As the full moon approached, spring tides made a return to coastal areas, with an increasing potential in coastal tidal flooding along east coast areas. This was further enhanced by a strong easterly wind component.
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The episode as NWS MFL wrote it up.
As the full moon approached, spring tides made a return to coastal areas, with an increasing potential in coastal tidal flooding along east coast areas. This was further enhanced by a strong easterly wind component.
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 29, 6:49 PM EST, 41 minutes earlier.
Area Forecast Discussion National Weather Service Miami FL 749 PM EDT Tue Sep 29 2020 Models/sfc analyses continue to depict a deepening trough across the SE CONUS, marching towards Florida and reaching SoFlo by Wednesday afternoon. Radar has been showing persisting convection over the Gulf coastal waters, frequently pushing across Collier county and producing brief periods of rain and embedded thunder. But synoptic flow remains robust enough to keep showers moving along, thus no significant localized flooding is expected at least tonight. Have adjusted POPs/Wx grids to better reflect current trend of passing showers over the west coast. As the front moves across the peninsula, expect increasing shower.storm coverage over SoFlo during the next 18-24 hours, with best chances on Wed afternoon. No other changes to the forecast package are required attm. && .Prev Discussion... /issued 728 PM EDT Tue Sep 29 2020/ Aviation... Overnight, expect frequent periods of SHRA with possible embedded thunder at times over APF, and possibly prevailing below VFR by after 14z. The Atlantic terminals will remain mainly VFR overnight and through around 16Z, when another round of showers and storms is expected. Winds will remain below 10 kt tonight, becoming light and variable at times, then NE around 10kt after 16Z. Prev Discussion... /issued 411 PM EDT Tue Sep 29 2020/ Short Term (Rest of Today through Wednesday)... The unsettled pattern continues as a mid-level trough progresses through the eastern two-thirds of the United States. The trough will also amplify southward into the Gulf of Mexico today into Wednesday. An associated surface front over the Gulf of Mexico today will approach Southwest Florida tonight and progress towards the rest of South Florida on Wednesday. Ahead and along of the front, increasing moisture will provide ample opportunity for convection to flourish. The available wind shear will remain modest as the mid to upper level supporting dynamics appear to remain north of South Florida. While some vigorous storms cannot be ruled out, particularly when localized influences at the mesoscale and below come into play, the primary concerns with this front will remain heavy rainfall and any flooding that develops due to that. Today's southerly pattern will keep storms moving better than previous days but the repeated passage of efficient rainfall producers over a saturated area could cause flooding as today continues. Overnight, the trend for increased convection to the north and west will also open the door for portions of Southwest Florida to see showers and storms. By Wednesday morning, showers and storms will likely overspread most of the peninsula and neighboring waters. The additional cloud cover will help keep temperatures from rising out of the 80s across most of the area with portions of Southwest Florida likely struggling to reach the lower 80s on Wednesday during the day. There is some uncertainty with how far south and east the front will be able to progress on Wednesday before the mid level trough departs. If the front were to stall north and west of the lake, the southwesterly wind flow could allow moisture to continue increasing and provide another chance for training heavy rain cells across the region. If the front were to progress into the southern peninsula or even the Keys, there could be some pockets of drier air that come in behind the front to help cut back coverage a little bit. Some guidance is hinting that some drier pockets of air could sneak in ahead of the front which could create some bouts of reduced coverage but this is highly uncertain at this point. Long Term (Thursday through Tuesday)... Thursday through Saturday South Florida will be under the influence of a short-wave trough and it's attendant cold front, originating from the mid-latitudes. The cold front is forecast to stall over the region, with an orientation from Palm Beach County down through southwest Florida. While this may provide a brief spell of drier and cooler air early on Thursday, this will change quickly as the front becomes modified at subtropical latitudes. This boundary is forecast to remain quasi- stationary, becoming a foci for convection to develop across the region. As the aforementioned trough is slow to lift out of the region, the right entrance region of a 250 hPa jet streak will encompass much of South Florida. Several perturbations in the form of 500 hPa vorticity maxima will advect over South Florida in association with the orientation of the mean upper level steering flow. 850 hPa 10-15kt S/SE advection of higher theta-e values indicates that modest moisture transport should develop as a low- level mass response transpires from these favorable upper level dynamics. Therefore, beginning Thursday evening, a region-wide heavy rainfall threat may materialize. Where the greatest impacts are realized as a result of this pattern will be highly dependent on mesoscale and localized conditions. NE surface flow is forecast to occur across most of the region. With higher speeds offshore owing to the lower friction over the water, low-level moisture convergence may be maximized along the Atlantic coastline. It is worth mentioning that uncertainty is high regarding where maximum precipitation amounts will occur. There is a large disparity in QPF totals between reasonable best-case and worst-case scenarios. With that being said, the synoptic setup and boundary orientation seems to favor widespread rainfall occurring over eastern and southern portions of South Florida, including the waters. The threat for an region-wide heavy rainfall event may persist through Saturday and potentially lingering into early Sunday. Sunday through Tuesday Mean steering flow is forecast to decouple the stalled surface boundary, with the low-level moist sector forecast to move westerly into the Gulf waters while the 500 