Plaincast

Messages

For the latest NE FL and SE GA Daily Key Messages please visit: https:/www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

Scattered Afternoon & Evening Thunderstorms Friday. Hazards: Wind Gusts of 35-45 mph, Frequent Lightning & Heavy Downpours

Increasing Coverage of Afternoon & Evening Thunderstorms This Weekend. Heavy Rainfall & Localized Flooding Possible on Sunday and Monday, mainly for northeast FL.

Moderate Rip Current Risk at the Northeast FL Beaches

Heat Advisory Conditions Possible Towards the Middle of Next Week

Update

No major updates needed on the forecast this evening, but did slightly adjust chance of rain to better align with current radar and model trends for after sunset. A few isolated showers/storms will be possible mainly over inland northeast Florida after sunset towards midnight. Tonight, lows will be in the mid to upper 70s.

Higher precipitation chances (especially over north central Florida) and warmer high temperatures than today are forecast for Friday.

Short Term

Main Highlights During Friday and Saturday:

Heavy Rain and Localized Flood Concerns for NE FL this Weekend Daily bouts of showers and storms

A Tropical Upper Tropospheric Trough (TUTT) will likely closing off into an upper low on Friday while drifting slowly northwestward into the northeastern Gulf of America. Cooling temperatures aloft associated with this feature, combined with deep tropical moisture (precipitable water near or above 2 inches), will increase afternoon and evening thunderstorm coverage compared to recent days. With prevailing northwesterly flow, the Atlantic sea breeze will push inland, focusing the primary corridor of convection near and west of the US- 301 corridor, with the highest coverage across inland northeast Florida and north central Florida.

The upper low is forecast to linger over the northeastern Gulf through Saturday before lifting northeastward late in the weekend as a northern-stream trough approaches the eastern United States. A weak surface low may attempt to develop beneath the upper feature and acquire some subtropical or tropical characteristics as it moves northeast on Sunday. However, confidence in surface low development remains low, with the National Hurricane Center maintaining only a 20 percent chance of tropical development and recent guidance trending less favorable.

Regardless of tropical development, a deep tropical airmass will overspread the region through the weekend, supporting numerous showers and thunderstorms each afternoon and evening, with the greatest coverage expected Sunday. The primary hazard will be periods of heavy rainfall capable of producing localized flooding, especially across northeast and north central Florida where repeated rounds of convection are most likely. Frequent lightning and locally gusty winds will accompany the stronger storms.

Temperatures will remain seasonably hot on Friday and Saturday, with highs in the lower to middle 90s and peak heat index values of 102 to 107 degrees. Increasing cloud cover and widespread convection should hold highs closer to the upper 80s to lower 90s by Sunday while maintaining humid conditions.

Long Term

Scattered to Numerous Afternoon Thunderstorms Potential heat advisory conditions by the middle of next week

he upper low may gradually lift northeastward early next week into the northeast Gulf of America, although some uncertainty remains regarding its exact timing. Regardless, deep tropical moisture will persist across the region through at least Monday as west to southwesterly flow develops behind the departing system. This will support scattered to numerous afternoon and evening showers and thunderstorms, with the greatest coverage Sunday and Monday. Periods of heavy rainfall capable of producing localized flash flooding will remain the primary concern, especially where storms repeatedly track over the same locations.

Sometime late Monday or Tuesday next week per Google Deepmind and some the European model AI ensemble members, the upper low should move away as mid-level ridging gradually builds eastward from the west-northwest, resulting in a more typical summertime pattern. While scattered afternoon and evening thunderstorms will continue each day, coverage should gradually decrease. At the same time, increasing heights aloft will allow temperatures to climb back into the middle 90s, with oppressive humidity pushing peak heat index values into the 105 to 110 degree range by midweek. Heat Advisory conditions may become increasingly likely, particularly across inland locations where storm coverage is lower and temperatures climb the highest.