Heavy rains developed in the late morning hours of the 23rd across the San Juan metro area, and persisted for several hours, producing widespread urban flash flooding. 70 feet, which is the highest on record, following Hurricane Hortense in 1996.
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.
Heavy rains developed in the late morning hours of the 23rd across the San Juan metro area, and persisted for several hours, producing widespread urban flash flooding. Numerous roads were inundated and river Rio Piedras went into flood, cresting at 20.70 feet, which is the highest on record, following Hurricane Hortense in 1996. There were up to 60 evacuations from a housing development near the river and several major roads impacted. The San Juan Municipal Emergency Management Agency indicated that around 300 homes were flooded, with damages estimated at least at half a million.
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, 5:05 AM AST, 7 hours 10 minutes earlier.
PUERTO RICO AND U.S. VIRGIN ISLANDS FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 505 AM AST SUN MAY 23 2004 .SYNOPSIS...MID TO UPPER LEVEL SUBTROPICAL RIDGING CONTINUES TO EXTEND AND BUILD INTO THE EASTERN CARIBBEAN AS A BROAD TROUGH EXTENDS FROM THE CENTRAL ATLANTIC SOUTHWEST ACROSS THE WEST ATLANTIC OVER CUBA INTO THE WESTERN CARIBBEAN. THE SUBTROPICAL JET WHICH CONTINUES TO RIDE THE PERIPHERY OF THIS BUILDING RIDGE AND CROSSES INTO THE ATLANTIC...HAS SHIFTED FURTHER THE NORTH OF THE LOCAL REGION. WEAK MID LEVEL SHORT WAVE VORTICIES IS STILL APPARENT MOVING ALONG THE TROUGH ACROSS THE WEST AND CENTRAL CARIBBEAN TOWARDS PORTIONS OF HISPANOLA. THE UPPER LEVEL WINDS OVER THE LOCAL AREA HAVE SOMEWHAT DECREASED...HOWEVER THE OVERALL PATTERN WILL CONTINUE TO MAINTAIN UPPER LEVEL SUPPORT ACROSS THE REGION. HIGH PRESSURE IN THE LOW LEVELS CONTINUE TO DOMINATE THE ATLANTIC...MEANWHILE AN ELONGATED TROUGH AND ASSOCIATED LOW PRESSURE CENTERED ACROSS THE CENTRAL CARIBBEAN...STRETCHES NORTH NORTHEAST INTO THE NORTHEAST CARIBBEAN AND OVER THE LOCAL AREA. A WEAK WAVE IN THE EASTERLY WIND FLOW NOW ACROSS THE WINDWARD AND LEEWARD ISLANDS CONTINUE TO SLOWLY MOVE WEST. THE COMBINATION OF THESE FEATURE IS ASSISTING IN MAINTAINING THE EAST SOUTHEAST LOW LEVEL WIND FLOW WITH ABUNDANT LOW LEVEL MOISTURE ADVECTION. && .DISCUSSION...CLOUDY SKIES CONTINUED ACROSS THE LOCAL AREA OVERNIGHT INTO THE EARLY MORNING HOURS. A MIXTURE OF LIGHT RAIN AND SCATTERED TO NUMEROUS SHOWER ACTIVITY WITH AN ISOLATED EMBEDDED AN THUNDERSTORM OR TWO CONTINUED TO MOVE NORTHWEST ACROSS THE REGIONAL WATERS AND AFFECT THE MAJORITY OF THE LOCAL ISLANDS. MODEL GUIDANCE REMAIN PERSISTENT AND CONTINUE TO SUGGEST THAT COPIOUS AMOUNTS OF MOISTURE FROM SURFACE TO UPPER LEVELS WILL CONTINUE OVER THE LOCAL AREA THROUGH EARLY