A low pressure area about 80 miles west of the Southwest Florida coast provided for moisture and instability to spread across South Florida and resulted in thunderstorm development across the area.
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The episode as NWS MFL wrote it up.
A low pressure area about 80 miles west of the Southwest Florida coast provided for moisture and instability to spread across South Florida and resulted in thunderstorm development across the area.
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 Miami, FL wrote its last area forecast discussion before the first event at Sep 20, 10:09 AM EST, 1 hour 46 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIAMI FL 1109 AM EDT THU SEP 20 2007 .UPDATE...TRICKY WEATHER SITUATION UNFOLDING ACROSS THE CWA TODAY. SATELLITE AND RADAR DATA...ALONG WITH SURFACE AND BUOY OBS...SHOW AN APPROXIMATELY 1007MB BROAD SFC LOW CENTERED 60-80 MILES OFF THE SOUTH FL WEST COAST...JUST ON THE SE SIDE OF THE MID/UPPER LEVEL CIRCULATIONS. THE GRADIENT HAS BEEN INCREASING THIS MORNING ACROSS THE CWA...WITH S/SSE WINDS GUSTING TO 20 MPH OUTSIDE OF PRECIPITATION ACROSS THE INTERIOR AND WEST COAST...WITH GUSTS AT FMY AND APF TO 30 MPH IN HEAVIER SHOWERS. RADAR IMAGERY SHOWS A SOLID LINE OF HEAVY SHOWERS/TSTMS FORMING FROM WESTERN GLADES COUNTY TO NEAR CAPE ROMANO. THIS LINE IS MARCHING EAST AT A STEADY CLIP INTO AN UNSTABLE ATMOSPHERE...AND THERE IS NOT MUCH REASON FOR IT TO FALL APART AS IT TRAVERSES THE PENINSULA. AGITATED CU FIELD IS DEVELOPING AHEAD OF THE LINE SO EXPECT AT LEAST SCATTERED PRE-LINE TSTMS TO DEVELOP OVER THE CWA THIS AFTERNOON. FEEL THAT THERE IS A THREAT FOR ISOLATED WEAK TORNADOES ACROSS THE CWA THIS AFTERNOON. S/SSE SFC WINDS ARE BECOMING STRONGER...WITH THE 12Z MIAMI SOUNDING SHOWING UNIDIRECTIONAL SOUTHERLY FLOW ABOVE THE SFC...HOWEVER THE FLOW IS FAIRLY STRONG AT 20-30 KNOTS. WHILE THERE IS NOT MUCH TURNING/LOW LEVEL HELICITY...GIVEN THESE MODEST WIND FIELDS FOR SOUTH FL OVER THE BOUNDARY LAYER AND MID LEVELS...THINK THAT LOCALIZED STORM-RELATIVE HELICITY COULD BE ENOUGH FOR A FEW BRIEF SPIN-UPS TODAY...ESPECIALLY ACROSS THE WESTERN HALF THROUGH THIS EVENING WHERE SFC FLOW IS STRONGEST AND MOST BACKED. THIS THREAT MAY SPREAD TO THE EAST COAST FOR THE MID AFTERNOON-EARLY EVENING HOURS. HERE...INITIALLY S/SSW SFC WINDS ARE PRETTY LIGHT AND SHOULD ALLOW FOR SEA BREEZE DEVELOPMENT BY LATE AFTERNOON...OR THE PRESSURE GRADIENT WILL ALLOW WINDS TO BACK VIA SYNOPTIC PROCESSES. THIS WOULD CREATE SLIGHTLY MORE HELICITY ACROSS THE EAST COAST THIS AFTERNOON...AND ENHANCE THE TORNADO THREAT...ESPECIALLY INVOF ANY BOUNDARIES OR SEA BREEZE INTERACTION AS STORMS CROSS THE BOUNDARIES. A FEW CELLS OVER THE GULF AND ATLANTIC WATERS HAVE ALREADY SHOWN MINI SUPERCELLULAR CHARACTERISTICS WITH BRIEF ROTATION THIS MORNING. OTHER MAIN CHANGE WAS TO BUMP HIGHS UP ACROSS THE EAST COAST METRO WHERE SLIGHT OFFSHORE COMPONENT TO THE SFC FLOW AND PLENTY OF SUNSHINE WERE ALREADY PUSHING TEMPS INTO THE MID 80S. && .AVIATION...AREA OF LOW PRESS OVER