A very weak low level wind flow and a broad upper level jet resulted in strong convection which remained nearly stationary for few hours. Showers moved through the northeastern portions of PR including the San Juan metro area.
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.
A very weak low level wind flow and a broad upper level jet resulted in strong convection which remained nearly stationary for few hours. Showers moved through the northeastern portions of PR including the San Juan metro area. Some urban and small streams advisories were issued for this area.
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 20, 11:51 AM AST, 3 hours 59 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1151 AM AST WED MAY 20 2015 .UPDATE...SHOWERS MOVED THROUGH THE NORTHEASTERN PORTIONS OF PR INCLUDING THE SAN JUAN METRO AREA. NO URBAN FLOODING WAS REPORTED WITH THIS ACTIVITY AND MOST OF THE SHOWERS MOVED QUICKLY WITH LIGHT TO MODERATE INTENSITY. VISIBLE SATELLITE INDICATES THAT CLOUDINESS HAS INCREASED SIGNIFICANTLY DURING THE DAY ACROSS THE LOCAL ISLANDS AS MOISTURE INCREASES. SOME SHOWERS HAVE ALSO DEVELOPED ACROSS THE USVI BUT THEY HAVE MOVED AWAY QUICKLY. THE INTERIOR AND WESTERN SECTIONS OF PR IS EXPECTED TO OBSERVE NUMEROUS SHOWERS WITH ISOLATED THUNDERSTORMS THIS AFTERNOON. LATEST GUIDANCE ALSO SUGGESTS THAT AS THE AFTERNOON PROGRESSES...SOME OF THE SHOWERS WILL SLOWLY DRIFT NORTH AND AFFECT PORTIONS OF NORTH CENTRAL AND NORTHWEST PR. MOISTURE WILL CONTINUE TO INCREASE SLIGHTLY TODAY INTO TONIGHT THEN HOLD FOR THE NEXT FEW DAYS. WITH THIS INCREASE IN MOISTURE ...IT WILL BE POSSIBLE FOR OVERNIGHT SHOWERS TO MOVE IN FURTHER INLAND AND AFFECT SOME SECTORS IN THE EASTERN INTERIOR OF PR. && .AVIATION...NO CHANGES FROM THE PREVIOUS DISCUSSION. SHRA/TSRA ACTIVITY EXPECTED TO DEVELOP ACROSS THE INTERIOR AND WESTERN SECTIONS OF PR THIS AFTERNOON...POSSIBLY AFFECTING TJMZ AND TJBQ AFTER 20/17Z. MTN OBSCURATIONS ARE TO BE EXPECTED AS WELL. WINDS WILL PREVAIL FROM THE EAST WITH SEA BREEZE VARIATIONS AT AROUND 10 TO 15 KTS UNTIL 20/23Z. && .MARINE...SEAS ARE EXPECTED TO BE MAINLY AT 4 FEET OR LESS AND WINDS UP TO AROUND 15 KNOTS. && .PREV DISCUSSION... /ISSUED 514 AM AST WED MAY 20 2015/ DISCUSSION...MOISTURE TO SLOWLY INCREASE OVER LOCAL ISLANDS THROUGH THU WITH PRECIPITABLE WATER APPROACHING 2 INCHES. 00Z TJSJ SOUNDING AND MIMIC-TPW PRODUCT SUGGEST IT MIGHT BE CLOSER TO 2 INCHES THAN GFS IMPLIES. ONLY A VERY WEAK LOW LEVEL WAVE IS APPROACHING IN THE EASTERN CARIBBEAN AND NOT LIKELY TO CONTRIBUTE TO DEVELOPING SHOWERS BY ITSELF. BUT A BROAD UPPER LEVEL JET IS OVER THE AREA TOO AND UPPER DIVERGENCE COULD HELP SUSTAIN CONVECTION ONCE IT STARTS...MORE LIKELY ON THU AS GFS SHOWS UPPER DIVERGENCE OVER THE AREA THEN FROM 18Z-24Z. CIRRUS CLOUDS DO NOT APPEAR WIDESPREAD OR THICK ENOUGH TO LIMIT DAYTIME HEATING SO EXPECT WESTERN PR ESPECIALLY TO RECEIVE GOOD RAINS. THUNDER TOO ESPECIALLY THU. FRI TO BEGIN A SLOW DRYING TREND AGAIN AS THE WAVE MOVES ON BUT DOES NOT BECOME VERY DRY AGAIN UNTIL EARLY NEXT WEEK WHEN A MID LEVEL RIDGE BUILDS OVER