NEXT WEEK. SOUNDINGS ACROSS THE REGION REMAIN VERY MOIST AND UNSTABLE WITH GOOD TROPICAL MOISTURE AND PRECIPITABLE WATER BETWEEN 1.80 TO 2.38 INCHES. THE LOW PRESSURE SYSTEM ACROSS THE CARIBBEAN WILL CONTINUE TO MOVE NORTH NORTHWEST AND IN DOING SO WILL MAINTAIN THE PRESENT WET PATTERN ACROSS THE LOCAL REGION THROUGH AT LEAST MONDAY AND THEN CONDITIONS SHOULD THEN TAPER OFF ON TUESDAY AND IMPROVING BY MID WEEK. EXPECT AN ACTIVE...CLOUDY AND WET WEATHER PATTERN ACROSS THE AREA TODAY THROUGH MONDAY WITH INTERMITTENT...VERY HEAVY RAIN AND OCCASIONAL THUNDERSTORM ACTIVITY. THE RISK FOR FLASH FLOODING IS HIGH AND WILL CONTINUE ISLAND WIDE WITH GOOD CHANCE OF MUDSLIDES OVER MOUNTAINOUS TERRAIN AS SOIL REMAINS VERY SATURATED AND MOST RIVERS AND STREAMS REMAIN AT OR NEAR HIGH LEVELS. A WATCH REMAIN IN PLACE FOR ALL OF THE LOCAL ISLANDS. && .PRELIMINARY POINT TEMPS/POPS... SJU 83 71 86 73 / 100 80 80 40 STT 82 71 84 75 / 100 80 80 60 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...FFA PRZ001>006-012-013 TIL 6 PM. VI...FFA VIZ001-002 TIL 6 PM. && MITCHELL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 610 AM AST SUN MAY 23 2004 PRZ001>013-AMZ710>750-241000- 610 AM AST SUN MAY 23 2004 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO. .TODAY...MOISTURE MOVING UP FROM SOUTH AMERICA ON THE EAST SIDE OF AN UPPER TROUGH EXTENDING FROM GUATEMALA TO CUBA WILL BRING MORE RAIN TO AN ALREADY SOGGY LAND. THIS COUPLED WITH STILL FAVORABLE UPPER LEVEL WINDS...AND A ZONE OF LOW AND MID LEVEL CONVERGENCE WILL PROLONG THE CLOUDY SKIES AND PRODUCE COPIOUS RAINS FOR PUERTO RICO. THE HEAVIEST RAINS WILL DEVELOP IN THE MORNING ALONG THE SOUTH COAST AND THEN DURING THE DAY OVER THE INTERIOR OF PUERTO RICO HEAVY RAINS ARE ALSO DEVELOPING IN THE ATLANTIC WATERS TO OUR NORTH. WIDESPREAD RAIN WILL CAUSE MANY RIVERS TO RISE...SOME TO FLOOD STAGE...AND CONSIDERABLE FLOODING OF LOW-LYING AREAS AS WELL AS THE VERY REAL DANGER OF MUDSLIDES AND TOPPLING TREES. THE HEAVIEST CONCENTRATION OF RAIN WILL BE AROUND MIDDAY BUT MAY CONTINUE INTO THE EVENING HOURS. A MODERATE TO OCCASIONALLY STRONG TRADE WIND FLOW OVER THE REGION WILL MAINTAIN ROUGH AND CHOPPY SEAS. NORTHEAST SWELL IS ALSO CONTRIBUTING TO ELEVATED SEAS. THE STRONGEST WINDS AND HIGHEST SEAS WILL BE IN THE ATLANTIC OFFSHORE WATERS. .SPOTTER CALL TO ACTION STATEMENT... SPOTTER ACTIVATION IS REQUESTED. .DAYS TWO THROUGH SEVEN... THE VERY MOIST AIR WILL CONTINUE IN THE AREA THROUGH WEDNESDAY EVEN THOUGH THE DYNAMICS GENERATING THE RAIN WILL BEGIN DECREASING TONIGHT. THAT SAID...HOWEVER...STRONG CONVECTION WILL CERTAINLY BE POSSIBLE NEARLY EVERY DAY THIS WEEK IN THE INTERIOR PORTIONS OF PUERTO RICO AND THE FLOODING OF ROADWAYS...URBAN AREAS...SMALL STREAMS AND THE RISK OF MUDSLIDES WILL CONTINUE THERE THROUGH AT