133 FXUS62 KMLB 271132 AFDMLBArea Forecast Discussion National Weather Service Melbourne FL 732 AM EDT Sat Sep 27 2025
...New AVIATION...
.KEY MESSAGES... Issued at 330 AM EDT Sat Sep 27 2025
- Scattered to numerous showers and storms are forecast today as a cold front approaches the Florida peninsula.
- Potential Tropical Cyclone 9 is anticipated to develop and strengthen into a tropical system as it moves northward across the southwestern Atlantic and parallel to the Florida coast late this weekend into early next week.
- Primary impacts to east central Florida from PTC 9 are anticipated to be dangerous beach and boating conditions along with a low chance for tropical storm force winds. Outer rain bands from the western side of PTC 9 are also forecast to move onshore, with localized flooding possible on Sunday.
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.DISCUSSION... Issued at 330 AM EDT Sat Sep 27 2025
Today-Tonight...A mid-level trough sweeps across the southeastern U.S. today, with its associated front drifting eastward towards the Florida peninsula and stalling overnight. Light southwesterly flow is forecast to persist locally out ahead of the front, with temperatures reaching the upper 80s to low 90s once again this afternoon. This heating will prompt the development of the east coast sea breeze, with winds becoming more easterly this afternoon. Progression inland of the sea breeze will be slow as the predominant flow in the low and mid levels remains out of the west-southwest. The sea breeze will take advantage of the moist air mass out ahead of the front across the area, with PWATs of 2 inches and greater areawide supporting the development of showers and storms through this afternoon.
Similar to yesterday, current guidance supports MUCAPE exceeding 1500 J/kg across most of east central Florida along with steep low-level lapse rates, which would support storm development. While moisture is plentiful, model soundings do indicate a pocket of drier air around 700 mb that has helped keep DCAPE values above 500 J/kg. Overall, storm threats continue to be focused on frequent lightning strikes, wind gusts up to 50 mph, and heavy downpours that could lead to rainfall totals of 1 to 3 inches. The greatest coverage of activity is anticipated to occur sometime after 3 PM, particularly near the I-4 corridor as the sea breezes collide. Boundary interactions between the sea breezes as well as additional outflow boundaries from storms could lead to brief funnel cloud development, though confidence in this remains low. Shower and storm activity will be slow to diminish, moving towards the east coast and offshore through the evening and overnight hours. Coastal shower activity through the overnight hours cannot be ruled out, especially as winds turn more northeasterly. Overnight temperatures fall into the low to mid 70s across east central Florida.
Sunday-Monday...While the stalled boundary is forecast to remain in place across the Florida peninsula late this weekend into early next week, focus shifts to the tropics as Potential Tropical Cyclone 9 develops and strengthens across the southwestern Atlantic. PTC 9 is forecast to make an uncomfortably close pass near Florida late Sunday through Monday, with ensemble guidance continuing to favor a northward motion as it parallels the coast.
Locally, there are a number of potential impacts from PTC 9 that warrant monitoring over the next couple of days. The impacts with the highest confidence are deteriorating beach and boating conditions. Increasing seas and swells from PTC 9 will lead to dangerous boating conditions, with seas reaching up to 15 feet across the offshore waters. At the coast, breaking waves of 6 to 8 feet coupled with long period swells will make for dangerous beach conditions starting as early as Sunday afternoon. A high risk of rip currents is anticipated, and a High Surf Advisory will likely be needed starting on Sunday. Minor to moderate beach erosion as a result of these higher breaking waves will also be possible along the east central Florida coast.
In addition to the coastal and marine impacts, there are also wind and rain concerns relative to PTC 9. Breezy to windy conditions are forecast areawide as winds strengthen out of the northeast on Sunday, becoming northerly on Monday as PTC 9 moves parallel to the peninsula. There is a low chance (2 out of 10) for tropical storm force winds along the east central Florida coast, with even lower chances farther inland. As far as rainfall goes, outer bands on the western edge of PTC 9 are forecast to move onshore Sunday through early Monday, with the potential for multiple rounds of rainfall across the area. The highest rain chances are focused along the coast (70%), with slightly lower rain chances across the interior (50-60%). The Weather Prediction Center has highlighted the east central Florida coast in a Marginal Risk of excessive rainfall on Sunday and Sunday night, with rainfall totals of 1 to 3 inches and locally higher amounts exceeding 4 inches possible. Localized flooding will be a concern, particularly in low-lying areas and areas that are already saturated from previous days of rainfall. Storms cannot be ruled out within these rain bands, with lightning strikes and higher gusts possible. By Monday afternoon, PTC 9 is forecast to move farther away from the Florida peninsula, with drier air slowly filtering in across the area. Rain and storm chances decrease, though lingering activity cannot be fully ruled out.
