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

- Dangerously HOT throughout the Next Week. Extreme Heat Warning Today from 11 AM 8 PM for Brantley, Glynn & Camden Cos in southeast GA. Heat Advisories in Effect Elsewhere from 11 AM 8 PM Today. Daily Heat Advisories & Extreme Heat Warnings Likely throughout the Next Week

- Strong to Isolated Severe TStorms Late this Afternoon & Evening. Main Impact Area: Inland Southeast GA. Strong to Severe Storm Hazards: Damaging Wind Gusts of 40-60 mph, Frequent Lightning Strikes, Heavy Downpours and Localized Flooding

- Isolated to Scattered Afternoon & Evening Thunderstorms Next Week

NEAR TERM /THROUGH TONIGHT/

Main Highlights through Tonight:

- Extreme Heat Warning for coastal SE GA through this evening.

- Heat Advisory Conditions NE FL & inland SE GA through this evening. - Scattered Thunderstorms late this Afternoon and Evening, with Strong to Isolated Severe Storms Possible this Evening inland SE GA.

Forecast remains on track as high pressure ridge aloft and surface low pressure trough at the surface will continue hot and humid conditions this afternoon with above normal Max Temps into the mid/upper 90s inland and lower 90s at the Atlantic beaches. These are still expected to combine with typical mid August humidities to produce peak heat indices of 108-112F area-wide and into the 110- 114F range along the I-95 corridor of coastal SE GA as the east coast sea breeze remains trapped there. Despite the ridging and subsidence aloft, expect PWATs around 2 inches area-wide to still be enough to trigger at least widely scattered storms along sea breeze activity and other low level boundaries by the 2-4pm time frame, while some lingering NW flow aloft across the SE US states will be enough to still push some stronger to isolated severe storms into portions of inland SE GA by the evening hours. Main impacts from convection will be isolated severe downburst wind gusts up to 60 mph, due to the high instability in the lower atmosphere from extreme heat and expect downdraft CAPE values to reach close to 1000J/kg. The slower storm motion around 10 mph or less will still support heavy downpours and localized flood threat in the more intense storms. Convection will fade around sunset across NE FL, but will likely linger until closer to midnight across SE GA as potential for storms to drift SE into the local area still exists. Low temps overnight will generally be in the mid/upper 70s inland and around 80F along the Atlantic Coastal/St. Johns River areas. Some patchy fog possible towards sunrise Sunday morning over any inland areas that gets some heavier rainfall amounts this evening.

SHORT TERM /SUNDAY 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 /18Z SATURDAY THROUGH 18Z SUNDAY/

VFR conditions will prevail at local terminals for most of the upcoming TAF period. Westerly steering flow will keep the East Coast sea breeze pinned near the I-95 corridor this afternoon with only SSI/SGJ/CRG shifting to the S-SE around 10 knots this afternoon. The current pattern will keep storm chances on the lower side and will keep only PROB30 groups for late day TSRA activity, mainly in the 21- 01Z time frame at most locations. VFR conds and light winds return for the overnight hours Saturday Night with mostly a few mid and high clouds leftover from any evening convection that develops. Fog chances remain too low for inclusion at this time, but some brief MVFR VSBYS at VQQ not out of the question if rainfall occurs today. Any rainfall/storm chances for Sunday will likely occur after the end of the current TAF period and will leave out for now.

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 / 40 30 20 20 SSI 79 95 79 96 / 20 40 30 20 JAX 76 94 76 95 / 20 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 / 20 10 20 60

JAX WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory until 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. 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 until 8 PM EDT this evening for GAZ132>136-149- 151-162-163-250-264-350-364. Heat Advisory from 11 AM to 8 PM EDT Sunday for GAZ132>136-149- 151>154-162-163-165-166-250-264-350-364. Extreme Heat Warning until 8 PM EDT this evening for GAZ152>154-165-166. MARINE...None.