Area Forecast Discussion
Issued by NWS Miami, FL
Issued by NWS Miami, FL
006 FXUS62 KMFL 121119 AFDMFL Area Forecast Discussion National Weather Service Miami FL 719 AM EDT Sat Sep 12 2026 ...New AVIATION... .KEY MESSAGES... Updated at 716 AM EDT Sat Sep 12 2026 - Scattered showers and thunderstorms return again today, focusing mainly across interior and SW Florida. Frequent lightning, heavy rain and gusty winds will be possible. - High temperatures will generally rise into the low to mid 90s across South FL each day, resulting in widespread Moderate to Major HeatRisk. && .SHORT TERM... (Today through Sunday) Issued at 240 AM EDT Sat Sep 12 2026 We have an intriguing rex block pattern evident on water vapor imagery this evening across the eastern half of the country with an upper-level shortwave digging into the Mid-South positioned underneath broad mid-level ridging stretching across the Great Lakes. Just to the southeast of this unique configuration, we have another mid-level impulse churning over the Southeast CONUS and providing a moistened ambiance. Over the southwest Atlantic at the same isobaric height, we have apparent ridging which has continue to help escort the same upper-level disturbance that crossed the Florida peninsula yesterday away from our general proximity. South Florida remains nestled to the south of all these aforementioned features, but still enveloped in plenty of residual tropical moisture on the tail end of the same mid-level disturbance transiting along the outer fringes of our subtropical ridge aloft. There is also some impending moisture currently to our southeast over and around Andros Island and central Cuba associated with a westward-moving low-level perturbation. Closer to the surface, a few westward-propagating boundaries are being observed on KAMX over our nearshore Atlantic waters associated with the marine DMAX cycle. At the same time, a land breeze has developed along the east coast of South Florida as per our weather observing stations. These mesoscale boundaries have already been producing brief showers just offshore, but have been fizzling out rather quickly as they push toward the coastline with the presence of a stable boundary layer and lack of sufficient forcing. Regardless, we can continue to expect these pesky showers and perhaps some rumbles of thunder to thrive over the nearshore waters of South Florida and around the east coast through the rest of the overnight period through daybreak. As we look past sunrise and diagnose our subsequent diurnal weather pattern to start the weekend, a surface ridge over the subtropical Atlantic will continue to induce a light to moderate east- southeasterly flow across South Florida. As a matter of fact, ridging across nearly all pressure heights over the subtropical Atlantic will be in firm control of our overall regime. An important feature to track around the southwestern periphery of this same ridging will be the low-level disturbance that was seen over central Cuba and the Bahamas early this morning as it will bring a renewed moisture surge to South Florida and help keep our PWATs above climatological averages (between 2.0-2.2", representing the 75th-95th percentiles). With our prevailing easterlies in place, showers and thunderstorms across the eastern metros in the morning should become more numerous via daytime heating and plenty of instability (surface-based CAPE of 3500-4500 J/Kg as per high-res model output) as they push inland towards the western half of South Florida during the afternoon hours (where our highest regional PoPs of 70-80% will reside). Model guidance suggests the convergence of sea breezes occurring just inland of the Naples metro, where the collision of these two boundaries could cause slow-moving storms to produce locally heavy rainfall over this concentrated area. HREF shows the potential for localized rainfall totals of 4-6" across the western interior, which could undoubtedly cause some minor flooding should it materialize. Shortly following these initial boundary collisions, showers and storms should slowly drift to the north towards Lake Okeechobee at the expense of southerly winds in the low the mid-levels of the atmosphere. Look for dangerous cloud-to-ground lightning and gusty winds mainly below SPS thresholds (<45mph) to be the supplementary hazards in and around the most robust thunderstorms. NASA GEOS Dust Extinction Aerosol forecast shows the potential for a faint intrusion of Saharan dust, which is accurately represented in forecast soundings as a modest increase in DCAPE. Given this, cannot completely rule out an overachieving storm or two producing slightly higher wind gusts actually satisfying SPS criteria. Although we should remain generally unsettled on Sunday across South Florida, there have been a few changes to take note of within model runs with regards to storm placement. Our surface ridging over the subtropical Atlantic that was believed yesterday to have had more of a westward extent has now shifted slightly eastward as per recent model guidance. This will lead to winds being more south to southeasterly across South Florida, meaning we can anticipate afternoon convection to now favor the interior and to be reasonably scattered across the peninsula rather than strictly the western half of our region as we previously foresaw. Although the low-level disturbance that will cross South Florida and bring us a moisture surge today will be gradually disintegrating as its initial compact structure and overall vort max stretches out across the Florida peninsula, lingering moisture from its presence will keep our PWATs sufficiently high (2.1-2.3" as per the NBM) to support this widely scattered shower and thunderstorm activity. In addition, we will also be situated on the southernmost tail of a narrow band of deep moisture associated with elongated vorticity out ahead of the same shortwave trough that was seen over the Mid-South in this morning`s synoptic analysis as it advances eastward towards the