textproduct: Miami - South Florida

SHORT TERM

(Today through Thursday) Issued at 118 AM EDT Wed Jun 11 2025

05z Mesoanalysis indicates the continued influence on our area of a positively tilted mid level trough across the eastern United States as light westerly upper level flow continues around the far periphery of the trough. Veering 500mb flow also suggests that a weak shortwave may also be present just north of our region over Central Florida. ACARS data from local airports as well as earlier 00z upper air soundings from WFO Miami and WFO Key West indicate the continued presence of a moist saturated vertical profile with light southeasterly surface winds courtesy of continued low-level surface ridging situated in the western Atlantic waters. A brief lull in convective activity continues at the moment as a decaying cold pool over land (convective inhibition) combined with nocturnal stratification have stabilized our local atmosphere.

However, CAMs (HRRR, RAP, RRFS) and mesoscale probability guidance indicate a resurgence of shower activity (and perhaps a few thunderstorm) across the eastern half of the region by 6-10z this morning as a plume of deeper tropical moisture (precipitable water value of 2.0 to 2.2 inches) advects into the region via the anticyclonic flow of the surface ridge. Looking at the SPC Sounding Climatology page, these precipitable water values are above the 90th percentile and close to the daily max for WFO Miami's upper air soundings for the date. As the mid-level trough departs into the western Atlantic waters later today, mid and upper level flow will become light in nature as mid-level here,ridging gradually builds in across the region. Given the light southeasterly flow and a developing gulf breeze during the early afternoon hours, the foci for convective activity will once again reside across inland locales and southwestern Florida as both sea-breeze boundaries propagate inland and collide across the western two thirds of the area. Given the lack of shear and kinematic dynamics in the vertical profile, storm mode for convection will take the form of large multicellular clusters propagating and developing along outflow boundaries at the edge of cold pools. Forecast 500mb temperatures in the -7C to -8C range will support the threat of small hail with taller initial cores that fire up before expanding in spatial coverage. Although the amount of dry air today will be far less than yesterday with a more saturated vertical profile, gusty winds cannot be ruled out as wet microbursts occur with collapsing cores.

The main threat today with afternoon convection will be heavy rainfall and localized flooding due to extremely slow storm movement (the 00z WFO Miami sounding had a corfidi upshear and downshear vector of less than 5 knots) due to a lack of flow aloft. The combination of slow storm movement and precipitable water values of 2.0 inches plus will result in efficient rainfall rates of several inches per hour. While most of the region will see rainfall totals less than 1 inch, the saturated atmosphere present could be conducive in producing locally higher values. HREF's 00z LPMM shows one or two localized swaths of 2.0 to 3.0 plus inches possible with the heaviest thunderstorm activity. The latest HRRR/HREF/RRFS all indicate that the greatest probability of seeing these higher rainfall totals will reside mainly across inland areas, however there is still some lower potential of the SW Florida metro area getting in on some of the action. With the spatial uncertainty in the forecast, all of South Florida has been placed in a marginal risk of excessive rainfall today. In simple terms, a marginal risk is issued by the Weather Prediction Center when there is at least a 5% risk of flash flooding within 25 miles of a point. While the majority of locations will not experience localized or flash flooding, if heavy rainfall occurs over an urban area, it could create issues. If activity does indeed materialize closer to or over a portion of either metro, flood advisories may be needed accordingly.

A rinse and repeat pattern on Thursday as synoptic flow aloft remains absent as mid-level ridging expands further. Light southeasterly flow at the surface will continue to allow for the Atlantic sea-breeze to propagate inland with a period of shower activity during the morning hours along the east coast and a foci of afternoon showers and storms across inland areas and southwestern Florida. Outflow boundaries may allow for activity to build back towards both coasts later in the day, favoring southwestern Florida given the stronger southeasterly flow.

Forecast high temperatures will remain in the upper 80s to low 90s each day with wide variance in temperatures occurring in and around convection with the propagation of outflow boundaries and cloud debris overspreading the region.

LONG TERM

(Thursday night through Tuesday) Issued at 118 AM EDT Wed Jun 11 2025

A expansive and prevalent plume of Saharan Dust is forecast to arrive across the region on Thursday night into Friday morning according to the latest run of NASA's Dust Aerosol Optical Thickness Model. This will result in reduced air quality, colorful sunrise and sunsets, and hazy skies during the day outside of any shower or thunderstorm activity. At the same time, mid-level ridging aloft will create subsidence across the region which will also act to limit the spatial extent of shower and thunderstorm activity. Given the continued lack of synoptic flow aloft, any shower or thunderstorm activity will focus across inland areas during the afternoon hours along sea-breeze collisions if an updraft is able to break through the capping inversion created by the Saharan Air Layer. Temperatures will trend higher during this period, especially across inland areas that are away from the moderating influences of the ocean.

Deterministic model guidance and NASA's Dust Aerosol Optical Thickness show the gradual departure of the saharan dust to the west of the region during early next week. This may result in an slight uptick in rain chances, however considering that this is at the tail

AVIATION

(06Z TAFS) Issued at 120 AM EDT Wed Jun 11 2025

SHRA activity picks up around 9z/10z this morning. Widespread SHRA/TSRA expected once again this afternoon with bouts of sub- MVFR cigs possible at area terminals. Handled with VCSH and VCTS in the TAF forecast for now. Outside of convection, VFR conditions will prevail with onshore winds.

MARINE

Issued at 118 AM EDT Wed Jun 11 2025

Moderate southeasterly winds expected this week as high pressure continues to sit over the western Atlantic. Scattered showers and thunderstorms remain possible each day, which may result in locally hazardous winds and seas. Outside of convection, seas over the next several days generally 2 ft or less.

BEACHES

Issued at 118 AM EDT Wed Jun 11 2025

Rip current risks will remain elevated along the Atlantic coast as onshore winds increase through the week.

PRELIMINARY POINT TEMPS/POPS

Miami 88 79 88 81 / 80 40 70 20 West Kendall 88 76 89 77 / 80 40 70 30 Opa-Locka 89 78 89 80 / 70 40 70 20 Homestead 87 78 88 79 / 80 50 70 30 Fort Lauderdale 87 79 87 80 / 70 40 70 30 N Ft Lauderdale 87 79 88 80 / 70 40 70 20 Pembroke Pines 91 81 92 81 / 70 40 70 20 West Palm Beach 87 78 89 79 / 70 30 70 20 Boca Raton 89 78 89 79 / 70 40 70 20 Naples 89 74 88 75 / 80 60 70 40

MFL WATCHES/WARNINGS/ADVISORIES

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