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

- Elevated Rip Current Risk Continues Thursday

- Daily Heat Index up to 105 through Sunday

- Daily Afternoon & Evening Thunderstorms. Main Hazards: Locally Heavy Rain, Lightning & Gusty Winds Up to 40 mph

UPDATE /THROUGH TONIGHT/

Adjusted PoPs and thunder chances this evening based on latest trends, as latest radar imagery looks overall similar to this time yesterday with showers and isolated t'storms mainly pushed into western areas. It will be generally along and west of I-75 as well as the western I-10 area that will have the highest chances of showers and perhaps a few rumbles of thunder through the next few hours, before diurnal heating is quickly lost and activity transitions more towards area waters. As with the past several days, a few showers could reach coastal areas overnight, but otherwise mainly dry overnight as the pattern starts to break into Thursday, with some patchy fog and low stratus expected inland, especially in areas that received more rainfall today. Lows in the mid 70s will be common, with some upper 70s near the immediate coast.

SHORT TERM /THROUGH FRIDAY NIGHT/

Main Highlights Thursday through Friday Night:

- Daily potential for isolated strong thunderstorms and potential for localized flooding.

The pattern will evolve back to the typical summer-like light flow pattern with primary thunderstorm development along both the Atlantic and Gulf sea breezes on Thursday. A leftover boundary will dissipate by Thursday morning as deep moisture across Florida is advected northward into the southeast GA. While precipitable water will still be on the high side, upper level support for strong to severe thunderstorms will be limited by warm air aloft. Though strong storms will be throttled by weaker buoyancy, there will be enough instability for numerous showers and thunderstorms to develop. The most exapnsive coverage is likely to focus along the Highway 301 corridor, where the Gulf and Atlantic sea breeze will merge during the early evening Thursday. Locally heavy rainfall and gusty winds (30-50 mph) will be the marquee concerns for convective hazards Thursday and likely again Friday. On Friday, atmospheric moisture and instability will be similar to Thursday but a shifted steering flow will position the corridor of greatest thunderstorm coverage/chances toward the I-95 corridor.

Temperatures will trend above average with highs in the lower 90s for most inland locations to upper 80s to near 90 at the coast. Daily peak heat index values will range from the upper 90s up to 105 deg for inland locations. Muggy overnight lows will range in the low/mid 90s.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Main Highlights This Period Saturday through Wednesday:

- Above Average Temperatures & Daily Thunderstorms this Weekend

- Elevated Rip Current Risk Next Week

Relatively stubborn pattern will develop over the weekend and through next week as deep ridging becomes stacked well offshore. Initially over the weekend this positions a lower level ridge axis directly across the local area, resulting in a weak southerly flow regime. By Monday, the ridge axis moves north, reintroducing onshore flow early next week. The primary concerns each day will be localized potential for strong thunderstorms due to mesoscale boundary collisions with the potential for localized rainfall and flooding concerns.

Temperatures will moderate back more toward average highs for this time of year in the mid to upper 80s with the return of easterly flow with lows still ranging in the 70s.

AVIATION /00Z THURSDAY THROUGH 00Z FRIDAY/

Any lingering SHRA inland will dissipate from about 00Z onward, as the main impact over the next 12 hours or so being MVFR/IFR FG and stratus Thursday Morning, especially at VQQ and GNV where prevailing IFR is expected. Confidence is generally lower closer to the coast and further south towards SGJ, and only opted to include TEMPO MVFR vsby restricions at JAX and CRG at this time where lighter winds are expected overnight. Coastal showers are also expected to have less coverage tonight as the current pattern starts to break into Thursday, with this change being the main catalyst of uncertainty with respect to FG and stratus. Flow will overall be lighter Thursday afternoon, bringing a sea breeze inland towards the end of the forecast period, along with at least SHRA impacts with confidence too low at this time to include TSRA mention anywhere but VQQ and GNV.

MARINE

A stalled frontal boundary positioned across central Florida will dissipate over northeast Florida waters on Thursday. Meanwhile, strong high pressure stretching across the Carolinas and the southern Appalachians will gradually weaken as it shifts offshore of the southeastern states tonight and Thursday as a cold front pushes through the Ohio and Tennessee Valleys. Generally weak high pressure ridging is then expected to persist Friday and through the weekend.

Breezy onshore winds and breakers of 3-4 feet will keep a high rip current risk in place at area beaches through around sunset this evening. Diminishing onshore winds should allow for surf to gradually diminish, with 2-3 foot breakers on Thursday likely yielding a higher end moderate risk at area beaches. Prevailing winds will become south-southwesterly by Friday, with a lingering easterly ocean swell and onshore winds developing during the afternoon hours behind the inland moving sea breeze potentially keeping a lower end moderate risk at the northeast FL beaches.

FIRE WEATHER

Breezy east winds continue today with waves of morning coastal showers and isolated thunderstorms. Both Gulf Coast and Atlantic Coast sea breezes develop Thursday afternoon, with showers and storms developing along and between them. Highest rain and thunderstorm chance will be along Highway 301 where the sea breezes are likely to collide. No significant humidity or smoke dispersion concerns through the weekend.

Fog Potential: Gusty and erratic wind shifts will occur from thunderstorm activity. Patchy fog is expected across inland areas Thursday morning but widespread dense fog is unlikely.

HYDROLOGY

We expect water levels to peak in Action stage at the Atlantic coastal tide gauges during this evening's high tide, especially along the southeast GA coast, where a few locations may touch flood stage. Decreasing onshore winds overnight and Thursday morning should result in tide levels along the Atlantic coast peaking around Action stage during Thursday night's high tide. Mostly nuisance type flooding is expected, and water levels may approach action stage around times of high tide within portions of the St. Johns River basin during the next several days.

PRELIMINARY POINT TEMPS/POPS

AMG 73 92 73 92 / 10 40 30 60 SSI 77 89 77 90 / 20 30 20 50 JAX 76 91 74 91 / 10 40 20 80 SGJ 77 89 75 90 / 10 40 30 80 GNV 74 92 73 91 / 20 50 20 80 OCF 74 92 74 91 / 30 40 20 80

JAX WATCHES/WARNINGS/ADVISORIES

FL...High Risk for Rip Currents until 8 PM EDT this evening for FLZ124- 125-138-233-333. GA...High Risk for Rip Currents until 8 PM EDT this evening for GAZ154- 166. MARINE...None.