Afternoon thunderstorms formed between the east coast and Lake Okeechobee, moved northeast, and produced a downburst over eastern Indian River County. This resulted in severe winds and large but sub-severe hail.
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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 MLB wrote it up.
Afternoon thunderstorms formed between the east coast and Lake Okeechobee, moved northeast, and produced a downburst over eastern Indian River County. This resulted in severe winds and large but sub-severe hail.
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 Melbourne, FL wrote its last area forecast discussion before the first event at Sep 12, 2:20 PM EST, 1 hour 56 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 320 PM EDT MON SEP 12 2011 .DISCUSSION... THIS AFTERNOON-TONIGHT...UPPER LEVEL TROUGH AXIS NOW PUSHING THROUGH THE PENINSULA...DRIVING MUCH DRIER AIR INTO THE CENTRAL PENINSULA. SKIES HAVE REMAINED MOSTLY SUNNY OVER ALL BUT THE EXTREME SOUTHERN CWA...WITH DEWPOINTS DROPPING INTO THE UPPER 50S ACROSS LAKE AND SEMINOLE COUNTIES...AND LOW 60S ACROSS THE REMAINDER OF THE ORLANDO METRO AND INTERIOR VOLUSIA COUNTY. THE ONLY SHOWERS AND THUNDERSTORMS THAT HAVE DEVELOPED TODAY HEAVE BEEN ACROSS MARTIN AND SAINT LUCIE COUNTIES ALONG THE SEA BREEZE-LAKE OKEECHOBEE BREEZE COLLISION WHERE MOISTURE REMAINS CONSIDERABLY HIGHER. MOST OF THIS ACTIVITY...AND ANY ISOLATED SHOWERS THAT DEVELOP ACROSS INDIAN RIVER AND OKEECHOBEE COUNTIES WILL WIND DOWN BY SUNSET. PLEASANT EVENING ACROSS THE AREA WITH MOSTLY CLEAR SKIES OVERNIGHT AND LOWS IN THE LOW 70S...EXCEPT UPPER 60S IN THE SOUTHERN INTERIOR AND LAKE COUNTY. TUE-WED...THE AXIS OF UPPER LEVEL TROUGH WILL BE EAST OF THE AREA ON TUESDAY BRINGING DEEP LAYER DRYING ACROSS THE PENINSULA. A WEAK NORTH/NORTHEAST LOW LEVEL WIND FLOW WILL DEVELOP DUE TO WEAK SURFACE REFLECTION OF TROUGH ALOFT. THIS COMBINATION OF TYPICALLY DRY NORTHEAST FLOW AND DEEP DRY AIRMASS MEANS LITTLE IN THE WAY OF SHOWERS OR STORMS ACROSS THE REGION. WILL KEEP THE MENTION OF ISOLATED AFTERNOON SHOWERS AND STORMS AROUND LAKE OKEECHOBEE INTO SOUTH FLORIDA FOR TUESDAY...BUT HAVE NO MENTION OF RAIN ANYWHERE ON WEDNESDAY. LOW LEVEL DRYING WILL ALLOW MIN TEMPS TO REACH THE UPPER 60S TO LOWER 70S WHICH WILL BE A FEW DEGREES BELOW NORMAL...EXCEPT ALONG THE SPACE/TREASURE COAST WHERE SLIGHT ONSHORE FLOW WILL KEEP MIN TEMPS IN THE LOWER-MID 70S. LITTLE CHANGE IN MAX TEMPS WITH UPPER 80S TO LOWER 90S. FROM PREVIOUS DISCUSSION... THU-FRI...TROPICAL CYCLONE MARIA IS FORECAST TO LIFT INTO THE FAR NORTH ATLANTIC. WEAK HIGH PRESSURE OVER THE SOUTHEAST STATES SHOULD MAINTAIN A LIGHT NORTH/NORTHEAST LOW LEVEL FLOW. THEREFORE LITTLE MOISTENING IS ANTICIPATED. MOS POPS CONTINUE BELOW 10 PERCENT THU AND CREEP UP TO 15-20 PERCENT ON FRI...THOUGH DO NOT SEE MUCH REASON FOR THIS OTHER THAN THE TYPICAL MOS TREND TOWARDS CLIMO IN LATTER FORECAST PERIODS. THE