A broad trough extending from the Central Caribbean to the north of Hispaniola combined with a southeast wind and favorable upper level conditions and produced numerous showers with thunderstorms which caused heavy rain across the San Juan metropolitan area, as well over western interior and west section 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 broad trough extending from the Central Caribbean to the north of Hispaniola combined with a southeast wind and favorable upper level conditions and produced numerous showers with thunderstorms which caused heavy rain across the San Juan metropolitan area, as well over western interior and west section 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, 10:47 AM AST, 2 hours 15 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1047 AM AST FRI MAY 8 2009 .UPDATE...MOSTLY SUNNY SKIES PREVAILED ACROSS THE LOCAL AREA THIS MORNING. FOR THE REST OF THE DAY...AND THE AFTERNOON HOURS...AVAILABLE MOISTURE WILL COMBINE WITH LOCAL EFFECTS...TO PRODUCE SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS MAINLY ACROSS THE CORDILLERA CENTRAL THIS AFTERNOON. LATEST 12Z TJSJ SOUNDING INDICATED PW VALUES OF 2.01 INCHES...WHICH INDICATED A MOIST ATMOSPHERE MAINLY AT THE SURFACE...WHICH WILL HELP IN THE DEVELOPMENT OF SHOWERS THIS AFTERNOON. A LITTLE ADJUSTMENT WAS MADE TO MAX TEMP FOR THIS AFTERNOON ACROSS THE SAN JUAN METRO AREA...INCREASING A COUPLE OF DEGREES...DUE TO MORE SUNSHINE..AND LESS CLOUD COVER THIS MORNING...WHICH WILL ALLOW FOR BETTER DAYTIME HEATING THIS AFTERNOON. NO OTHER CHANGES WERE MADE TO FORECAST REASONING. && .AVIATION...EXPECT SURFACE WINDS GENERALLY FROM THE EAST AT 10-20KTS AT ALL TAF SITES...EXCEPT ACROSS TJMZ...WHERE VARIABLE WINDS ARE EXPECTED THIS AFTERNOON. EXPECT SHRA DEVELOPMENT POSSIBLE ACROSS EASTERN PR AND THE VI 17-22Z. IN ADDITION...ISOLATED TSRA WILL BE POSSIBLE OVER THE NORTH CENTRAL AND WEST INTERIOR SECTIONS OF PR AS WELL AS IN THE VICINITY OF TJMZ...TJBQ...AND TJPS AFTER 18Z. && .PREV DISCUSSION... /ISSUED 549 AM AST FRI MAY 8 2009/ SYNOPSIS...UPPER LEVEL TROUGHFINESS EXPECTED TO DOMINATE THE LOCAL AREA THROUGH EARLY SATURDAY...THEN A MORE ZONAL FLOW EXPECTED TO TAKE OVER THE CARIBBEAN FOR THE REST OF THE UPCOMING WEEKEND. AFTERWARD...A RIDGING NORTHWEST FLOW WILL BE WITH US FOR MUCH OF THE APPROACHING WEEK. AT MID LEVELS...A WEAK SOUTHERLY FLOW PROJECTED TO PREVAIL ACROSS THE LOCAL AREA FOR THE NEXT FEW DAYS AS HIGH PRESSURE RIDGE WEAKENS NORTHEAST OF THE FORECAST AREA...AND AN AREA OF HIGH PRESSURE BUILDS NORTH OF BAHAMAS. AT LOW LEVELS...HIGH PRESSURE SYSTEM IS CONTROLLING THE ATLANTIC BASIN...CREATING A MODERATE TO FRESH EASTERLY WIND FLOW ACROSS THE CWA. THIS HIGH WILL REMAIN IN PLACE FOR THE NEXT FOUR TO FIVE DAYS AT LEAST. THEREFORE...WE WILL CONTINUE UNDER THE SAME TRADE WIND FLOW REGIME. ON THE OTHER HAND...THIS FLOW WILL CONTINUE TO BRING PATCHY CLOUDS AND SHOWERS ACROSS THE LOCAL ISLANDS FOR DAYS AND DAYS TO COME. DISCUSSION...LATEST WATER VAPOR IMAGERY SHOWING SOUTHWEST FLOW ALOFT ACROSS THE FORECAST AREA. THIS FLOW IS STREAMING MID TO UPPER LEVEL CLOUDS ACROSS THE AREA DISCUSSION FROM CENTRAL AMERICA AND THE NORTHERN PART OF SOUTH AMERICA. AS APPEARS ON SATELLITE...THESE CLOUDS LOOK LIKE THEY WILL BE LINGERING AROUND FOR ONE OR TWO DAYS. THEREFORE...VARIABLY TO MOSTLY CLOUDY SKIES TO GOVERN THE LOCAL AREA FOR THIS PERIOD. AT LOW LEVELS...A MOIST TROPICAL AIR MASS WILL CONTINUE TO PUSH GROUP OF CLOUDS AND SHOWERS FROM THE NORTHEASTERN CARIBBEAN TOWARDS THE FORECAST AREA. THIS WET WEATHER PATTERN IS ANTICIPATED TO PERSIST THROUGH THE WEEKEND WITH A SMALL BREAK PROJECTED FOR LATE SUNDAY INTO MONDAY. AFTERWARD...A WET PATTERN RETURNS FOR MUCH OF THE UPCOMING WEEK. EXPECT MODERATE TO HEAVY INTENSITY SHOWERS AND EVEN A FEW THUNDERSTORMS TO POP ACROSS THE AREA WATERS AND OVER THE CENTRAL INTERIOR...PARTS OF THE NORTHERN COASTS AND NORTHWEST PUERTO RICO THIS AFTERNOON. ONCE THE EVENING...ARRIVE...MOST OF THIS ACTIVITY SHOULD BE CALMING DOWN. HOWEVER...WITH THIS AFTERNOON SHOWER ACTIVITY...SOME MINOR FLOODING ARE EXPECTED TO OCCUR OVER SOME AREAS. ALSO...THE RISK OF MUDSLIDES STILL EXIST MAINLY ACROSS THOSE AREAS AFFECTED