Intense diurnal heating contributed to locally strong thunderstorms over Mayaguez, producing gusty conditions and small hail, as reported by an NWS employee and the public. Several Special Weather Statements and a Flood Advisory were issued for|the area, with radar-estimated rainfall totals reaching up to 2 inches.
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.
Intense diurnal heating contributed to locally strong thunderstorms over Mayaguez, producing gusty conditions and small hail, as reported by an NWS employee and the public. Several Special Weather Statements and a Flood Advisory were issued for|the area, with radar-estimated rainfall totals reaching up to 2 inches.
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 29, 1:29 PM AST, 1 hour 1 minute earlier.
Area Forecast Discussion...UPDATED
National Weather Service San Juan PR
129 PM AST Thu Aug 29 2024
.UPDATE...Relative humidities have remained high with strong
insolation. Some heat indices along the coasts from Ponce to
Mayaguez to Arecibo have exceeded 112 degrees. Vega Baja reached
114 degrees and Ponce saw a brief heat index of 125 degrees.
Therefore the excessive heat warning has been extended to those
areas.
&&
.AVIATION...
(12Z TAFs)
VFR conds will prevail except alg the Cordillera Central from
Ponce to Hormigueros where +SHRA/TSRA will dvlp from 29/18-21Z. E
flow from 10-15 kt with hir gusts in sea breezes till 29/22Z. Then
land breezes will dvlp, but less than 7 kt. USVI will have E winds
7-11 kt.
&&
.PREV DISCUSSION... /issued 1122 AM AST Thu Aug 29 2024/
UPDATE...Shower coverage has decreased considerably across the
forecast area and deep convection has yet to develop therefore
temperatures have been able to rise rapidly. Although mid levels
are somewhat drier than yesterday, sufficient instability still
exists to form showers and thunderstorms this afternoon over the
area--especially western and interior Puerto Rico. Indeed a
streamer has already developed over central Saint Croix and
extends out over the waters to the west and others are appearing
downstream from the other islands east of Puerto Rico.
CLIMATE...Recent rains left standing water in many places that is
now evaporating into the air under bright sunshine. Dewpoints are
holding in the high 70s to mid 80s along the lower elevations of
both the U.S. Virgin Islands and Puerto Rico. With high
temperatures already reaching maximum forecast temperatures the
heat advisory was extended to all but interior Puerto Rico and the
heat advisory of the U.S. Virgin Islands was upgraded to an
excessive heat warning.
PREV DISCUSSION... /issued 638 AM AST Thu Aug 29 2024/
SYNOPSIS...
We anticipate a drier and more stable air mass to move across the
area today. However, residual moisture from the wave passage
combined with daytime heating and the sea breeze convergence will
cause afternoon shower and thunderstorm development over portions
of central and western PR. Light to moderate trade winds will
prevail for the rest of the forecast period due to weak high
pressure anchored over the Atlantic.
SHORT TERM...Today through Saturday...
Showers and thunderstorms due to a tropical wave crossing the
islands left between one half to an inch of rain over portions of
eastern PR, including Vieques and Culebra. Isolated thunderstorms
with lighter rainfall accumulations were noted across the USVI.
Minimum temperatures were in the low 80s across the lower
elevations of the islands. The wind was from the east between 10
and 15 mph, with land breeze variations observed across the
western half of PR. Shower activity will continue to stream
westward across PR and the Mona Passage as the wave exits the
region during the morning hours.
Thereafter, a small area of drier and more stable air is expected
to move from the east. However, residual moisture from the wave
passage combined with daytime heating and sea breeze convergence
will cause shower and thunderstorm development over portions of
central and western PR. These thunderstorms could produce gusty
winds, and locally heavy rainfall that can lead to urban and
small stream flooding. In addition, hot temperatures and dewpoints
in the lower 80s will cause excessive heat conditions across most
coastal areas of the islands, so a Heat Advisory (NPWSJU) is in
effect.
Similar condtions are expected on Friday and Saturday, as pockets
of moisture will bring passing showers across the windward areas
of the islands during the night, followed by diurnally induced
afternoon showers and thunderstorms over the interior and western
PR. Heat advisory conditions will likely continue each day.
LONG TERM...Sunday through Thursday...
The inherited forecast remains on track. Most recent guidance
suggests precipitable water values ranging from 2.00 to 2.25
inches from Sunday onwards as a low-to-mid-level ridge northeast
of the region promotes moderate east to southeast winds, allowing
tropical moisture to increase across Puerto Rico and the U.S.
Virgin Islands. Additionally, a tropical wave is forecast to move
across the local area from Tuesday into Wednesday. Therefore,
expect an additional increase in shower and thunderstorm activity
across the islands on both days. Some of the potential hazards of
this weather event are urban and small-stream flooding, as well as
localized flash flooding, which can be expected too. Model
guidance continues to show sufficient moisture across all levels
of the atmosphere through the long-term period, particularly by
mid-week, due to the passage of the tropical wave being monitored
by the National Hurricane Center (NHC). NHC still classifies this
tropical wave across the central tropical Atlantic with a low
probability of tropical cyclone formation in the next seven days.
While its too early to determine any potential impact on our
forecast area, its encouraged to stay informed, especially as we
enter the peak of hurricane season.
On Thursday, expect to see a gradual change in weather conditions
as a mass of dry air will filter across the islands from the
east, reducing the precipitable water values to between the 50th
(near normal )and 25th percentile (below normal). However,
diurnally induced afternoon showers and thunderstorms are expected
to develop over the interior and western sections of PR while
passing trade wind showers with lighter rainfall amounts are
expected across the USVI.
AVIATION...
