The combination of a tropical wave and a mid level perturbation and their associated moisture, decent upper level ventilation and an upper level trough, produced scattered showers with isolated strong thunderstorms over the northwest section of Puerto Rico.
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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.
The combination of a tropical wave and a mid level perturbation and their associated moisture, decent upper level ventilation and an upper level trough, produced scattered showers with isolated strong thunderstorms over the northwest section of Puerto Rico.
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 18, 11:06 AM AST, 2 hours 39 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1106 AM AST WED JUL 18 2012 .UPDATE...SHOWERS WITH ISOLATED THUNDERSTORMS HAVE BEEN MOVING OVER PUERTO RICO AND THE U.S. VIRGIN ISLANDS THIS MORNING. CONDITIONS WILL GET WETTER THIS AFTERNOON AS AN UPPER LEVEL TROUGH COMBINE WITH DAYTIME HEATING AND LOCAL EFFECT TO PRODUCE SCATTERED TO NUMEROUS SHOWERS WITH THUNDERSTORMS MAINLY ALONG THE CORDILLERA CENTRAL. NO CHANGES TO GRIDS NEEDED AT THIS TIME. && .AVIATION...BRIEF PERIODS OF MVFR CONDITIONS WILL OCCUR THIS AFTERNOON OVER TJMZ...TJSJ...TJPS..AND TJBQ IN SHRA/TSRA. LATEST 18/12Z TJSJ SOUNDING INDICATED EASTERLY WINDS OF 15 TO 20 KTS AT THE SURFACE. && .PREV DISCUSSION... /ISSUED 444 AM AST WED JUL 18 2012/ SYNOPSIS...BROAD TUTT WITH MULTIPLE LOW PRESSURE CENTERS SPREAD ACROSS THE CENTRAL ATLANTIC...NORTHEAST OF THE NORTHERN LEEWARDS... AND YET ANOTHER ACROSS HISPANIOLA WHICH EXTENDS INTO THE NORTHWEST ATLANTIC. TUTT INDUCED LOW TO MID LEVEL TROUGH/EASTERLY PERTURBATION WITH AXIS JUST EAST OF THE LESSER ANTILLES IS AIDING IN CREATING A PREVAILING MODERATE NORTHEAST WIND FLOW. STRONG SURFACE HIGH PRESSURE NORTH THROUGH NORTHEAST OF THE LOCAL AREA WILL REMAIN IN PLACE AND CONTINUE TO PROMOTE MODERATE TO FAIRLY STRONG EASTERLY TRADES THROUGH THE END OF THE WORK WEEK...AND POSSIBLY INTO THE UPCOMING WEEKEND. THE NEXT TROPICAL WAVE WITH AXIS NOW NEAR 52 WEST IS STILL FORECAST TO CROSS THE LESSER ANTILLES AND MOVE ACROSS THE EASTERN CARIBBEAN THURSDAY THROUGH FRIDAY. DISCUSSION...PREVAILING NORTHEAST WIND FLOW WILL CONTINUE TO BRING PATCHES OF LOW TO MID LEVEL CLOUDINESS AND ACCOMPANYING SHOWERS TO THE NORTH AND NORTHEAST COAST OF THE ISLANDS THROUGH THE EARLY MORNING HOURS. SOME OF THESE SHOWERS WERE BEING ENHANCED DUE TO THE PROXIMITY OF THE TUTT. CLOUDINESS AND AFTERNOON CONVECTION WILL GRADUALLY SHIFT AND DEVELOP ACROSS PARTS OF THE INTERIOR AND WEST TO SOUTHWEST SECTIONS OF PUERTO RICO...AS WELL AS OVER ISOLATED SPOTS IN CULEBRA AND VIEQUES AND THE WEST SECTIONS OF THE VIRGIN ISLANDS. BY LATE WEDNESDAY INTO EARLY THURSDAY EXPECT SLIGHTLY DRIER CONDITIONS IN ADVANCE OF THE AFOREMENTIONED TROPICAL WAVE...FOLLOWED BY A SURGE OF TROPICAL MOISTURE ACCOMPANYING AND TRAILING THE TROPICAL WAVE THROUGH A LEAST FRIDAY. LATEST MODEL GUIDANCE ALSO SUGGEST AN EASTERLY WIND SURGE OF 20 TO 25 KTS AT THE SURFACE...QUICKLY TRAILING THE WAVE FRIDAY THROUGH SATURDAY ACCOMPANYING A DRIER AIR MASS WHICH IS SO FAR EXPECTED FOR THE UPCOMING WEEKEND. OVERALL THE AMOUNT OF MOISTURE ADVECTION AGAIN WILL BE DEPENDENT ON HOW FAST THESE EASTERLY PERTURBATIONS/TROPICAL WAVES ACTUALLY MOVE ACROSS THE REGION. WILL THEREFORE CONTINUE TO MAKE THE USUAL ADJUSTMENTS TO THE FORECAST GRIDS OVER TIME. HOWEVER...WIDESPREAD CONVECTION AND RAINFALL ACCUMULATIONS ARE SO FAR NOT EXPECTED OVER THE NEXT COUPLE OF DAYS... EXCEPT FOR PERIODS OF MODERATE TO LOCALLY HEAVY RAINFALL AND SOME ENHANCED CONVECTION