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

- Waves of Showers and Thunderstorms Expected through this Evening. Isolated Strong Storms Possible. Hazards: Wind Gusts of 35-45 mph, Frequent Lightning & Heavy Downpours. Localized Flooding Possible, Mainly at Urban & Low-Lying Areas

- Isolated to Widely Scattered Afternoon & Evening TStorms Wed - Mon

- Heat and Humidity Builds this Weekend and Early Next Week. Heat Advisory Conditions Possible by Sunday and Monday

NEAR TERM /THROUGH TONIGHT/

Main Highlights This afternoon and Tonight:

- Waves of Downpours and Embedded Thunderstorms Will Move Across Our Area through Late this Evening

- A Few Strong Storms and Localized Flooding at Urban Locations Possible through Tonight

A frontal boundary currently positioned near the Altamaha River will stall and weaken just south of the river by this evening. The presence of the boundary will provide more numerous convection to develop diurnally along and south of the boundary, with the highest coverage expected to be across interior GA. Moisture is plentiful with PWATs in the 2-2.25 inch range, but with drier/cooler air less abundant aloft, expecting heavy rainfall and localized minor flooding to be the primary potential hazard with convection today, with gusty winds being secondary and more isolated after several days in a row of higher DCAPE and stronger downdrafts observed. Higher chances for gusty downbursts will be generally across northeast FL, and especially towards the nearly pinned east coast sea breeze where the best convergence and instability will be. Hi res guidance is suggesting showers and t'storms to linger through the 04 to 06Z range for some areas tonight thanks to the presence of the boundary.

Despite plenty of mid and high clouds and the frontal boundary sitting over southeast GA, highs will still top out in the upper 80s and lower 90s this afternoon. Lows tonight will fall to the low and mid 70s area-wide.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/

Main Highlights During This Period:

-Reduced chances for storms

Predominantly westerly flow through Wednesday will gradually veer to northwesterly by Thursday as surface high pressure centered near the Florida Peninsula shifts westward toward the northern Gulf coast. At the same time, the lingering frontal boundary will lift north over north GA becoming increasingly diffuse, allowing drier air and a more stable airmass to filter into the region. As a result, convective coverage will trend downward through the period, with Wednesday featuring widely scattered to scattered afternoon and evening showers and thunderstorms, with highest POPS along the I-95 corridor south of Jacksonville. By Thursday, drier air aloft and increasing subsidence should further suppress convection, with only isolated afternoon showers and thunderstorms expected (PoPs around 15 to 25 percent).

High temperatures will gradually warm as the week progresses, reaching the upper 80s to lower 90s across southeast Georgia and the lower to middle 90s across northeast Florida Wednesday, with the warmest readings expected on Thursday under greater sunshine. Overnight lows will remain seasonably warm in the lower to middle 70s. Despite the warming trend, afternoon heat index values will generally peak between 100 and 105 degrees, remaining below Heat Advisory criteria.

LONG TERM /FRIDAY THROUGH MONDAY/

Main Highlights During This Period:

- Daily bouts of showers and storms - Potential heat advisory conditions this late week into the weekend

A typical mid summer pattern will prevail from Friday through Monday as Atlantic high pressure strengthens offshore and extends westward across the Florida Peninsula, maintaining predominantly westerly to southwesterly low-level flow. An upper ridge centered over the southern Plains and lower Mississippi Valley will remain the dominant large scale feature, while weak northwesterly flow aloft and passing perturbations may provide enough support for isolated to scattered convection. Slightly lower PWAT values and the potential for some Saharan dust intrusion, particularly late in the week, may further suppress convective coverage.

Daily afternoon and evening showers and thunderstorms will continue, driven primarily by daytime heating and sea breeze interactions. Rain chances will generally range from 20 to 35 percent on Friday before increasing to 40 to 50 percent over the weekend as weak disturbances aloft move through the region. Although coverage will remain lower than earlier in the week, any storms that develop will be capable of producing frequent lightning, locally heavy rainfall, and isolated gusty winds.

Above-normal temperatures will persist through the extended period, with afternoon highs in the lower to middle 90s across southeast Georgia and the middle 90s across northeast Florida. Overnight lows will remain in the middle 70s inland and upper 70s along the coast. The combination of hot temperatures and humid conditions will routinely push peak heat index values into the 105 to 110 degree range, with portions of the area potentially reaching Heat Advisory criteria, especially late in the weekend into early next week. Forecast trends will continue to be monitored.

AVIATION /18Z TUESDAY THROUGH 18Z WEDNESDAY/

Afternoon convection has continued to develop over the last few hours, already have affected GNV as of 1730Z. Pushed back TEMPO groups a bit further with the latest update and continued to include all terminals, as guidance continues to show several "rounds" of showers and t'storms continuing this evening, which could last into the start of tonight as well. Confidence is shaky with respect to coverage, especially with TS coverage, and therefore maintained PROB30 groups north of GNV and SGJ. Generally I-10 and northward will have the best chance for convection lasting through about the 04 to 06Z time frame closer to a nearly stalled frontal boundary. Flow becomes slightly more out of the northwest this evening and into Wednesday thanks to the aforementioned front nudging southward, which will also reduce the coverage of convection on Wednesday, enough to only include VCSH towards the end of the period.

MARINE

A frontal boundary pushing slowly southward towards the Georgia waters will stall this afternoon, with this feature then weakening on Wednesday. Rounds of showers and thunderstorms will impact all of our local waters at times through Wednesday, with a few strong storms containing briefly gusty west winds and frequent lightning strikes possible. Coverage of showers and thunderstorms will then decrease by Thursday as the frontal boundary dissipates. Surface troughing developing over the southeastern states this weekend could bring scattered afternoon and evening showers and thunderstorms to our local waters as offshore winds prevail.

Rip Currents:

Prevailing offshore winds and low surf heights will continue to keep the rip current risk low at area beaches throughout this week.

FIRE WEATHER

- Areas Of High Dispersions Through Thursday

The region will remain positioned between high pressure to the south and a gradually weakening frontal boundary to the north through the week. Daily afternoon and evening showers and thunderstorms are expected, with the greatest coverage occurring early in the week before becoming less widespread later in the period as the boundary dissipates. Above-normal temperatures will persist throughout the week, with a gradual warming trend developing late in the week.

Fog Potential and Other Remarks: Significant fog development is not expected tonight. Gusty and erratic winds will be possible in and near thunderstorms, with occasional outflow boundaries capable of producing sudden wind shifts well away from ongoing convection.

PRELIMINARY POINT TEMPS/POPS

AMG 89 72 90 73 / 70 40 30 10 SSI 91 74 92 77 / 70 60 40 20 JAX 91 73 93 74 / 60 40 40 10 SGJ 92 75 93 76 / 60 20 50 10 GNV 91 73 93 74 / 40 20 40 10 OCF 91 73 93 75 / 40 10 30 0

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...None.