textproduct: Miami - South Florida

KEY MESSAGES

Updated at 108 PM EDT Thu May 28 2026 - Slow moving or training storms could produce localized flooding today along the eastern half of south Florida.

- Heat stress indices will generally be a level 2 of 4 the next few days which could result in heat illness during prolonged exposure if precautions are not taken.

UPDATE

Issued at 108 PM EDT Thu May 28 2026

Mesoanalysis and ACARS data indicate that the eastern periphery of a plume of deep tropical moisture has arrived across the region this afternoon with observed precipitable water values now in the 2.0 to 2.3 inch range which is above the 10th percentile and close to the daily maximum PWAT value for today's date. Sounding data reveals a moist atmospheric column with ample saturation in the low and mid levels and a large warm cloud layer (-6C to -7C at 500mb) present. Ample instability (SBCAPE of 2000-3000 J/kg) has resulted in the development of numerous shower and thunderstorm activity across the region thus far this afternoon with a foci of convection currently present across inland locales of the region, as convective activity moves briskly along outflow boundaries. With the continued movement of the gulf breeze inland and a background south- southwesterly flow regime, the remainder of the afternoon will feature convection gradually migrating northwards across inland areas with some potential of a secondary round of shower and thunderstorm activity along the east coast of South Florida during the late afternoon into the early evening hours of today. Enhanced ascent and convergence along the Atlantic sea- breeze and destabilization may erode the leftover inhibition from morning activity enough to get a resurgence of shower and thunderstorm development. If this occurs, atmospheric ingredients point to an environment that could be conducive to high rainfall rates in a short period of time. Several individual HREF members indicate the potential of an additional isolated rainfall swaths of 1-3 inches of rainfall which may result in localized urban flooding, especially at locations that have already seen 1-2 inches of rainfall this morning or have poor drainage. Even after the loss of diurnal heating, the above average moisture in the vertical column may still support the potential of shower activity during the overnight hours, especially across coastal locales.

SHORT TERM

(Today through Friday) Issued at 235 AM EDT Thu May 28 2026

The upper-level pattern consists of a closed low over the west coast, a trough over the Northeast, and a ridge across the center of the country through the Southeast. Between the west coast low and the ridge is an additional shortwave positioned over the Southern Plains. At the surface, there's an area of low pressure off the Northeast coast, a ridge centered over the Great Lakes and another ridge across the western Atlantic, and a generally weak pressure pattern across the Deep South.

The consensus is for the eastern CONUS trough to spread further down the Eastern Seaboard as multiple shortwaves rotate through it. At the same time, the Southern Plains wave is expected to stretch and fracture into multiple sections moving north through the northern Plains, east through the Deep South, and ESE through the southwest/south-central Gulf. All of this will help displace the western Atlantic ridge and open up a channel of tropical moisture advection from the western Caribbean into the eastern Gulf, and across the state of Florida.

For the local area it becomes a rather low predictability regime as we remain mostly away from a deep-layer lifting mechanism. While the transition to westerly flow would favor convection initiating across the interior and moving to the east coast each afternoon/evening, mesoscale boundaries and outflow from upstream convection/MCS' may disrupt that more predictable pattern. Nonetheless, rain chances will be on the rise with forecast PWATs in the top 10th percentile for this time of year. The high PWATs also bring the potential for heavy rainfall in storms that develop. Thus, the WPC has outlooked the eastern half of south Florida in a Marginal Risk for excessive rainfall today. The risk for isolated flooding concerns is highest today of the coming days as flow transitions from easterly to westerly. The southerly low- level flow and more westerly flow aloft could result in training or slow moving storms as the seabreezes eventually collide and drift eastward. The risk decreases a bit after today as flow becomes more solidly westerly, increasing the progressiveness of afternoon storms (though coverage will remain high).

While highs will generally be near normal (~90), the increasing moisture will ensure heat indices remain in the low 100s each afternoon. The risk for heat illness from prolonged time outdoors is roughly a level 2 of 4 for the next couple of afternoons.

LONG TERM

(Friday night through Wednesday) Issued at 235 AM EDT Thu May 28 2026

The wet, low predictability pattern continues through the extended range. With deep-layer forcing getting closer to the region as the eastern CONUS trough gradually spreads south, chances increase that our convective pattern could remain dependent on how we're affected by upstream convection, and how that disrupts the typical seabreeze regime. The official forecast keeps high rain chances focused across the eastern half of south Florida through the period, but just know that at least the pattern more rooted in climo, with higher rain chances due to the anomalous moisture. Early next week the omega pattern breaks down a bit as shortwaves from the western low advect through the ridge and further amplify the eastern low, resulting in a more progressive pattern that brings a frontal boundary into Florida. At this time, it appears this is our next best chance for more widespread heavy rainfall.

Temperatures through the weekend will be similar to the end of the week, with a slight relief early next week due to the anticipated coverage of showers and storms.

AVIATION

(18Z TAFS) Issued at 108 PM EDT Thu May 28 2026

Scattered to numerous SHRA/TSRA will continue across the region today with bouts of sub-MVFR cigs possible at east coast terminals in and around SHRA/TSRA activity. Winds may become erratic and gusty if SHRA/TSRA directly impacts terminals. L/V winds expected overnight with SHRA/TSRA activity waning in coverage.

MARINE

Issued at 235 AM EDT Thu May 28 2026

Southeasterly flow will become southerly through the day, and then southwesterly by tomorrow. The southwesterly flow should then prevail into early next week. Away from the seabreeze zone, winds will generally remain below 15 knots. Low seas are expected over the next several days. Rain chances will be relatively high over the upcoming week, with the pattern generally resulting in convection blowing into the Atlantic from the Peninsula each evening. Storms in the Gulf will be dominated more by upstream convection in the central and northern Gulf.

BEACHES

Issued at 235 AM EDT Thu May 28 2026

The high rip current risk will continue down the east coast beaches today as onshore flow gradually veers from onshore to southerly. The southerly turn could favor the development of a weak longshore current. As winds weaken by tomorrow, the rip current risk will fall below headline levels.

PRELIMINARY POINT TEMPS/POPS

Miami 75 89 76 89 / 50 70 40 60 West Kendall 73 90 74 90 / 40 70 30 60 Opa-Locka 75 90 76 91 / 50 70 40 60 Homestead 76 89 77 90 / 50 70 30 40 Fort Lauderdale 76 88 77 88 / 60 70 40 60 N Ft Lauderdale 75 87 76 88 / 50 70 40 60 Pembroke Pines 77 91 77 92 / 50 70 40 60 West Palm Beach 75 88 76 89 / 50 70 50 60 Boca Raton 76 88 77 89 / 50 70 50 60 Naples 76 89 78 89 / 30 20 20 20

MFL WATCHES/WARNINGS/ADVISORIES

FL...High Rip Current Risk until 8 PM EDT this evening for FLZ168-172- 173.

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