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

- Afternoon Isolated To Scattered Thunderstorms Today, Decreasing Chances Through the Week

- Heat Advisory Wednesday (12-6 PM). Peak Heat Index 105-112 Most Areas. Major Heat Risk through the week.

- Moderate Rip Current Risk Beaches Today

UPDATE

Convection is beginning to dwindle as surface begins to cool. There are still a few boundaries and isolated thunderstorms trekking along I-10 where residual instability may support a few more showers or storms through 10 PM before activity completely fades. Otherwise, no significant changes to the forecast. The big concern over the next few days will be the heat as convective relief will be much more limited. A new heat advisory will be in effect Wednesday during the noon to 6 PM window where Heat Index values may peak into the upper 100s as temperatures reach the mid/upper 90s.

NEAR TERM /THROUGH WEDNESDAY/

Main Highlights for Today and Tonight:

- Hot / above normal temperatures. Heat Advisory for coastal southeast GA. Other locations will see heat indices near 103-107. - Typical summer-time scattered afternoon/early evening storms

High pressure ridge axis will remain just south of the local area across the Central/Southern Florida Peninsula and will continue a hot and humid Southwest Flow with scattered afternoon/early evening storms along and ahead of the Gulf Coast sea breeze which will meet the East Coast sea breeze along the I-95 corridor late this afternoon into the early evening hours before pushing offshore into the Atlantic after sunset. Mid level lapse rates remain weak and expect just a few strong storms with gusty winds 40-50 mph, frequent lightning and heavy downpours, but cannot rule out an isolated severe storm along the I-95 corridor where sea breeze mergers could produce brief wind gusts to 60 mph and/or funnel cloud/waterspout activity. PWATs around 2 inches will promote a quick 1-2 inches in the more intense storms, but overall heavy rainfall threat remains only low to moderate due to the storm motion around 15 mph or so.

Temps will peak in the middle 90s this afternoon before convection and outflows from storms reach most locations, and peak heat indices generally around 105F, with some locations along coastal SE GA reaching around 108F, and will keep Heat Advisory in place, as any convection will reach these areas latest in the day. Above normal temps continue tonight with lows in the mid 70s inland, and upper 70s to near 80F along the St. Johns River and Atlantic Coastal areas.

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/

Main Highlights During This Period:

- Heat Advisory potential for Wednesday and Thursday afternoons - Lower convective chances

Weak surface ridging will stretch across southern FL Wednesday. With the ridge to the south, the flow from the southwest will continue. However, with the ridge fairly weak the flow will be lighter than the last few days. The lighter flow will result in a slower progression of convection from southwest to northeast across area. The lighter flow will also allow the east coast sea breeze to move further inland that recently, likely reaching the I95 corridor in the afternoon. In general Wednesday will be drier, but the clash of the sea breeze boundaries over the I95 corridor, will result in greatest chance there. With lower convective chances, and a slower progression of the Gulf sea breeze, temperatures will be trend warmer, with the potential for heat advisory criteria heat indices increasing.

The ridge will strengthen as it moves north over forecast area Thursday into Thursday night. With the ridge building overhead, subsidence will help to minimize convective chances. The light flow, and lower convective chances will again push heat indices near, or into heat advisory range.

LONG TERM /FRIDAY THROUGH TUESDAY/

Main Highlights During This Period:

- Heat Advisory potential Friday and Saturday afternoons - Convective chances increase this period

The surface ridge will remain overhead through Saturday, as it slowly weakens. The ridge will continue to suppress convective chances, especially on Friday when ridge will be stronger. The heat indices near or above advisory criteria will continue into Saturday day.

The ridge will move more to the south Sunday into Monday, as a cold front approaches from the northwest. This pattern will yield a flow from the west. Convective chances will be greater Sunday, and likely on Monday due to the proximity of the front. It will not be as warm Sunday into Monday due to precipitation and cloud coverage, but still trend above average.

The cold front is currently forecast to slide all the way to near the GA/FL line Tuesday. Convergence along this front will yield higher than normal precipitation chances. Temperatures will be near to a little below average Tuesday.

AVIATION /00Z WEDNESDAY THROUGH 00Z THURSDAY/

For the most part the afternoon convection is winding down at area terminals. However, there's still "untapped" instability lingering across portions of NE FL which may result in showers and isolated TSRA through 01-02z. Beyond that, VFR conditions will persist with light southwesterly flow overnight. Possible to have some shallow fog near at inland terminals as clouds scatter out. More limited convective coverage is expected Wednesday as upper ridging establishes over Florida. Still anticipate, a chance of showers is possible but confidence on timing right now so have only included VC SHRA at this time but expect a later sea breeze merger. Otherwise, southwesterly flow will keep the sea breeze from pushing beyond KCRG/KSSI/KSGJ Wednesday afternoon.

MARINE

High pressure ridge will remain anchored across central and south Florida this week as low pressure troughing develops to the north. This pattern will maintain a prolonged southwest flow during the day followed by evening wind surges from the south to Small Craft Exercise Caution wind speeds. The offshore flow will allow for a chance of afternoon and evening thunderstorm over the local coastal waters each day through the week. Mariners should expect locally strong wind gusts and frequent lightning with any developing thunderstorms.

Rip Currents:

Low to Moderate risk of rip currents through the end of the week in the mostly offshore flow with afternoon/early evening sea breeze, while surf remains generally in the 1-2 feet range.

FIRE WEATHER

High pressure will be the prevailing weather feature through Monday. A cold front is expected to move south into the area Tuesday. Lower than normal precipitation chances forecast through Saturday, then above normal for Sunday through Tuesday. Heat Advisory conditions will be possible each afternoon from Wednesday through Saturday.

Fog Potential and other remarks: Significant fog potential is not expected Tonight. Erratic wind gusts possible in and near thunderstorms, and at times, at a distance due to outflows.

PRELIMINARY POINT TEMPS/POPS

AMG 75 97 77 97 / 20 10 10 0 SSI 78 96 80 96 / 30 10 10 10 JAX 77 97 78 98 / 30 20 10 10 SGJ 77 96 77 96 / 20 20 10 10 GNV 75 96 75 97 / 10 10 10 20 OCF 74 95 76 96 / 10 10 10 20

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from 11 AM to 6 PM EDT Wednesday 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 11 AM to 6 PM EDT Wednesday for GAZ136- 152>154-162-163-165-166-264-350-364. MARINE...None.