A low level trough that extended south and then southwest from a low pressure north of Puerto Rico combined with daytime heating and sea breeze convergence to produce numerous showers and isolated strong thunderstorms over the San Juan metropolitan area. and San Juan.
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 level trough that extended south and then southwest from a low pressure north of Puerto Rico combined with daytime heating and sea breeze convergence to produce numerous showers and isolated strong thunderstorms over the San Juan metropolitan area. Periods of very heavy rain induced road flooding mostly over the municipalities of Guaynabo...Bayamon...Catano...and San Juan. Doppler radar rainfall estimates indicated accumulations of over 5 inches in some areas.
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 Nov 18, 3:26 PM AST, 55 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 326 PM AST WED NOV 18 2009 .SYNOPSIS...HIGH PRESSURE WILL CONTINUE TO BUILD IN THE MID TO UPPER LEVELS OF THE ATMOSPHERE HELPING TO LIMIT SHOWER ACTIVITY ACROSS THE LOCAL ISLANDS THROUGH THE END OF THE WEEK. INCREASING MOISTURE FROM THE SOUTHEAST WILL RESULT IN MORE NUMEROUS SHOWER ACTIVITY ACROSS THE LOCAL ISLANDS OVER THE UPCOMING WEEKEND. && .DISCUSSION...WHILE HIGH PRESSURE AND SUBSIDENCE IS ANCHORED ACROSS THE REGION THIS AFTERNOON...STILL MANAGED TO SEE QUITE A BIT OF DIURNALLY DRIVEN SHOWER ACTIVITY ACROSS THE NORTHERN HALF OF PUERTO RICO THE PAST FEW HOURS. EXPECT THIS SHOWER ACTIVITY TO RAPIDLY DIMINISH AROUND SUNSET...AND FOR ONLY A FEW SHOWERS IN SOUTHEASTERLY FLOW TO PASS BY THE VI AND EASTERN SECTIONS OF PUERTO RICO OVERNIGHT. EXPECT HIGH PRESSURE TO DOMINATE THE MID TO UPPER LEVELS OF THE ATMOSPHERE FOR THE NEXT SEVERAL DAYS...HOWEVER...AMPLE LOW LEVEL MOISTURE AND LOCAL ISLAND CONVERGENCE WILL RESULT IN LIMITED AFTERNOON CONVECTION...ESPECIALLY OVER THE INTERIOR AND NORTHERN SECTIONS OF THE ISLAND AS WE WILL REMAIN IN A EAST SOUTHEASTERLY WIND FLOW PATTERN. A SURGE IN MOISTURE FROM THE SOUTHEAST WILL HELP TO BRING MORE WIDESPREAD SHOWER COVERAGE TO THE LOCAL AREA OVER THE UPCOMING WEEKEND. && .AVIATION...TEMPORARY MVFR CONDITIONS WILL BE POSSIBLE ACROSS TJSJ...TJBQ AND ACROSS THE VI THROUGH 18/23Z. PREVAILING VFR CONDITIONS EXPECTED ACROSS THE REMAINDER OF THE TAF SITES OVERNIGHT THROUGH AT LEAST 19/16Z. VA FROM MONTSERRAT EXPECTED TO REMAIN SOUTH OF TKPK OVERNIGHT. && .PRELIMINARY POINT TEMPS/POPS... SJU 75 86 75 86 / 10 20 20 30 STT 77 87 77 86 / 10 20 30 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && 64/04
HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS NATIONAL WEATHER SERVICE SAN JUAN PR 922 AM AST WED NOV 18 2009 AMZ710>745-PRZ001>013-191000- 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- 922 AM AST WED NOV 18 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. AMZ715-725-VIZ001-002-191000- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 922 AM AST WED NOV 18 2009 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...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The San Juan radar (TJUA), 31 km away, was scanning. The volume nearest the first event began at 20:21 UTC.
9 heavy rain, 2 flash flood. Local standard time, as filed.
One home was reported flooded at Sierra Linda neighborhood in Bayamon City.
One home was reported flooded at Miraflores neighborhood in Bayamon City.
One home was reported flooded at Progreso street in Catano City.
Road flooding was reported at Bello Monte neighborhood in Guaynabo City.
Road flooding was reported behind the Victory Shopping Center, at the Country States neighborhood in Bayamon.
Road flooding was reported in several parts of Bayamon City, along Main Avenue in Santa Rosa, and along the north marginal road, in Jardines de Caparrra neighborhood.
Central Juanita avenue was reported flooded, below Highway 22 bridge in the municipality of Guaynabo.
A house was flooded at road 833, Km12, H12 in Bo. Santa Rosa III in the municipality of Guaynabo.
Houses flooded and Malaga street flooded at Urb. Torrimar in the municipality of Guaynabo.
Roads and homes were reported flooded in the University Gardens sector of San Juan.
John F. Kennedy Avenue was reported flooded in the vicinity of Audi and Volvo car dealers.
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, November 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 2026-09-30. Each event’s entry at NCEI: 200714, 200716, 200719, 200593, 200723, 200727, 200728, 200818, 200819, 200847, 203096.