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 Area-Wide Sunday. Daily Heat Advisories & Extreme Heat Warnings Likely throughout the Next Week

- Strong to Severe Storm Hazards on Sunday: Damaging Wind Gusts of 30-50 mph, Frequent Lightning Strikes, Heavy Downpours and Localized Flooding

- Isolated to Scattered Afternoon & Evening Thunderstorms Next Week

UPDATE

The heat advisory and extreme heat headlines have ended this evening. Weaker instability, sampled by the afternoon upper air, has checked convection through out the day with very isolated diurnal activity thus far. There remains potential for isolated to scattered development north of Waycross in SE GA through midnight as outflow from more robust convection to the north continues southward into the region. Generally expecting thunderstorms to be of the weaker variety this evening as they attempt to develop. Elsewhere, a relatively hot (low 90s) evening will gradually trend cooler with the setting sun then fall to the middle 70s overnight tonight.

A ridge-splitting upper impulse will slowly move into the SE GA region tomorrow (Sunday), generating stronger instability. This will aid in more convective coverage Sunday afternoon and evening as the Atlantic sea breeze pushes inland. Dry air aloft may still act to cannibalize updrafts across portions of NE FL through the day.

SHORT TERM /THROUGH MONDAY NIGHT/

Main Highlights This Period:

- Isolated Strong to Severe Storms Sunday & Monday Afternoon/Evening

- Heat Index Values Near or Above Heat Advisory Each Day

A frontal boundary from out of the northwest will settle in over southeast Georgia by Monday resulting in more inhibited convection over southeast Georgia compared against Sunday and with higher chances for storms occurring ahead of the boundary over northeast Florida. Prevailing flow will shift to become more out of the northwest with moist air maintaining over northeast Florida south of the frontal boundary and north of high pressure ridging crossing over the southern Florida peninsula. High temperatures for the end of the week will rise into the upper 90s and potentially reaching upwards to 100 over portions of southeast Georgia. Overnight low temperatures will drop down into the mid to upper 70s over inland areas and in the upper 70s and lower 80s for coastal areas and along the St Johns River. Heat index values during this period will reach upwards of 106 up to over 113, resulting in heat advisory and extreme heat conditions into the beginning of next week. .

LONG TERM /TUESDAY THROUGH SATURDAY/

Main Highlights This Period:

- Hazardous Heat Continues into Next Week, with Daily Heat Headlines Possible

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

Prevailing flow continue from out of the west and northwest through the end of the week with the stalled frontal boundary acting to inhibit convection over southeast Georgia through Wednesday, with flow expected to become more southwesterly for the end of the week as the frontal boundary disperses resulting in a more uniform pattern of diurnal convection before the weekend with a potential for strong to severe storms forming under the influence of upper level instability nearer to the end of the period. High temperatures will continue to be in the upper 90s through next week with heat index values likely to reach heat advisory levels through at least midweek.

AVIATION /00Z SUNDAY THROUGH 00Z MONDAY/

VFR conditions will generally hold with winds trending light and variable at or below 5 knots. Localized mist or ground fog may develop at KVQQ or KGNV during the early hours Saturday. Stronger instability will offer higher potential for TSRA development, especially along the I-95 corridor during the early evening. Vicinity mentions have been added to most TAF sites but highest potential for TSRA (30-40%) will be at sites along and north of I-10.

MARINE

Atlantic high pressure will build westward across the Florida peninsula today. Only isolated to widely scattered thunderstorms are expected to develop late this afternoon and evening, mainly for the waters north of St. Augustine. The axis of Atlantic high pressure will then shift southward on Sunday and Monday as a frontal boundary pushes into the southeastern states, with this feature stalling just north of the Georgia waters by midweek. Southwest to westerly winds will prevail from Sunday through midweek, with evening wind surges likely increasing speeds to Caution levels. Only isolated to widely scattered afternoon and evening thunderstorms are expected on Sunday and Monday, with coverage potentially increasing towards midweek as the frontal boundary approaches from the north.

Rip Currents: Low to very borderline moderate risk of rip currents will continue this weekend into early next week, with mostly offshore flow and surf/breakers into the 1-2 ft range with a sea breeze pinned close to the beaches each day. Any increase in surf for the mid to late week time frame will depend on the development of any tropical waves in the Central Atlantic.

FIRE WEATHER

- Heat Headlines In Effect Today - Areas Of High Dispersions Inland Southeast Ga Monday

Hot conditions are expected to persist through the rest of the weekend and into at least the start of next week, with heat headlines likely to continue each day for most or all of the region. This will come with a flow direction generally out of the southwest to west through the next several days, as well as slightly lower chances for afternoon/evening showers and thunderstorms, especially over interior GA. Good mixing, especially outside of any showers or storms, will result in mostly good dispersions, which could be high over portions of inland GA late weekend.

Fog Potential: Significant fog developments are not expected, however late-night or early-morning fog developments are expected to be shallow and patchy, mainly occurring over areas that have received locally heavy rainfall. Gusty and erratic winds are often possible within and nearby any stronger showers or storms.

CLIMATE

Near record high temperatures are possible at some of our designated climate sites during the next several days:

Saturday August 15: KJAX: 99/1956 KGNV: 100/1918 KAMG: 99/1995 KCRG: 97/2011

Sunday, August 16: KJAX: 97/1957 KGNV: 97/1918 KAMG: 100/1995 KCRG: 95/2022

Monday, August 17: KJAX: 99/1954 KGNV: 97/1954 KAMG: 104/1995 KCRG: 97/2005

Tuesday, August 18: KJAX: 98/1954 KGNV: 98/1954 KAMG: 105/1995 KCRG: 96/2023

PRELIMINARY POINT TEMPS/POPS

AMG 75 95 76 96 / 20 30 20 20 SSI 78 95 79 96 / 10 40 30 20 JAX 76 94 76 95 / 10 30 30 40 SGJ 77 95 77 95 / 10 10 20 60 GNV 75 94 75 94 / 10 10 10 70 OCF 75 95 76 95 / 10 10 20 60

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from 11 AM to 8 PM EDT Sunday 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 8 PM EDT Sunday for GAZ132>136-149- 151>154-162-163-165-166-250-264-350-364. MARINE...None.