EARLY IN THE WEEK AS SOILS ARE NEAR SATURATION STAGE. AVIATION...PERIODS OF IFR/MVFR CONDITIONS EXPECTED ACROSS TNCM AND TKPK AT LEAST THROUGH 10Z DUE TO PASSING SHOWERS. PREVAILING VFR CONDITIONS EXPECTED ACROSS ALL OTHER THE LOCAL TAF SITES DURING THE EARLY MORNING HOURS WITH CIGS BETWEEN 4-10 KFT...AND WINDS GENERALLY FROM THE EAST SOUTHEAST 5 TO 15 KNOTS. HOWEVER...EXPECT INTERMITTENT MVFR IN PASSING SHRA AT LEAST THROUGH 12Z ENROUTE BTWN EASTERN PUERTO RICO AND THE VIRGIN ISLANDS. THEREAFTER...EXPECT SFC WNDS GENERALLY FROM THE EAST AT 10-20KTS AT ALL TAF SITES...WITH MORE SHRA DEVELOPMENT POSSIBLE ACROSS EASTERN PR AND THE VI 17-22Z. IN ADDITION...ISOLATED TSRA WILL BE POSSIBLE OVER THE NORTH CENTRAL AND WEST INTERIOR SECTIONS OF PR AS WELL AS IN THE VCNTY OF TJMZ AND TJPS AFTER 18Z. MARINE...WIND DRIVEN WAVES FROM THE NORTHEAST WILL BE DOMINATING THE REGIONAL WATERS FOR THE NEXT SEVERAL DAYS. FOR THE OFF SHORE ATLANTIC WATERS...SCA IS IN EFFECT THROUGH LATE TONIGHT. SMALL CRAFT SHOULD EXERCISE CAUTION ELSEWHERE. && .PRELIMINARY POINT TEMPS/POPS... SJU 84 75 84 75 / 50 50 50 40 STT 83 73 84 73 / 60 60 60 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && 71/64
HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS NATIONAL WEATHER SERVICE SAN JUAN PR 614 AM AST FRI MAY 8 2009 AMZ710>745-PRZ001>013-091015- 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- 614 AM AST FRI MAY 8 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT STILL AN ABUNDANCE OF TROPICAL MOISTURE SPREAD ACROSS THE REGION TODAY. THIS COMBINED WITH DIURNAL AND LOCAL EFFECTS...AND A PREVAILING EAST SOUTHEAST WIND FLOW WILL LEAD TO MODERATE TO HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ACROSS PARTS OF PUERTO RICO...ESPECIALLY OVER THE NORTH CENTRAL AND WEST SECTIONS OF THE ISLAND. THEREFORE THE POTENTIAL FOR FLASH FLOODING AND MUDSLIDES DUE TO SATURATED SOIL IN AREAS OF STEEP TERRAIN...REMAIN HIGH THROUGH THE EVENING HOURS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY AT LEAST THROUGH SUNDAY...SHOWERS DEVELOPMENT WILL CONCENTRATE MAINLY ACROSS THE WESTERN INTERIOR SECTIONS OF THE ISLAND...WHERE MINOR FLOODING MAY OCCUR ESPECIALLY ACROSS LOW LYING AND POOR DRAINAGE AREAS...URBAN LOCATIONS AND LOCAL STREET AND HIGHWAYS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION NOT REQUIRED AT THE MOMENT. HOWEVER...REPORTS OF RAINFALL AMOUNTS AND FLOODING WOULD BE GREATLY APPRECIATED. AMZ715-725-VIZ001-002-091015- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 614 AM AST FRI MAY 8 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT STILL AN ABUNDANCE OF TROPICAL MOISTURE SPREAD ACROSS THE REGION TODAY. THIS COMBINED WITH THE PREVAILING EAST SOUTHEAST WIND FLOW WILL BRING PERIODS OF MODERATE TO LOCALLY HEAVY SHOWERS ACROSS PARTS OF THE ISLANDS ESPECIALLY DURING THE MORNING HOURS. THIS WILL LEAD TO MINOR PONDING OF WATER ON STREETS AND ROADWAYS AND POORLY DRAINED AREAS. NO OTHER HAZARDOUS WEATHER CONDITIONS EXPECTED THEREAFTER. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY NO WEATHER HAZARDOUS CONDITIONS EXPECTED FOR THIS PERIOD. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.
The San Juan radar (TJUA), 35 km away, was scanning. The volume nearest the first event began at 16:59 UTC.
3 heavy rain, 1 debris flow, 1 flash flood. Local standard time, as filed.
Road 165 along the Fort Buchanan sector was reported flooded in front of the Federal Prison.
A mudslide was reported along highway PR-105, and at Liceo Arriba, Polvorin sector along road 349 km 0.8 in the municipality of Mayaguez.
Urban and road flooding was reported on Martinez Nadal Expressway and Summit Hills. Motorists were stranded on area streets.
Urban flooding was reported in the municipality of Dorado.
Flooded roads were reported across Rio Piedras, Hato Rey, Puerto Nuevo and Bo. Obrero sectors of the San Juan Metro area. Motorists were stranded in several areas of Rio Piedras, Puerto Nuevo and Kennedy Avenue.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2009Every state in 2009This day in weather historyWarnings in Puerto Rico, May 2009
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: 176184, 169956, 176189, 170025, 176155.