ridge dominate the local weather through at least Sunday morning. However, the evaluable moisture will be enough to result in another round of showers mainly along and to the west of the Cordillera Central of Puerto Rico during the afternoon hours. The next tropical wave is forecast to reach the local islands late Sunday through Monday. SHORT TERM...Today through Monday... Sufficient low level moisture convergence across the region during the overnight hours will bring passing showers and low level clouds across the region. These showers will produce periods of of moderate to locally heavy rains over the coastal waters and parts of the northeast and southeast coastal areas of Puerto Rico and some of the the islands during the rest of the early morning hours. An overall drying trend is expected today, but still sufficient pockets of residual moisture across the islands to support locally and diurnally induced afternoon convection. Some of the afternoon showers and isolated thunderstorms will produce locally heavy rains at times. For the rest of the weekend, stable mid to upper level conditions should persist, as the high pressure ridge is forecast to hold across the region and limit significant vertical development. Passing early morning showers are however expected to persist across region and affect the coastal waters and mainly the east coastal areas of the islands, followed by locally and diurnally induced convection each afternoon mostly over portions of the central and west sections of PR with lesser shower activity around the San Juan metro and the adjacent islands. At this time the next tropical wave is forecast enter the eastern Caribbean and cross the islands and local waters late Sunday through Monday. The mid to upper level ridge should however hold and limit significant or widespread development of afternoon thunderstorms. However the increasing low level moisture convergence along with local and diurnal effect will increase the potential for shower activity across the islands along with areas of locally heavy rains with isolated thunderstorms. Therefore minor urban and small stream flooding along with quick rises along small rivers and streams will remain likely in isolated areas. LONG TERM...Tuesday through Saturday... Model guidance suggests that the trailing edge of the aforementioned tropical wave could persist over the region through at least Tuesday morning. However, the upper level forcing should be marginal through this period. By midweek, GFS and ECMWF suggests that the ridge aloft should erodes providing better chance for vertical development during the afternoon hours. During that time, another tropical wave could reach the islands by Wednesday or Thursday. The confidence about the timing and impacts that this wave could produce is low due to some discrepancy amongst the global models. After the passage of this feature, model guidance are suggesting the arrival of dry air and Saharan dust particulates over the local area around Thursday. A seasonal weather pattern should prevail through the rest of the week with the typical passing showers across the U.S. Virgin Islands and the eastern half of Puerto Rico during the overnight and morning hours followed by afternoon convection across the western sections of PR. AVIATION... Prevailing VFR...Few top FL150...Sct SHRA with brief MVFR conds and Mtn Top obscr due to low CIG and SHRA to continue over the local flying area and portions of eastern PR til 18/14Z with prevailing easterly flow of 10-20 kt blo FL200...bcmg fm SE and incr w/ht ABV. SFC wnds LGT/VRB bcmg mainly fm E 10-15 kts aft 18/14z with sea breeze variations and ocnly higher gusts. Isold TSRA/SHRA ovr W-NW PR btw 18/16Z-18/22z. MARINE... Mariners can expect choppy seas between 3 and 5 feet across open waters due to a moderate to fresh easterly wind flow. Seas are forecast at 2 to 4 feet across protected waters. These conditions will hold through much of the forecast period. There is a moderate risk of rip currents across several beaches of our forecast domain, please refer to the Surf Zone Forecast (SRFSJU) for more information. && .PRELIMINARY POINT TEMPS/POPS... SJU 89 77 90 78 / 20 20 30 60 STT 89 78 89 78 / 20 30 30 50 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && SHORT TERM...99 LONG TERM....99
