Vigorous showers and thunderstorms grew during the afternoon hours over western PR due to local effects.
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.
Vigorous showers and thunderstorms grew during the afternoon hours over western PR due to local effects.
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 21, 2:47 PM AST, 1 hour 53 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 247 PM AST MON SEP 21 2015 .SYNOPSIS...AT UPPER LEVELS...THE LOW TO THE NORTHEAST OF THE AREA WILL MOVE TO NORTH OF THE AREA THURSDAY ALLOWING NORTHWEST FLOW TO SHIFT TO THE WEST...THEN HIGH PRESSURE WILL BUILD OVER THE WESTERN CARIBBEAN GENERATING A JET OVER HISPANIOLA OF NORTHEASTERLY FLOW THAT WILL WEAKLY INFLUENCE THE LOCAL AREA THROUGH THE END OF NEXT WEEK. AT MID LEVELS...WEAK GRADIENTS WILL PREVAIL IN GENERALLY HIGH PRESSURE. THE UPPER LEVEL LOW WILL ALSO BE REFLECTED WEAKLY AT MID LEVELS. A BAND OF MOISTURE WILL ROTATE AROUND THIS LOW SO AS TO HOLD OVER THE FORECAST AREA THROUGH THURSDAY. DRIER AIR WILL RETURN UNTIL THE FOLLOWING TUESDAY. AT LOWER LEVELS...A RIDGE OF HIGH PRESSURE WILL EXTEND TO THE SOUTHWEST OFF THE MAIN HIGH IN THE EAST CENTRAL ATLANTIC THAT WILL MAINTAIN A GENTLE TO MODERATE EAST SOUTHEASTERLY TRADE WIND FLOW ACROSS THE REGION. THIS FLOW WILL GAIN A SLIGHT NORTHERLY COMPONENT ON MONDAY WHEN TROPICAL STORM IDA BEGINS TO MOVE NORTH ON MONDAY FROM HER POSITION ALMOST 900 MILES NORTH OF THE LEEWARD ISLANDS. && .DISCUSSION...VIGOROUS SHOWERS AND THUNDERSTORMS GREW DURING THE EARLY AFTERNOON HOURS OVER THE WESTERN TWO THIRDS OF PUERTO RICO AND WERE STILL FIRING OFF AS OF 3 PM AST. SHOWERS AND THUNDERSTORMS WILL LIKELY CONTINUE PAST SUNSET BY SEVERAL HOURS AS INSTABILITY CONTINUES OVER THE AREA. THE GFS INDICATES THAT MOISTURE AND INSTABILITY WILL BE VERY SIMILAR TUESDAY AND WEDNESDAY. LOW LEVEL FLOW WILL REMAIN THE SAME ALTHOUGH UPPER LEVEL FLOW WILL BACK TO THE WEST. THIS WILL CREATE VERY SIMILAR CONDITIONS WITH HEAVY DOWNPOURS AND FREQUENT LIGHTING BOTH TOMORROW AND WEDNESDAY. BEGINNING THURSDAY...STABILITY WILL SHOW A GRADUAL INCREASE THROUGH SATURDAY WHILE MOISTURE BEGINS A STEADY DECLINE UNTIL PRECIPITABLE WATER BECOMES AS LOW AS 1.25 INCHES. ALTHOUGH THIS WILL NOT ELIMINATE THUNDERSTORM ACTIVITY IT SHOULD GRADUALLY REDUCE IT THURSDAY THROUGH SATURDAY. URBAN AND SMALL STREAM FLOODING EACH AFTERNOON WILL BE LIKELY THROUGH THURSDAY...BUT SHOULD DIMINISH BY SATURDAY. && .AVIATION...MVFR CONDITIONS EXPECTED IN SHRA/TSRA SPECIALLY ACROSS WESTERN AND AND INTERIOR PUERTO RICO WITH MOUNTAIN OBSCD AFTER 21/17Z. SHRA AND POSSIBLE TSRA ALSO EXPECTED WEST AND NORTHWEST OF USVI AND INTO SAN JUAN METRO. WIND BELOW FL100 FROM E-ESE AT 5-14 KT THRU TUESDAY...WIND NORTH ABOVE FL100 AND INCREASING WITH HIGH THEN BACKING TO W-NW TONIGHT-TUESDAY. && .MARINE...SEAS