A low to mid level trough and its associated moisture combined with very favorable upper level dynamics and orographical effects to produce very heavy rain across Puerto Rico between July 12-14.
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 low to mid level trough and its associated moisture combined with very favorable upper level dynamics and orographical effects to produce very heavy rain across Puerto Rico between July 12-14.
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 Jul 13, 12:20 PM AST, 1 hour 48 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN JUAN PR 1220 PM AST WED JUL 13 2011 .UPDATE...TROPICAL WAVE WILL CONTINUE TO MOVE WEST NORTHWEST ACROSS THE LOCAL AREA THIS AFTERNOON THROUGH EARLY TONIGHT. MOISTURE ASSOCIATED WITH THIS FEATURE WILL CONTINUE TO SPREAD ACROSS THE LOCAL ISLANDS AND WILL INTERACT WITH LOCAL EFFECTS AND FAVORABLE UPPER LEVEL CONDITIONS...TO PRODUCE A GOOD DEAL OF CLOUDINESS... SHOWERS AND A FEW THUNDERSTORMS. PERIODS OF HEAVY RAIN...BRIEF STRONG AND GUSTY WINDS...LIGHTNING AND SOME MINOR LOW LYING FLOODING WILL OCCUR IN A FEW LOCATIONS. INHERITED SHORT TERM GRIDS AND ZFP HAD A GOOD HANDLE ON EXPECTED CONDITIONS FOR THIS AFTERNOON...BUT SENT A QUICK UPDATE TO BOTH TO ALTER WEATHER... SKY COVER...POPS AND WINDS IN MOST ZONES. FOR THE COASTAL WATERS...MADE A COUPLE OF SEMANTIC ALTERATIONS TO THE PREVIOUS CWF...MAINLY TO THE SYNOPSIS...OTHERWISE NO CHANGES. && .AVIATION...PREVAILING VFR CONDITIONS WILL CONTINUE ACROSS THE LOCAL ISLANDS AND TAF SITES DURING THE NEXT 24 HOURS. HOWEVER... MORE FREQUENT THAN NORMAL MVFR CONDITIONS ARE EXPECTED THIS AFTERNOON AND TONIGHT...IN DEVELOPING AND EXPANDING SHOWERS AND THUNDERSTORMS. && .PREV DISCUSSION... /ISSUED 421 AM AST WED JUL 13 2011/ SYNOPSIS...A LOW TO MID LEVEL TROUGH (TUTT REFLECTION) EXTENDING ACROSS MONA PASSAGE OVERNIGHT AND ITS ASSOCIATED MOISTURE...WILL CONTINUE MOVING WEST NORTHWEST AND AWAY FROM THE LOCAL REGION TODAY. A WEAK TROPICAL WAVE WILL MOVE ACROSS THE LOCAL AREA LATE TODAY THROUGH TONIGHT OR EARLY THURSDAY. DISCUSSION...PARTLY CLOUDY SKIES PREVAILED ACROSS THE LOCAL ISLANDS OVERNIGHT AND EARLY IN THE MORNING. THE DOPPLER WEATHER RADAR DETECTED SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE SOUTHEASTERN SECTIONS OF PUERTO RICO AS WELL AS ACROSS THE SURROUNDING COASTAL WATERS OVERNIGHT. A LOW TO MID LEVEL TROUGH (TUTT REFLECTION) EXTENDING ACROSS THE MONA PASSAGE OVERNIGHT AND ITS ASSOCIATED MOISTURE...WILL CONTINUE MOVING WEST NORTHWEST AND AWAY FROM THE REGION TODAY. LATEST SATELLITE IMAGES AS WELL AS MIMIC-TPW FROM CIMSS...DEPICTED A NARROW BAND OF DRY AIR ACROSS THE NORTHEASTERN CARIBBEAN OVERNIGHT. THIS NARROW DRY SLOT IS ASSOCIATED WITH THE SUBSIDENCE AHEAD OF A WEAK TROPICAL WAVE...ENTERING THE EASTERN CARIBBEAN THIS MORNING. THIS SHORT LIVED BRIEF SUBSIDENCE WILL LAST ONLY THROUGH EARLY TODAY. TROPICAL WAVE AND ITS ASSOCIATED MOISTURE WILL MOVE ACROSS THE LOCAL AREA LATE TODAY THROUGH TONIGHT AND PROBABLY EARLY THURSDAY... RESULTING IN AN INCREASE IN CLOUDINESS...SHOWERS AND THUNDERSTORMS ACROSS THE FA. FOR THURSDAY AND FRIDAY...LINGERING MOISTURE SHOULD COMBINE WITH LOCAL EFFECTS TO PRODUCE SOME DIURNALLY AND NOCTURNALLY INDUCED CLOUDINESS...