Mid-Atlantic US. Heavy downpours, localized flooding, frequent lightning, and gusty and erratic winds will be the main hazards if you are in or within the general vicinity of thunderstorms. Some Saharan dust could possibly linger into Sunday, so isolated stronger wind gusts up to marginally severe levels cannot completely be ruled out. High temperatures will continue to climb into the low to mid 90s over this weekend time frame, with heat index values reaching the 100-105F range and mainly staying below heat advisory criteria. Regardless, try to limit your time outdoors in the direct sunlight and know how to not only protect yourself from the heat but those around you as well. Stay hydrated, stay cool, and stay safe! && .LONG TERM... (Sunday night through Friday) Issued at 240 AM EDT Sat Sep 12 2026 To start to following work week, we will look to be nestled between weak surface ridging over the northern Gulf and southwest Atlantic, which should allow our winds to be fairly light to perhaps occasionally moderate as one could say they will be mainly sea breeze-driven while still maintaining a faint easterly component. This will drastically change beginning Tuesday and lasting through much of the upcoming week as strong surface ridging sets up over New England and Atlantic Canada and expands spatially to the south and west to encompass nearly the entire eastern seaboard of the CONUS. The reason as to why this ridge will be having such an impact on South Florida despite its axis being located over 1500 miles to our northeast is the significant expansion it will undergo and the anomalous near-surface pressures that will overspread the eastern United States. Both NAEFS (combination of GEFS and GEPS members) and ECMWF ENS (ensemble) forecasts continue to indicate 1000-mb geopotential heights being above the 90th climatological percentile, ultimately equating in stronger northeasterly winds that will noted across South Florida from Tuesday onward. Aloft, an even stronger ridge that could be at or near all-time records with respect to 500- mb height anomalies will be building over the eastern US. The only difference we are noticing amongst the newest model runs, specifically towards the latter half of next week, is the potential for a pronounced cut-off low that will be separating from the mainstream flow of a large upper trough traversing eastern Canada to drop southward and approach South Florida. Previous model runs had the expansive upper-level ridge largely dominating the eastern US and even the western Atlantic for that matter, but have since shown a retrograde to the west. Though this potential outcome could give the aberrant cutoff low a chance to ride the eastern periphery of this upper ridge all the way down towards the southwest Atlantic and possibly South Florida, it is too early to know what kind of impact, if any, it could have on our local weather. Saharan dust is another meteorological component we will be monitoring next week as NASA GEOS Dust Extinction Aerosol forecast shows a potential intrusion into South Florida as early as Monday evening and lasting through at least midweek, though it is important to note that the thickest concentrations will be staying to our south courtesy of the abnormally strong ridging over the eastern US. NBM has our regional PWATs dropping to at or below 2" through midweek, which could act to lower our overall rain chances with more uncertainty as to whether some dust will linger or more moisture will enter the region for the second half of the week. With the increasing northeasterly flow we will experience by Tuesday (and even on Monday with a light easterly flow in place), expect the majority of showers and thunderstorms to favor the western half of South Florida during each afternoon cycle (which is indicated in our daily PoPs and backed by Day 1-5 QPFs). Highs temperatures each afternoon next week should be reaching the low 90s across our eastern metros (possibly throwing some upper 80s in there especially when that stronger northeasterly wind component kicks in) and the mid 90s across the interior and SW Florida with hotter feels-like temperatures areawide generally in the 100-105F range. Evenings will be warm and muggy with overnight lows dropping into the low to mid 70s across the interior and around Lake Okeechobee and into the mid to upper 70s across both our coastal metros. && .AVIATION... (12Z TAFS) Issued at 716 AM EDT Sat Sep 12 2026 VFR prevails for most of the period. Light winds early this AM will increase out of the ESE around 5-10 kts today after 13-14Z. This is expected to coincide with the development of scattered SHRA around 12Z and potential VCTS after 14Z. At this time, not quite enough confidence in coverage at any site for TEMPOs, however at least VCTS is probable throughout the day and short fuse amendments may be necessary. At KAPF, winds increase out of the WSW after 16-17Z with VCSH/VCTS through the afternoon. && .MARINE... Issued at 240 AM EDT Sat Sep 12 2026 Gentle to lightly moderate southeasterly winds will prevail across the South Florida local waters through the weekend and into the start of next week. Seas in the Atlantic are expected from 1-3 feet with the Gulf waters at 1-2 feet. Scattered showers and thunderstorms will continue to develop across the local waters each day, which may result in locally hazardous winds and seas. Deteriorating marine conditions are possible towards the middle of next week as a stronger surface flow develops. && .PRELIMINARY POINT TEMPS/POPS... Miami 90 79 90 77 / 60 20 80 10 West Kendall 90 76 90 75 / 70 20 80 10 Opa-Locka 90 79 90 78 / 60 20 80 10 Homestead 90 78 90 76 / 70 20 80 20 Fort Lauderdale 90 79 89 77 / 60 20 80 20 N Ft Lauderdale 90 78 90 77 / 60 20 80 20 Pembroke Pines 90 78 90 77 / 60 20 80 10 West Palm Beach 91 78 91 76 / 70 20 80 10 Boca Raton 89 79 89 78 / 60 20 80 20 Naples 90 77 90 76 / 50 30 60 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && $$ SHORT TERM...AD LONG TERM....AD AVIATION...Rizzuto