hPa trough lifts out towards the east. This will result in the synoptic flow to become more zonally oriented, with low-level easterly flow prevalent across the region. This will temper rain chances across the region, with PoPs trending from 60/70s down to 40/50s. Although chances for precipitation decrease across the region, local regions that experienced high antecedent rainfall totals will have to be monitored for a localized flooding risk. This is especially true of any slow-moving storms that are efficient rainfall producers. Regardless, more seasonable conditions should return, with higher maximum temperatures and lower precipitation chances, Maximum temperatures are forecast to decrease slightly across South Florida in association with the approaching cold front. Maximum high temperatures are forecast to be in the mid-upper 80s on Thursday with the front moving through. These lower maximum temperatures in the mid 80s may last through Saturday in association with increasing cloud-cover/rainfall, with .Long Term... a slight increase towards the upper 80s again from Sunday onward. Marine... Shower and thunderstorm activity will be the primary concern into early week. Some of the showers and storms may bring locally gusty conditions and possibly even a few waterspouts. A cold front approaching the waters mid week could lead to increasing shower and thunderstorm chances. There is some uncertainty with the front's progress and the potential for low pressure developing over the northwest Caribbean Sea which could impact the marine forecast later this week. Aviation... A lull in convection along the east coast with a peak expected this afternoon inland of the terminals and along the Gulf waters near APF. Sub-VFR conditions are possible around convection with brief bouts of IFR/LIFR possible at terminals directly impacted by convection. Light winds could become gusty and variable around convection. Short-fused amendments will likely be necessary through the period. Overnight, increasing showers and storms may cause APF to fall below VFR by 12z Wednesday. Beach Forecast... The rip current risk should remain fairly low through mid-week. Increasing easterly to northeasterly wind flow will allow the rip current risk to become elevated late this week into the weekend. Astronomically high tides will lead to minor coastal flood concerns again as we approach full moon later this week into the weekend. This may possibly be enhanced if a strong enough wind with an easterly component develops this week. Therefore, a Coastal Flood Statement is in effect for the Atlantic coast through at least Friday. Will continue to monitor the high tide forecast to see if a Coastal Flood Advisory will be needed for the Atlantic coast. && .Preliminary Point Temps/PoPs... West Palm Beach 75 87 75 87 / 30 50 30 70 Fort Lauderdale 78 89 77 89 / 30 50 30 70 Miami 77 89 76 89 / 20 50 30 70 Naples 75 85 72 88 / 50 50 20 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. &&
Hazardous Weather Outlook for South Florida National Weather Service Miami FL 317 PM EDT Tue Sep 29 2020 AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676- 300730- Lake Okeechobee-Biscayne Bay- Coastal waters from Jupiter Inlet to Deerfield Beach FL out 20 NM- Coastal waters from Deerfield Beach to Ocean Reef FL out 20 NM- Waters from Jupiter Inlet to Deerfield Beach FL from 20 to 60 NM- Waters from Deerfield Beach to Ocean Reef FL from 20 to 60 NM excluding the territorial waters of Bahamas-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- Coastal waters from Chokoloskee to Bonita Beach FL out 20 NM- Coastal waters from East Cape Sable to Chokoloskee FL out 20 NM- Waters from Chokoloskee to Bonita Beach FL from 20 to 60 NM- 317 PM EDT Tue Sep 29 2020 ...Late Week/Weekend: Heavy Rainfall Becoming More Likely with Flooding Possible... This hazardous weather outlook is for South Florida. .DAY ONE...THIS AFTERNOON AND TONIGHT Thunderstorms: Isolated to scattered thunderstorms are possible over South Florida with the best coverage over the Lake Okeechobee and northeast areas of South Florida. The main concern will be lightning, gusty wind, and street flooding in urban areas due to poor drainage for all metro areas on both coasts. Flooding: There is a slight chance of urban flooding of the roadways for the coastal metro areas, especially in typical flood prone areas, low lying areas, as well as areas with poor drainage with any thunderstorms. Coastal Flooding: Coastal flooding is also possible during high tides due to the spring tides of the full moon. Wind: Some of the storms could produce strong wind gusts of 45 to 50 mph this evening, mainly in the interior. Waterspouts: There is a slight risk of waterspouts for all South Florida waters. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A frontal boundary could stall out somewhere over the region by mid week, which could lead to increased chances of showers and thunderstorms through the end of the week into the weekend. At the same time, a coastal trough could set up over the eastern areas of South Florida, a possible tropical low develops over the Western Caribbean and moves west northwest into the Northwest Caribbean. This will allow for deep tropical moisture to work into South Florida late this week into this weekend which could enhance the potential heavy rainfall along with some flooding. The spring tide (high astronomical tide) may bring coastal flooding to the east coastal areas through this weekend. .SPOTTER INFORMATION STATEMENT... Widespread spotter activation is not anticipated, however individual spotters are encouraged to report winds and flooding to the National Weather Service forecast office in Miami. Please relay any information about observed severe weather to the NWS while following all local, state, and CDC guidelines. For more information...visit the National Weather Service in Miami website at www.weather.gov/miami.
The national radar mosaic for the moment the first event began.
1 coastal flood. Local standard time, as filed.
An NWS employee reported water on portions of roadways, drives, and walks around times of high tide. Locations include Alton Road between North Bay Road and Pine Tree Drive and Collins Avenue between West 63rd Street and West 41st Street.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Florida in 2020Every state in 2020This day in weather historyWarnings in Florida, September 2020
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: 920520.