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS EACH DAY. AVIATION...INTERMITTENT PERIODS OF LOW LEVEL CLOUDS AND PASSING SHOWERS WILL CONTINUE TO MOVE ACROSS PUERTO RICO AND THE NORTHERN LEEWARDS ISLANDS UNTIL AT LEAST 13/15Z...PRODUCING BRIEF PERIODS OF MVFR CONDITIONS NEAR SHRA/TSRA. AFTER 13/16Z...CONVECTIVE SHRA/TSRA ASSOCIATED WITH A TROPICAL WAVE WILL LEAD TO TEMPO PERIODS OF MVFR OR EVEN IFR CONDITIONS AND LOCAL MOUNTAIN OBSCURATIONS OVER MOST OF THE TAF SITES. EAST WINDS WILL CONTINUE AT AROUND 5 TO 20 KTS FROM THE SFC TO AROUND 15 KFT...BECOMING LIGHT AND VARIABLE ABOVE. && .PRELIMINARY POINT TEMPS/POPS... SJU 87 77 90 78 / 50 50 50 30 STT 87 78 88 80 / 50 50 50 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 539 AM AST WED JUL 13 2011 AMZ710>745-PRZ001>013-140945- 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- 539 AM AST WED JUL 13 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT ATLANTIC COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT SUFFICIENT MOISTURE AVAILABLE ACROSS THE ISLAND...TO COMBINE WITH LOCAL AND DIURNAL EFFECTS TO PRODUCE AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. SOME STORMS MAY PRODUCE LOCALLY HEAVY DOWNPOURS... ESPECIALLY OVER THE CENTRAL AND WESTERN INTERIOR...WEST AND SOUTHWEST SECTIONS OF PUERTO RICO DURING THE DAY. PERIODS OF CLOUD TO GROUND LIGHTNING...BRIEF GUSTY WINDS AND AT LEAST SOME LOCALIZED FLOODING ARE POSSIBLE IN A FEW LOCATIONS THROUGH THE EVENING HOURS...AS A TROPICAL WAVE IS ALSO EXPECTED TO MOVE ACROSS THE REGION. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY AT LEAST THROUGH THURSDAY...A TROPICAL WAVE MOVING ACROSS THE EASTERN CARIBBEAN...WILL BRING ADDITIONAL TROPICAL MOISTURE TO THE FORECAST AREA. THIS WILL INCREASE THE CHANCES FOR THUNDERSTORM ACTIVITY AND PERIODS OF LOCAL HEAVY RAINFALL ACROSS THE LOCAL WATERS AND PARTS OF THE ISLANDS. THIS RAINFALL MAY LEAD TO URBAN AND SMALL STREAM FLOODING IN ISOLATED AREAS. THEREAFTER...NO OTHER HAZARDOUS WEATHER CONDITIONS ARE ANTICIPATED. .SPOTTER INFORMATION STATEMENT... SPOTTER REPORTS OF ACTIVE WEATHER OR ANY FLOODING WOULD BE GREATLY APPRECIATED. AMZ715-725-VIZ001-002-140945- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 539 AM AST WED JUL 13 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT SUFFICIENT MOISTURE WILL BE AVAILABLE ACROSS THE ISLANDS...TO COMBINE WITH LOCAL AND DIURNAL EFFECTS TO PRODUCE ISOLATED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. SOME STORMS MAY PRODUCE LOCALLY HEAVY DOWNPOURS IN ISOLATED SPOTS. PERIODS OF CLOUD TO GROUND LIGHTNING... BRIEF GUSTY WINDS AND SOME MINOR PONDING OF WATER ON ROADWAYS AND IN POOR DRAINAGE AREAS...WILL REMAIN POSSIBLE THROUGH THE EVENING HOURS AS A TROPICAL WAVE IS EXPECT TO MOVE ACROSS THE REGION. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY AT LEAST THROUGH THURSDAY...A TROPICAL WAVE MOVING ACROSS THE EASTERN CARIBBEAN...WILL BRING ADDITIONAL TROPICAL MOISTURE TO THE FORECAST AREA. THIS WILL INCREASE THE CHANCES FOR THUNDERSTORM ACTIVITY AND PERIODS OF LOCAL HEAVY RAINFALL ACROSS THE LOCAL WATERS AND PARTS OF THE ISLANDS. THIS RAINFALL MAY LEAD TO URBAN AND SMALL STREAM FLOODING IN ISOLATED AREAS. THEREAFTER...NO OTHER HAZARDOUS WEATHER CONDITIONS ARE ANTICIPATED. .SPOTTER INFORMATION STATEMENT... SPOTTER REPORTS OF ACTIVE WEATHER OR ANY SIGNIFICANT FLOODING WOULD BE GREATLY APPRECIATED.
The San Juan radar (TJUA), 28 km away, was scanning. The volume nearest the first event began at 18:08 UTC.
1 heavy rain, 1 thunderstorm wind, 1 flash flood. Local standard time, as filed.
Flooded roads were reported near Plaza del Mercado at Road 2 in the municipality of Bayamon.
Strong winds and dime size hail reported were reported in the municipality of San Sebastian.
River Rio Fajardo was reported out of its banks between Highway 3 and 53. USGS river gage sensor at Paraiso along river Fajardo indicated the level rose above flood stage to 8.97 feet.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2011Every state in 2011This day in weather historyWarnings in Puerto Rico, July 2011
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: 332764, 332763, 332069.