Deep tropical moisture and a stalled boundary draped across the region worked together to bring wet and unsettled weather to South Florida. Heavy rainfall over already saturated soils produced flooding in Palm Beach.
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The episode as NWS MFL wrote it up.
Deep tropical moisture and a stalled boundary draped across the region worked together to bring wet and unsettled weather to South Florida. Heavy rainfall over already saturated soils produced flooding in Palm Beach.
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 30, 6:54 PM EST, 7 hours 6 minutes earlier.
Area Forecast Discussion National Weather Service Miami FL 754 PM EDT Wed Sep 30 2020 .Update... Remnant convection lingers just along the coastline and the near shore waters of Palm Beach, while a few showers are still shown on radar across the Miami metro area. With the frontal boundary stalling right over SoFlo, will keep inherited POPs/Wx grids, as new Model blend is once again going below ongoing trends, which are better align with HURR/global models. Best chances for rain and/or isolated storms remain over the Atlantic metro areas and the southern-most portion of the state. And with the front being shown as basically lingering over us during the next day or so, expect more showers on Thursday and likely on Friday. && .Aviation... Periods of MVFR are still possible for the rest of tonight across the Atlantic terminals, but most significant convection is now moving over the coastal waters. Winds will remain mostly NE through around 14Z, then ENE for Thursday afternoon. Another round of showers/TS also expected after 14Z with a lingering frontal boundary across the area. && .Prev Discussion... /issued 337 PM EDT Wed Sep 30 2020/ Short Term (Now through Thursday)... A stalled frontal boundary is currently over the region and should remain overhead through the short term period. Visible satellite imagery shows this feature well with more sunshine occurring to the south and east (upstream) of the cold front with more low level cloudiness. A line of showers has developed early this afternoon in response to the front. At this juncture it would appear the best potential for rainfall through the afternoon and early evening hours will be across the Atlantic metro...basically Homestead to Boca Raton and east. CAMs also shows this scenario with HRRR coming in just a bit more robust with precip/T'storm chances that prior runs. Although the front is not forecast to move much, if convection slightly behind the front develops, mesoscale boundaries (outflow) may move the front a bit more downstream with time. Showers and storms will weaken overnight except for the immediate coast. Otherwise, generally northerly or northeasterly winds can be expected. The boundary will remain in place through Thursday and in fact Thursday looks fairly similar to today. Models are picking up on a bit better QPF signal across the interior portions of the state and Atlantic coast. Again, there will be at least a limited hydro concern across the metro. In fact, WPC has delineated a marginal risk of excessive rainfall for the region on Thursday and with PWATs in the 2.2"-2.4" range, can't argue with that assessment. Temperatures will range from around 90s across the southern areas to middle and upper 80s during the afternoon up around the Lake Okeechobee region. Long Term... Friday through Sunday... Wet and unsettled weather will continue through the extended period as broad mid-upper level troughing encompasses the eastern half of the CONUS. At the surface, the quasi-stationary boundary draped across the region will ever-so-slowly inch northward through the weekend, keeping South Florida under the influence of northeasterly flow in the lower levels and south/southwesterly flow aloft. Therefore, sufficient tropical moisture will remain through the atmospheric column, in fact, model derived PWATs values remain in the 2.1 to 2.4 inches range over the region, translating to a potential flood risk. Current experimental PQPF indicate rainfall totals of 1 to 3 inches are possible across South Florida, with higher accumulations of 4 to 6 inches potentially over the eastern metro areas. Thus, the main concerns are currently for the east coast, where several days of antecedent rainfall could accumulate over flood prone areas. While highly uncertain at this time, additional moisture could work it's way into the area from a tropical low that currently has a 10 percent chance of development in the next 2 days and a 60 percent chance of development in the next 5 days from the National Hurricane Center. Current model iterations depict the aforementioned low moving west-northwest into the Yucatan Peninsula this weekend. However, if the low keeps more eastward