textproduct: Miami - South Florida

KEY MESSAGES

Updated at 643 PM EDT Tue Oct 20 2026

- Hazardous marine and beach conditions continue through tomorrow for the Atlantic and Gulf waters.

- Minor to moderate coastal flooding possible as early as mid to late week. Peak tidal levels will be reached late this weekend into early next week and could reach Major flood stage for points along the coast.

- Heavy rain, isolated flash flooding, and windy conditions are forecast for this weekend.

SYNOPSIS

Issued at 357 PM EDT Tue Oct 20 2026

Water vapor and upper-air analysis data show a frontal system off the Mid-Atlantic coast embedded within the larger eastern US longwave trough. Vapor imagery and model analysis fields also show that, within the longwave trough, a couple of elongated shortwaves sit over the Tennessee Valley and Great Lakes region, and stretch back over the central CONUS ridge. At the surface, the 12z WPC analysis depicts a large eastern and central CONUS ridge with the surface low off the Mid-Atlantic coast associated with the aforementioned frontal system. A local surface analysis indicates that a frontal boundary associated with this low still exists across the northeast Gulf, through north-central Florida, and up the Southeast coast. Across South Florida, a surface trough sits along the east coast, with the warmer and more moist maritime air advecting inland in the northeasterly flow regime around the broader surface ridge. Observed sounding analysis data from 12z this morning reveals that solid northwesterly flow associated with the upper trough gradually transitions to northeasterly between 500-700mb when the low-level ridge gains influence. Deep-layer dry air was above 700mb, with a nearly saturated lower troposphere. Precipitable water values across the lower half of the state range from 0.75" at TBW, up to 1.1-1.2" between MFL and KEY.

Visible imagery across South Florida shows bands of cloudiness moving inland from the near shore waters and radar imagery this morning showed the presence of scattered showers along the immediate coast. These features seem to be driven by the very low level thermal trough resultant from maritime influence over our coastal waters and the cooler temperatures over land. The background northeasterly flow is lifting the warmer and more moist air as it advects northeast to southwest across the state. As the day progresses, this influence should continue diminishing and the threat for showers should decrease.

SHORT TERM

(Rest of today through Friday) Issued at 357 PM EDT Tue Oct 20 2026

The above mentioned shortwaves, and an additional one riding over the ridge from the Central Plains, will superposition with the quasi- stationary upper low and result in an upper trough extending from the Mid-Atlantic through Florida and into the Gulf. A stable layer between 700-900mb, indicated by packed isentropes, will likely keep the upper level trough from influencing the surface pattern much. In fact, this stable layer remains in place through at least Friday as another shortwave currently over Alberta and Saskatchewan dives through the Great Lakes region and into the Southeast. The sensible weather will then be primarily influenced by features in the lower atmosphere, and more specifically, the the thermal trough development and advection mentioned above. The continued northeasterly low-level flow between the surface ridge and Mid- Atlantic low will result in multiple days of widely scattered morning showers developing near the coast and moving inland, mostly dissipating by early afternoon. Overnight lows will be consistently in the mid to upper 60s inland, and closer to 70 along the coasts. Highs will also mostly be near or just below climatology, in the low to mid 80s. Winds will gradually decrease through the week as the western Atlantic low slowly drifts northward.

LONG TERM

(Saturday through next Monday) Issued at 357 PM EDT Tue Oct 20 2026

As all the aforementioned shortwaves eventually spill into the western Caribbean, they'll find a more unstable region to initiate and organize convection. At the same time, the upper trough will become more positively tilted as the core of the main longwave trough moves northeast and a wave breaking pattern sets up with the latest shortwave starting to cutoff over FL and the SW Atlantic. This will create a pathway for convection to gain latitude out of the Caribbean and enter the Bahamas. Traditional 500mb ensemble cluster analysis is primarily focusing on other sources of variance in determining extended range scenarios, and this is likely due to our focus area being on the edge of the domain and focused primarily above 500mb. However, we can still identify a few scenarios from the clusters to clue us into the fact that where this upper-low cuts off will have an implication on QPF forecasts this weekend and into next week. Thankfully WPC QPF clusters can at least shed light on what the potential impacts may be depending on the evolution of the upper pattern. What we can say is that the east coast metros will be the target of heavy rainfall over the weekend. What's uncertain is just how much and exactly when. Generally speaking, there's a lower QPF scenario that on average brings 1-2" of rain to much of the southeast coast of Florida, then there are multiple more impactful scenarios that differ on placement of the highest precip amounts across the east coast from Cape Canaveral down to Homestead. The higher end scenarios generally agree on amounts between 5-7" over the 48 hour period this weekend, with the potential for scattered to isolated locations receiving somewhere near double those amounts. For this reason we remain in a Slight Risk (15%) for flash flooding in WPCs Day 5 Excessive Rainfall Outlook. Winds and gusts (non- thunderstorm) will also be a concern over the weekend as the gradient between convection in the Bahamas and an approaching front tightens. There's currently a high probability of sustained winds in the 25-30 mph range across east and west coast metros, with a moderate chance of gusts exceeding 40 mph. The main window for these high winds will be on Sunday. The wet pattern will likely continue into next week as the northern stream frontal system and cutoff low interact and eventually dissipate or advect out of the region.

