textproduct: Tampa Bay Area

KEY MESSAGES

Issued at 157 PM EDT Sat Sep 12 2026

- There is a low risk for mainly urbanized flooding this afternoon and evening for portions of West Central and Southwest Florida. The greatest potential for this to materialize is in SWFL, where there is a 20% chance that rainfall totals may exceed 3 inches.

- Scattered showers and thunderstorms will continue into early next week, but perhaps with slightly lower coverage. Heavy rainfall and gusty winds will continue to be the primary concerns with storms that do form.

- An unsettled pattern arrives mid-week, with hazardous marine conditions developing across coastal waters and the potential for numerous to widespread thunderstorms areawide.

DISCUSSION

Issued at 157 PM EDT Sat Sep 12 2026

Weak upper-level ridging dominates across Florida as a shortwave propagates to the north through the Tennessee River Valley. The shortwave is advecting deep tropical moisture around the periphery of the ridge northward into the SE, fueling convective activity over the Northern Gulf, FL panhandle, and beyond. Closer to home, high pressure is still in control near the surface. A light background flow means that sea breeze boundaries can move with ease, propagating inland through the afternoon and evening and serving as a catalyst for thunderstorm development when coupled with the moist and conditionally unstable airmass that is in place across the Florida peninsula.

The 12Z sounding came in with a PWAT of 2.16 inches. Climatologically, this is above the 90th percentile, suggesting there is more than ample moisture to work with. Further analyzing the atmospheric profile, there is no appreciable dry air throughout the column. The winds are also very light, suggesting slow movement of storms that do form. That combination is favorable for heavy rainfall, and perhaps localized flooding in isolated locations. Given how there will likely be a few more boundary collisions (and thus more storms) in SWFL, this is where the threat remains the greatest. Some gusty winds of 40 to 50 mph are also possible across SWFL where ACARS soundings show slightly more dry air in the mid-levels (and thus greater DCAPE values approaching 1000 j/kg due to precip loading). That potential decreases farther north around Tampa Bay and across the Nature Coast.

As the shortwave passes to the north and pulls away, the flow looks to become even lighter and more variable for Sunday and into Monday. However, the upper-level flow veers more WNW, suggesting that some slightly drier air might sneak in. So while showers and thunderstorms remain in the forecast, the probability of actually seeing a thunderstorm - especially over the Nature Coast - is a little lower tomorrow. There are actually some indications that rain chances may remain lower through the first half of the week across the Nature Coast as an upper-level ridge settles to the north of Florida, favoring mid-level dry air advection.

By mid-week, a retrograding upper-level low is forecast to arrive in our area from the Atlantic. While this would initially favor a drier pattern, if the low does indeed get west of the FL peninsula, this will almost certainly enhance rain chances across the area. Keeping the forecast conservative for now, though, to see how the setup evolves. It also favors a tighter pressure gradient, and thus breezy conditions over land. Hazardous marine conditions are expected to develop over coastal waters in response as well as seas build towards 5 to 8 feet.

This unsettled pattern then looks to stick around for a bit. Trapped between ridging to the east and west, the low parks overhead and probably won't clear out until being swept up by a deeper trough that digs into the area more than a week from now. Until the low clears out, one can expect the unsettled pattern to continue.

AVIATION

(18Z TAFS) Issued at 157 PM EDT Sat Sep 12 2026

Showers and thunderstorms are developing in the vicinity of coastal terminals now. For the coastal terminals around Tampa Bay, the thunderstorms are expected to shift inland and east by 21Z, with a low probability that storms could move back towards the coast later this evening. For SWFL terminals, the window for on-station impacts still looks to come in a couple hours. The storms in SWFL could be a bit stronger and have a greater potential to produce microbursts. After a quiet overnight period, a similar pattern repeats again tomorrow, with perhaps a slightly earlier convective initiation given the light and variable flow. The pattern will continue into early next week.

MARINE

Issued at 157 PM EDT Sat Sep 12 2026

Scattered showers and thunderstorms continue across coastal waters, especially to the north of Tarpon Springs. Hazardous winds and seas are possible in the vicinity. Otherwise, light winds for the next couple days support seas of two feet or less. As an upper-level low moves into the area mid-week, mariners should expect marine conditions to deteriorate. Winds of 20 to 30 knots, with some higher gusts, look increasingly likely by late week. This will favor building seas to at least 5 to 8 feet, if not higher. Additionally, thunderstorm activity may increase late in the week. This will be a hazardous combination for mariners, especially those operating small craft.

FIRE WEATHER

Issued at 157 PM EDT Sat Sep 12 2026

Ample moisture and humidity favors scattered showers and thunderstorms each day this week. Sunday and Monday look to be the "driest" days for the week; but thunderstorms are still expected. Given current conditions, there are no red flag concerns at this time. However, light winds through Monday favor low dispersion

HYDROLOGY

Issued at 157 PM EDT Sat Sep 12 2026

With pockets of heavy rainfall over the last couple of weeks, soils have begun to become more saturated in the areas where heavier rainfall has occurred. The most notable soil saturation has taken place across portions of SWFL, where once again there is a higher probability for heavier rainfall to occur. This favors a higher potential for localized flooding when compared to the rest of the region. It also means that a shorter duration of heavier rainfall may be capable of producing some flooding.

Given the scattered nature of summertime convection, conditions are not uniformly saturated areawide. In fact, most areas outside SWFL have not yet seen soils reach saturation. Thus, outside urbanized areas and portions of SWFL, the overall threat for flooding remains low.

Additionally, conditions continue to be monitored on some of the more rainfall-sensistive rivers mainly in SWFL. The most notable one with potential impacts is Horse Creek. The current forecast has the river reaching minor flood stage in the next several days. However, this is still contingent on the basin receiving nearly another inch or so of rainfall in the next 48 hours. If the rainfall misses the basin, then Horse Creek probably won't rise at all. This is true for other rivers in the area as well: if rainfall occurs in the basin, then the river will respond. If it misses, flows and thus current river stages should remain largely unchanged.

PRELIMINARY POINT TEMPS/POPS

TPA 78 89 78 90 / 20 50 10 70 FMY 77 90 76 91 / 30 70 20 80 GIF 75 92 75 93 / 30 60 20 70 SRQ 77 91 77 91 / 20 50 30 60 BKV 74 91 74 92 / 10 50 10 70 SPG 79 89 79 90 / 20 50 20 60

TBW WATCHES/WARNINGS/ADVISORIES

FL...None. Gulf waters...None.