FL AND BAHAMAS. GFS SHOWS IT NOT CAUSING SIGNIFICANT MID-LEVEL DRYING THOUGH UNTIL ABOUT WED. AVIATION...VFR CONDS WILL CONTINUE ACROSS MOST OF THE TERMINALS THRU THE FORECAST PERIOD. HOWEVER...AFTERNOON CONVECTION OVER THE INTERIOR AND WESTERN PR COULD PRODUCE BRIEF MVFR/IFR CONDS IN AND AROUND TJBQ AND TJMZ BETWEEN 20/19-22Z. MOUNTAIN OBSCURATIONS ARE ALSO LIKELY ACROSS CENTRAL AND WEST INTERIOR OF PR. WINDS WILL VEER TO ESE THROUGHOUT THE DAY...RANGING BETWEEN 10-15 KTS BELOW FL070. MARINE...WINDS TO BE 15 KNOTS OR LESS TODAY AND WILL GRADUALLY INCREASE TOWARDS THE WEEKEND. BUT SEAS TO BE GENERALLY 4 FT OR LESS UNTIL TRADE WINDS INCREASE AGAIN...REACHING 5 FT PROBABLY FRI NIGHT/SAT. && .PRELIMINARY POINT TEMPS/POPS... SJU 88 77 90 77 / 30 20 40 40 STT 86 77 87 79 / 40 40 40 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. AM...NONE. && 25/09
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 604 AM AST WED MAY 20 2015 AMZ710>745-PRZ001>013-211015- 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- 604 AM AST WED MAY 20 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT ATLANTIC COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT LOCALIZED FLOODING IS POSSIBLE IN PARTS OF THE INTERIOR...NORTH AND WEST PUERTO RICO THIS AFTERNOON. THUNDERSTORMS MAY PRODUCE INTENSE RAINFALL...LEADING TO URBAN AND SMALL STREAM FLOODING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY CONDITIONS BECOME MORE FAVORABLE FOR SHOWERS AND THUNDERSTORMS LATE WEDNESDAY AND THURSDAY WITH INCREASING MOISTURE AND INSTABILITY. HEAVY RAINFALL AND MINOR FLOODING ARE POSSIBLE ACROSS THE LOCAL AREA. THE CHANCE FOR SHOWERS AND STORMS WILL GRADUALLY DECREASE ON FRIDAY AND CONTINUE THROUGH THE WEEKEND. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED. AMZ715-725-VIZ001-002-211015- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 604 AM AST WED MAY 20 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...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED.
The San Juan radar (TJUA), 29 km away, was scanning. The volume nearest the first event began at 19:48 UTC.
6 flood, 4 flash flood. Local standard time, as filed.
Person trapped in car on flooded road 181 intersection with road 199 in front of Walgreens and JF Montalvo.
Flooding on 21st street int 54 street, Urb. Reparto Metropolitano.
Home and street flooded on 38Street number 1200, Reparto Metropolitano.
Home flooded on 5th street, Villa Nevares, close to Villa Nevares park.
Flooded 18th street on Urb. Villa Nevarez.
Flooding on Expreso Las Americas into 21st street, former Oso blanco jail ramp.
Flooding on 15th street intersection with 14 at Alturas de Interamericana.
Street flooded and car trapped on street number 1, in front of UMET.
Street and home flooding on 16th street, Villa Nevarez, number 355.
Street and home flooded in Urb. Sagrado Corazon, San Genaro street 381, 387, 389.
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, May 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: 574382, 574383, 574472, 575333, 575334, 575335, 576015, 576020, 576021, 576170.