textproduct: Jacksonville

KEY 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

- Heat Advisory for NE FL and Much of SE GA this Afternoon/Evening. Max Heat Indices 105 -110 F

- Scattered to Numerous Afternoon & Evening TStorms Today and

- Low Potential for Slow Tropical Development off the Southeast U.S.

- Coast Later This Week

NEAR TERM /THROUGH TONIGHT/

Main Highlights Today and Tonight:

- Heat Advisory for NE FL and Much of SE GA this Afternoon/Evening

- Isolated strong storm potential north-central FL this afternoon/evening

"Heat Wave" ridging aloft strengthens as it remains centered to our northwest bringing another hot day to the region. Temperatures will soar into the mid-upper 90s area-wide with peak heat indices this afternoon in the 105-110 F range. Heat Advisories are in place for NE FL and portions of SE GA mainly south of Alma. Light WNW flow today will allow for the Atlantic sea breeze to shift slightly further inland into the St Johns river basin by mid-afternoon. Meanwhile, a shortwave aloft and corresponding surface trough will shift southward down the southeastern seaboard adding additional forcing along the sea breezes. Isolated showers and storms will develop along the sea breezes becoming widely scattered as boundaries collide and the influence of the added forcing aloft moves overhead. Best chance for numerous storms will be in north- central FL where the highest moisture (PWATs 2+ in) are located this afternoon. A few strong to marginally severe storms could develop along boundary interactions with gusty winds as the main threat. Another round of showers and storms move in from the north later this evening as a stronger passing shortwave associated with remnant MCS outflow pushes into SE GA. Convection gradually wanes through the night. Overnight lows will be above seasonable in the mid to upper 70s.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/

Tuesday & Wednesday...

Main Highlights This Period:

- Breezy East Winds & Elevated Rip Current Risk - Inland Strong Afternoon & Evening Storms

A transition to a stronger east coast sea breeze regime and drier conditions across southeast GA with the position of the 1000-500 mb ridge centered across TN/KY. This pattern will bring a chance of a a few spotty morning showers and early afternoon thunderstorms along the dominant east coast sea breeze as it shifts inland, with convection blossoming into the afternoon and evening across inland areas. Sea breeze and outflow boundary mergers will focus toward the I-75 corridor and westward each afternoon and into the evening.

The highest rain chances focus across inland NE FL each day where deeper moisture lingers. Tuesday, a frontal zone combined with sea breeze forcing across inland northeast FL favors higher than climo rain chances, especially for locations west of Highway 301 toward the Interstate 75 corridor during the afternoon and evening. Below average precipitable water and mid/upper level subsidence across southeast GA invades Tuesday afternoon into Tuesday evening brining below average rain chances. Wednesday, the drier airmass continues to linger across locations generally near and north of the Interstate 10 corridor with a continuation of mostly dry weather across southeast GA with the higher daily shower and thunderstorm rain chances southward across inland north-central FL in the afternoon and evening. For all locales, Wednesday is trending drier than Tuesday with more abundant mid and upper level dry air in place.

With the pattern shift of onshore, easterly winds, high temperatures will top out near 90 at the beaches and rise into the mid to upper 90s inland. With the drier air, dew pts mixing down into the low 70s to evening mid/upper 60s across parts of southeast GA will bring lower peak heat index values compared to recent days, generally in the 100-105 degF range, below local Heat Advisory criteria.

LONG TERM /THURSDAY THROUGH SUNDAY/

Thursday through Sunday...

Main Highlights This Period:

- Higher Rain Chances Return for Northeast FL - Building Heat for Southeast GA

Thu & Fri...The mean layer 1000-500 mb ridge dominates north to northeast of the region as a broad upper level low/trough approaches Florida from the east. This pattern will bring a continued easterly steering flow and more dominant Atlantic/east coast sea breeze regime. Moisture and thus rain chance will be higher across northeast FL with the approaching upper level feature, and rainfall may not follow a typical sea breeze regime given upper level forcing and more abundant cloud cover. Warmer temperatures and drier weather continues across southeast GA closer to the influence of the upper level ridge.

