External bands from Tropical Storm Franklin produced showers and thunderstorms, along with gusty winds and flooding rains across portions of Puerto Rico.
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.
External bands from Tropical Storm Franklin produced showers and thunderstorms, along with gusty winds and flooding rains across portions of Puerto Rico.
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 21, 5:50 AM AST, 2 hours 47 minutes earlier.
Area Forecast Discussion
National Weather Service San Juan PR
550 AM AST Mon Aug 21 2023
.SYNOPSIS...Tropical moisture will continue to filter into the
islands steered by Tropical Storm Franklin, currently over the
Caribbean Sea. Through midweek, external bands of this system
with showers and thunderstorms, along with gusty winds, can reach
sectors of the islands. Urban and small stream flooding likely and
local flash flooding possible. Hazardous marine conditions are
also present, therefore several Small Craft Advisories in effect.
&&
.SHORT TERM...Today through Wednesday...
Tropical Storm Franklin was 235 mi SSW of Cabo Rojo at 21/08Z and
movg W or 280 deg at 10 kts. A second area of convection is E of the
system with minor rainbands seen ovr lcl waters. Showers formed over
the island for most of the night, but had dissipated by 4 AM AST.
Considerable lighting was noted over the waters south of the local
area, but few strikes were noted after 10 PM AST last night in the
local area. Surface and mid level winds and pressure systems are
dominated by T.S. Franklin. At upper levels, a weak trough is found
over the Windward Passage with a ridge from the Lesser Antilles
across the Caribbean Sea to central America. The ridge will
continue. However the weak trough over the Windward Passage will be
squeezed out by a low east of Miami that will push into the Florida
Strait by Wednesday. The ridge aloft will also move north over the
eastern Caribbean during the interim.
Unusual tropical moisture will surge north with the low-level flow
associated with T.S. Franklin today and tonight, with precipitable
water values pushing up to 2.5 inches by 22/09Z. This will generate
showers and thunderstorms across the area with urban and small
stream flooding likely and local flash flooding possible. With winds
up to 40 knots near 4000 ft, gusty winds are likely to reach the
surface and some will be strong enough to be damaging. The showers
will make today the coolest of the week for most areas.
Models diverge considerably with regard to the track of T.S.
Franklin and a track closer to the ECMWF which strays to the west
would bring drier weather to the area and increasing temperatures.
The current track over Hispaniola, being most likely, will still
leave plenty of moisture for showers and thunderstorms Tuesday and
Wednesday, and residual moisture should keep rain in the forecast
through the short term period. The heaviest rainfall is expected
along the south coast of Puerto Rico and over the Cordillera Central.
Temperatures will be near or above normal for the north coast of
Puerto Rico in the short term.
&&
.LONG TERM...Thursday through Monday...
On the current forecast track by the NHC, and according to recent
model guidance, Tropical Storm Franklin should be well northwest of
the forecast area to start the long term forecast period. The system
is forecast to continue moving northeastward. There is disagreement
between the GFS and ECMWF, with the GFS favoring more 850-700mb
tropical moisture being pulled into the islands under southerly
winds due to the influence of Franklin and the ECMWF having less
moisture. The GFS model also suggests more humidity through the mid
to upper levels with overall PWAT values near and above 2.0
inches for most of the long term period. An upper level ridge is
expected to build over the islands to start the period. Conditions
will still lead to showers across windward sectors of the islands
and afternoon convection across sectors of the interior to
northern half of Puerto Rico. Hot and humid conditions are
expected with maximum temperatures reaching the low 90s,
particularly across coastal, urban and low elevations sectors of
the islands along with high heat indices from late morning to late
afternoon. Uncertainty remains in the long term forecast, as it
is dependent on the behavior of Tropical Storm Franklin and other
areas of interest in the Atlantic. Please, stay tuned to the
latest updates by the National Hurricane Center (NHC) and WFO San
Juan PR.
&&
.AVIATION...Tropical Storm Franklin was 235 mi SSW of Cabo Rojo at
21/08Z and movg W or 280 deg at 10 kts. A second area of convection
is E of the system with rainbands seen ovr lcl waters. SHRA/TSRA
expected to incr ovr PR/USVI aft 21/14Z with MVFR/IFR conds and mtn
obscurations, but VFR conds expected to prevail. Winds E 10 kt incrg
aft 21/14Z to 10 to 20 kt with gusts to 28 kt common but gusts to 35
kt psbl nr TSRA. Sfc winds bcmg ESE aft 21/15Z. Maximum winds E 35-
40 kts btwn FL029-049 and SW btwn FL425-475.
&&
.MARINE...The combination of a surface high pressure across the'
west-central Atlantic, and Tropical Storm Franklin, over the
Caribbean Sea, will maintain moderate to locally strong east-
northeast winds through the next several days. Building
seas up to around 8 feet, with winds up to 25 knots, are expected
across the offshore Caribbean waters and local passages.
This will yield hazardous marine conditions across most regional
waters and passages, with increased potential for thunderstorm
activity. Therefore, several small craft advisories are in effect
until Wednesday.
A High Rip of Rip Currents will be in effect for southeast Puerto
Rico through this afternoon, and then for southwest Puerto Rico
from this evening through late tonight. Moderate risk for most
other beaches, but decreasing to low risk of rip currents tonight
for the USVI.
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...High Rip Current Risk through this afternoon for PRZ003.
Heat Advisory until 3 PM AST this afternoon for PRZ008.
High Rip Current Risk from this evening through late tonight for
PRZ011.
VI...High Rip Current Risk until 6 AM AST early this morning for
VIZ002.
AM...Small Craft Advisory until 8 AM AST this morning for AMZ711.
Small Craft Advisory until 2 PM AST this afternoon for AMZ723.