(06Z TAFS)
A tropical wave crossing the CWA early this morning may cause
tempo MVFR conds at TJSJ/TJPS thru at least 29/10z. Thereafter,
mainly VFR conditions are expected to prevail across all terminals
through the fcst period. Diurnally induced afternoon SHRA/TSRA
over central and western PR should cause VCTS at TJPS/TJBQ btw
29/18z-22z. East winds expected at 12-16 kt with locally higher
gusts and sea breeze variations aft 29/14z.
MARINE...
Surface high pressure over the Atlantic and a weak surface trough will
promote moderate east winds through most of the workweek. During the
day, expect showers to linger across the area as the tropical wave
exits the region completely. However, by the afternoon into evening
hours, we anticipate a drier airmass to move across the islands
reducing the chance of significant rainfall development. The passage
of the next tropical wave could deteriorate marine conditions by
midweek.
BEACH FORECAST...
There is a moderate risk of rip current for the north and
northwestern beaches of Puerto Rico, as well as Culebra, and Saint
Croix.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...Heat Advisory until 5 PM AST this afternoon for PRZ001>003-012-
013.
Excessive Heat Warning until 5 PM AST this afternoon for PRZ005-
007-008-010-011.
VI...Excessive Heat Warning until 5 PM AST this afternoon for VIZ001-
002.
AM...None.
&&
SHORT TERM...WS
LONG TERM....YZRPerspectiva sobre las Condiciones Peligrosas del Tiempo Servicio Nacional de Meteorología San Juan PR 106 PM AST jueves 29 de agosto de 2024 AMZ711>745-PRZ001>013-301545- San Juan y Vecindad-Noreste-Sureste-Este Interior- Norte Central-Central Interior-Ponce y Vecindad-Noroeste- Oeste Interior-Mayagüez y Vecindad-Suroeste-Culebra-Vieques- Las aguas cercanas y fuera de la costa del Atlántico y del Caribe- 106 PM AST jueves 29 de agosto de 2024 Esta perspectiva sobre las condiciones peligrosas del tiempo es para sectores de Puerto Rico. .DÍA UNO...Esta tarde y esta noche .Rayos...Tormentas eléctricas numerosas posibles a través del centro y el oeste de Puerto Rico. Planee detener toda la actividad al aire libre y moverse a refugios. .Lluvia Excesiva...Inundaciones en áreas urbanas, carreteras, riachuelos y lavados. Inundaciones repentinas aisladas posibles. .Calor Excesivo...Este nivel de calor afecta a cualquier persona sin enfriamiento efectivo y/o hidratación adecuada. Impactos probables en algunos sistemas de salud, industrias sensibles al calor e infraestructura. .Viento...Condiciones de brisa. Los artículos no asegurados podrían salir volando. .Corrientes Marinas...Hay un riesgo moderado de corrientes marinas amenazantes a la vida en la zona de olas a lo largo de las costas del norte. .DÍAS DOS A SIETE...viernes a miércoles Se espera calor excesivo todos los días de la semana. Hay un riesgo de tormentas eléctricas e inundaciones urbanas y de riachuelos cada día. Un riesgo moderado de corrientes marinas continuará en la costa norte y este de Puerto Rico hasta el fin de semana. Se pronostica que una onda tropical fuerte se mueva cerca de las islas a mediados de la semana, aumentando la actividad de tormentas eléctricas, vientos y mar. .COMUNICADO SOBRE INFORMACIÓN DE OBSERVADORES... No será necesaria la activación de observadores. AMZ716-726-VIZ001-002-301545- San Thomas San John e islas adyacentes-Santa Cruz- Aguas cercanas a la costa del Atlántico y aguas costeras adyacentes del Caribe- 106 PM AST jueves 29 de agosto de 2024 Esta Perspectiva sobre las Condiciones Peligrosas del Tiempo es para sectores de las Islas Vírgenes Americanas. .DÍA UNO...Esta tarde y esta noche .Calor Excesivo...Este nivel de calor afecta a cualquier persona sin enfriamiento efectivo y/o hidratación adecuada. Impactos probables en algunos sistemas de salud, industrias sensibles al calor e infraestructura. .Viento...Condiciones de brisa. Los artículos no asegurados podrían salir volando. .Condiciones Marítimas...Las embarcaciones pequeñas deben ejercer precaución a través del Pasaje de Anegada. .Corrientes Marinas...Corrientes marinas amenazantes a la vida son posibles en la zona de olas. .DÍAS DOS A SIETE...viernes a miércoles Un riesgo moderado de corrientes marinas prevalecerá durante la mayor parte del período a través de las islas, pero particularmente a través de Santa Cruz. Se esperan condiciones de advertencia de calor hasta el martes en Santa Cruz. Se pronostica que una onda tropical fuerte se mueva cerca de las islas a mediados de la semana, aumentando la actividad de tormentas eléctricas, vientos y mar. .COMUNICADO SOBRE INFORMACIÓN DE OBSERVADORES... No será necesaria la activación de observadores.
Preliminary Local Storm Report
National Weather Service San Juan PR
215 PM AST Thu Aug 29 2024
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0215 PM Extreme Heat 2 W Capitanejo 18.02N 66.57W
08/29/2024 M125 F Ponce PR AWOS
Mercedita Airport AWOS has reported Heat
Index over 113 degrees for five (5)
consecutive hours. The highest Heat Index of
125 degrees was reported around 12:35 PM
AST. Additionally, temperatures have peaked
around 97-99 degrees.
&&
ICPThe San Juan radar (TJUA), 113 km away, was scanning. The volume nearest the first event began at 18:29 UTC.
2 hail. Local standard time, as filed.
An employee from NWS/WFO San Juan reported small hail hitting his car while driving over the PR-2 N Avenida Hostos bridge, just south of Mayaguez Town Center.
A public report on social media indicated small hail in downtown Mayaguez, near the town hall.
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, August 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: 1214599, 1214600.