The combination of an upper low pressure close to the local area and strong daytime heating resulted in rapidly developing strong to near severe thunderstorms over the southern part of Puerto Rico. Penuelas, Ponce, Juana Diaz and Guayanilla were the most affected municipalities.
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.
The combination of an upper low pressure close to the local area and strong daytime heating resulted in rapidly developing strong to near severe thunderstorms over the southern part of Puerto Rico. Penuelas, Ponce, Juana Diaz and Guayanilla were the most affected municipalities. A trained spotter in Penuelas reported 2.26 inches of rainfall during the event.
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 19, 10:53 AM AST, 3 hours 29 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1053 AM AST THU AUG 19 2010 .UPDATE...MOSTLY CLEAR AND HAZY SKIES WILL PERSIST ACROSS THE LOCAL REGION TODAY...AS A RELATIVELY DRIER AND STABLE AIR MASS PREVAIL ACROSS THE LOCAL ISLANDS. HOWEVER...THIS AFTERNOON AS SEA BREEZES DEVELOP WILL START TO SEE THE USUAL AFTERNOON CONVECTION OVER THE WESTERN AND SOUTHWESTERN PORTIONS OF PUERTO RICO DUE TO A PREVAILING NE WIND FLOW CONVERGING ON THE LEEWARD SIDE OF THE ISLAND. THEN... TOMORROW THE TUTT LOW AND AN INDUCED LOW LEVEL PERTURBATION WILL BE LOCATED NORTH OF OUR LOCAL FORECAST AREA ENHANCING SHOWERS AND THUNDERSTORMS DEVELOPMENT AT LEAST UNTIL SATURDAY. & .AVIATION...VFR CONDS WILL PREVAIL ACROSS MOST OF THE TAF SITES DURING REST OF THE DAY. SUSPENDED PARTICULATES OF SAHARAN DUST ACROSS FLYING AREA WILL CONTINUE TO LIMIT SLANT VISIBILITIES EN ROUTE AND AT LOCAL TAF SITES TO AROUND 8 MILES OR LESS TODAY. HOWEVER...VCSH/VCTS ARE PSBL AFT 19/17Z ACROSS TNCM AND TKPK DUE TO THE PROXIMITY OF THE TUTT LOW AND THE INDUCED LLVL PERTURBATION. FOR THIS AFTERNOON...SHRA/TSRA WILL OCCUR ONCE AGAIN ACROSS TJMZ AND VCTY...WITH LOCAL MTN OBSCURATIONS PSBL ACROSS THE INTERIOR SECTIONS. && .PREV DISCUSSION... /ISSUED 414 AM AST THU AUG 19 2010/ SYNOPSIS...A RELATIVELY DRIER AND STABLE AIR MASS WILL PREVAIL OVER THE LOCAL REGION THROUGH THIS AFTERNOON. A TUTT WILL APPROACH TO THE REGION FROM THE EAST LATE THURSDAY AND FRIDAY INDUCING AN INCREASE IN MOISTURE ACROSS THE REGION. NEXT SIGNIFICANT TROPICAL WAVE WILL BE REACHING OUR LOCAL WATERS EARLY MONDAY. DISCUSSION...LATEST RADAR AND SATELLITE OBSERVATIONS EARLY THIS MORNING DEPICTED ONLY ISOLATED TO SCATTERED SHOWERS MAINLY ACROSS THE CARIBBEAN COASTAL WATERS. UNDER A PREVAILING EAST NORTHEASTERLY TRADE WIND FLOW...FEW OF THESE SHOWERS BRUSHED THE NORTHERN SECTIONS OF PUERTO RICO AS WELL AS VIEQUES...CULEBRA AND THE U.S. VIRGIN ISLANDS...BUT IN GENERAL MINIMAL RAINFALL ACTIVITY WAS DETECTED OVER LAND AREAS OVERNIGHT AND EARLY THIS MORNING...AS A RELATIVELY DRIER AND STABLE AIR MASS PREVAIL ACROSS THE LOCAL ISLANDS. LATEST SATELLITE IMAGERY AND MIMIC-TPW FROM CIMSS SHOWED THAT THE PREVAILING DRIER AIR MASS WILL CONTINUE ACROSS THE NORTH EASTERN CARIBBEAN UNTIL LATE THIS AFTERNOON. LATEST TPW PRODUCTS AS WELL AS SAL ANALYSIS INDICATED PRECIPITABLE WATER VALUES WELL BELOW 2.0 INCHES FOR TODAY AND TONIGHT. FOR THIS AFTERNOON HOWEVER...SOME CONVECTION WILL DEVELOP ACROSS THE WEST AND WEST INTERIOR SECTIONS OF PUERTO RICO. A TUTT LOW JUST EAST OF THE FA THIS MORNING WILL MOVE CLOSER TO THE REGION IN A MORE FAVORABLE POSITION TONIGHT AND FRIDAY. SEVERAL LOW LEVEL REFLECTIONS OF THE AFOREMENTIONED TUTT LOW WILL PASS ACROSS THE LOCAL ISLANDS FROM TIME TO TIME TO COMBINE WITH DAYTIME HEATING AND GOOD UPPER LEVEL DYNAMIC TO IGNITE SHOWERS AND THUNDERSTORMS ESPECIALLY FRIDAY AFTERNOON AND POSSIBLE SATURDAY. SUNDAY WILL BE A QUIET WEATHER DAY AS STABLE CONDITIONS WILL PREVAIL ACROSS THE REGION. NEXT SIGNIFICANT TROPICAL WAVE WILL BE REACHING OUR LOCAL WATERS EARLY MONDAY. LOOKING AHEAD...COMPUTER MODELS GUIDANCE SUGGEST THAT