WILL CONTINUE TO BE GENERALLY 4 FEET OR LESS THROUGH THE FORECAST PERIOD. HOWEVER A FEW AREAS APPROACHING 5 FEET MAY BE FOUND IN THE NORTHERN OUTER ATLANTIC WATERS WEDNESDAY. SEAS WILL CONTINUE LOWER IN THE CARIBBEAN. NO SMALL CRAFT ADVISORIES ARE ANTICIPATED DURING THE NEXT 10 DAYS BUT A FEW SHOWERS OVER THE AREA MAY BE VERY HEAVY AND HAVE GUSTY WINDS DURING THE AFTERNOONS. SCATTERED SHOWERS ARE EXPECTED IN THE LOCAL WATERS AROUND THE U.S. VIRGIN ISLANDS DURING THE OVERNIGHT HOURS. && .PRELIMINARY POINT TEMPS/POPS... SJU 78 89 78 89 / 20 40 30 30 STT 79 88 78 88 / 30 30 30 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. AM...NONE. && 72/12
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 544 AM AST MON SEP 21 2015 AMZ710>745-PRZ001>013-220945- 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- 544 AM AST MON SEP 21 2015 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 MODERATE TO HEAVY RAINFALL...BRIEF GUSTY WINDS...AND FREQUENT LIGHTNING AGAIN THIS AFTERNOON...MAINLY ACROSS THE INTERIOR AND WESTERN SECTIONS OF PUERTO RICO. AREAS IN AND AROUND THE SAN JUAN METROPOLITAN AREA MAY ALSO OBSERVE ISOLATED THUNDERSTORMS. .FLOODING...HEAVY RAINS COULD LEAD TO URBAN AND SMALL STREAM FLOODING. .RIP CURRENTS...THERE IS A MODERATE RISK OF RIP CURRENTS FOR BEACHES ACROSS THE NORTH COAST OF PUERTO RICO. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY MOISTURE WILL REMAIN HIGH THROUGH WEDNESDAY ALONG WITH A LOW LEVEL TROUGH. THERE WILL BE POTENTIAL FOR THUNDERSTORMS AND POSSIBLE URBAN AND SMALL STREAM FLOODING ACROSS PARTS OF PUERTO RICO BOTH TUESDAY AFTERNOON AND WEDNESDAY AFTERNOON. .SPOTTER INFORMATION STATEMENT... WIDESPREAD SPOTTER ACTIVATION IS NOT ANTICIPATED, HOWEVER INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT FLOODING AND RAINFALL AMOUNTS TO THE NATIONAL WEATHER SERVICE IN SAN JUAN. AMZ715-725-VIZ001-002-220945- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 544 AM AST MON SEP 21 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY NO HAZARDOUS WEATHER IS EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN JUAN PR
118 PM AST MON SEP 21 2015
PRZ005-006-009-211845-
NORTH CENTRAL-CENTRAL INTERIOR-WESTERN INTERIOR-
118 PM AST MON SEP 21 2015
...A STRONG THUNDERSTORM IS AFFECTING PART OF THE NORTH CENTRAL...
CENTRAL INTERIOR AND WESTERN INTERIOR MUNICIPALITIES OF PUERTO
RICO...
AT 110 PM AST...A CLUSTER OF THUNDERSTORMS IS PRODUCING FREQUENT AND
INTENSE LIGHTNING OVER MOST OF THE MUNICIPALITIES OF NORTH
CENTRAL...CENTRAL INTERIOR AND WESTERN INTERIOR PUERTO RICO. THESE
THUNDERSTORMS ARE NEARLY STATIONARY OVER THESE MUNICIPALITIES.
STRONG GUSTY WINDS ARE ALSO POSSIBLE WITH THESE THUNDERSTORMS.
FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THESE STORMS.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.