GFS SHOWS A FEW SMALL AREAS OF MOISTURE CONVERGENCE BOTH DAYS IN THE LIGHT NORTH/NORTHEAST FLOW BUT WOULD BE SURPRISED TO GET COVERAGE ABOVE 10 PERCENT. NEVERTHELESS...HAVE MAINTAINED SLIGHT CHANCE POPS FRI. && .AVIATION...ISOLD-SCT SHRA/TSRA SOUTH OF A KVRB-KOBE LINE THROUGH SUNSET...OTHERWISE VFR CONDITIONS THROUGH TUESDAY. && .MARINE...NORTHWEST-NORTHEAST WINDS WILL CONTINUE OVER THE WATERS THIS AFTERNOON AND EVENING AS THE SURFACE REFLECTION OF THE UPPER LEVEL TROUGH MOVES THROUGH. CLOSER TO THE COAST WINDS WILL CONTINUE TO HAVE A MORE EASTERLY COMPONENT ASSOCIATED WITH THE SEA BREEZE CIRCULATION. LIGHT AND VARIABLE WINDS OVERNIGHT WILL BECOME NORTH-NORTHEAST THROUGH LATE WEEK AS A WEAK HIGH PRESSURE RIDGE MOVES OVER THE SOUTHEAST STATES. SPEEDS WILL GENERALLY BE 10KTS OR LESS...BUT COULD SEE 10-15KTS OR WEDNESDAY AS THE GRADIENT TIGHTENS IN RESPONSE TO THE DISTANT TS MARIA MOVING NORTHWARDS. THE LEADING EDGE OF SWELLS FROM MARIA IMPACTING THE WATERS THIS AFTERNOON...WITH DOMINANT WAVE PERIODS NOW SETTLED AROUND 12-13S. SEAS WILL SLOWLY BUILD THROUGH MID WEEK...PEAKING AT 4-5FT NEARSHORE AND 6-7FT OFFSHORE ON WEDNESDAY. THIS MAY PRODUCE EXERCISE CAUTION CONDITIONS...ESPECIALLY AT INLETS DURING THE OUTGOING TIDE. && .PRELIMINARY POINT TEMPS/POPS... DAB 91 71 90 71 / 10 10 10 0 MCO 92 71 92 71 / 10 10 10 0 MLB 90 73 89 74 / 20 10 10 10 VRB 89 72 90 72 / 20 10 10 10 LEE 92 71 92 71 / 10 10 10 0 SFB 92 72 92 72 / 10 10 10 0 ORL 92 74 92 73 / 10 10 10 0 FPR 90 71 89 71 / 30 20 10 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && SHORT TERM/AVIATION...MOSES RADAR/IMPACT WEATHER UPDATES....HAGEMEYER
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MELBOURNE FL 450 AM EDT MON SEP 12 2011 AMZ550-552-555-570-572-575-FLZ041-044>047-053-054-058-059-064-141- 144-147-122100- COASTAL WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE OUT 20 NM- COASTAL WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET OUT 20 NM- COASTAL WATERS FROM SEBASTIAN INLET TO JUPITER INLET OUT 20 NM- WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM OFFSHORE- WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET 20 TO 60 NM OFFSHORE- WATERS FROM SEBASTIAN INLET TO JUPITER INLET 20 TO 60 NM OFFSHORE- INLAND VOLUSIA-NORTHERN LAKE-ORANGE-SEMINOLE-SOUTHERN BREVARD- OSCEOLA-INDIAN RIVER-OKEECHOBEE-ST. LUCIE-MARTIN-COASTAL VOLUSIA- SOUTHERN LAKE-NORTHERN BREVARD- 450 AM EDT MON SEP 12 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL FLORIDA. .DAY ONE...TODAY AND TONIGHT. .THUNDERSTORM IMPACT... SCATTERED SHOWERS AND STORMS WILL DEVELOP ACROSS MUCH OF THE AREA INTO THE AFTERNOON...INITIALLY ALONG AND AHEAD OF THE EAST COAST SEA BREEZE BOUNDARY. CONVECTIVE COVERAGE HOWEVER WILL BE SLIGHTLY LESS NORTHWEST OF THE INTERSTATE 4 CORRIDOR WHERE THE ARRIVAL OF A DRIER AIRMASS IS EXPECTED LATE IN THE DAY. STORMS WILL MOVE TOWARD THE EAST TO NORTHEAST AROUND 10 TO 15 MPH AND WILL HAVE THE