A broad trough at the upper levels and a very moist and unstable atmosphere allowed for showers and thunderstorms to develop across the western interior during the afternoon.
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 broad trough at the upper levels and a very moist and unstable atmosphere allowed for showers and thunderstorms to develop across the western interior during the afternoon.
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 Sep 23, 10:37 AM AST, 3 hours 53 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 1037 AM AST WED SEP 23 2009 .UPDATE...MINOR CHANGES WERE MADE TO SHORT TERM GRIDS...TO ADJUST SLIGHTLY THE AREA COVERAGE...POPS...AND CLOUD COVER FOR THIS AFTERNOON. ACTIVE WEATHER IS EXPECTED THIS AFTERNOON ONCE AGAIN MAINLY OVER THE WESTERN INTERIOR AND WEST SECTIONS OF PUERTO RICO. MUDSLIDES ARE HIGHLY POSSIBLE...DUE TO ALREADY SATURATED SOILS ACROSS THESE AREAS. NO OTHER CHANGES MADE TO PREVIOUS FORECAST REASONING. && .AVIATION...EXPECT DEVELOPING MVFR OR POSSIBLY EVEN BRIEF IFR CONDITIONS AND MOUNTAIN OBSCURATIONS IN NUMEROUS TO WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS...ESPECIALLY OVER THE CENTRAL AND WESTERN INTERIOR...WEST AND NORTHWEST SECTIONS OF PUERTO RICO...INCLUDING TJMZ AND PROBABLY TJBQ...BETWEEN 17Z AND 23Z. && .PREV DISCUSSION... /ISSUED 400 AM AST WED SEP 23 2009/ SYNOPSIS...BROAD TROUGH ALOFT TO DOMINATE MUCH OF THE FCST PERIOD. MID LEVEL RIDGING TO BUILD INTO THE REGION LATE IN THE WEEK AND PREVAIL INTO NEXT WEEK. DISCUSSION...REALLY NOT MUCH CHANGE FROM PAST DAYS. ATMOSPHERE REMAINS VERY MOIST AND CONVECTIVELY UNSTABLE SO EXPECT STRONG CONVECTION TO DEVELOP ACROSS THE WESTERN INTERIOR DURING THE AFTERNOON. LOCALIZED HEAVY RAINFALL OCCURRED YESTERDAY IN THE GUANAJIBO AND ANASCO RIVER BASINS AS THE LOCAL WRF-NMM MODEL ACCURATELY PREDICTED. TODAY THE MODEL IS MORE AGGRESIVE IN TERMS OF QPF AND CVRG. TJUA VWP PROFILE SHOWS WINDS MORE FROM THE EAST SOUTHEAST AT 10-15 KT BETWEEN 3-8 KFT WITH HARDLY ANY WIND ABOVE THAT LEVEL CONSISTENT WITH MODEL GUIDANCE. BASED ON THIS...WOULD EXPECT THE TSTMS TO BE VERY SLOW MOVERS AND DRIFT TO THE NORTH AND AFFECT THE CULEBRINAS RIVER BASIN EVENTUALLY. I COULD HAVE ISSUED A FFA FOR ALL OF THE WEST BUT HAVE LEFT THAT DECISION TO THE NEXT SHIFT. DRYING TREND IS STILL EXPECTED BEGINNING THU AND LASTING INTO SAT AS MID LVL RIDGING BUILDS IN. ANTICIPATING A SIGNIFICANT DROP IN CONVECTIVE COVERAGE ESPECIALLY FRI AND SAT AS MID-LVL DRY AIR AND A STRENGHTENING SUBSIDENCE CAP LIMITS CONVECTION. THIS WILL BE WELCOME NEWS FOR AREAS OF WRN PR WHERE HEAVY RAINS HAVE PLAGUED THOSE AREAS FOR ALMOST A WEEK NOW. SUN-MON...SOUTHWARD AMPLIFICATION OF UPPER LVL TROUGH ACROSS THE ATLC INTO THE CARIBBEAN AND THE APPROACH OF A TROPICAL WAVE SUNDAY WILL DRAW MOISTURE NWD FROM THE ITCZ INTO OUR AREA. MODELS NOT AS BULLISH AS THEY WERE YESTERDAY BUT DO EXPECT AN INCREASE IN CONVECTIVE CVRG. AVIATION...PREVAILING VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL ISLANDS AND AT MOST LOCAL TAF SITES TODAY AND TONIGHT. HOWEVER... EXPECT DEVELOPING MVFR OR POSSIBLY EVEN BRIEF IFR CONDITIONS AND MOUNTAIN OBSCURATIONS IN NUMEROUS TO WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS...ESPECIALLY OVER THE CENTRAL AND WESTERN INTERIOR...WEST AND NORTHWEST SECTIONS OF PUERTO RICO...INCLUDING TJMZ AND PROBABLY TJBQ...BETWEEN 17Z AND 23Z. MARINE...SEAS 2-3 FT NEAR SHORE AND 4-5 FT OFFSHORE. TSTMS THE MAIN HAZARD. && .PRELIMINARY POINT TEMPS/POPS... SJU 89 79 90 79 / 40 30 40 30 STT 88 79 89 80 / 50 20 40 40 && .SJU WATCHES/WARNINGS/ADVISORIES... PR...NONE. VI...NONE. && 71/10