Hazardous Weather Outlook...CORRECTED National Weather Service San Juan PR 555 AM AST Sat Aug 18 2018 AMZ710>745-PRZ001>013-190900- San Juan and Vicinity-Northeast-Southeast-Eastern Interior- North Central-Central Interior-Ponce and Vicinity-Nortwest- Western Interior-Mayaguez and Vicinity-Southwest-Culebra-Vieques- The nearshore and off shore Atlantic and Caribbean Coastal Waters- 555 AM AST Sat Aug 18 2018 This Hazardous Weather Outlook is for Puerto Rico and the adjacent Atlantic Coastal Waters. .Day One...Today and Tonight .Thunderstorms...There is a chance of thunderstorms with heavy rainfall and brief gusty mainly across portions of the interior and western Puerto Rico during the afternoon hours. .Flooding...Heavy rains could lead to urban and small stream flooding. .Wind...Sustained winds up to 20 MPH expected across the coastal areas of northern and southern Puerto Rico. .Waves...Choppy seas up to 5 feet occasionally up to 6 feet expected mainly across the offshore Atlantic and Caribbean waters and local passages. .Rip Currents....There is a moderate risk of rip currents for beaches of northern and southeastern Puerto Rico, as well as some beaches of Vieques and Culebra. .Days Two through Seven...Sunday through Friday Another tropical wave is forecast to increase the chance for shower and thunderstorm development late Sunday through Monday. The moderate risk of rip current will continue through the weekend. .Spotter information statement... Widespread spotter activation is not anticipated, however individual spotter are encouraged to report Flooding and Rip Currents to the National Weather Service in San Juan. AMZ715-725-VIZ001-002-190900- St. Thomas St. John adjacent Islands-St Croix- Nearshore Atlantic and adjacent Caribbean Coastal Waters- 555 AM AST Sat Aug 18 2018 This Hazardous Weather Outlook is for the U.S. Virgin Islands and the ADJACENT Coastal Waters. .Day One...Today and Tonight .Rip Currents...There is a moderate risk of rip currents for some of the beaches of St Croix. .Days Two through Seven...Sunday through Friday Another tropical wave is forecast to increase the chance for shower and thunderstorm development late Sunday through Monday. The moderate risk of rip current will continue through the weekend for some of the beaches of St Croix. .Spotter information statement... Widespread spotter activation is not anticipated, however individual spotter are encouraged to report Flooding and Rip Currents to the National Weather Service in San Juan.
Special Weather Statement
National Weather Service San Juan PR
1239 PM AST SAT AUG 18 2018
PRZ010-011-181715-
Mayaguez and Vicinity-Southwest-
1239 PM AST SAT AUG 18 2018
...A STRONG THUNDERSTORM WILL AFFECT LAJAS...CABO ROJO...MAYAGUEZ AND
HORMIGUEROS MUNICIPALITIES...
At 1239 PM AST, a strong thunderstorm was located near Puerto Real,
or near Cabo Rojo, moving west at 10 mph.
Winds in excess of 30 mph are possible with this storm.
Locations impacted include...
Hormigueros, Cabo Rojo, Mayaguez, Puerto Real, Monte Grande and
Betances.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
LAT...LON 1821 6712 1803 6711 1802 6717 1803 6718
1804 6721 1805 6720 1806 6720 1807 6718
1807 6720 1809 6720 1811 6718 1813 6719
1815 6718 1817 6718 1820 6715 1822 6716
TIME...MOT...LOC 1639Z 087DEG 9KT 1812 6719
TWComunicado Especial de las Condiciones del Tiempo 1239 PM AST sabado 18 de agosto de 2018 PRZ010-011-181715- Mayaguez y Vecindad-Suroeste- 1239 PM AST sabado 18 de agosto de 2018 ...UNA TRONADA FUERTE AFECTARA A LAJAS...CABO ROJO...MAYAGUEZ Y HORMIGUEROS... A las 12:39 PM AST, una tronadas fuerte estaba localizada cerca de Puerto Real o cerca de Cabo Rojo, moviendose hacia el oeste a 10 mph. Vientos en excess de 30 mph son posibles con esta tronada. Localidades impactadas incluyen... Hormigueros, Cabo Rojo, Mayaguez, Puerto Real, Monte Grande y Betances. Lluvias torrenciales tambien estan ocurriendo con esta tronada, y pudieran resultar en inundaciones localizadas. No conduzca su vehiculo por carreteras inundadas. Rayos de nube a tierra frecuentes estan ocurriendo con esta tronada. Los rayos pueden caer a 10 millas de una tronadas. Busque refugio dentro de un edificio o vehiculo. TW/ERG
Special Weather Statement
National Weather Service San Juan PR
112 PM AST SAT AUG 18 2018
PRZ008>010-181800-
Northwest-Mayaguez and Vicinity-Western Interior-
112 PM AST SAT AUG 18 2018
...A STRONG THUNDERSTORM WILL AFFECT LAS MARIAS...ANASCO...
MAYAGUEZ...RINCON...AGUADA...MOCA AND AGUADILLA MUNICIPALITIES...
At 110 PM AST, a strong thunderstorm was located over Anasco, moving
west at 5 mph.
Winds in excess of 30 mph are possible with this storm.