Sat & Sun...

Tropical Outlook: The weak southeast trough will continue to be monitored for potential subtropical development through the end of the week. However, forecast confidence of a potential tropical low remains very low (10%), and significant local impacts are not expected from this system.

AVIATION /12Z MONDAY THROUGH 12Z TUESDAY/

Northwesterly breezes, following the passage of a weak front overnight, will develop after 14z at around 5-12 knots. This front will enhance convergence along the Atlantic sea breeze this afternoon, with scattered showers developing around 16z-18z. Timing confidence is increasing with the best window for convection and associated impacts most likely between 18z-22z along the coast and 21z-02z at inland airfields along I-75, including KGNV. With convective impacts, the typical potential of gusty erratic winds, IFR to LIFR visibility, and brief periods of lower ceilings will be possible during the aforementioned windows. Area t'storms will fade this evening with VFR mid and high clouds lingering through the morning. Late in the period, there is a low chance for predawn showers moving in off the Atlantic at KSSI and possibly KCRG by daybreak Tuesday.

MARINE

A frontal boundary will then approach the Georgia waters from the north tonight, with this boundary then stalling over the northeast Florida waters later on Tuesday and dissipating on Wednesday. Showers and thunderstorms will increase in coverage on today into tonight over our local waters, with activity then shifting from the waters adjacent to St. Augustine southward on Tuesday. High pressure wedging down the southeastern seaboard in the wake of this stalling frontal boundary will result in breezy northeasterly winds throughout our local waters on Tuesday and Wednesday, followed by onshore winds gradually diminishing later this week.

Rip Currents:

Lower surf heights today will drop the rip current risk to low at the southeast GA beaches, with a lower end moderate risk continuing at the northeast FL beaches. Persistent and breezy northeasterly winds on Tuesday should yield a solid moderate risk at all area beaches, with a potential high risk on Wednesday.

FIRE WEATHER

- Areas Of High Daytime Dispersion Monday - Areas Of High Dispersion Across Se Ga Tuesday

A weak surface trough will shift southeast across the area on Monday, accompanied by a wind shift to the northwest. The trough will interact with the sea breezes, resulting in numerous afternoon and evening showers and thunderstorms, with a few strong storms possible. By Tuesday, increasing northeasterly to easterly winds of 10 to 15 mph will shift the highest rain and thunderstorm chances westward toward the Interstate 75 corridor and the Florida Big Bend region.

Increasing northwesterly transport winds on Monday may produce areas of high daytime dispersion across portions of the forecast area. Dispersions will remain high across Southeast Georgia on Tuesday. FOG POTENTIAL AND OTHER REMARKS: Significant fog is not expected during the next several days. Stronger storms will be capable of producing strong and erratic wind gusts, along with frequent lightning strikes and heavy downpours, especially on Tuesday afternoon and evening.

HYDROLOGY

Minor flooding continues along lower portions of the Satilla River Basin, as water levels have crested in minor flood stage at the gauge near Atkinson. Minor flooding will continue during the next several days.

PRELIMINARY POINT TEMPS/POPS

AMG 97 75 95 72 / 20 30 30 10 SSI 95 79 90 79 / 30 40 10 0 JAX 97 76 93 76 / 30 40 20 10 SGJ 96 77 92 77 / 30 40 20 10 GNV 97 75 95 73 / 30 40 60 10 OCF 96 76 93 75 / 40 40 80 20

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from noon today to 7 PM EDT this evening for FLZ021-023-024-030-031-035-038-120-124-125-132-136>138- 140-220-225-232-233-236-237-240-322-325-333-340-422-425- 433-522-533-633. GA...Heat Advisory from noon today to 7 PM EDT this evening for GAZ136-152>154-162-163-165-166-264-350-364. MARINE...None.