textproduct: Miami - South Florida

KEY MESSAGES

Updated at 139 PM EDT Tue May 12 2026

- Scattered to numerous thunderstorms this afternoon into early evening. A few thunderstorms may contain strong wind gusts. Locally heavy rain may result in isolated instances of urban flooding across the east coast metro.

- Hot and humid weather continues today, with heat indices around 100 this afternoon.

SHORT TERM

(Rest of today through Wednesday) Issued at 139 PM EDT Tue May 12 2026

Plenty of beneficial rainfall is forecast for the region today, with scattered to numerous sea-breeze induced storms looking to develop along interior and eastern parts of South Florida this afternoon. Synoptically, the subtropical jet will be rounding the base of a southern stream shortwave, currently over the northern Gulf. This mid level disturbance has induced a weak surface low just south of the Florida panhandle, which is tapping into some rich moisture over the region and producing widespread showers near the Big Bend region as it interacts with a stationary front in north-central Florida. Diffluent flow aloft ahead of the trough will provide favorable ascent, while the front at the surface will provide that extra forcing to invigorate thunderstorms, something which has been lacking the last couple of days. In fact, strong to severe thunderstorms are already developing early this afternoon along the boundary in north-central Florida.

However, the best dynamics for strong storms will remain north of South Florida, closer to the front. The main trough axis of the southern stream shortwave will be crossing the state during the early evening, which may coincide with the peak of storm activity for today. The surface front looks to wash out as it makes its way south and it doesn't really make it's way into our region until tomorrow, so it doesn't appear to be much of a factor for storm development this afternoon. Regardless, there is increasing confidence for heavy rainfall and an isolated severe threat for the late afternoon through early evening period. Model soundings indicate a much more moist profile compared to the last several days, with PWATs climbing into the 1.8 to 2 inch range. The mid- level dry layer looks to be much more depleted today, and forecast soundings are showing a deep warm cloud layer of 3 to 4 km. Tall and skinny CAPE with values up to 3000 J/kg should make for storms with efficient rainfall rates. HREF ensemble PMMs show most likely rain amounts of 0.5 to 1.5 inches of rainfall. Probabilities for greater than 2 inches of rainfall are low, only around 20%, but localized heavier amounts from strong storms may produce a few 3 to 5 inch hot spots. As a result, WPC has put us in a Marginal Risk (level 1 of 4) for localized urban flooding for eastern metros, mainly affecting low lying and poor drainage areas.

As for the severe weather threat, feeling a little more confident today due to the depleted dry layer and increased forcing, but expect the threat to be isolated to only a few storms. Stronger westerly flow aloft will raise 0-6 km bulk shear values into the 40 to 50 kt range, making for a much more favorable environment to sustain stronger storms. Low level SRH values are much higher over central Florida due to frontal interactions and greater directional shear. But, SPC still included parts of Palm Beach county in a very low 2% Tornado Risk, which would most likely arise from quick spin ups from sea-breeze boundary interactions. With DCAPE near 800 J/kg, the main threat will once again be strong wind gusts. Strong diurnal heating will give way to steep low level lapse rates over interior portions of the state, where sea breeze collisions will create the first storms mid afternoon. Clusters of storms then look to make their way eastward towards the Atlantic through the early evening. With mid-level lapse rates once again not looking too impressive, minor hail is possible, but the threat is very low.

Outside of the storm threat, the increased moisture across the region will lead to some pretty muggy conditions. Relative humidity values will continue to climb throughout the day, which will result in widespread heat indices near 100 F. The NWS Probabilistic HeatRisk tool is showing about a 50% chance of Major (level 3 of 4) heat related impacts for both Gulf and Atlantic metro areas. These conditions will affect anyone without proper cooling or hydration.

Storm activity will wane after sunset, with zonal westerly flow looking to take over during the early morning hours on Wednesday. Despite mid-level troughing lingering over the region and the frontal boundary pushing further south (albeit much weaker and washing out), guidance has trended much drier for Wednesday. Both global models and hi-res forecast soundings are showing a level of dry and stable air moving over the region during the early morning hours. Forcing from the shortwave aloft, should be able to eek out some showers moving from west to east during the morning and early afternoon hours. Stronger westerly flow at the surface will keep the Atlantic sea breeze pinned to the immediate coast. As a result, showers and isolated storms will focus mainly along eastern areas. HREF ensemble probabilities are only showing up to an inch at most for rainfall, but PoPs will be 25% to 50% across South Florida for the afternoon.

LONG TERM

(Wednesday night through Monday) Issued at 101 AM EDT Tue May 12 2026

An overall drier pattern is expected for the end of the week into the weekend as the shortwave moves off to the east and upper level ridging builds into the region. There will still be chances of convection each day that will mainly be diurnally driven sea-breeze convection.

Temperatures during the extended period will remain above normal with highs ranging from the upper 80s to lower 90s across the metro areas, and low to mid 90s over the interior. Overnight lows will be in the 60s/70s.

AVIATION

(18Z TAFS) Issued at 139 PM EDT Tue May 12 2026

Light to breezy southeast winds will prevail for most sites this afternoon. A Gulf breeze will develop at KAPF where winds will increase out of the SW at around 10 kts. Scattered thunderstorms are expected to impact east coast sites for the mid afternoon through early evening period, bringing gusty and erratic winds with periods of MVFR and IFR visibilities and ceilings. Storms will wane after sunset, with winds becoming light and variable overnight. Winds look to shift from the west at all sites tomorrow morning, with some light passing showers through the afternoon hours.

MARINE

Issued at 101 AM EDT Tue May 12 2026

Scattered thunderstorms are expected over the area waters the next several days, which may result in locally hazardous winds and seas. Outside of convection, gentle to moderate SE winds expected in the Atlantic today with W to NW winds in the Gulf. Seas today 2 ft or less in the Atlantic and a foot or less in the Gulf. A brief northerly swell is expected in the northern Atlantic waters late Wednesday into early Thursday which may elevate seas to near advisory criteria.

PRELIMINARY POINT TEMPS/POPS

Miami 76 90 75 90 / 50 40 10 30 West Kendall 73 91 72 91 / 40 40 10 30 Opa-Locka 75 90 74 91 / 50 40 10 30 Homestead 75 90 74 91 / 40 30 10 30 Fort Lauderdale 77 88 75 87 / 60 40 10 30 N Ft Lauderdale 75 88 74 87 / 60 50 10 30 Pembroke Pines 77 92 75 92 / 60 40 10 30 West Palm Beach 75 88 73 87 / 70 60 20 20 Boca Raton 76 87 75 87 / 70 60 10 30 Naples 75 88 75 88 / 20 20 10 10

MFL WATCHES/WARNINGS/ADVISORIES

FL...None. AM...None. GM...None.