An upper level low northeast of the area combied with strong daytime heating and favorable upper level dynamics to produce strong thunderstorms. These strong thunderstorms produced marble size hail over Yauco, San German, and at La Parguera in Lajas.
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.
An upper level low northeast of the area combied with strong daytime heating and favorable upper level dynamics to produce strong thunderstorms. These strong thunderstorms produced marble size hail over Yauco, San German, and at La Parguera in Lajas. A weather station in Lajas measured a wind gust of 38 mph from the north northeast.
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 16, 2:54 PM AST, 1 hour 1 minute earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 254 PM AST FRI SEP 16 2011 .SYNOPSIS...TUTT LOW IS LOCATED NORTH NORTHEAST OF THE LEEWARD ISLANDS WITH A DEEPENING TROUGH NOW EXTENDING ACROSS THE NORTHERN LEEWARDS WELL SOUTH INTO THE EASTERN CARIBBEAN...AS UPPER HIGH PRESSURE RIDGE SHIFTS FURTHER WEST ACROSS HISPANIOLA. THIS PATTERN WILL SUPPORT A CONVERGENT PATTERN AND MILD MID TO UPPER LEVEL SUBSIDENCE CAP OVER MUCH OF THE LOCAL AREA TODAY. THE TUTT WILL SLOWLY DRIFT WEST SOUTHWEST ACROSS THE REGION THROUGH SATURDAY... THEN GRADUALLY BEGIN TO LIFT NORTHWARDS AND SLOWLY FILL BEGINNING SUNDAY AND INTO THE EARLY PART OF NEXT WEEK. IN THE LOW LEVELS... SURFACE HIGH PRESSURE RIDGE ACROSS THE CENTRAL ATLANTIC AND TUTT INDUCED LOW LEVEL TROUGH JUST EAST OF THE LESSER ANTILLES WILL MOVE WESTWARD ACROSS THE NORTHEAST CARIBBEAN THROUGH THE UPCOMING WEEKEND. THIS WILL BRIEFLY INDUCE A MODERATE EAST TO NORTHEAST LOW LEVEL LEVEL WIND FLOW OVER THE NEXT FEW DAYS. && .DISCUSSION...OVERALL DRIER CONDITIONS EXPECTED OVER MUCH OF THE REGION TODAY AS WE ARE CURRENTLY ON THE CONVERGENT/SUBISDENT SIDE OF THE APPROACHING TUTT. EXPECT THIS PATTERN TO BE SHORT LIVED AND LAST ONLY UNTIL LATE TODAY. EXPECT LINGERING POCKETS OF MOISTURE OVER THE ISLANDS TO COMBINE WITH DAYTIME HEATING AND LOCAL EFFECTS TO SUPPORT DIURNALLY INDUCED AFTERNOON AND EARLY EVENING CONVECTION. AS THE UPPER LOW AND ASSOCIATED TROUGH DRIFTS WEST SOUTHWEST... EXPECT SUFFICIENT VENTILATION AND WEAK DIVERGENCE ALOFT ACROSS THE REGION LATER THIS AFTERNOON. ALTHOUGH LATEST UPPER AIR SOUNDING ACROSS THE AREA SHOWED SIGNIFICANT DECREASE IN PWAT VALUES STILL FEEL THE UPPER LEVEL DYNAMICS AND LIMITED MOISTURE AVAILABILITY... COMBINED WITH MAX DAYTIME HEATING AND LOCAL EFFECTS WILL SUPPORT AFTERNOON CONVECTION ACROSS PARTS OF THE VIRGIN ISLANDS...AND IN ISOLATED SPOTS IN THE INTERIOR AND WEST SECTIONS OF PUERTO RICO. BY SATURDAY AFTERNOON AND THROUGH SUNDAY EXPECT INCREASING INSTABILITY IN THE UPPER LEVELS...AS THE TUTT REPOSITIONS ITSELF ACROSS THE ISLANDS...AND ITCZ MOISTURE IS GRADUALLY LIFTED ACROSS THE AREA WITH THE PASSING INDUCED TROUGH. LATEST GFS MODEL GUIDANCE SUGGEST INCREASING PWAT VALUES IN EXCESS OF 2.00 INCHES THROUGH THE MIDDLE OF NEXT WEEK. THIS WILL AGAIN INCREASE THE CHANCES FOR SHOWER AND THUNDERSTORMS ACTIVITY WITH HIGH PROBABILITY OF LOCALLY HEAVY RAINFALL AND STRONG TO POSSIBLY SEVERE THUNDERSTORMS