Strong daytime heating combined with local orographics effects and sea breeze convergence to produced scattered to numerous showers with strong thunderstorms over the western interior and northwest sections 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.
Strong daytime heating combined with local orographics effects and sea breeze convergence to produced scattered to numerous showers with strong thunderstorms over the western interior and northwest sections 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 Sep 30, 11:27 AM AST, 1 hour 49 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1127 AM AST SUN SEP 30 2012 .UPDATE...NO CHANGES WERE MADE TO THE CURRENT FORECAST. WEATHER IS CONSISTENT WITH THE FORECAST AND THE LATEST GUIDANCE STILL SUGGESTS SHOWERS AND THUNDERSTORMS ACROSS THE NORTHWESTERN QUADRANT OF PUERTO RICO...WHILE LITTLE TO NO RAINFALL IS EXPECTED ELSEWHERE. 30/12Z SOUNDING INDICATED A BIT DRIER AIR THAN YESTERDAY. HAVING SAID THAT...THERE SHOULD STILL BE ENOUGH MOISTURE AND INSTABILITY FOR SHOWERS AND THUNDERSTORMS TO DEVELOP. HOWEVER...WIDESPREAD SHOWERS ARE NOT EXPECTED. && .AVIATION...NO CHANGES FROM PREVIOUS DISCUSSION. LATEST GUIDANCE AND OBSERVED DATA SUGGESTS SHRA/TSRA DEVELOPMENT IN THE AFTERNOON ACROSS NW PR...WHICH MAY AFFECT TJBQ UNTIL ABOUT 30/21Z WITH TEMPO MVFR CONDITIONS. AFTER 30/22Z...VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF SITES. && .PREV DISCUSSION... /ISSUED 506 AM AST SUN SEP 30 2012/ SYNOPSIS...MID-UPPER LEVEL RIDGE WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH MONDAY. MEANWHILE THE UPPER LEVEL TROUGH ACROSS THE EAST CENTRAL ATLANTIC WILL BECOME MORE AMPLIFIED AND DIP FURTHER SOUTHWEST ACROSS THE LESSER ANTILLES BY TUESDAY...THEN RETROGRESS WESTWARD INTO THE SOUTHEASTERN CARIBBEAN BY THE END OF THE UPCOMING WEEK. SURFACE HIGH PRESSURE RIDGE NORTH OF THE AREA ACROSS THE CENTRAL ATLANTIC...WILL CONTINUE TO BUILD AND EXTEND SOUTHWEST ACROSS THE LOCAL REGION THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. FURTHER EAST OF THE LESSER ANTILLES...A TROPICAL WAVE WITH AXIS NEAR 37 WEST IS FORECAST TO CONTINUE WESTWARDS OVER THE NEXT SEVERAL DAYS...AND SHOULD ENTER THE EASTERN CARIBBEAN DURING THE LATTER PART OF THE UPCOMING WEEK. DISCUSSION...FAIRLY STRONG UPPER RIDGE ACROSS THE REGION WILL SUPPRESS ANY SIGNIFICANT OR WIDESPREAD CONVECTION TODAY. HOWEVER STILL EXPECT LOCAL AND DIURNAL EFFECTS TO HELP TRIGGER SOME SHORT LIVED AFTERNOON SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS MAINLY ACROSS THE NORTHWEST SECTIONS OF PUERTO RICO UNDER THE CURRENT SOUTHEASTERLY WIND FLOW. MOSTLY FAIR WEATHER SKIES AND HOT CONDITIONS WILL DOMINATE ELSEWHERE INCLUDING OVER THE VIRGIN ISLANDS. AS THE ATLANTIC HIGH REESTABLISHES ITSELF NORTH OF THE AREA...LOCAL WINDS WILL GRADUALLY BECOME MORE EASTERLY DURING THE NEXT 24 TO 36 HOURS OF SO WITH A SLIGHT TIGHTENING OF THE SURFACE PRESSURE GRADIENT. LATEST GFS MODEL GUIDANCE INITIATED WELL AND CONTINUED TO SUGGEST SUBSIDENCE INVERSION TO HOLD FOR THE NEXT FEW DAYS...WITH A