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

- Daily Afternoon & Evening Thunderstorms Tues through Sun. Heavy Rainfall Potential Wed & Thurs for Northeast & North Central FL

- Moderate Rip Current Risk at All Area Beaches. High Risk Possible at the Northeast FL Beaches Later this Week

NEAR TERM /THROUGH TONIGHT/

Highlights Today and Tonight:

- Heavy rainfall/localized flooding threat with thunderstorm activity today, mainly across Northeast Florida

East to Northeast steering flow will push coastal trough over the Atlantic Coastal waters into the NE FL through the afternoon and evening hours. This will combine with PWATs around 2 inches or more and the inland moving East Coast sea breeze to produce scattered to numerous showers and storms with heavy rainfall/localized flooding as the main impact, although a few strong storms with gusty winds to 40-50 mph and frequent lightning are expected as well. A slight influx of drier air mass aloft across portions of SE GA will lower the rainfall coverage slightly there with coverage more on the order of 20-40%, while 50-70% coverage is expected for most of NE FL. Convection will push onshore along the Atlantic Coast and I-95 corridor through the morning hours then translate inland through the afternoon hours, the best chances for strong storms and heavy rainfall is along the I-75 corridor of inland NE FL late this afternoon. Max temps will top out in the upper 80s/near 90F along the Atlantic Coast/I-95 corridor, with mostly lower 90s inland along with peak heat indices of 100-105F. Another quick end to convection after sunset with a return to showers and storms over the Atlantic Coastal waters during the overnight hours, with a few reaching the coast towards morning. Low temps still generally near normal in the lower/middle 70s inland and upper 70s along the Atlantic Coast. Patchy fog and low stratus is expected during the late night and early morning hours, but widespread dense fog is not expected.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Main Highlights This Period:

- Daily shower and thunderstorm potential, with strong storms possible over inland locations away from the coast.

As high pressure sits over the Appalachian region, an offshore trough will steadily shift westward towards the FL peninsula during the forecast period. Overall flow from the east, then southeast as the trough shifts west. Offshore showers during the early morning hours each day will push towards the coastal locations, then inland locations as the Atlantic sea breeze begins to push onshore. With the prevailing onshore flow, moisture will continue to advect into the area, with PWATs expected to remain above 2" across NE FL and much of SE GA. As such increased chances of precipitation is expected for these locations, with 60% to 80% chances each day, higher coverage of activity on Thursday. With the far inland progression of the Atlantic sea breeze, expect to see increased chances for thunderstorm development from central to western locations of NE FL and SE GA by the afternoon hours. Heavy downpours will be possible due to elevated moisture aloft. WPC has highlighted Marginal Risk of Excessive Rainfall for locations across north central FL and near the I-75 corridor on Wednesday, by Thursday the Marginal Risk encompasses all of NE FL portions and a majority of SE GA by Thursday as wind flow shifts to be from the southeast.

Daytime highs in the upper 80s to lower 90s and dewpoints in the mid to upper 70s each afternoon will allow for Heat Index values to rise above 100F for some locations across NE FL on Wednesday and once again on Thursday with a few locations across SE GA as well.

LONG TERM /FRIDAY THROUGH MONDAY/

Main Highlights This Period:

- Daily Thunderstorms, Isolated Strong Storms Possible Inland.

The high pressure north of the area is expected to weaken and make way for a cold front as it shift south towards the local area by this upcoming weekend. Current guidance suggests the cold front to shift into the area by late Saturday/early Sunday, pushing through much of the area by Monday morning.

The onshore flow from earlier in the week will transition to become southerly, then southwesterly-westerly by the upcoming weekend ahead of the cold front. Friday, the onshore flow persists which will again see the highest chances of precipitation for inland locations towards the I-75 corridor. By Saturday, mostly scattered chances of precipitation for much of the area outside of north central FL. Guidance shows and an increase in showers and storms on Sunday as the front begins to pushes through the area. Behind the front, drier air begins to advect into the area, leading to diminishing chances of showers and storms at the start of the upcoming week.

Temperatures in the lower to mid 90s over the weekend, with Heat index values rising over 100F could bring a chance for heat advisory criteria to be met.

AVIATION /06Z TUESDAY THROUGH 06Z WEDNESDAY/

VFR conds early should give way to low stratus/patchy fog development at the inland TAF sites of GNV/JAX/VQQ with LIFR/IFR CIGS and MVFR VSBYS from the 08-12Z time frame, while the onshore flow will increase the chances of MVFR CIGS and isolated showers (VCSH) at the coastal TAF sites of SSI/SGJ/CRG. After sunrise, MVFR CIGS will linger through the mid morning hours as the East Coast sea breeze triggers SHRA/TSRA activity at the coastal TAF sites in the 14-18Z time frame, that pushes to the inland TAF sites from 18-22Z time frame, and will need at least PROB30 groups at all terminals and possibly TEMPO groups at GNV/VQQ where highest rainfall chances are. VFR conds return late in the period as convection ends and pushes west of all terminals after sunset.

MARINE

Weak coastal troughing remaining situated over the local waters through mid week. Onshore winds will prevail through Saturday, followed by winds shifting to westerly by Saturday Night into Sunday as a frontal boundary enters the southeast states. Several rounds of showers and thunderstorms are possible during the upcoming weekend ahead of this frontal boundary.

Rip Currents: Solid Moderate Risk in the onshore flow today with surf generally in the 2-3 ft range. Slight uptick in surf into the 2- 4 ft range for Wednesday/Thursday may bring the NE FL beaches to a High Risk, but overall expect Moderate risk through the end of the week.

FIRE WEATHER

Onshore flow continues through midweek bringing early morning showers across coastal locations, and then towards inland locations as the Atlantic sea breeze moves inland. By the afternoon hours, amplified showers and thunderstorms will be possible with diurnal heating. With weaker winds aloft, dispersions will continue to generally be in the poor to fair range much of the week. But with moisture continuing to be brought in from the Atlantic, this will help maintain Good min RH values across the area.

Fog Potential: Gusty and erratic winds can be expected in and near thunderstorms with briefly localized flooding rainfall. Late night and early morning patchy fog and low stratus will be possible, especially in areas that received more rainfall.

PRELIMINARY POINT TEMPS/POPS

AMG 92 72 91 73 / 20 10 30 0 SSI 87 78 87 78 / 40 20 30 20 JAX 89 75 88 74 / 40 20 50 20 SGJ 87 75 87 75 / 50 30 70 20 GNV 90 73 88 73 / 60 20 70 20 OCF 90 73 89 73 / 80 30 70 20

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...None.