It is important to note that there is still a level of uncertainty relative to rain and wind impacts, and any shifts in the track of PTC 9 will influence whether these threats increase or decrease. Residents and visitors of east central Florida are strongly encouraged to remain up to date on the latest information regarding PTC 9 and ensure any plans or supplies are in place should they be needed. Ensure you are receiving forecasts from reliable sources, as that will be key in having the best and most up-to-date information on PTC 9.
Tuesday-Friday...As PTC 9 moves farther away from Florida, the stalled boundary is anticipated to wash out across the peninsula, with a broad mid-level trough remaining situated across the southeastern U.S. through the end of the forecast period. Drier air lingers in the wake of PTC 9, resulting in lower rain chances through next week (20-50%). Storm development will continue to be possible through the extended forecast period, with lightning strikes, gusty winds, and heavy downpours all possible. A cooling trend is also forecast through the period, with highs on Tuesday in the upper 80s to low 90s falling into the low to mid 80s later in the week. Overnight lows remain in the upper 60s to low 70s.
Despite the departure of PTC 9, there will likely still be lingering coastal and marine impacts locally. Persistent northeasterly to easterly winds will make it hard for seas to subside, with additional long period swells traveling towards the area from Major Hurricane Humberto through next week. Seas remain elevated around 11 feet across the offshore waters, with breaking waves along the coast of 4 to 7 feet still anticipated. A high risk of rip currents through the extended period will be likely, especially if the forecasted wave heights continue to stay consistent. Residents and visitors will need to continue to monitor coastal and marine impacts even after PTC 9 departs.
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.MARINE... Issued at 330 AM EDT Sat Sep 27 2025
A cold front will continue its slow approach towards the Florida peninsula today, resulting in high chances of showers and storms. This activity is anticipated to move offshore through the overnight hours, with winds remaining below 15 knots and seas generally 2 to 4 feet through tonight.
Boating conditions then deteriorate starting on Sunday as PTC 9 tracks northward, eventually moving parallel to the east central Florida coast on Monday. Northeast winds on Sunday increase to 15 to 25 knots, becoming northerly on Monday at 20 to 30 knots. Tropical storm force winds will be possible across the offshore waters on Monday as PTC 9 makes it closest approach to the area. Seas quickly climb late this weekend into early next week, reaching 6 to 11 feet across the nearshore waters and 9 to 15 feet across the offshore waters. Dangerous boating conditions will exist not only as a result of the wave heights but also from increasing swell periods. Outer rain bands from the western side of PTC 9 are also anticipated to move across the local Atlantic waters, keeping coverage of showers and storms high through late weekend and into early next week.
Poor to dangerous boating conditions are anticipated to persist across the local waters through much of next week. Seas will be slow to subside behind PTC 9 for two reasons; continued northeast to east winds as well as long period swells approaching the local waters from distant Major Hurricane Humberto. Seas up to 11 feet are forecast to persist, along with wind speeds of 15 to 20 knots. Slightly lower coverage of showers and storms is anticipated, though activity is still likely to remain scattered across the local waters.
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.AVIATION... (12Z TAFs) Issued at 652 AM EDT Sat Sep 27 2025
Light south to southwesterly flow today will be influenced by the sea breezes. Onshore flow developing along the coast early in the afternoon as the east coast sea breeze develops and struggles to progress inland. Meanwhile, the more dominant west coast breeze is expected to produce southwesterly flow for interior sites (MCO). This will lead to a sea breeze collision today, mainly along the I-4 corridor after 20-22Z. TEMPOs have been included, with convection then drifting offshore into the evening hours (perhaps well past 00Z). MLB looks to have the lowest chance for impacts today, so have not included any VCTS mention there. Meanwhile, the sea breeze near the Treasure Coast is forecast to develop its own showers and storms, mainly between 18-22Z.
CAMs suggest the outflow from earlier showers and storms continuing into the offshore waters into the evening, similar to late Friday. However, increasingly NNE/NE flow as PTC Nine develops looks to pin this boundary near to just offshore from the coast overnight. Thus, have included a VCSH mention from MLB southward along the coast through the remainder of the period. Winds remaining around 10 kts or less.
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.PRELIMINARY POINT TEMPS/POPS... DAB 88 73 86 74 / 60 60 70 50 MCO 91 75 88 74 / 70 50 70 30 MLB 89 76 86 75 / 50 60 70 50 VRB 90 75 87 74 / 50 50 70 50 LEE 89 73 88 73 / 70 30 50 20 SFB 91 74 88 74 / 70 50 70 30 ORL 91 75 88 74 / 70 50 70 30 FPR 90 74 86 74 / 50 50 70 40
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.MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. &&
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DISCUSSION...Tollefsen AVIATION...Leahy
NWS MLB Office Area Forecast Discussion