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

- Oppressive Heat & Humidity Continues Area-Wide. Heat Advisories In Effect Today. An Extreme Heat Warning for Coastal Southeast GA Today and Extreme Heat Watch for same area for Friday. Daily Heat Advisories Likely Continue for Much of Our Area into Next Week

- A Few Strong Thunderstorms this Afternoon & Evening. Damaging Wind Gusts of 40-55 mph, Frequent Lightning Strikes & Heavy Downpours.

- Daily Isolated to Scattered Afternoon & Evening TStorms Friday through Wednesday

NEAR TERM /TODAY THROUGH TONIGHT/

Main Highlights:

- Extreme Heat Warning and Heat Advisories in Effect today

- A Few Strong thunderstorms this Afternoon through Early Evening. Stronger Storms Will Be Capable of Producing Strong Wind Gusts, Frequent Lightning Strikes, and Torrential Downpours.

Left over debris mid to high clouds over area early this morning which should slowly diminish. With lows in the lower 70s and moist ground, patchy fog and low stratus may form early this morning.

Sweltering heat will continue today with prevailing west to northwest surface flow keeping the Atlantic sea breeze held to about the I-95 corridor by late afternoon. A Heat advisory remains in effect for today with an Extreme Heat Warning for coastal southeast GA. Max temps in the mid to upper 90s will combine with mid 70s dewpoints to produce heat indices of around 106 to 111 in the heat advisory and about 111-114 in the Extreme Heat Warning. One area that may narrowly escape widespread advisory conditions is over inland southeast GA from Alma GA northward where favored daytime boundary layer mixing lowers dewpoints to the lower 70s.

The convection today will largely be driven by diurnal instability and low level convergence. It does look like less convection today than Wednesday, and mainly focused over the southern 2/3rds of the area with POPs of about 30-55 percent, with some small areas of about 60 percent over inland northeast FL. From Highway 84 northward in southeast GA, will advertised more in the 20-30 percent range. A few strong storms remain possible for today with gusty winds the main threat. Model soundings show MLCAPE again reaching upwards of about 3000 J/jg and downdraft CAPE nearing 1000. The main limiting factors for more convection is the suppression affects of the ridge aloft to our west and lower amounts of low level moisture, especially over inland southeast GA. Isolated convection expected this evening, but is likely to quickly fade with loss of heating.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/

Main Highlights This Period:

- Daily Isolated to Scattered Afternoon Thunderstorms, some of which could be strong

- Heat Index Values near Heat Advisory levels each day. Extreme Heat Watch in place along coastal SE GA Friday

The high pressure over the Gulf will begin to shift northward as a trough shifts south along the SE coast through Saturday. This will bring a bit weaker westerly-southwesterly flow, which would allow for the Atlantic breeze to push inland a bit past the I-95 corridor. Scattered showers and storms will develop as the Gulf breeze pushes inland, with convective activity increasing during the afternoon hours as the breezes merge near and east of US-301. By Saturday, the trough will bring a cold front south into the area, with the front sinking near the FL/GA state line by Saturday evening. With the advancement of the front, highest chances of showers and storms will be focused over SE GA south towards the I-10 corridor by the afternoon hours.

Warm temperatures continue through the end of the week as daytime highs will remain in the upper 90s, close to 100F for some locations. Heat Advisory may be needed both days, but as was seen yesterday, showers and storms will likely limit the amount of time that Heat Index values sit at or above criteria levels. Another Extreme Heat Watch is in place for coastal SE GA as Heat Index values may rise to 112F to 114F Friday afternoon.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Main Highlights This Period:

- Warm temperatures continue over the weekend and next week, with Heat Advisories likely

- Isolated to scattered thunderstorms each afternoon evening, which could become strong

The cold front over SE GA will begin to lift Sunday and out of the area at the start of the new week. By Tuesday, another front will approach from the north and sit north of the area heading into midweek. Isolated to scattered showers and storms on Sunday as the front lifts from the area, with lower coverage by Monday. Chances increase once again as the next front nears SE GA on Tuesday and through midweek.