This storm will be near...
Las Marias and Anasco around 120 PM AST.
Luyando around 135 PM AST.
Aguada and La Playa around 150 PM AST.
Rincon around 200 PM AST.
Other locations impacted by this storm include Stella and Espino.
Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
LAT...LON 1838 6704 1825 6708 1825 6718 1829 6719
1829 6720 1830 6724 1836 6727 1837 6727
1837 6726 1838 6723 1839 6719 1840 6719
TIME...MOT...LOC 1710Z 091DEG 5KT 1830 6713
TWComunicado Especial de las Condiciones del Tiempo
112 PM AST sabado 18 de agosto de 2018
PRZ008>010-181800-
Noroeste-Mayaguez y Vecindad-Suroeste-Oeste Interior
112 PM AST sabado 18 de agosto de 2018
...UNA TRONADA FUERTE AFECTARA A LAS MARIAS...ANASCO...MAYAGUEZ...
RINCON...AGUADA...MOCA Y AGUADILLA...
A las 1:10 PM AST, una tronada fuerte estaba localizada sobre
Anasco, moviendose hacia el oeste a 5 mph.
Vientos en excess de 30 mph son posibles con esta tronada.
La tronada estara cerca...
Las Marias y Anasco a alrededor de 1:20 PM AST.
Luyando alrededor de las 1:35 PM AST.
Aguada y La Playa a alrededor de las 1:50 PM AST.
Rincon alrededor de las 2:00 PM AST.
Otros lugares afectados incluyen a Stella y Espino.
Lluvias torrenciales tambien estan ocurriendo con esta tronada, y
pudieran resultar en inundaciones localizadas. No conduzca su
vehiculo por carreteras inundadas.
Rayos de nube a tierra frecuentes estan ocurriendo con esta
tronada. Los rayos pueden caer a 10 millas de una tronadas. Busque
refugio dentro de un edificio o vehiculo.
TW/ERGSpecial Weather Statement
National Weather Service San Juan PR
205 PM AST SAT AUG 18 2018
PRZ005>007-009-010-182000-
North Central-Mayaguez and Vicinity-Central Interior-Western
Interior-Ponce and Vicinity-
205 PM AST SAT AUG 18 2018
...THUNDERSTORMS WITH FREQUENT LIGHTNING NOW ACTIVE OVER INTERIOR
WESTERN PUERTO RICO...
At 201 PM AST, the strongest thunderstorms were located in western
Las Marias and Lares. Thunderstorms will continue to be active
across most of Puerto Rico's mountain interior through 4 PM AST.
Locations impacted include...
Jayuya, Adjuntas, Utuado, Lares, Maricao, Cayuco and Juncal.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
LAT...LON 1810 6677 1812 6707 1825 6708 1832 6690
1832 6652 1816 6653
TIME...MOT...LOC 1801Z 240DEG 0KT 1823 6675
SnellComunicado Especial de las Condiciones del Tiempo 205 PM AST sabado 18 de agosto de 2018 PRZ005>007-009-010-182000- Norte Central-Mayaguez y Vecindad-Central Interior-Oeste Interior-Ponce y Vecindad- 205 PM AST sabado 18 de agosto de 2018 ...TRONADAS CON RAYOS FREQUENTES AHORA ACTIVAS SOBRE EL OESTE INTERIOR DE PUERTO RICO... A las 2:01 PM AST, las tronadas mas fuertes estuvieron localizadas en el oeste de Las Marias y Lares. Las tronadas continuaran activas a traves de la mayoria del interior de Puerto Rico hasta las 4 PM AST. Las localidades impactadas incluyen... Jayuya, Adjuntas, Utuado, Lares, Maricao, Cayuco y Juncal. Rayos de nube a tierra frecuentes estan ocurriendo con esta tronada. Los rayos pueden caer a 10 millas de una tronadas. Busque refugio dentro de un edificio o vehiculo. Snell/GL
The national radar mosaic for the moment the first event began.
2 flood. Local standard time, as filed.
A 24 year old woman drowned after being swept away due to a water surge along the Portuguese River in Barrio Tibes near road PR-10.
Road PR-503 impassable as water from Rio Portugues in Barrio Tibes penetrated through the road.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Flood, Ponce | 2018-08-18 | 24 | Female | In Water | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2018Every state in 2018This day in weather historyWarnings in Puerto Rico, August 2018
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: 783385, 783386.