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 Weather Continues this Week. Heat Advisory/Extreme Heat Warning Monday. Heat Advisories & Extreme Heat Warnings Possible Tuesday through Thursday

- A Few Strong Thunderstorms Possible this Evening. Main Impact Area: The Interstate 95 Corridor.

- Scattered to Numerous Afternoon & Evening TStorms from Mon Sat. Strong to Isolated Severe Storms are Possible Each Day, Mainly Along the I-95

UPDATE

Most of today's convective coverage focused along a surface trough north of the Altamaha River. Once convection became established it developed a well-defined outflow boundary that pushed south- southeastward and interacted with a stalled Atlantic sea breeze through the late afternoon and early evening hours.

Currently, ongoing convection continues along the boundary as it pushes into the the I-10 corridor. With only isolated showers, there's still ample instability available for additional scattered convection over the next few hours. The main focus for activity will be between outflow collisions and the remnant convergence zone offered up by the Atlantic sea breeze, generally along the I-95 corridor in NE FL. While strong thunderstorms, capable of gusty winds, are fairly unlikely, there's still potential for heavy downpours that could lead to pockets of localized flooding especially in urban centers.

Outside of convection, the miserably hot temperatures are beginning to cool some and the heat advisory that was in effect has been allowed to expire on time. Unfortunately, there isn't much relief in terms of the heat through at least Thursday. That said, another Heat Advisory is in effect Monday with an Extreme Heat Warning for coastal SE GA as heat index will reach the 112-115 degree range.

SHORT TERM /THROUGH TUESDAY NIGHT/

Main Highlights This Period:

- Isolated Strong to Severe Storms Monday & Tuesday Afternoon/Evening, Especially for Northeast FL

- 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 and with higher chances for storms occurring ahead of the boundary over northeast Florida. Prevailing flow will shift to become more out of the west and 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, with PWAT values measuring upwards of over 2.5 inches. High temperatures for the beginning of next 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 possible extreme heat conditions through Tuesday.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Main Highlights This Period:

- Hazardous Heat Continues Next Week

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

Prevailing flow will shift to become more out of the northwest by the end of the week as the stalled frontal boundary over southeast Georgia, which had been acting to inhibit convection for portions of the northern forecast area through much of the week, begins to disperses and move off to the northeast and results in a more uniform pattern of diurnal convection going into the weekend. High temperatures will continue to be in the upper 90s through next week with heat index values likely to reach heat advisory levels through the end of the week.

AVIATION /00Z MONDAY THROUGH 00Z TUESDAY/

Ongoing convective activity will push outflow across the Jacksonville Metro terminals and south along I-95 through 02z, which may lead to isolated or vicinity TSRA at NE FL terminals along the coast. Activity will diminish late this evening and fade completely by midnight. Aside from slightly reduced visibility during the predawn hours skies will clear overnight. Westerly steering winds will delay the inland movement of the Atlantic sea breeze on Monday. Latest guidance does favor higher convective potential along and south of I-10 Monday afternoon and evening. Highest confidence of TSRA impacts will be at KGNV and KSGJ (40-50%), so introduced PROB30 groups for the late afternoon hours, 20z onward.

MARINE

Atlantic high pressure will continue to extend its axis westward across the Florida peninsula, creating a prevailing westerly wind pattern across our local waters. A frontal boundary will then push into the southeastern states by Monday afternoon, with this feature stalling just north of the Georgia waters by midweek. Chances for mainly afternoon and evening thunderstorms will increase across our local waters during the work week. Southwest to westerly winds will continue to prevail, with brief evening surges of wind speeds to Caution levels through the work week.

Rip Currents: A lower end moderate risk this afternoon at area beaches as the sea breeze creates an onshore flow that will combine with the outgoing tide and a persistent long period southeasterly ocean swell. Prevailing offshore winds will strengthen on Monday and Tuesday, creating a low risk that will likely continue through the end of the work week at all area beaches.

FIRE WEATHER

- Heat Advisory In Effect Today - Patchy High Dispersions Inland Southeast Ga Monday And Tuesday

Hot conditions are expected to persist through the rest of the weekend and into at least the start of next week, with Heat Advisories likely and possibly even Extreme Heat Warnings possible 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 except for a wind shift with the sea breeze generally east of the I-95 corridor. A frontal boundary dropping southward tonight and Monday will return more "usual" chances for showers and storms for all today, then mainly over northeast Florida for early to mid week as some drier air moves into southeast GA behind the front. Better mixing and transport winds will result in good to patchy high dispersions over inland GA, with fair to good dispersions elsewhere. The front will linger just north of the region by late week, with shower and storm chances generally increasing as well.

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:

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 76 97 78 98 / 20 10 0 10 SSI 78 97 80 98 / 30 20 10 20 JAX 77 95 77 96 / 30 40 20 30 SGJ 77 95 78 96 / 30 50 20 40 GNV 76 94 77 95 / 20 50 20 60 OCF 75 95 77 96 / 10 50 10 70

JAX WATCHES/WARNINGS/ADVISORIES

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