AVIATION

(00Z TAFS) Issued at 643 PM EDT Tue Oct 20 2026

VFr conditions will prevail through the period. Northeasterly winds continue through the night and into tomorrow, potentially becoming gusty at times. Isolated showers will be possible overnight into early tomorrow morning along the East Coast.

MARINE

Issued at 357 PM EDT Tue Oct 20 2026

Advisory level winds are expected through tomorrow for Gulf and Atlantic waters, though the magnitude will be gradually decreasing. It's unlikely that seas will have time to fall below Advisory levels along the Atlantic coast before our next wind/swell event this weekend, so the Advisory will likely continue here for many days. Scattered showers are forecast for each of the next few mornings, diminishing by early afternoon.

As a front approaches from the north, and an area of low pressure emerges from the south, another strong wind event is expected to unfold over our Atlantic and Gulf waters this weekend. Solid Advisory level conditions are forecast, with Gale conditions not out of the question for Atlantic waters.

BEACHES

Issued at 357 PM EDT Tue Oct 20 2026

Hazardous surf conditions are expected to briefly improve by Thursday, but will likely return at some point this weekend. A high rip current risk will continue for the foreseeable future.

HYDROLOGY

Issued at 357 PM EDT Tue Oct 20 2026

We're beginning to come out of an ebb in the astronomical tides as we head towards the full moon and peak of the tide forecasts late this weekend and into early next week. Observed water-levels are already over-performing predictions and we'll likely begin reaching Minor flooding thresholds tomorrow or Thursday at all of our east coast tidal stations. It's likely we'll also reach Moderate flooding levels by the weekend; even before the peak of the King Tide cycle. It's not out of the question that Palm Beach county may even reach Major flooding levels at the peak of the King Tide. The normal King Tides are complicated by the fact that we'll be dealing with a complex upper/surface low pressure pattern that will feature an approaching front from the north and convection rising out of the Caribbean from the south. This will likely increase the onshore wind component and magnify the already high tides. This is somewhat accounted for in the predictions mentioned above, but only crudely. Furthermore, the potential for heavy rainfall during periods of high tide is also something to be aware of that could further aggravate coastal flooding. In short, we're heading into what could be a rather impactful period for coastal flooding and sensitive locations should consider preparations.

PRELIMINARY POINT TEMPS/POPS

Miami 71 85 72 84 / 10 10 10 20 West Kendall 70 86 70 85 / 0 10 10 20 Opa-Locka 71 85 71 84 / 10 10 10 20 Homestead 71 85 70 85 / 10 10 10 10 Fort Lauderdale 72 84 72 83 / 20 20 30 30 N Ft Lauderdale 72 85 72 84 / 20 20 30 30 Pembroke Pines 70 85 71 84 / 20 10 20 20 West Palm Beach 71 85 72 84 / 20 20 40 20 Boca Raton 71 84 71 83 / 20 20 30 30 Naples 66 85 68 84 / 0 0 0 0

MFL WATCHES/WARNINGS/ADVISORIES

FL...High Rip Current Risk through Thursday evening for FLZ168-172- 173.

High Surf Advisory until 8 PM EDT Wednesday for FLZ168.

High Surf Advisory until 8 PM EDT this evening for FLZ172.

AM...Small Craft Advisory until 2 AM EDT Wednesday for AMZ610-630.

Small Craft Advisory until 8 PM EDT Thursday for AMZ650-651-670- 671.

GM...Small Craft Advisory until 8 PM EDT Wednesday for GMZ656-657-676.