GRADUAL DECREASE IN PWAT VALUES ACROSS THE AREA BEGINNING ON MONDAY AND CONTINUING THROUGH WEDNESDAY. THIS WILL BE FOLLOWED BY INCREASING TROPICAL MOISTURE ONCE AGAIN DURING THE LATTER PART OF THE WEEK AS THE PREVIOUSLY MENTIONED TROPICAL WAVE ENTERS THE SOUTHEASTERN CARIBBEAN. UNTIL THEN EXPECT MOSTLY ISOLATED TO SCATTERED LOCAL AND DIURNALLY INDUCED CONVECTION EACH DAY WITH ONLY A FEW EARLY MORNING PASSING PASSING SHOWERS IN SOME COASTAL AREAS FROM TIME TO TIME. NO SIGNIFICANT OR WIDESPREAD RAINFALL IN SIGHT FOR NOW. AVIATION...MAINLY VFR CONDITIONS WILL PREVAIL ACROSS ALL OF THE LOCAL FLYING AREA FOR THE NEXT 24 HRS WITH AN ISOLATED SHOWER OR TWO IN AND AROUND TIST/TISX. AFT 30/17Z...SHRA/TSRA EXPECTED TO DEVELOP ACROSS NW PR...RESULTING IN BRIEF MVFR CONDITIONS AT TJBQ THROUGH ABOUT 30/21Z. WINDS MAINLY FROM THE SOUTHEAST AT 10-15 KT. CLIMATE...SEPTEMBER 2012 AT THE SJU LUIS MUNOZ MARIN INTERNATIONAL AIRPORT WILL END AS THE WARMEST SEPTEMBER ON RECORD. SEPTEMBER 2012 HAS NOW MOVED INTO FIRST PLACE WITH AN AVG TEMP OF 85 DEGREES FAHRENHEIT SO FAR. ANOTHER HOT DAY IS EXPECTED TODAY WITH TEMPERATURES POSSIBLY IN THE LOW 90S WHICH COULD CHALLENGE TODAYS RECORD OF 94 DEGREES. IN TERMS OF RAINFALL...SEPTEMBER 2012 WILL END AS AS THE SECOND DRIEST SEPTEMBER ON RECORD WITH A TOTAL OF 1.66 INCHES OF RAIN SO FAR. VERY LITTLE ADDITIONAL RAIN IS EXPECTED TODAY. AT THE CYRIL E. KING AIRPORT IN ST. THOMAS...SEPTEMBER 2012 CURRENTLY RANKS AS THE DRIEST SEPTEMBER ON RECORD WITH 0.92 INCHES OF RAIN. THE SECOND DRIEST SEPTEMBER ON RECORD WAS IN 1986 WITH 1.08 INCHES AND THIRD WAS 1987 WITH 1.42 INCHES. VERY LITTLE ADDITIONAL RAIN IF ANY IS EXPECTED TODAY. && .PRELIMINARY POINT TEMPS/POPS... SJU 89 79 90 79 / 10 10 10 20 STT 89 80 89 80 / 20 20 20 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. COASTAL WATERS...NONE. && 25/06
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 514 AM AST SUN SEP 30 2012 AMZ710>745-PRZ001>013-010915- 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- 514 AM AST SUN SEP 30 2012 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...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. AMZ715-725-VIZ001-002-010915- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 514 AM AST SUN SEP 30 2012 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...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The San Juan radar (TJUA), 84 km away, was scanning. The volume nearest the first event began at 17:14 UTC.
2 thunderstorm wind, 1 hail. Local standard time, as filed.
Hail was reported at the Cavernas Del Rio Camuy park.
At the Cavernas del Rio Camuy park, tarps were reported blown away, seven trees down and 40 people had to be taken into safe area.
Three trees down along road PR-129 in Bayanes sector. Cars were damaged due to trees falling on them.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2012Every state in 2012This day in weather historyWarnings in Puerto Rico, September 2012
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: 414865, 414866, 414867.