POTENTIAL TO PRODUCE FREQUENT CLOUD TO GROUND LIGHTNING... STRONG WIND GUSTS UP TO 40 TO 50 MPH AND LOCALLY HEAVY RAINFALL. .RIP CURRENT IMPACT... LONG PERIOD OCEAN SWELLS WILL GENERATE A MODERATE RISK OF RIP CURRENTS ALONG AREA BEACHES TODAY. THE GREATEST THREAT WILL EXIST FROM LATE MORNING THROUGH LATE AFTERNOON DUE TO TIDAL INFLUENCES. ALWAYS SWIM NEAR A LIFEGUARD AND NEVER SWIM ALONE. .MARINE THUNDERSTORM GUST IMPACT... SCATTERED AFTERNOON THUNDERSTORMS THAT DEVELOP ALONG THE COAST AND INLAND WILL MOVE TOWARD THE EAST TO NORTHEAST AROUND 10 TO 15 MPH. ANY OF THIS CONVECTIVE ACTIVITY WILL BE ABLE TO PRODUCE GUSTY WINDS IN EXCESS OF 34 KNOTS OVER INLAND LAKES AND ALONG THE INTRACOASTAL AND NEARSHORE WATERS AS STORMS MOVE OFFSHORE. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY. A DRIER AIRMASS WILL EXIST OVER CENTRAL FLORIDA FROM TUESDAY INTO LATE WEEK...WITH LITTLE TO NO RAINFALL EXPECTED ACROSS THE AREA. SWELLS FROM TROPICAL CYCLONE MARIA WILL BEGIN TO IMPACT THE NEAR SHORE ATLANTIC WATERS DURING THE WORK WEEK...ESPECIALLY FROM TUESDAY ONWARD. THIS WILL INCREASE SEAS AND SURF...AS WELL AS THE THREAT OF RIP CURRENTS. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE REQUESTED TO MONITOR THE WEATHER AND SELF ACTIVATE IF NEEDED. WEITLICH
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MELBOURNE FL
147 PM EDT MON SEP 12 2011
FLZ064-121830-
MARTIN-
147 PM EDT MON SEP 12 2011
...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR STRONG WIND GUSTS
BETWEEN 45 AND 55 MPH AND SMALL HAIL OVER EASTERN MARTIN COUNTY...
* UNTIL 230 PM EDT.
AT 144 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STORM CAPABLE OF PRODUCING STRONG WINDS AND SMALL HAIL 5 MILES
SOUTHWEST OF PORT SALERNO...MOVING EAST AT 10 MPH TOWARD THE HOBE
SOUND AREA.
THE PRIMARY THREAT WILL BE CLOUD TO GROUND LIGHTNING STRIKES AND
GUSTY WINDS OF 45 TO 55 MPH...WHICH CAN CAUSE UNSECURED OBJECTS TO
BLOW AROUND...SNAP TREE LIMBS OR CAUSE POWER OUTAGES. HEAVY RAINFALL
WILL TEMPORARILY REDUCE VISIBILITY. SEEK SHELTER INDOORS UNTIL THE
STORM PASSES.
LAT...LON 2696 8036 2718 8034 2722 8017 2721 8016
2719 8015 2716 8015 2702 8008 2697 8007
2697 8014 2695 8015
TIME...MOT...LOC 1746Z 254DEG 12KT 2708 8023The Melbourne radar (KMLB), 56 km away, was scanning. The volume nearest the first event began at 21:16 UTC.
2 hail, 1 thunderstorm wind. Local standard time, as filed.
An afternoon thunderstorm produced penny hail at Indian River Memorial Hospital, as reported by a citizen.
The Vero Beach Municipal Airport ASOS measured a 52 knot wind gust during a thunderstorm downburst.
Staff in the control tower at Vero Beach Municipal Airport reported dime to nickel sized hail during an afternoon thunderstorm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2011Every state in 2011This day in weather historyWarnings in Florida, September 2011
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: 332472, 332464, 332473.