GULF WATERS JUST OFFSHORE OF THE SW FL COAST BECOMING MORE ACTIVE THIS MORNING WITH SHWRS/TSTMS MOVING ONSHORE INVOF KAPF. MOST TSRA WELL W OF KAPF BUT NONETHELESS IS INCREASING AND WILL CONTINUE THE VCTS FOR KAPF AFT 14Z. OVER THE ERN TERMINALS...MOSTLY VFR CONDITIONS WILL CONTINUE THROUGH THIS MORNING EXCEPT FOR A SHRA OR TWO INVOF KTMB AND KMIA. NEVERTHELESS...TSTMS SHOULD BE EXPECTED INVOF ALL TERMINALS THIS AFTERNOON AND SO WILL KEEP VCTS FROM 19Z TO 00Z TONIGHT BUT IF THE CONVECTION DOES BEGIN EARLIER WILL AMEND AS NECESSARY. && .MARINE...MAIN CHANGE TO THE MARINE WAS TO INCREASE WINDS TO AROUND 15 KNOTS OVER LAKE OKEE. PER MORNING LAKE TOWER OBS. OTHERWISE...BUOY OBS AND 10Z QUICKSCAT PASS SHOW MARINE FORECAST IS ON TRACK FOR TODAY. SMALL CRAFT SHOULD EXERCISE CAUTION OUTER GULF WATERS...AND WINDS AND SEAS WILL BE HIGHER IN ANY THUNDERSTORMS TODAY. THERE IS ALSO THE RISK OF WATERSPOUTS WITH ANY SHOWER/TSTM AND MARINERS SHOULD BE ON ALERT. UPDATE/MARINE: STRASSBERG AVIATION: KOB && .PREV DISCUSSION... /ISSUED 339 AM EDT THU SEP 20 2007/ DISCUSSION... CURRENTLY A SURFACE LOW ROTATING NW ACROSS N CENTRAL FLA WITHIN A BROAD AREA OF LOW PRES ACROSS S CENTRAL/S FLA. A MID TO UPPER LEVEL LOW PRES SYSTEM IN THE SE GULF OF MEX WITH SURFACE LAPS WINDS INDIC -ATING A SECONDARY LOW PRES DEVELOPING. AS THE DAY PROGRESSES...THE GULF SURFACE LOW WILL CONSOLIDATE UNDER THE UPPER LOW AND BECOME THE PRIMARY FEATURE IN THE SHORT TERM...TODAY THROUGH SAT. DEEP MOISTURE WRAPPING TIGHTLY ABOUT UPPER LOW IN GULF CURRENTLY WITH SHOWERS AND SOME THUNDER...WHILE OVER THE PENINSULA AND ADJACENT ATLC...ONLY ISOLATED SHOWERS AT BEST AS VERY DRY AIR ALOFT FROM LOWER FLA STRAITS/W CUBA BEING CIRCULATED OVER THIS AREA. SOME VARIATION IN GUIDANCE DEPENDANT UPON GULF DEVELOPMENT. S FLA WILL BE BENEATH A DEEP SOUTHERLY WIND FLOW THAT WILL GRADUALLY MOISTEN UP TODAY FROM W TO E AS MOISTURE PULEED NORTHWARD TO WRAP ABOUT THE UPPER LOW. TODAY...DEEPER MOISTURE AND BEST CHANCES OF RAIN ON THE W COAST WITH POPS WILL BE LIKELY THERE AND DECREASING INCREMENTALLY EASTWARD. BY FRI AND SAT...THE ATMOSPHERE WILL BE AMPLY MOIST ACROSS ALL OF S FLA. EXTENDED...SUNDAY THROUGH WEDNESDAY...UPPER-LEVEL RIDGE AND SLIGHTLY DRIER AIR BECOMES ESTABLISHED OVER THE AREA WITH A RETURN TO SCATTERED DIURNAL CONVECTION. THE DEEPER EASTERLY FLOW WILL HAVE THE HIGHER POPS INTERIOR AND W. AVIATION...AREA OF LOW PRESS OVER GULF WATERS SW OF KAPF BECOMING MORE ACTIVE THIS MORNING WITH SHWRS/TSTMS RAPIDLY INCREASING OVER WATER. DRAINAGE FLOW OVR WEST COAST MAY KEEP THIS ACTIVITY OFFSHORE TIL SUNRISE BUT WILL EXPECT IT TO MOVE ONSHORE AFTER 12Z WHEN DRAINAGE FLOW SUBSIDE. WILL INDICATE VCTS FOR KAPF FOR THE TIME BEING DUE TO UNCERTAINTIES ON THE TIMING OF CONVECTION MOVING INLAND...BUT WILL CONSIDER THE POSSIBILITY OF INDICATING PREVAILING MVFR CONDITIONS FROM 12Z TO 18Z IN THE NEXT KAPF TAF. OVER THE ERN TERMINALS...MOSTLY IFR CONDITIONS WILL CONTINUE THROUGH THIS MORNING EXCEPT FOR A SHRA OR TWO INVOF KTMB AND KMIA. NEVERTHELESS...TSTMS SHOULD BE EXPECTED INVOF