Moisture due to an upper level low combined with daytime heating and local effects to produced showers with isolated strong thunderstorms over the western and central interior and coastal sections, with a number of areas of heavy rain needing an urban and small stream advisory.
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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.
Moisture due to an upper level low combined with daytime heating and local effects to produced showers with isolated strong thunderstorms over the western and central interior and coastal sections, with a number of areas of heavy rain needing an urban and small stream advisory.
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 23, 3:05 PM AST, 10 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 305 PM AST SAT MAY 23 2015 .SYNOPSIS...AT MID AND UPPER LEVELS...THE JET STREAM OVERHEAD AT UPPER LEVELS...WILL MOVE EAST AND A WEAK TROUGH WILL PASS THROUGH MONDAY AFTERNOON OR EVENING. LOW PRESSURE WILL CUT OFF OVER THE WEST CENTRAL ATLANTIC ON MONDAY NIGHT AND MOVE TOWARD THE AREA WHILE DEEPENING TUESDAY AND TUESDAY NIGHT. THIS LOW WILL FILL SLOWLY WHILE MOVING WEST STILL ABOUT 825 MILES NORTH OF PUERTO RICO BY FRIDAY. HIGH PRESSURE WILL RIDGE OVER THE EASTERN CARIBBEAN OVER THE FOLLOWING WEEKEND. AT LOWER LEVELS...HIGH PRESSURE OFF THE VIRGINIA COAST WILL MOVE INTO THE WESTERN ATLANTIC AND TIGHTEN THE GRADIENTS OVER THE LOCAL AREA. THIS WILL KEEP TRADE WIND FLOW ACTIVE THROUGH THE FIRST HALF OF THE WEEK. A TROPICAL WAVE NEAR 31 WEST EARLIER TODAY WILL MOVE INTO THE AREA ON WEDNESDAY WITH SOME INCREASED SHOWER ACTIVITY. LOW PRESSURE WILL BE GENERATED BY THE APPROACH OF THE WAVE AND THE UPPER LEVEL LOW...MAINLY ABOVE THE SURFACE NORTH OF THE LOCAL AREA...AND WILL GENERATE A SWATH OF SOUTHERLY FLOW OVER THE AREA BEGINNING ON THURSDAY. THIS WOULD PULL CONSIDERABLE MOISTURE ACROSS THE AREA FRIDAY AND SATURDAY IF IT DEVELOPS IN THIS MANNER. && .DISCUSSION...MOISTURE CONTINUED TO DEVELOP OVER THE LOCAL AREA AND SHOWERS AND THUNDERSTORMS DEVELOPED JUST AFTER NOON FROM GUAYNABO TO DORADO WITH SOME LOCAL URBAN AND SMALL STREAM FLOODING IN GUAYNABO MUNICIPALITY. THEN STRONG SHOWERS AND THUNDERSTORMS FORMED OVER THE WESTERN CENTRAL INTERIOR AND COASTAL SECTIONS...WITH A NUMBER OF AREAS OF HEAVY RAIN NEEDING AN URBAN AND SMALL STREAM FLOOD ADVISORY. THESE AREAS OF RAIN SHOULD DISSIPATE AFTER SUNSET OVER LAND LEAVING A FEW SHOWERS...AND CONTINUE FOR A FEW HOURS MORE OVER THE WATERS TO THE WEST. MORE MOISTURE WILL MOVE INTO THE LOCAL AREA TONIGHT AND BRING SCATTERED SHOWERS TO THE LOCAL ATLANTIC WATERS AND EASTERN PUERTO RICO. SOME SHOWERS ARE ALSO EXPECTED ACROSS THE U.S. VIRGIN ISLANDS TONIGHT...BUT ACCUMULATIONS SHOULD BE SLIGHT. THIS GENERAL PATTERN WILL CONTINUE THROUGH THE WEEK WITH ENHANCEMENTS WEDNESDAY AND THURSDAY DUE TO THE PASSING TROPICAL WAVE. THEN ON FRIDAY...ACCORDING TO THE CURRENT SOLUTION OF THE GFS...SIGNIFICANTLY BETTER MOISTURE WITH PRECIPITABLE WATER VALUES OVER 2 INCHES WILL MOVE INTO THE AREA ON SOUTHERLY FLOW BRINGING MUCH BETTER CHANCES OF RAIN IN MUCH GREATER QUANTITIES THAN HAD LATELY. && .AVIATION...SCT SHRA/TSRA OVER THE INTERIOR AND WESTERN PR WILL CONTINUE AT LEAST THRU 22Z...CREATING MTN TOP OBSCD AND MVFR TO BRIEF IFR CONDS MAINLY AT JMZ. VFR ELSEWHERE. LAND/SEA BREEZE VARIATIONS AND EAST WINDS WILL CONTINUE AT 10-20 KT BLO FL100...LIGHT AND VARIABLE OVERNIGHT AT THE SFC. && .MARINE...WINDS AND SEAS WILL INCREASE SLIGHTLY CAUSING THE SPREAD OF EXERCISE CAUTION CONDITIONS OVER THE EXPOSED WATERS SUNDAY. WINDS AND SEAS SHOULD ABATE MID WEEK. && .PRELIMINARY POINT TEMPS/POPS... SJU 78 88 77 88 / 30 30 40 40 STT 78 88 78 86 / 30 30 40 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. AM...NONE. && 13/12
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 544 AM AST SAT MAY 23 2015 AMZ710>745-PRZ001>013-240945- 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- 544 AM AST SAT MAY 23 2015 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...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. AMZ715-725-VIZ001-002-240945- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 544 AM AST SAT MAY 23 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 AT THIS TIME. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The San Juan radar (TJUA), 108 km away, was scanning. The volume nearest the first event began at 19:16 UTC.
1 thunderstorm wind. Local standard time, as filed.
PREMA relayed information from 911 call center about possible thunderstorm wind damages at Barrio Mora, road 112, Isabela. Wind damages were reported.
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: 574319.