POTENTIAL ACROSS PARTS OF THE ISLANDS. UNDER INFLUENCE OF THE INDUCED TROUGH...EXPECT THE CONVECTION TO BE FOCUSED IN THE EAST TO THE SOUTHEAST. THIS WILL FOCUS AFTERNOON CONVECTION ACROSS THE SAN JUAN METRO AREA EARLY SATURDAY...THEN SPREAD TO THE NORTH CENTRAL AND WEST TO SOUTHWEST SECTIONS OF PUERTO RICO LATER IN THE AFTERNOON. THE POTENTIAL FOR URBAN AND SMALL STREAM FLOODING AS WELL AS MINOR FLOODING OF SOME MAJOR RIVERS WILL REMAIN POSSIBLE THROUGH THE WEEKEND. LONG TERM...THE NEXT TROPICAL WAVE EXPECTED TO SIGNIFICANT AFFECT THE REGION WILL BE DURING THE LATTER PART OF NEXT WEEK INTO THE FOLLOWING WEEKEND BUT THIS FEATURE IS STILL HAS A LONG WAY TO GO BEFORE IT ENTERS THE EASTERN CARIBBEAN AS USUALLY MODEL GUIDANCE AND FORECAST WILL HAVE TO BE ADJUSTED WITH TIME. && .AVIATION...PREVAILING VFR CONDITIONS ARE EXPECTED TO CONTINUE ACROSS THE ISLANDS AND ALL TAF SITES THROUGH THE NEXT 12 HOURS. HOWEVER...FEW LOW LEVEL CLOUDS AND PASSING TRADE WIND SHOWERS CAN BE EXPECTED ACROSS TJSJ...TISX AND TIST AND ON ROUTE BTW THE NRN LEEWARDS AND ERN PR FM 17/00-17/12Z. AN INCREASE IN AFTERNOON SCATTERED SHOWERS AND THUNDERSTORMS IS EXPECTED LATE SAT AND SUN. 16/12Z TJSJ SOUNDING INDICATED AN EAST NORTHEAST WIND FLOW UP TO 25 KNOTS...ALL THE WAY FROM THE SURFACE TO 20K FEET...BECOMING NORTHWARD AND STRONGER ALOFT. && .PRELIMINARY POINT TEMPS/POPS... SJU 76 87 77 89 / 40 40 50 50 STT 77 88 78 87 / 40 40 60 60 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && 72/09
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 602 AM AST FRI SEP 16 2011 AMZ710>745-PRZ001>013-171015- 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- 602 AM AST FRI SEP 16 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT ATLANTIC COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY CHANCES OF AFTERNOON THUNDERSTORMS INCREASE LATE SATURDAY AND SUNDAY WITH SEVERE STORMS POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY. AMZ715-725-VIZ001-002-171015- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 602 AM AST FRI SEP 16 2011 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 AT THIS TIME. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE SAN JUAN PR 308 PM AST FRI SEP 16 2011 PRC023-043-055-059-067-075-079-097-111-113-121-125-133-149-153- 162000- COAMO PR-GUANICA PR-GUAYANILLA PR-HORMIGUEROS PR-JUANA DIAZ PR- LAJAS PR-PENUELAS PR-PONCE PR-SABANA GRANDE PR-SAN GERMAN PR- SANTA ISABEL PR-VILLALBA PR-YAUCO PR-CABO ROJO PR-MAYAGUEZ PR- 308 PM AST FRI SEP 16 2011 AT 303 PM AST...NATIONAL WEATHER SERVICE METEOROLOGIST DETECTED A STRONG THUNDERSTORM OVER GUAYANILLA...MOVING SOUTHWEST AT 10 MPH. THIS STORM CAN BE CAPABLE OF PRODUCING STRONG GUSTY WINDS...VERY HEAVY RAIN AND INTENSE LIGHTNING THROUGH AT LEAST 4 PM AST. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP ACROSS THE SOUTH CENTRAL AND SOUTHWEST SECTIONS OF PUERTO RICO. HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS AS THEY MAY BE WASHED OUT. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE...THEREFORE SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS. INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.