THE TROPICAL ATLANTIC WILL BECOME A LITTLE MORE ACTIVE DURING THE UPCOMING WEEK AS SEVERAL LOW PRESSURE SYSTEMS DEVELOP INTO TROPICAL CYCLONES...BUT THE SAME GUIDANCE MOVES THE SYSTEMS IN A WEST NORTHWEST PATH...AWAY FROM THE FA. STAY TUNED AVIATION...VFR CONDS WILL PREVAIL ACROSS ALL THE TAF SITES THROUGH THE FORECAST PERIOD. FEW PASSING LOW LEVEL CLOUDS AND SHOWERS WILL DRIFT WEST SOUTHWEST ACROSS THE LOCAL WATERS AT LEAST TIL AROUND 19/12Z. GENERAL L/LVL FLOW WILL CONTINUE FM ENE AT 10 TO 15 KNOTS. SHRA AND ISOLD TSRA PSBL AFT 19/17Z MAINLY ACROSS WRN PR... VCTY TJMZ...WITH LOCAL MTN OBSCURATIONS PSBL. SUSPENDED PARTICULATES OF SAHARAN DUST ACROSS FLYING AREA WILL CONTINUE TO LIMIT SLANT VISIBILITIES EN ROUTE AND AT LOCAL TAF SITES TO AROUND 8 MILES OR LESS TODAY AT LEAST TIL 20/00Z. && .PRELIMINARY POINT TEMPS/POPS... SJU 91 78 88 76 / 30 40 40 30 STT 90 79 89 78 / 20 40 40 20 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && 11/06
HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS NATIONAL WEATHER SERVICE SAN JUAN PR 425 AM AST THU AUG 19 2010 AMZ710>745-PRZ001>013-200830- 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- 425 AM AST THU AUG 19 2010 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...FRIDAY THROUGH WEDNESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED. AMZ715-725-VIZ001-002-200830- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 425 AM AST THU AUG 19 2010 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...FRIDAY THROUGH WEDNESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
PRC059-075-111-113-191915-
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN JUAN PR
215 PM AST THU AUG 19 2010
THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED A SPECIAL WEATHER
STATEMENT EFFECTIVE UNTIL 315 PM AST FOR PEOPLE IN THE FOLLOWING
MUNICIPALITIES
IN PUERTO RICO
GUAYANILLA...JUANA DIAZ...PONCE AND PENUELAS
AT 206 PM AST NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORMS AT ABOUT 4 MILES EAST OF PENUELAS...MOVING
SOUTHWEST AT 5 MPH. THESE THUNDERSTORMS WILL ALSO BE ACCOMPANIED BY
DANGEROUS LIGHTNING...SMALL HAIL...GUSTY WINDS AND HEAVY RAINS.
INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY
AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF
POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID
USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.
HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS AS THEY
MAY BE WASHED OUT. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO
RISE...THEREFORE SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS.
ERPRC079-121-125-191915-
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN JUAN PR
222 PM AST THU AUG 19 2010
THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED A SPECIAL WEATHER
STATEMENT EFFECTIVE UNTIL 315 PM AST FOR PEOPLE IN THE FOLLOWING
MUNICIPALITIES
IN PUERTO RICO
SABANA GRANDE...SAN GERMAN AND LAJAS
AT 217 PM AST NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
THUNDERSTORM OVER SABANA GRANDE...MOVING SOUTHWEST AT 15 MPH. THESE
THUNDERSTORMS WILL ALSO BE ACCOMPANIED BY DANGEROUS LIGHTNING...
SMALL HAIL...GUSTY WINDS AND HEAVY RAINS.
INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY
AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF
POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID
USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.
ERThe San Juan radar (TJUA), 71 km away, was scanning. The volume nearest the first event began at 18:23 UTC.
1 thunderstorm wind, 1 flood. Local standard time, as filed.
Road 385 was reported impassable due to downed trees.
Several houses were reported flooded at Barrio Caracoles I in Penuelas.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2010Every state in 2010This day in weather historyWarnings in Puerto Rico, August 2010
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: 256804, 256805.