A subtropical Jet Maxima, combined with an upper level trough and ample moisture at the surface to produce numerous showers with thunderstorms mainly over the central interior and north central sections of Puerto Rico.
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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.
A subtropical Jet Maxima, combined with an upper level trough and ample moisture at the surface to produce numerous showers with thunderstorms mainly over the central interior and north central 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 May 8, 4:19 PM AST, 1 hour 41 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 419 PM AST TUE MAY 8 2012 .SYNOPSIS...A SOUTHWEST JET CORE STRENGTHENS OVER PUERTO RICO BETWEEN NOW AND WEDNESDAY AFTERNOON AS AN APPROACHING SHORT WAVE TROUGH DEEPENS OVER THE CENTRAL CARIBBEAN. THEN SEVERAL SMALL TROUGHS WILL PASS THROUGH BEFORE THE MAIN TROUGH PASSES ON FRIDAY. AFTER SUNDAY A RIDGE BUILDS OVER THE CARIBBEAN PUTTING NORTHWEST FLOW OVER PUERTO RICO AND THE U.S. VIRGIN ISLANDS FOR THE REST OF NEXT WEEK. AT MID LEVELS...HIGH PRESSURE CONTINUES OVER THE TROPICAL ATLANTIC THROUGH THE PERIOD. A TROUGH DIGS INTO THE CENTRAL CARIBBEAN TONIGHT THROUGH THURSDAY BUT WEAKENS BEFORE ARRIVING IN THE LOCAL AREA. HIGH PRESSURE THEN DOMINATES THE CARIBBEAN FOR THE REST OF THE FOLLOWING WEEK. AT LOWER LEVELS...HIGH PRESSURE BUILDING SOUTH INTO THE CENTRAL ATLANTIC WILL CAUSE FLOW TO BECOME MORE SOUTHEAST OVER THE LOCAL AREA AND FORCE THE WEAK TROUGH OVER THE LEEWARD ISLANDS TOWARD THE LOCAL AREA WEDNESDAY THROUGH FRIDAY...BRINGING AN INCREASE IN MOISTURE. AS SOUTHEAST WINDS INCREASE OVER THE AREA SOME DRY AIR WILL BE IMPORTED FROM THE TROPICAL ATLANTIC SATURDAY THROUGH MONDAY...BUT IT WILL BE MIXED WITH MOISTURE FROM THE SOUTHEAST RESULTING IN A DRYING TREND...THAT WILL STILL SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS NEXT WEEK...ESPECIALLY DURING THE AFTERNOONS OVER THE INTERIOR OF PUERTO RICO. && .DISCUSSION...AFTER A NEARLY RAIN FREE MORNING OVER PUERTO RICO SHOWERS AND THUNDERSTORMS EXPLODED OVER THE INTERIOR DURING THE EARLY AFTERNOON LEAVING UP TO 2 TO 4 INCHES OF RAIN IN SOME AREAS. SOME OF THESE SHOWERS WILL DRIFT TOWARD THE NORTH COAST DURING THE LATE AFTERNOON HOURS. THE DRIER PERIOD THAT THE REST OF THE AREA HAS BEEN EXPERIENCING WILL GRADUALLY END TONIGHT AND TOMORROW AS MOISTURE RETURNS FROM THE SOUTHEAST WITH A WEAK TROUGH THAT WAS STATIONARY OVER THE LEEWARD ISLANDS. MOISTURE WILL CONTINUE WITH SHOWERS AND THUNDERSTORMS THROUGH FRIDAY...AND THEN BEGIN TO TAPER OFF AS AIR FROM WEST AFRICA BEGINS TO SEEP INTO THE AREA FROM THE EAST. THERE WILL BE SUFFICIENT MIXING IN THE WIDER AREA HOWEVER...TO BRING PATCHES OF MOISTURE AND KEEP AT LEAST SCATTERED SHOWERS IN THE FORECAST THROUGH THE WEEKEND. MOISTURE FROM THE EAST NORTHEAST THEN ARRIVES AND BRINGS MORE SCATTERED SHOWERS IN A TREND THAT WILL CONTINUE FOR MUCH OF THE FOLLOWING WEEK. SOME AREAS WILL HAVE SUFFICIENT RAIN NOW THROUGH FRIDAY FOR URBAN AND SMALL STREAM FLOODING. && .AVIATION...MVFR AND IFR CONDITIONS WITH MOUNTAIN OBSCURATIONS WILL CONTINUE THROUGH 09/00Z OVER THE INTERIOR OF PUERTO RICO...BUT TAF SITES WILL BE LITTLE AFFECTED EXCEPT FOR TJSJ LATE AFTERNOON AND EARLY EVENING WHEN SOME SHOWERS AND THUNDERSTORMS MAY APPROACH FROM THE SOUTHWEST. ELSEWHERE VFR CONDS WILL PREVAIL EXCEPT FOR SOME MVFR IN TNCM AND TKPK THROUGH 09/22Z. LLVL WINDS ARE SHIFTING TO THE SE AND WILL INCREASE SOMEWHAT WEDNESDAY. WINDS ABOVE 10 KFT ARE WSW-W INCREASING TO 70 KTS NEAR 40 KFT. && .MARINE...MARINE CONDS REMAIN TRANQUIL AT 4 FEET OR LESS...BUT WILL INCREASE GRADUALLY NOW THROUGH TUESDAY TO 6 FEET IN THE ATLANTIC WATERS. GENTLE TO MODERATE WINDS WILL ALSO INCREASE SOMEWHAT IN THE NEXT 6 DAYS. && .PRELIMINARY POINT TEMPS/POPS... SJU 77 86 77 84 / 20 20 40 70 STT 76 86 77 85 / 30 30 50 60 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. COASTAL WATERS...NONE. && 10/12
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 534 AM AST TUE MAY 8 2012 AMZ710>745-PRZ001>013-090945- 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- 534 AM AST TUE MAY 8 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. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY NO HAZARDOUS WEATHER IS EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. AMZ715-725-VIZ001-002-090945- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 534 AM AST TUE MAY 8 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. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY NO HAZARDOUS WEATHER IS EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The San Juan radar (TJUA), 19 km away, was scanning. The volume nearest the first event began at 22:00 UTC.
1 flash flood. Local standard time, as filed.
Extreme flash flooding occured due to Rio La Plata out of its banks. Rio De la Plata flooded also two bridges. One in Road PR-156 at Barrio Higuero where several families were uncommunicated. The other was in the intersection of roads PR-156 and PR-776 in Barrio Rio Hondo.
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, May 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: 384282.