ALL TERMINALS THIS AFTERNOON AND SO WILL KEEP VCTS FROM 19Z TO 00Z TONIGHT. MARINE...WITH THE LOW DEVELOPING IN THE GULF...AN INCREASING SOUTHERLY WIND DEVELOPING WITH THE STRONGEST WINDS IN THE GULF WATERS. EXERCISE CAUTION ON TAP TODAY AND TONIGHT FOR THE OUTER GULF WATERS BEYOND 20 NAUTICAL MILES AS S 15 TO 20 KNOT WINDS WILL DEVELOP WITH SEAS TO 5 FEET. N SWELL OFF OF PALM BEACH COUNTY THIS MORNING AROUND 2 FEET WILL GRADUALLY DISAPEAR TODAY IN THE INCREASING SOUTHERLY WINDS. FIRE WEATHER...NO FIRE WEATHER CONCERNS. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 90 77 90 78 / 50 30 60 40 FORT LAUDERDALE 90 77 88 78 / 50 30 60 40 MIAMI 90 76 89 79 / 60 30 60 40 NAPLES 85 75 89 75 / 70 60 60 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && LONG TERM...15/JR SHORT TERM/AVIATION...47/RHG
HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA NATIONAL WEATHER SERVICE MIAMI FL 942 AM EDT THU SEP 20 2007 FLZ063-066>075-168-172>174-210130- GLADES-HENDRY-INLAND PALM BEACH-METRO PALM BEACH-COASTAL COLLIER- INLAND COLLIER-INLAND BROWARD-METRO BROWARD-INLAND MIAMI DADE- METRO MIAMI DADE-MAINLAND MONROE-COASTAL PALM BEACH- COASTAL BROWARD-COASTAL MIAMI DADE-FAR SOUTH MIAMI DADE- 930 AM EDT THU SEP 20 2007 ...ISOLATED WEAK TORNADOES POSSIBLE THIS AFTERNOON... ...SCATTERED TO NUMEROUS THUNDERSTORMS EXPECTED TODAY... ...SLIGHT RISK OF WATERSPOUTS TODAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS: SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED ACROSS ALL OF MAINLAND SOUTH FLORIDA AND THE ADJACENT COASTAL WATERS TODAY INTO EARLY THIS EVENING. FREQUENT LIGHTNING STRIKES, LOCALLY HEAVY RAINS AND WIND GUSTS TO 50 MPH CAN BE EXPECTED IN THE STRONGEST STORMS. TORNADOES: COUNTERCLOCKWISE CIRCULATION AROUND A SURFACE LOW PRESSURE SYSTEM IN THE SOUTHEAST GULF OF MEXICO MAY CAUSE A BRIEF WEAK TORNADO TO OCCUR IN THE STRONGEST THUNDERSTORMS THIS AFTERNOON. WATERSPOUTS: AN UPPER LEVEL LOW, AND ASSOCIATED SURFACE LOW PRESSURE SYSTEM, OVER THE EASTERN GULF OF MEXICO, WILL RESULT IN FAVORABLE ATMOSPHERIC CONDITIONS FOR WATERSPOUTS TO DEVELOP ACROSS ALL COASTAL WATERS, EXCEPT LAKE OKEECHOBEE, TODAY. WIND: THE STRONGEST THUNDERSTORMS MAY PRODUCE WIND GUSTS TO 50 MPH THIS AFTERNOON. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY SCATTERED THUNDERSTORMS ARE EXPECTED TO OCCUR EACH DAY THROUGH THE PERIOD. LIGHTNING STRIKES AND LOCALLY HEAVY RAINFALL WILL BE THE MAIN IMPACTS FROM THE STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUESTED THIS AFTERNOON. FOR MORE INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN MIAMI WEBSITE AT WWW.WEATHER.GOV/MIAMI.
The Miami radar (KAMX), 68 km away, was scanning. The volume nearest the first event began at 16:54 UTC.
1 thunderstorm wind. Local standard time, as filed.
Power lines reported down at Commercial Boulevard and NW 70th Avenue in Tamarac.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2007Every state in 2007This day in weather historyWarnings in Florida, September 2007
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: 60546.