An upper level disturbance located north of Puerto Rico together with a moisture influx at the mid and upper levels from the tropics generated favorable conditions for scattered to numerous showers and isolated thunderstorms to develop during the afternoon hours mainly across the northern half of the island. A flash flood warning was issued for parts of San Juan and Guaynabo.
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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.
An upper level disturbance located north of Puerto Rico together with a moisture influx at the mid and upper levels from the tropics generated favorable conditions for scattered to numerous showers and isolated thunderstorms to develop during the afternoon hours mainly across the northern half of the island. A flash flood warning was issued for parts of San Juan and Guaynabo.
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 Aug 30, 11:01 AM AST, 2 hours 46 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1101 AM AST SUN AUG 30 2009 .UPDATE...NO CHANGES WERE DONE TO THE PREVIOUS FORECAST PACKAGE. && .AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED TO CONTINUE ACROSS ALL TAF SITES DURING THE REST OF THE MORNING HOURS AND UNTIL 30/1800Z. AFTER THAT TIME...CONVECTION IS EXPECTED TO DEVELOP ONCE AGAIN ACROSS THE WESTERN INTERIOR...WEST AND NORTHERN SECTIONS OF PUERTO RICO. THIS WILL RESULT IN PERIODS OF MVFR CONDITIONS ACROSS TJSJ...TJMZ..AND TJBQ...ALONG WITH MOUNTAIN OBSCURATIONS UNTIL AT LEAST 30/2200Z. && .PREV DISCUSSION... /ISSUED 429 AM AST SUN AUG 30 2009/ SYNOPSIS...DEVELOPING TUTT LOW NORTH OF PR WILL DRIFT TO THE SOUTH SOUTHWEST OVR THE NEXT 48 HRS AND HELP MAINTAIN A WET PATTERN ACROSS THE REGION OVER THE NEXT COUPLE OF DAYS. TROPICAL WAVE ALONG 45W WILL TRACK ACROSS THE REGION DURING THE LATTER PART OF THE WORK WEEK. DISCUSSION...WATER VAPOR IMAGERY SHOWS DEVELOPING TUTT LOW NORTH OF PR EARLY THIS MORNING. THIS FEATURE IS FCST TO DRIFT SOUTH SOUTHWEST DURING THE NEXT 48 HRS AND SETTLE OVR HISPANIOLA BY MON EVENING. VEERING WINDS IN THE MID AND UPPER LVLS OF THE ATMOSPHERE WILL HELP DRAW MOISTURE NWD FROM THE DEEP TROPICS INTO OUR AREA AND KEEP US WET FOR THE NEXT COUPLE OF DAYS. FOR TUE-WED AND POSSIBLY INTO THU...GLOBAL MODELS SHOW INCREASING SUBSIDENCE/DRYING AS HEIGHTS RISE AS MID-UPPER LVL RIDGE ACROSS THE TROP ATLC BUILDS WESTWARD. HOWEVER...CAP DOES NOT LOOK STRONG ENOUGH TO COMPLETELY SUPPRESS CONVECTION BUT DO EXPECT A SIG DROP IN CONVECTIVE CVRG. THE FORECAST FOR THE END OF THE NEW WORK WEEK WILL BE HIGHLY DEPENDENT ON THE TRACK/EVOLUTION OF TROPICAL WAVE CURRENTLY ALONG 45W. FIRST IMAGES AFTER THE SATELLITE ECLIPSE SHOW A MARKED INCREASE IN CONVECTION WITH A CIRCULATION TRYING TO CLOSE OFF NEAR 11.2N AND 45.1W. NOT SURE IF THIS IS THE BEGINNING OF A INTENSIFICATION PHASE OR A SHORT TERM TREND GIVEN FVRBL CONVECTIVE UPSWING SEEN WITH TROPICAL SYSTEMS AT NIGHT BUT SYSTEM DEFINITELY LOOKING MUCH BETTER ORGANIZED THAN 24 HRS AGO. SVRL GLOBAL MODELS STILL SHOW DEVELOPMENT OF THIS WAVE INTO A TROPICAL CYCLONE DURING THE NEXT FEW DAYS. THE EUROPEAN MODEL WHICH HAS BEEN THE MOST RELIABLE/CONSISTENT MODEL THIS YEAR TRACKS THIS SYSTEM VERY CLOSE TO THE AREA DURING THE LATTER PART OF THE WORK WEEK. IT HAS ALSO BEEN THE MOST CONSISTENT WITH THIS SYSTEM KEEPING IT SOUTH OF 20N OVER THE PAST THREE DAYS. MODELS ALSO INDICATE SYSTEM SLOWING DOWN SIGNIFICANTLY ONCE IT REACHES 55W. GREAT AMOUNT OF UNCERTAINTY HERE ESPECIALLY WITH RESPECT TO TIMING AND INTENSITY. AVIATION...VFR THRU 16Z. MVFR CONDITIONS WITH TSRA AT JBQ/JMZ BETWEEN 18Z-23Z. MARINE...GOOD BOATING CONDITIONS THRU THE FIRST PART OF THE WEEK. INCREASING WINDS AND SEAS ARE EXPECTED DURING THE MIDDLE TO LATTER PART OF THE WORK WEEK WITH PASSAGE OF TROPICAL WAVE NOW ALONG 45W. && .PRELIMINARY POINT TEMPS/POPS... SJU 89 78 89 79 / 50 40 50 30 STT 89 79 89 79 / 30 40 40 30 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && 72/10
HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS NATIONAL WEATHER SERVICE SAN JUAN PR 457 AM AST SUN AUG 30 2009 AMZ710>745-PRZ001>013-310900- 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- 457 AM AST SUN AUG 30 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...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. AMZ715-725-VIZ001-002-310900- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 457 AM AST SUN AUG 30 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...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The San Juan radar (TJUA), 33 km away, was scanning. The volume nearest the first event began at 17:44 UTC.
1 flash flood. Local standard time, as filed.
U.S. Geological Survey sensor at the Puerto Nuevo river indicated the river went above the flood stage of 15 feet and reached 16.54 feet.
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, August 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 2026-09-24. Each event’s entry at NCEI: 194332.