Above average temperatures are expected throughout this period as the warm temperatures and dewpoints in the 70s will continue to bring near Heat Advisory conditions this weekend and into next week, with Tuesday afternoon the warmest of the forecast period.

AVIATION /06Z THURSDAY THROUGH 06Z FRIDAY/

Mostly high clouds left over from the convection on Wednesday with some light mist vsby and scattered low stratus possible for VQQ and JAX through early morning. West-northwest winds 5-10 kts develop after 14Z. For coastal sites, winds shift to southerly after 18Z as the Atlantic sea breeze shifts inland. Generally, scattered showers and storms expected this afternoon and early evening, but not as much coverage/chance as on Wednesday. For now, will stick to PROB30 MVFR TSRA from about 19z to 24z with further updates to refine this.

MARINE

A trough of low pressure will develop over the southeast states through the weekend while high pressure ridge remains positioned over the eastern Gulf and central FL. This will result in westerly winds during the next several days, with the sea breeze shifting winds to southeast or south over the near shore waters each afternoon, followed by south evening wind surges that may briefly increase speeds to near caution levels before subsiding after midnight. Strong offshore flow may develop Monday and Tuesday next week. Scattered mainly afternoon and evening thunderstorms will remain possible each day through the upcoming weekend, and some of the storms capable of producing strong gusty winds and locally high seas.

Rip Currents: Prevailing offshore winds and little, if any, east- southeast swell energy will keep surf heights near or below 2 feet at area beaches. Thus, generally low risk of rip currents through Friday. The only heightened risk of rip currents will be around piers and jetties and also around the times of low tide, which for today and Friday will be around 3 PM to 5 PM. Going into the weekend, there is not much change with low surf heights so the low risk of rips may continue.

FIRE WEATHER

- Heat Headlines in Effect

Warm temperatures continue with highs in the mid 90s inland and lower to mid 90s at the coast Today. Heat Advisory is in place across NE FL and coastal locations of SE GA as peak heat index values of 106-112. With warm temperatures expected to continue through the end of the week, heat advisories may likely be needed, though isolated to scattered thunderstorms each afternoon and evening may limit the amount of time that Heat Index values sit at or above criteria levels. A front will move south into the area Saturday, before stalling near the FL/GA line Sunday. Storm activity will be focused along and south of the boundary towards the I-10 corridor on Saturday. Fog Potential: Significant fog development is not expected, with shallow, patchy fog late overnight limited to areas that receive locally heavy rainfall.

CLIMATE

Daily record high temperatures are possible by Thu-Sat. Also record warm minimums possible at GNV the next couple of days:

Thursday, August 13th: KJAX: 99/2023 KGNV: 99/2023 KAMG: 100/9999 KCRG: 96/2023

Friday August 14th: KJAX: 99/2023 KGNV: 97/2023 KAMG: 101/2023 KCRG: 98/2023

Saturday August 15th: KJAX: 99/1956 KGNV: 100/1918 KAMG: 99/1995 KCRG: 97/9999

PRELIMINARY POINT TEMPS/POPS

AMG 96 76 97 76 / 20 10 40 20 SSI 96 80 95 80 / 10 10 40 20 JAX 96 76 96 77 / 30 10 50 10 SGJ 94 77 94 77 / 30 10 30 10 GNV 95 75 96 75 / 50 20 60 20 OCF 94 75 96 75 / 40 20 50 20

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from 11 AM this morning to 8 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 11 AM this morning to 8 PM EDT this evening for GAZ132>136-149-151-152-162-163-250-264-350-364. Extreme Heat Warning from 11 AM this morning to 8 PM EDT this evening for GAZ153-154-165-166. Extreme Heat Watch from Friday morning through Friday evening for GAZ153-154-165-166. MARINE...None.