HAZARDOUS WEATHER OUTLOOK FOR PUERTO RICO AND THE U.S. VIRGIN ISLANDS NATIONAL WEATHER SERVICE SAN JUAN PR 546 AM AST WED SEP 23 2009 AMZ710>745-PRZ001>013-241000- 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- 546 AM AST WED SEP 23 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PUERTO RICO AND THE ADJACENT COASTAL WATERS. .DAY ONE...TODAY AND TONIGHT SHOWERS AND ISOLATED TO SCATTERED THUNDERSTORMS WILL OCCUR AGAIN TODAY...ESPECIALLY OVER THE CENTRAL AND WESTERN INTERIOR...WEST... NORTHWEST AND NORTH CENTRAL SECTIONS OF PUERTO RICO THIS AFTERNOON. ALTHOUGH NO WIDESPREAD FLOODING IS EXPECTED AT THIS TIME...A FEW LOCATIONS WILL RECEIVE ENOUGH RAINFALL TO RESULT IN URBAN AND SMALL STREAM FLOODING...WITH THE POTENTIAL FOR LOCALIZED FLASH OR RIVER FLOODING. FREQUENT LIGHTNING AND BRIEF GUSTY WINDS WILL ACCOMPANY SOME THUNDERSTORMS. IN ADDITION...MUDSLIDES ARE POSSIBLE OVER AREAS OF STEEP TERRAIN...DUE TO SATURATED SOILS FROM HEAVY RAINFALL OF PREVIOUS DAYS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED. AMZ715-725-VIZ001-002-241000- ST. THOMAS ST. JOHN ADJACENT ISLANDS-ST CROIX- NEARSHORE ATLANTIC AND ADJACENT CARIBBEAN COASTAL WATERS- 546 AM AST WED SEP 23 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.
PRC001-003-005-011-013-027-065-071-073-081-083-099-131-141-231900-
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SAN JUAN PR
145 PM AST WED SEP 23 2009
THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED A SPECIAL WEATHER
STATEMENT EFFECTIVE UNTIL 300 PM AST FOR PEOPLE IN THE FOLLOWING
MUNICIPALITIES
IN PUERTO RICO
ISABELA...JAYUYA...ADJUNTAS...MOCA...SAN SEBASTIAN...UTUADO...
AGUADILLA...AGUADA...LAS MARIAS...LARES...CAMUY...HATILLO...
ANASCO AND ARECIBO
AT 139 PM AST NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS OVER WESTERN INTERIOR SECTIONS OF PUERTO RICO.
THESE THUNDERSTORMS HAVE A HIGH POTENTIAL TO GENERATE HAIL.
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.PRC001-003-005-011-013-027-065-071-073-081-083-099-131-141-231900- COMUNICADO ESPECIAL SOBRE LAS CONDICIONES DEL TIEMPO SERVICIO NACIONAL DE METEOROLOGIA SAN JUAN PR 145 PM AST MIERCOLES 23 DE SEPTIEMBRE DE 2009 EL SERVICIO NACIONAL DE METEOROLOGIA EN SAN JUAN HA EMITIDO UN COMUNICADO ESPECIAL EN EFECTO HASTA LAS 3:00 PM AST PARA LAS PERSONAS EN LOS SIGUIENTES MUNICIPIOS EN PUERTO RICO ISABELA...JAYUYA...ADJUNTAS...MOCA...SAN SEBASTIAN...UTUADO... AGUADILLA...AGUADA...LAS MARIAS...LARES...CAMUY...HATILLO... ANASCO Y ARECIBO A LAS 1:39 PM AST...EL RADAR DOPPLER DEL SERVICIO NACIONAL DE METEOROLOGIA INDICO FUERTES TRONADAS SOBRE EL OESTE INTERIOR DE PUERTO RICO. ESTAS TRONDAS TIEN ALTO POTENCIAL PARA PRODUCIR GRANIZO. RAYOS INTENSOS HAN SIDO REPORTADOS CON ESTA TORMENTA. SI SE ENCUENTRA EN EL EXTERIOR... MANTENGASE ALEJADO DE OBJETOS ALTOS AISLADOS COMO ARBOLES. ENTRE A ALGUN LUGAR SI ES POSIBLE. MIENTRAS ESTE DENTRO DE UN EDIFICIO...MANTENGASE ALEJADO DE VENTANAS Y PUERTAS Y EVITE USAR EL TELEFONO A MENOS QUE SEA UNA EMERGENCIA. TRATE DE DESCONECTAR ENSERES ELECTRICOS QUE NO SEAN NECESARIOS ANTES DE QUE LAS TRONADAS SE ACERQUEN.
The San Juan radar (TJUA), 99 km away, was scanning. The volume nearest the first event began at 18:30 UTC.
1 thunderstorm wind. Local standard time, as filed.
Heavy rains and gusty winds were responsible for 16 downed tress and a few bamboo trees in the municipality of San Sebastian. Soils were saturated from previous days rainfall.
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, September 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: 197512.