SPECIAL WEATHER STATEMENT...CORRECTED NATIONAL WEATHER SERVICE SAN JUAN PR 310 PM AST FRI SEP 16 2011 PRC023-043-055-059-067-075-079-097-111-113-121-125-133-149-153- 162015- COAMO PR-GUANICA PR-GUAYANILLA PR-HORMIGUEROS PR-JUANA DIAZ PR- LAJAS PR-PENUELAS PR-PONCE PR-SABANA GRANDE PR-SAN GERMAN PR- SANTA ISABEL PR-VILLALBA PR-YAUCO PR-CABO ROJO PR-MAYAGUEZ PR- 310 PM AST FRI SEP 16 2011 AT 303 PM AST...NATIONAL WEATHER SERVICE METEOROLOGIST DETECTED A STRONG THUNDERSTORM OVER GUAYANILLA...MOVING SOUTHWEST AT 10 MPH. THIS STORM CAN BE CAPABLE OF PRODUCING STRONG GUSTY WINDS...VERY HEAVY RAIN...INTENSE LIGHTNING AND SMALL HAIL THROUGH AT LEAST 4 PM AST. ADDITIONAL SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP ACROSS THE SOUTH CENTRAL AND SOUTHWEST SECTIONS OF PUERTO RICO. HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS AS THEY MAY BE WASHED OUT. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE...THEREFORE SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS. INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.
COMUNICADO ESPECIAL SOBRE LAS CONDICIONES DEL TIEMPO SERVICIO NACIONAL DE METEOROLOGIA SAN JUAN PR 308 PM AST VIERNE 16 DE SEPTIEMBRE DE 2011 PRC023-043-055-059-067-075-079-097-111-113-121-125-133-149-153- 162000- COAMO PR-GUANICA PR-GUAYANILLA PR-HORMIGUEROS PR-JUANA DIAZ PR- LAJAS PR-PENUELAS PR-PONCE PR-SABANA GRANDE PR-SAN GERMAN PR- SANTA ISABEL PR-VILLALBA PR-YAUCO PR-CABO ROJO PR-MAYAGUEZ PR- 308 PM AST VIERNES 16 DE SEPTIEMBRE DE 2011 A LAS 3:03 PM AST...EL METEOROLOGO DEL SERVICIO NACIONAL DE METEOROLOGIA DETECTO TRONADAS FUERTES SOBRE GUAYANILLA...MOVIENDOSE AL SUROESTE A 10 MPH. ESTA TORMENTA ES CAPAZ DE PRODUCIR FUERTES RAFAGAS DE VIENTO...AGUACEROS FUERTES...RAYOS INTENSOS Y GRANIZO PEQUENO POR LO MENOS HASTA LAS 4 PM AST. AGUACEROS Y TRONADAS ADICIONALES CONTINUARAN DESARROLLANDOSE A TRAVES DEL LOS SECTORES DEL SUR CENTRAL Y SUROESTE DE PUERTO RICO. LLUVIAS FUERTES DE ESTAS TORMENTAS PUDIERAN INUNDAR AREAS BAJAS...TAL COMO CUNETAS Y AREAS DEBAJO DE LOS PUENTES. EVITE ESTAS AREAS Y NO CRUCE CARRETERAS INUNDADAS YA QUE PUDIERAN HABERSE DESLISADO. NIVELES DE AGUAS EN LAS QUEBRADAS Y RIOS TAMBIEN PUEDEN AUMENTAR...POR LO TANTO SI SE ENCUENTRA AMENAZADO POR INUNDCIONES... MUEVASE A TERRENO MAS ALTO. RALLOS INTENSOS HAN SIDO REPORTADO CON ESTAS TORMENTAS. SI SE ENCUENTRA AL AIRE LIBRE...ALEJESE DE AREAS CON OBJETOS ALTOS TAL COMO ARBOLES. MUEVASE A UNA ESTUCTURA SI ESPOSIBLE. SI ESTA DENTRO DE UNA ESTRUCURA...ALEJESE DE LAS VENTANAS Y PUERTAS Y EVITE USAR TELEFONOS ALAMBRICOS A MENOS QUE SEA UNA EMERGENCIA. INTENTE DESCONECTAR ENSERES ELECTRICOS QUE NO ESTEN EN USO ANTES DE QUE SE ACERQUE LA TORMENTA. VIENTOS EN RAFAGAS DE 35 A 40 MPH O MAS Y GRANIZO DE HASTA UN CUARTO DE PULGADA SON POSIBLES CON ESTAS TORMENTAS POR LO MENOS HASTA LAS 5:30 PM AST.