textproduct: Miami - South Florida

KEY MESSAGES

Updated at 635 PM EDT Thu Sep 17 2026

- Scattered thunderstorms expected today. Rainfall chances remain elevated this weekend into early next week as an upper level low moves across the region.

- Heavy downpours from the stronger showers and thunderstorms could lead to localized flooding over the urban and low lying areas. - Hazardous marine conditions continue in the Gulf waters through this evening. A high risk of rip currents continues for the Palm Beaches through early Friday, with an elevated risk of rip currents for the rest of the Atlantic beaches.

SHORT TERM

(Rest of today through Friday) Issued at 156 PM EDT Thu Sep 17 2026

Heavy rainfall has been plaguing the eastern metros of South Florida this morning as a tight moisture gradient between dry air to our north associated with anomalous ridging and a plume of moisture draped across our region has set up over northern Broward and Palm Beach Counties. Mesoanalysis data has also confirmed that we had coastal convergence along the east coast due to brisk northeasterly winds at the surface and a counteracting northwesterly upwind propagation vector just aloft at around the 850 mb level. MRMS and local rain gauges have indicated pockets of as much as 4-6" that have fallen within a matter of just an hour or two across portions of Palm Beach County. Further south, isolated areas of up to 3 inches have been observed over portions of coastal/metro Broward.

As a result of all of this morning activity, it has been a rarely cool and comfortable start to our day with more of a Fall-like ambiance across our eastern metros. These gloomy conditions, composed of plentiful cloud cover/anvil debris, should continue to keep much of South Florida rather stabilized through the majority of the day and limit any widespread convective coverage across the mainland. In correspondence, high-res models are not overly optimistic with regards to shower/thunderstorm coverage over interior/SW Florida as the rest of the afternoon progresses and in fact, continue to focus convection along our recently-drenched eastern metros as our local Atlantic waters stay generally unstable with an abundance of moisture and forcing aloft from an adjacent upper-level low. Given the saturation that has occurred across the metros this morning, additional instances of urban flooding will be possible through the rest of our Thursday with any supplementary passing showers as they move in from the Atlantic along our swift onshore flow. All the convective inhibition, in addition to poor overall atmospheric dynamics that remain in place today, should prevent showers and thunderstorms moving onshore during the remainder of the day from becoming strong or from even producing as heavy of rainfall rates as this morning.

We can continue to expect periodic Atlantic showers and storms to keep pushing onshore through the overnight hours and into our Friday morning before activity subsequently becomes more scattered in nature across South Florida during the afternoon and early evening hours. A weakening northeasterly flow across the region, in addition to our upper-level steering flow becoming more west to southwesterly and a developing Gulf sea breeze at the surface, should allow most of Friday's convection to focus over the interior with the potential to drift towards each metro. Given these counteracting wind vectors at different pressure heights, the potential for slower-moving cells will exist (which could lead to more flood concerns with an emphasis on the eastern metros with how much rain they already received today). The prolonged anticipated arrival of an upper-level low will finally come to fruition, as ensemble guidance has our mid-level temperatures dropping to around - 8C and therefore steepening our lapse rates. This also reflected in our high-res models with 700-500 mb lapse rates cooling to 6.0- 6.5C/Km, which could evidently lead to a few stronger cores. It is important to note, however, that with the encroachment of this upper- level low this evening and our winds aloft shifting to more of a northerly direction will come some dry intrusion from the parched antecedent air mass situated over the Southeast US in association with our upper-level ridging. Although this is yet to be determined, it will have to be monitored as to how much residual dry air persists in our atmospheric column (models have PWATs dropping to 1.7-2.0", which is below to around average for this time of year) and how it could potentially impact thunderstorm growth in the vertical. Nonetheless, the atmosphere should be fairly primed with barotropically-driven instability gradients from the presence of the upper-level low and sufficient low-level moisture to produce scattered showers and thunderstorms across South Florida during peak daytime heating hours.

It will be difficult for temperatures across South Florida's eastern metros (currently in the mid 70s) to recover from all the ongoing cloud cover from this morning's activity, as they are forecast to glacially climb to around the mid 80s later this afternoon with some forthcoming breaks in the cloud cover. Highs across Southwest Florida should peak in the upper 80s. Tomorrow's high temperatures should be reaching the upper 80s to low 90s across much of the region.

LONG TERM

(Friday night through Wednesday) Issued at 100 AM EDT Thu Sep 17 2026

As we head into the weekend and early into next week, the mid/upper level low will move into the Gulf, and higher moisture levels move into the region. Light ESE flow this weekend will eventually become southerly by early next week. With deep tropical moisture moving into South FL, higher than normal PoPs (80-90%) are expected each day. With generally weak steering flows expected along with efficient rainfall rates, urban and poor drainage flooding will likely be the main threat each day. All of this will continue to be good news for the ongoing improving drought conditions.

Temperatures during the extended period will be right around normal with highs generally in the upper 80s to lower 90s, and low temps in the mid to upper 70s.

AVIATION

(00Z TAFS) Issued at 635 PM EDT Thu Sep 17 2026

Periods of showers and storms possible through much of the early overnight period, with a lull possible around 06-08Z through mid morning. Additional shower and storm development likely by around 18Z, although confidence on exact timing is on the lower end. Short fuse amendments may be necessary for any sites directly impacted by lower ceilings or variable winds within shower and storm activity.

MARINE

Issued at 100 AM EDT Thu Sep 17 2026

Hazardous northeast winds today in the Gulf waters, with cautionary winds in the Atlantic. Seas 3-6 ft in the Atlantic waters and 2-3 ft in the Gulf waters. Conditions continue to improve on Friday as moderate easterly winds are expected and seas continue to subside.

BEACHES

Issued at 100 AM EDT Thu Sep 17 2026

A moderate ENE flow and elevated swell will result in a high risk of rip currents for the Palm Beaches through early Friday, and an elevated risk for the rest of the Atlantic beaches.

PRELIMINARY POINT TEMPS/POPS

Miami 77 89 77 88 / 40 70 40 90 West Kendall 76 89 75 88 / 30 70 40 90 Opa-Locka 78 89 76 89 / 40 60 40 90 Homestead 77 89 75 89 / 40 60 50 90 Fort Lauderdale 79 88 76 88 / 50 60 50 80 N Ft Lauderdale 78 89 77 89 / 50 70 50 80 Pembroke Pines 77 89 75 88 / 40 60 50 90 West Palm Beach 78 89 76 89 / 50 70 40 90 Boca Raton 77 88 75 88 / 50 70 50 80 Naples 74 91 74 89 / 20 70 40 80

MFL WATCHES/WARNINGS/ADVISORIES

FL...High Rip Current Risk through Friday morning for FLZ168.

AM...None. GM...Small Craft Advisory until 11 PM EDT this evening for GMZ656-657- 676.