Plaincast

Messages

Heat indices between 105-108 possible through the evening hours. Take appropriate precautions during extended periods outdoors.

Isolated to scattered showers and thunderstorms again possible this afternoon and evening favoring interior and eastern areas of South Florida.

Any thunderstorm will be capable of producing strong wind gusts, frequent lightning, heavy downpours, and small hail.

Short Term

(Rest of today through Friday) Issued at 323 PM EDT Thu Jul 16 2026

A fairly unchanged weather pattern in comparison to yesterday as our atmospheric column continues to be dominated by a plume of lingering Saharan dust. Despite this relatively dry environment, the 12z MFL sounding data today reveals higher amounts of low level moisture, with precipitable water of 1.78 inches. This may be a result of a more southeasterly shift in winds, increasing moisture transport into the region. Another indication of a more moist atmosphere is the increase in high level clouds across the region. Much of the cirrus deck is associated with an upper level disturbance currently over the Florida Straits.

The high pressure ridge over the Gulf will introduce a stronger surface flow out of the northwest across the peninsula today, allowing the developing Atlantic sea breeze to stay pinned closer to the coast this afternoon. HREF guidance is not overly optimistic on coverage of showers and thunderstorms this afternoon/evening with chance of rain only hovering around the 20-30% range. These lower chance of rain are likely the result of all the ambient dry air in place from the SAL. However, the overall consensus is that isolated to scattered storms will be capable of developing over the interior and east coast metros along colliding sea breeze and mesoscale boundaries. With surface storm energy of 2500-3000 J/Kg and steep low level lapse rates, if a few storms were to get strong enough, the presence of some mid-level dry air may support a few strong downburst signatures. Since 500mb temperatures will remain on the warmer side, the hail threat will be little to none.

Heat will continue to be a major concern across much of South Florida. A Heat Advisory will continue through 7 PM EDT for the east coast metro areas and Collier county, where heat indices could peak in the 105 to 108 F degree range. Widespread Major HeatRisk will continue for tomorrow, so will need to monitor guidance to see whether another Heat Advisory will be necessary. These conditions will increase the threat of heat illness. Limit your time outdoors, take frequent breaks in the shade, and stay plenty hydrated.

The overall pattern appears to become more active on Friday across South Florida in terms of rain chances. Troughing will begin to extend across the Gulf, which may begin to induce the development of an upper low over the eastern Gulf waters. The greater moisture looks to remain north of our region, however, HREF guidance is indicating a modest increase in regional precipitable water (into the 1.6 to 2.0 inch range). A moist and unstable environment will be conducive for scattered to numerous thunderstorms during the afternoon and evening hours, mainly favoring interior South Florida and the eastern metros. Once again, the stronger westerly surface flow will keep the Atlantic sea breeze pinned closer to the coast, increasing chances of storms for Broward, Palm Beach, and Dade counties. Heavy rainfall, frequent lightning, and gusty downburst winds look to be the primary threat with each thunderstorm.

Long Term

(Friday night through next Wednesday) Issued at 323 PM EDT Thu Jul 16 2026

Ensemble guidance has been trending towards the breaking down of upper level ridging across much of the Southeast this weekend. The trend that many solutions are favoring is the deepening of longwave troughing over the eastern CONUS and upper level ridging strengthening over the Intermountain West. Shortwave energy looks to propagate southward into the northern Gulf, deepening a Tropical Upper Tropospheric Trough (TUTT), just off the coast of western Florida. It is around this time that the the Saharan Air Layer (SAL) also begins to lose some influence over Florida, with the highest concentration of dust looking to remain to the south over the Caribbean and over the western Gulf. Current guidance indicates that the TUTT could deepen and close off into an upper low by late Friday and into Saturday. There is still quite a bit of uncertainty regarding the exact positioning and strength of this system, but with surface low pressure strengthening over the Florida Panhandle and high pressure remaining strong over the western Atlantic, the wind pattern should become more southerly throughout the region. Overall, rich tropical moisture will funnel northwards along the Florida Gulf coast, where precipitable water may climb into the 2.3 to 2.4 inch range (for Tampa area). However, current guidance is showing that a large portion of South Florida may be under some sort of dry slot, with precipitable water near or even below average on Saturday and Sunday (for Miami area). This could be a result of southeast flow keeping some lingering Saharan dust from the Caribbean. If the upper low disturbance were to shift south and trend stronger, South Florida would likely see a surge of moisture and increased chances of precipitation.

The National Hurricane Center is currently indicating about a 20% chance of tropical development over the next 7 days for central Florida, associated with the eastern Gulf disturbance. At this time, most guidance has this disturbance meandering near the Florida Big Bend through the end of the weekend, before ejecting out east by Monday or Tuesday. With this current forecast, there will be a north to south chance of rain gradient, favoring southwest Florida and the Lake Okeechobee region. chance of rain then decrease further south and east along the peninsula. With increased forcing and ascent aloft, there will be an increased potential of heavy rainfall. However, expected rainfall cluster ensembles keep the highest precipitation over central Florida, closer to the core of the disturbance. Storm activity in South Florida will likely be tied to sea breeze and mesoscale boundary collisions during the afternoon, with frequent lighting, heavy rain, and gusty winds being the main threats.