LAT...LON 1835 6635 1825 6639 1827 6657 1835 6660
1843 6654 1841 6648 1840 6647
TIME...MOT...LOC 1713Z 284DEG 16KT 1832 6643
JFIGUEROACOMUNICADO ESPECIAL SOBRE LAS CONDICIONES DEL TIEMPO SERVICIO NACIONAL DE METEOROLOGIA SAN JUAN PR 118 PM AST LUNES 21 DE SEPTIEMBRE DE 2015 PRZ005-006-009-211845- NORTE CENTRAL-INTERIOR CENTRAL-OESTE INTERIOR- 118 PM AST LUNES 21 DE SEPTIEMBRE DE 2015 ...UNA TRONADA FUERTE AFECTA PARTE DEL NORTE CENTRAL...INTERIOR CENTRAL...Y OESTE INTERIOR DE PUERTO RICO... A LA 1:10 PM AST...UN GRUPO DE TRONADAS FUERTES ESTA PRODUCIENDO FRECUENTES E INTENSOS RAYOS SOBRE LA MAYOR PARTE DEL NORTE CENTRAL...INTERIOR CENTRAL Y OESTE INTERIOR DE PUERTO RICO. ESTAS TRONADAS ESTAN CASI ESTACIONARIAS SOBRE ESTOS MUNICIPIOS. ADEMAS...FUERTES RAFAGAS DE VIENTO SON POSIBLES CON ESTAS TRONADAS. RAYOS FRECUENTES DE NUBE A SUELO ESTAN OCURRIENDO CON ESTA TORMENTA. LOS RAYOS PUEDEN CAER A 15 MILLAS DE LA TRONADA. BUSQUE REFUGIO SEGURO DENTRO DE UN VEHICULO O EDIFICIO. JF/RVT
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE SAN JUAN PR 223 PM AST MON SEP 21 2015 PRZ009-010-211945- MAYAGUEZ AND VICINITY-WESTERN INTERIOR- 223 PM AST MON SEP 21 2015 ...A STRONG THUNDERSTORM WILL AFFECT SAN SEBASTIAN...ANASCO... MARICAO...LARES...LAS MARIAS...MAYAGUEZ AND MOCA MUNICIPALITIES... AT 220 PM AST...A CLUSTER OF THUNDERSTORMS IS PRODUCING FREQUENT AND INTENSE LIGHTNING OVER MOST OF THE MUNICIPALITIES OF WESTERN PUERTO RICO. THESE THUNDERSTORMS ARE NEARLY STATIONARY OVER THESE MUNICIPALITIES. STRONG GUSTY WINDS ARE ALSO POSSIBLE WITH THESE THUNDERSTORMS. FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THESE STORMS. LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE SHELTER INSIDE A BUILDING OR VEHICLE. LAT...LON 1818 6686 1820 6705 1833 6704 1827 6685 TIME...MOT...LOC 1821Z 180DEG 0KT 1824 6696 JFIGUEROA
COMUNICADO ESPECIAL SOBRE LAS CONDICIONES DEL TIEMPO SERVICIO NACIONAL DE METEOROLOGIA SAN JUAN PR 223 PM AST LUNES 21 DE SEPTIEMBRE DE 2015 PRZ009-010-211945- MAYAGUEZ Y VECINDAD-OESTE INTERIOR- 223 PM AST LUNES 21 DE SEPTIEMBRE DE 2015 ...UNA TRONADA FUERTE AFECTARA A SAN SEBASTIAN...ANASCO... MARICAO...LARES...LAS MARIAS...MAYAGUEZ Y MOCA... A LAS 2:20 PM AST...UN GRUPO DE TRONADAS FUERTES ESTA PRODUCIENDO RAYOS FRECUENTES E INTENSOS SOBRE EL OESTE DE PUERTO RICO. ESTAS TRONADAS ESTAN CASI ESTACIONARIAS SOBRE ESTOS MUNICIPIOS. ADEMAS...FUERTES RAFAGAS DE VIENTO SON POSIBLES CON ESTAS TRONADAS. RAYOS FRECUENTES DE NUBE A SUELO ESTAN OCURRIENDO CON ESTA TORMENTA. LOS RAYOS PUEDEN CAER A 15 MILLAS DE LA TRONADA. BUSQUE REFUGIO SEGURO DENTRO DE UN VEHICULO O EDIFICIO. JF/RVT
The San Juan radar (TJUA), 106 km away, was scanning. The volume nearest the first event began at 20:41 UTC.
1 heavy rain, 1 flash flood. Local standard time, as filed.
Heavy rainfall across Mayaguez and vicinity lead to several mudslides in rural areas reported along road 354, sector Rio Canas.
Vega Alta PREMA officers reported closed roads 647 and 620, due to a surge of water along Rio Cibuco.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2015Every state in 2015This day in weather historyWarnings in Puerto Rico, September 2015
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: 602942, 602949.