LEAST WEDNESDAY. MORE RAIN IS ALSO POSSIBLE OVER EASTERN PUERTO RICO BY THE END OF THE WEEK. A MODERATE TO FRESH TRADE WIND FLOW AND CHOPPY SEAS WILL PREVAIL ACROSS THE LOCAL ISLANDS THROUGH AT LEAST EARLY NEXT WEEK BUT WINDS AND SEAS WILL BEGIN TO SUBSIDE BY MID TO LATE WEEK. VIZ001-002-AMZ710>730-241000- 610 AM AST SUN MAY 23 2004 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS. .TODAY...MOISTURE MOVING UP FROM SOUTH AMERICA ON THE EAST SIDE OF AN UPPER TROUGH EXTENDING FROM GUATEMALA TO CUBA WILL BRING MORE RAIN TO THE VIRGIN ISLANDS. THIS COUPLED WITH STILL FAVORABLE UPPER LEVEL WINDS...AND A ZONE OF LOW AND MID LEVEL CONVERGENCE PASSING OVERHEAD FROM THE SOUTH TODAY WILL PROLONG THE CLOUDY SKIES AND PRODUCE MUCH ABOVE NORMAL RAINFALL. SKIES WILL REMAIN CLOUDY WITH OCCASIONAL SHOWERS AND RAIN IN THE U.S. VIRGIN ISLANDS. THE HEAVIEST AND MOST FREQUENT RAIN SHOULD OCCUR IN THE NORTHERN VIRGIN ISLANDS TODAY. SOME OF THESE STORMS MAY PRODUCE INTERMITTENT HEAVY RAINS THAT MAY CAUSE LOCALIZED FLOODING OF STREETS AND POOR DRAINAGE AREAS. TONIGHT RAIN WILL DIMINISH AND THE DANGER OF FLASH FLOODING WILL DECREASE. A MODERATE TO OCCASIONALLY STRONG TRADE WIND FLOW OVER THE REGION WILL MAINTAIN ROUGH AND CHOPPY SEAS. NORTHEAST SWELL IS ALSO CONTRIBUTING TO ELEVATED SEAS. THE STRONGEST WINDS AND HIGHEST SEAS WILL BE IN THE ATLANTIC OFFSHORE WATERS. .SPOTTER CALL TO ACTION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED. .DAYS TWO THROUGH SEVEN...THE FOCUS OF THE CONVECTIVE ACTIVITY WILL MOVE NORTH TONIGHT...BUT THE ATMOSPHERE WILL CONTINUE TO BE VERY MOIST AND SOMEWHAT UNSTABLE. THE VERY MOIST AIR WILL CONTINUE IN THE AREA THROUGH WEDNESDAY EVEN THOUGH THE DYNAMICS GENERATING THE RAIN WILL BEGIN DECREASING TONIGHT. PERIODS OF OCCASIONAL MODERATE TO HEAVY RAINS AT LEAST THROUGH TUESDAY AND AGAIN DURING THE MORNINGS THURSDAY THROUGH SATURDAY...WILL CAUSE LOCALIZED FLOODING OF STREETS AND POOR DRAINAGE AREAS. A MODERATE TO FRESH TRADE WIND FLOW AND CHOPPY SEAS WILL PREVAIL ACROSS THE LOCAL ISLANDS THROUGH AT LEAST EARLY NEXT WEEK BUT WINDS AND SEAS WILL BEGIN TO SUBSIDE MIDDLE AND LATE WEEK. STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER DETAILS OR UPDATES. FOR ADDITIONAL INFORMATION...VISIT THE NATIONAL WEATHER SERVICE WEB SITE FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS AT (ALL LOWERCASE LETTERS): HTTP://WWW.SRH.NOAA.GOV/SJU.
1 flood. Local standard time, as filed.
Heavy rains affected the San Juan municipality and caused flooding of highways, roads and thirty homes mainly in Santurce, Rio Piedras, and Puerto Nuevo sections.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2004Every state in 2004This day in weather historyWarnings in Puerto Rico, May 2004
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: 5398482.