310 FXUS62 KMLB 060005 AFDMLBArea Forecast Discussion National Weather Service Melbourne FL 805 PM EDT Fri Sep 5 2025
...New KEY MESSAGES, UPDATE, AVIATION...
.KEY MESSAGES... Issued at 805 PM EDT Fri Sep 5 2025
- There is a 30-50% chance of a few downpours and isolated storms tonight, mainly along the coast near and south of Cape Canaveral.
- There is a low threat for locally heavy rain and minor flooding through at least the middle of next week as multiple rounds of showers and storms are forecast.
- Peak heat index values reach 100 to 105 this weekend, before temperatures trend near to below normal next week.
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.UPDATE... (For Tonight & Saturday) Issued at 805 PM EDT Fri Sep 5 2025
We`re still tracking a pesky front over South Florida this evening along with a weak disturbance in the Gulf. Rich, tropical moisture is streaming over the peninsula as well: PW values jump from around 2.0" at Orlando to 2.5" near Miami. In response to a subtle height rise at H5 and a weak shortwave approaching Louisiana, the front is set to slowly lift northward overnight into Saturday, dragging even deeper moisture over the district.
Hi-res guidance hints at a couple waves of storm chances over the next 24 HR that, conceptually, make sense...
First off, the moisture advection/convergence along the coast south of Cape Canaveral late this evening into the early overnight may force redevelopment of a few storms. Handled this with 30-50% rain chance for these coastal areas; if such redevelopment occurs, locally heavy rain may persist for a few hours before the activity lifts away from any given location. Will monitor for any minor flooding issues.
Also had a chance to peek ahead at Saturday afternoon`s storm chances. After reviewing the latest guidance, it appears that some sort of a sea-breeze/boundary collision is favored over the interior. Ample instability (due to surface heating) and lumbering storm motions raise the concern for locally heavy rain, particularly if it falls over the Orlando urban corridor. REFS 90th percentile to max-member rainfall tallies are in the 3-6" range, arcing from near Orlando to Fort Pierce. Chances are your backyard will not pick up this much rain, but it does indicate the 5-10% chance of an excessive rainfall event occurring somewhere across Central Florida on Saturday.
This required an increase in storm chances to 70-80% for Orange, southern Lake, Okeechobee, and interior portions of the Treasure Coast counties on Saturday afternoon.
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.PREVIOUS DISCUSSION... Issued at 245 PM EDT Fri Sep 5 2025
Now-Tonight...A very weak surface boundary/trough remains over central Florida this afternoon as clouds overspread much of the south-central FL Peninsula. East-northeasterly flow is occasionally gusting around 20 mph at the coast, and RAP MSLP analysis shows a very subtle tightening of the pressure gradient over the local Atlantic. GOES-derived PW indicates a south-to-north push of higher moisture content, and as a result, KMLB radar is a bit more active this afternoon. Bands of scattered showers are ongoing from Cape Canaveral to Orlando and portions of Osceola County, surrounded by more isolated activity to the north and south. There are a few embedded lightning strikes, but moderate to heavy showers will be the main mode of activity through the evening (lacking instability and higher lapse rates).
CAM guidance drifts the bulk of activity west of the area by early evening, but with deeper moisture and persistent onshore flow, rain chances could linger along the immediate coast through tonight. Interestingly, NBMEXP guidance does show higher rain probs (up to 60- 70%) near the Cape to Sebastian through early Saturday morning. This will be something to monitor, especially if training bands of rainfall set up over the same locations. Localized street flooding can occur as a result of repeated moderate/heavy rains. Lows overnight are forecast to settle in the mid 70s.
This Weekend (previous)...A few mid-level shortwaves move through the persistent broad troughing pattern over the eastern US. The resident stationary frontal boundary and associated higher moisture over South Florida lifts north a bit into Central Florida Saturday. Then, a weakening cold front and its attendant moisture over the Southeast pushes towards North Florida Sunday, setting the stage for another period of unsettled weather. Rain chances increase well above normal across the area, though we do keep a slight gradient of higher chances (up to 80%) to the south and somewhat lower chances (up to 60%) across the north until the next front properly arrives. Instability remains unimpressive, but a few lightning storms capable of occasional cloud to ground lightning and gusty winds will be possible.
Temperatures creep up a degree or so Saturday, but remain mostly around normal with highs in the U80s along the coast and U80-L90s inland, resulting in peak afternoon heat indices in the U90s-L100s, approaching the M100s in a few spots Saturday.
Next Week (modified previous)...The pattern stays fairly stagnant through mid-week, as weak broad troughing remains in place over the eastern US, weakly stretching across the Southeast. H5 anomalies favor building heights over the Upper Midwest with continued eastern CONUS troughing through at least the end of next week. With little forcing, a weakened front and associated high moisture sag into Central Florida, becoming stationary once again. Rain chances remain well above normal as even ensemble mean PWATs come in at or above the 90th percentile. While overnight showers will be possible, the highest chances will be focused along the afternoon sea breezes, as usual. There is potential for a weak low pressure system or two to develop along the boundary, which would shift the location of the highest rain chances around, depending where, when, and if they form. Daytime temperatures remain near to slightly (a degree or two) below normal in the U80s/L90s, accompanied by lows in the M70s.
Looking ahead to next weekend, models keep us locked in to a similar pattern with not much movement in the stalled frontal boundary over central/south Florida. Additional mid-level energy may gain latitude and head in our direction from the southeastern Gulf, which would mainly work to reinforce moisture and higher rain chances over east central Florida. Ensemble guidance favors near to slightly below normal temperatures continuing into the third week of September, aided by additional cloud cover.
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.MARINE... Issued at 245 PM EDT Fri Sep 5 2025
Generally favorable boating conditions are forecast through the weekend and into early next week, though rain and occasional lightning storm chances gradually increase each day across the local Atlantic. Surface flow remains 10-14 kt or less through Sunday, predominantly onshore during the day and turning offshore at night. However, the presence of a weak front may make for light/variable wind directions at times. A second (weakening) cold front is forecast to approach early next week and effectively stall over the local Atlantic. Winds increase near the front (around 15 kt), mainly north of the Cape, through mid to late week. Seas build from Monday onward, up to 5 ft or so offshore, across the offshore Volusia and Brevard waters.
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.AVIATION... (00Z TAFs) Issued at 805 PM EDT Fri Sep 5 2025
Complicated forecast tonight as deep moisture and a weak front team up to keep the area unsettled at times. First up will be a 30-50% chance for storms from MLB to FPR between now and around 6Z as the front tries to lift northward. Thereafter, should be rather quiet through midday before storms gather and push toward the interior in the afternoon and evening. Have TEMPOs in for TS at most inland terminals, including MCO, after 19Z or so. Storm coverage is more questionable at the coast in the afternoon as the sea breeze tries to push inland.
NE winds becoming light overnight, shifting E/SE on Saturday up to 12 KT. Outside of convection, VFR prevails in the TAFS, but some occasional MVFR cigs would not surprise us due to the rich moisture.
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.PRELIMINARY POINT TEMPS/POPS... DAB 76 88 75 89 / 20 30 20 50 MCO 76 91 75 91 / 20 70 50 60 MLB 77 89 75 89 / 40 60 50 70 VRB 75 91 74 89 / 50 60 50 70 LEE 75 91 75 91 / 10 60 40 50 SFB 76 91 75 90 / 20 60 40 60 ORL 76 91 75 90 / 20 70 50 60 FPR 73 91 74 89 / 50 60 50 80
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.MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. &&
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UPDATE...Heil AVIATION...Heil
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