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE SAN JUAN PR 338 PM AST FRI SEP 16 2011 PRC055-059-079-093-111-121-125-153-162030- GUANICA PR-GUAYANILLA PR-LAJAS PR-MARICAO PR-PENUELAS PR- SABANA GRANDE PR-SAN GERMAN PR-YAUCO PR- 338 PM AST FRI SEP 16 2011 ...SIGNIFICANT WEATHER ADVISORY FOR STRONG THUNDERSTORMS OVER YAUCO...SABANA GRANDE AND GUANICA... AT 326 PM AST...NATIONAL WEATHER SERVICE CONTINUES TO DETECT STRONG THUNDERSTORMS OVER GUAYANILLA...GUANICA...SABANA GRANDE AND LAJAS...MOVING SOUTHWEST AT 5 MPH. EMERGENCY MANAGEMENT OFFICIALS REPORTED HAIL OVER YAUCO. THESE INTENSE STORMS WILL CONTINUE TO PRODUCE SMALL HAIL...VERY HEAVY RAIN...INTENSE LIGHTNING AND STRONG GUSTY WINDS THROUGH AT LEAST 4:30 PM AST. HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS AS THEY MAY BE WASHED OUT. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE...THEREFORE SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS. INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES. ER
COMUNICADO ESPECIAL SOBRE LAS CONDICIONES DEL TIEMPO SERVICIO NACIONAL DE METEOROLOGIA SAN JUAN PR 338 PM AST VIERNE 16 DE SEPTIEMBRE DE 2011 PRC055-059-079-093-111-121-125-153-162030- GUANICA PR-GUAYANILLA PR-LAJAS PR-MARICAO PR-PENUELAS PR- SABANA GRANDE PR-SAN GERMAN PR-YAUCO PR- 338 PM AST VIERNES 16 DE SEPTIEMBRE DE 2011 ...ADVERTENCIA SIGNIFICATIVO POR FURTES TRONADAS QUE SE ESTAN DESARROLLANDO SOBRE YAUCO...SABANA GRANDE Y GUANICA... A LAS 3:26 PM AST...EL SERVICIO NACIONAL DE METEOROLOGIA CONTINUA DETECTANDO TRONADAS FUERTES SOBRE GUAYANILLA...GUANICA...SABANA GRANDE Y LAJAS...MOVIENDOSE HACIA EL SUROESTE A 5 MPH. OFICIALES DEL MANEJO DE EMERGENCIAS REPORTARON GRANIZOS PEQUENO SOBRE YAUCO. ESTAS TRONADAS INTENSAS CONTINUARAN PRODUCIENDO GRANIZO PEQUENO...LLUVIAS FUERTES...RAYOS INTENSOS Y RAFAGAS DE VIENTOS POR LO MENOS HASTA LAS 4:30 PM AST. LLUVIAS FUERTES DE ESTAS TORMENTAS PUDIERAN INUNDAR AREAS BAJAS...TAL COMO CUNETAS Y AREAS DEBAJO DE LOS PUENTES. EVITE ESTAS AREAS Y NO CRUCE CARRETERAS INUNDADAS YA QUE PUDIERAN HABERSE DESLISADO. NIVELES DE AGUAS EN LAS QUEBRADAS Y RIOS TAMBIEN PUEDEN AUMENTAR...POR LO TANTO SI SE ENCUENTRA AMENAZADO POR INUNDCIONES... MUEVASE A TERRENO MAS ALTO. RALLOS INTENSOS HAN SIDO REPORTADO CON ESTAS TORMENTAS. SI SE ENCUENTRA AL AIRE LIBRE...ALEJESE DE AREAS CON OBJETOS ALTOS TAL COMO ARBOLES. MUEVASE A UNA ESTUCTURA SI ESPOSIBLE. SI ESTA DENTRO DE UNA ESTRUCURA...ALEJESE DE LAS VENTANAS Y PUERTAS Y EVITE USAR TELEFONOS ALAMBRICOS A MENOS QUE SEA UNA EMERGENCIA. INTENTE DESCONECTAR ENSERES ELECTRICOS QUE NO ESTEN EN USO ANTES DE QUE SE ACERQUE LA TORMENTA. VIENTOS EN RAFAGAS DE 35 A 40 MPH O MAS Y GRANIZO DE HASTA UN CUARTO DE PULGADA SON POSIBLES CON ESTAS TORMENTAS POR LO MENOS HASTA LAS 5:30 PM AST. ER/TS
The San Juan radar (TJUA), 82 km away, was scanning. The volume nearest the first event began at 19:55 UTC.
1 thunderstorm wind. Local standard time, as filed.
Marble size hail was reported in Yauco and at La Parguera in Lajas. A downed tree was reported along Highway 2, exit 181 from Sabana Grande to Yauco.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2011Every state in 2011This day in weather historyWarnings in Puerto Rico, September 2011
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: 349895.