into the Yucatan Channel and NW Caribbean Sea, then additional tropical moisture could become lofted into South Florida, leading to greater coverage of rainfall across the region. Monday through Wednesday... Regardless of the outcome of the low that NHC is currently monitoring, the overall synoptic pattern will remain favorable for scattered showers and thunderstorms to continue each day across South Florida next week. Although, the lows evolution will certainly be something we will continue to monitor with each model run and as we get closer in time. Greatest coverage of convection next week will be focused over the interior and west coast of South Florida with flow returning out of the east. Marine... A cold front across the region will continue to bring northerly or northeasterly winds through the remainder of the workweek before a more easterly transition takes shape this weekend. Outside of the potential for scattered showers and storms, wind and seas should remain somewhat favorable through Friday. On Saturday pressure gradient begins to increase, especially over the Gulf waters as a surface low develops across the western Caribbean. Aviation (18z Aviation)... Despite the close proximity to a cold frontal boundary, mostly MVFR/VFR conditions expected this cycle. Some isolated to scattered showers or T'storms may develop, especially today through early evening. Brief VIS/CIG reductions may be possible with storms or perhaps with low stratus just behind the front late tonight. Otherwise, expect light northerly winds through the cycle. && .Preliminary Point Temps/PoPs... West Palm Beach 75 87 74 85 / 40 70 50 60 Fort Lauderdale 77 89 76 86 / 40 70 50 70 Miami 77 89 76 86 / 40 70 50 70 Naples 72 87 73 84 / 20 50 40 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. &&
Hazardous Weather Outlook for South Florida National Weather Service Miami FL 345 PM EDT Wed Sep 30 2020 AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676- 010745- 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- 345 PM EDT Wed Sep 30 2020 ...Scattered Thunderstorms Possible This Afternoon... ...Flooding Potential Late This Week... This hazardous weather outlook is for South Florida. .DAY ONE...THIS AFTERNOON AND TONIGHT Thunderstorms: possible through this evening with greatest chance over the east coast metro areas. Lightning and street flooding are the primary hazards. Flooding: the east coast metro areas may see street flooding through this evening due to slow moving showers and storms. Coastal Flooding: flooding is possible near high tide along the Atlantic coast. Waterspouts: There is a slight risk of waterspouts for all South Florida waters. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY The flooding potential across the region may increase into this weekend, especially for the eastern metro and coastal areas due to the combination of heavy rainfall and high astronomical tides. There is uncertainty in how widespread and impactful this flooding may be, so keep up with forecast changes. .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.
Special Weather Statement National Weather Service Miami FL 1157 PM EDT Wed Sep 30 2020 FLZ068-168-010430- Coastal Palm Beach County FL-Metro Palm Beach County FL- 1157 PM EDT Wed Sep 30 2020 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN PALM BEACH COUNTY UNTIL 1230 AM EDT... * At 1156 PM EDT, National Weather Service meteorologists were tracking a strong thunderstorm near Highland Beach. This storm was moving very slowly westward. * Funnel clouds possible with this storm. * Locations impacted include... Boca Raton, Delray Beach, Highland Beach, Kings Point, Boca Del Mar and Fau South Campus. PRECAUTIONARY/PREPAREDNESS ACTIONS... Although typically weak and short lived, a landfalling waterspout can cause property damage and serious injury. To report severe weather, contact your nearest law enforcement agency. You can also share your report with NWS Miami on Facebook and Twitter. && LAT...LON 2646 7997 2633 7996 2633 8014 2647 8014 TIME...MOT...LOC 0356Z 084DEG 4KT 2638 8004 BAXTER
The national radar mosaic for the moment the first event began.
2 flood. Local standard time, as filed.
Tequesta Police Department reported the interesection of Tequesta Drive and Old Dixie Highway was closed due to ponding of water. Rain gauges in the area measured 4 to 6 inches of rainfall in only a few hours.
Palm Beach County Warning Point reported heavy rain caused flooding of roadway. The road near the intersection of Northlake Blvd and Prosperity Farms Road was closed due to flooding. Rainfall gauges in the area measured 4 to 6 inches of rainfall in only a few hours.
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, October 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: 919854, 924241.