IN ISOLATED SPOTS DUE TO THE PROXIMITY OT THE TUTT...ALONG WITH LOCAL AND DIURNAL EFFECTS. AVIATION...CLOUDINESS AND SHOWERS WILL CONTINUE THROUGH THE FORECAST PERIOD AS MOISTURE ASSOCIATED WITH A WEAK INDUCED TROUGH MOVES ACROSS THE LOCAL AREA...BUT ONLY BRIEF PERIODS ON MVFR CONDITIONS ARE EXPECTED. FRESH NORTHEASTERLY TRADES WILL BRING OCCASIONAL SHRA ACROSS THE WINDWARD SIDE OF THE ISLANDS. SAHARAN DUST CONCENTRATIONS WILL CONTINUE TO DIMINISH ACROSS THE LOCAL DURING THE REST OF THE MORNING HOURS. && .PRELIMINARY POINT TEMPS/POPS... SJU 89 78 90 79 / 40 60 60 50 STT 90 80 89 81 / 40 60 60 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. COASTAL WATERS...NONE. && 71/06
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN JUAN PR 501 AM AST WED JUL 18 2012 AMZ710>745-PRZ001>013-190915- 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- 501 AM AST WED JUL 18 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT ATLANTIC COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT THE LOCAL ISLANDS WILL CONTINUE UNDER THE INFLUENCE OF AN INDUCED SURFACE TROUGH TODAY. THIS FEATURE WILL CONTINUE TO PRODUCE CLOUDINESS AND SHOWERS ACROSS PORTIONS OF THE LOCAL ISLANDS THIS MORNING. THE COMBINATION OF THIS MOISTURE WITH DAYTIME HEATING AND LOCAL OROGRAPHIC EFFECT WILL PROMOTE THE DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS AND A FEW THUNDERSTORMS ACROSS WESTERN...INTERIOR AND SOUTHWEST SECTIONS OF PUERTO RICO THIS AFTERNOON. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY A TROPICAL WAVE IS EXPECTED TO MOVE INTO THE EASTERN CARIBBEAN LATE THURSDAY NIGHT THROUGH EARLY FRIDAY...AND SHOULD AFFECT THE LOCAL ISLANDS LATER FRIDAY AND FRIDAY NIGHT THROUGH MUCH OF SATURDAY. THIS WAVE AND ASSOCIATED MOISTURE MAY RESULT IN AN ADDITIONAL EXTENDED PERIOD OF CLOUDINESS...SHOWERS AND THUNDERSTORMS ACROSS THE FA DURING THIS TIME FRAME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED...HOWEVER INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT FLOODING AND ANY STRONG THUNDERSTORMS TO THE NATIONAL WEATHER SERVICE OFFICE SAN JUAN. AMZ715-725-VIZ001-002-190915- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 501 AM AST WED JUL 18 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE U.S. VIRGIN ISLANDS AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT THE LOCAL ISLANDS WILL CONTINUE UNDER THE INFLUENCE OF AN INDUCED SURFACE TROUGH TODAY. THIS FEATURE WILL CONTINUE TO PRODUCE CLOUDINESS AND SHOWERS ACROSS PORTIONS OF THE LOCAL ISLANDS TODAY. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY A TROPICAL WAVE IS EXPECTED TO MOVE INTO THE EASTERN CARIBBEAN LATE THURSDAY NIGHT THROUGH EARLY FRIDAY...AND SHOULD AFFECT THE LOCAL ISLANDS LATER FRIDAY AND FRIDAY NIGHT THROUGH MUCH OF SATURDAY. THIS WAVE AND ASSOCIATED MOISTURE MAY RESULT IN AN ADDITIONAL EXTENDED PERIOD OF CLOUDINESS...SHOWERS AND THUNDERSTORMS ACROSS THE FA DURING THIS TIME FRAME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED...HOWEVER INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT FLOODING AND ANY STRONG THUNDERSTORMS TO THE NATIONAL WEATHER SERVICE OFFICE SAN JUAN.
The San Juan radar (TJUA), 126 km away, was scanning. The volume nearest the first event began at 17:47 UTC.
1 lightning. Local standard time, as filed.
A 14 year old boy was hit by a lightning strike at Sandy Beach. He was transported to the hospital in stable conditions.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Puerto Rico in 2012Every state in 2012This day in weather historyWarnings in Puerto Rico, July 2012
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: 403700.