Small Craft Advisory until 2 PM AST Tuesday for AMZ733-735.
Small Craft Advisory until 2 PM AST Wednesday for AMZ741.
Small Craft Advisory from 8 AM to 2 PM AST Tuesday for AMZ742.
Small Craft Advisory from 8 PM this evening to 2 PM AST
Wednesday for AMZ745.
&&
SHORT TERM....WS
LONG TERM.....MRR
PUBLIC DESK...GRS/EMPerspectivas sobre las Condiciones Peligrosas del Tiempo Nacional de Meteorologia en San Juan PR 510 AM AST lunes 21 de agosto de 2023 AMZ711>745-PRZ001>013-220915- San Juan y Vecindad-Noreste-Sureste-Este Interior-Norte Central- Interior Central-Ponce y Vecindad-Noroeste-Oeste Interior-Mayaguez y Vecindad-Suroeste-Culebra-Vieques-Aguas cercanas y lejanas a la costa del Atlantico y del Caribe- 510 AM AST lunes 21 de agosto de 2023 Esta perspectiva sobre las condiciones peligrosas del tiempo es para Puerto Rico. .DIA UNO...Hoy y esta noche .Rayos...Son posibles tormentas electricas numerosas. Preparese a parar todas las actividades al aire libre y moverse a refugios. .Lluvia Excesiva...Inundaciones de areas urbanas, carreteras, riachuelos, y quebradas. Inundaciones repentinas aisladas son posibles. .Calor Excesivo...Indices de calor de 108 a 111 grados a traves de areas costeras y urbanas del noroeste de Puerto Rico. Agotamiento por calor es probable con exposicion prolongada. Golpes de calor son posibles. Indices de calor de 102-107 grados en Culebra, Vieques y la mayoria de las las localidades costeras de Puerto Rico. .Vientos...Condiciones de brisa. Los articulos no asegurados podrian salir volando. .Condiciones Maritimas...Oleaje igual o mayor a 7 pies a traves de las aguas locales del Caribe. Condiciones peligrosas para embarcaciones pequenas. .Corrientes Marinas...Corrientes marinas amenazantes a la vida son posibles en la zona de olas rompientes particularmente en el sureste de Puerto Rico esta noche. .DIAS DOS A SIETE...martes a domingo Riesgo de calor excesivo continuara hasta el domingo para muchas areas costeras y de elevaciones bajas urbanas. Existe un riesgo elevado de inundaciones urbanas y de pequenos riachuelosen el sur de Puerto Rico y un riesgo limitado de inundaciones el miercoles y jueves mayormente como acumulaciones de agua en carreteras. Se esperan tormentas electricas a traves del areas cada dia. Se espera oleaje de 7 a 8 pies cada dia en el Pasaje de la Mona y las aguas del Caribe hasta el miercoles. Oleaje mayor de 5 pies se espera tambien el jueves hasta el domingo en las aguas mar afuera del Atlantico. .Comunicado sobre informacion reportada por observadores... No se recomienda la activacion de los observadores. AMZ716-726-VIZ001-002-220915- San Tomas, San John y las Islas Adyacentes-Santa Cruz- Aguas cercanas a la Costa del Atlantico y aguas costeras adyacentes del Caribe- 510 AM AST lunes 21 de agosto de 2023 Esta perspectiva sobre las condiciones peligrosas del tiempo es para las Islas Virgenes Estadounidenses. .DIA UNO...Hoy y esta noche .Rayos...Son posibles tormentas electricas de aisladas a dispersas. .Lluvia Excesiva...Inundaciones de areas urbanas, carreteras, riachuelos, y quebradas. Inundaciones repentinas aisladas son posibles. .Calor Excesivo...Indices de calor de 102 a 107 grados a traves de sectores de Saint Thomas. Agotamiento por calor es posible con exposiciones prolongadas. .Vientos...Condiciones de brisa. Los articulos no asegurados podrian salir volando. .Condiciones Maritimas...Oleaje igual o mayor a 7 pies a traves de las aguaslocales del sur del Caribe. Condiciones peligrosas para embarcaciones pequenas. .Corrientes Marinas...Existe un riesgo de corrientes marinas amenazantes a la vida en la zona de olas rompientes, particularmente en el norte de las Islas Virgenes Americanas. .DIAS DOS A SIETE...lunes a sabado Existe un riesgo limitado de calor excesivo en el norte de las Islas Virgenes Americanas. Algunas acumulaciones de agua son posibles en el norte de las Islas Virgenes Americanas el miercoles y jueves. Se esperasn tormentas electricas aisladas el martes hasta el jueves. Oleaje mayor de 5 pies se espera el jueves hasta el domingo en las aguas mar afuera del Atlantico. .Comunicado sobre informacion reportada por observadores... No se requiere la activacion de los observadores.
Preliminary Local Storm Report
National Weather Service San Juan PR
837 AM AST Mon Aug 21 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0828 AM Debris Flow 1 WNW Rosa Sanchez 18.07N 65.93W
08/21/2023 Yabucoa PR 911 Call Center
911 Call Center reported a landslide in
PR-9918 in Yabucoa.
&&
GRSThe San Juan radar (TJUA), 16 km away, was scanning. The volume nearest the first event began at 12:38 UTC.
1 debris flow, 1 flash flood, 1 thunderstorm wind. Local standard time, as filed.
A 911 Call Center reported a landslide in PR-9918 in Yabucoa.
Emergency managers indicated that road PR-31 in Naguabo is impassable due to flood waters from Rio Blanco.
A 911 Call Center reported a downed tree next to Office Gallery on Road 172 in Caguas.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2023Every state in 2023This day in weather historyWarnings in Puerto Rico, August 2023
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: 1122509, 1122508, 1122510.