Marine Weather and Tide Forecast for St. Augustine, FL

NEAR TERM /THROUGH TODAY/
Main Highlights This Period:

- Another Hot Day with Heat Index Peaking Around 102-107 Degrees

- Scattered to Numerous Afternoon Thunderstorms, A Few Strong Storms Possible

The region will remain on the west to northwestern periphery of surface ridging once again today, which will persist a general southwest flow across the region. The Gulf sea breeze pushing inland quickly with this flow will result in a general earlier onset of daytime convection, with some enhancement likely towards the I-95 corridor as the breeze reaches the Atlantic sea breeze that is expected to push only about 5-10 miles inland at most. In addition, a weak remnant pre frontal trough associated with a frontal boundary northwest of the region looks to move into the region during the afternoon and evening, further enhancing coverage of showers and t'storms inland during the afternoon and evening hours. Forecast soundings are suggesting a bit less instability with warmer temps aloft, though still cannot rule out an isolated strong thunderstorm, especially with sea breeze and/or t'storm cell collisions. With PWATs of 2+ inches, minor flooding from torrential downpours will be the main hazard along with wind gusts of 40-55 mph. Despite some mid/high clouds and early convection, southwest flow will still yield high temps in the mid 90s for most of the area today.

Some convection will likely linger through around 9-10 PM with any lingering instability and boundary collisions, with an otherwise mild night with decreasing clouds and min temps in the low to mid 70s.

SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/
Main Highlights This Period:

- Heat index values approaching Advisory levels by Tuesday afternoon.
- Scattered to numerous afternoon and evening thunderstorms each day.
- Locally heavy rainfall and isolated strong wind gusts possible, especially Monday.

A moist and unsettled summertime pattern will persist through the short-term period as deep southwesterly flow continues to transport Gulf and tropical moisture across the region. This pattern will support scattered to numerous showers and thunderstorms each afternoon and evening, fueled by strong daytime heating, abundant moisture, and sea breeze interactions.

On Monday, thunderstorms will develop by early afternoon and increase in coverage through the evening hours. Locally heavy rainfall will be possible as precipitable water values remain near 2 inches. Frequent lightning, torrential downpours, and brief wet microburst wind gusts of 40 to 60 mph will be the primary hazards with stronger storms. While organized severe weather is not expected, an isolated stronger storm capable of producing damaging wind gusts cannot be ruled out. Convection will gradually diminish after sunset with lingering showers ending overnight.



LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
Main Highlights This Period:

- Daily scattered to numerous afternoon and evening thunderstorms.
- Locally heavy rainfall and isolated flooding concerns possible.
- Above-normal temperatures with heat indices approaching Advisory levels late week into next weekend.

A similar pattern is anticipated on Tuesday, although a weak frontal boundary approaching from the north will furnish additional focus for convective development across southeast Georgia and portions of inland northeast Florida during the afternoon and evening. Locally heavy rainfall, frequent lightning, and isolated strong wind gusts will remain possible with the strongest storms before activity diminishes overnight.

Temperatures will remain above seasonal normals with afternoon highs reaching the lower to middle 90s inland and the upper 80s along the immediate coast. Overnight lows will remain muggy in the middle and upper 70s. Combined heat and humidity will result in peak heat index values of 100 to 105 degrees each afternoon, with a few inland locations potentially approaching Heat Advisory criteria on Tuesday.

A broad trough over the eastern United States will gradually drive a frontal boundary southward near the Altamaha River Wednesday morning. The boundary is forecast to sag into southeast Georgia during the day Wednesday and toward north Florida by Thursday before stalling and gradually dissipating late in the week. Bolstered lift/forcing along the stalled front combined with abundant moisture streaming in off of the Gulf (progged PWATs between 2" and 2.5")
will support chances for showers and thunderstorms that exceed that of a typical, summer-like day.

The frontal boundary, combined with persistent southwesterly flow and abundant tropical moisture, will provide a favorable environment for scattered to numerous showers and thunderstorms each afternoon and evening. Daily convective coverage will be enhanced by sea breeze interactions, boundary collisions, and occasional weak disturbances embedded within the southwesterly flow aloft. While widespread severe weather is not anticipated, stronger storms will be capable of producing frequent lightning, locally heavy rainfall, and isolated strong wind gusts.

Deep moisture across the region may also support localized flooding concerns, particularly where thunderstorms repeatedly move over the same locations. Storm coverage and placement will vary from day to day depending on the exact position of the frontal boundary and mesoscale influences.

Temperatures may moderate slightly Wednesday and Thursday as the boundary settles into the region, with highs generally ranging from the upper 80s to lower 90s. As the boundary weakens and dissipates late in the week, a more typical summertime pattern will re- establish itself, with highs climbing back into the lower and middle 90s and overnight lows remaining in the middle and upper 70s.
Extended range show short wave ridging late week where there is a potential an additional but lower latitude upper level trough that will bring a short wave from TX across the northern Gulf into our region. We will see how this scenario plays out through the work week.

Heat and humidity will steadily build late in the week and into next weekend, with afternoon heat index values approaching or exceeding 105 degrees across portions of inland northeast Florida and southeast Georgia, potentially reaching Heat Advisory criteria.

AVIATION /06Z SUNDAY THROUGH 06Z MONDAY/
Remaining mid and high cloud cover will mostly dissipate this morning with VFR expected through the next 6-9 hours. Some patchy FG is possible for inland terminals, though chances too low to include in the current forecast. Convection is likely from west to east this afternoon and evening, with confidence high enough for PROB30 groups at all airfields. SSI will have the greatest chance for sustained 10 kt winds or higher prior to any convection onset. Convection looks to clear out by around by around the 02Z time frame with VFR returning.

MARINE

The region will be between high pressure to the south southeast, and a frontal zone to the north through the early part of next week, which will move towards southeast GA waters tonight before stalling and dissipating into Monday. Another frontal boundary will move south over area mid week, and stall while it dissipates through the end of the week.

Rip Currents:

Generally a low risk of rip currents today and through Monday. There will be a slight increase in the risk to a low-end moderate level during the afternoon with the sea breeze, combined with a moderate onshore but low amplitude swell.

FIRE WEATHER
- Areas Of High Afternoon Dispersions Today And Monday

Persistent southwesterly flow will persist through much of the upcoming week. This flow pattern will keep the Atlantic sea breeze pinned near the immediate coast while allowing the Gulf coast sea breeze to progress inland each afternoon. As a result, scattered to numerous showers and thunderstorms are expected daily, primarily during the afternoon and evening hours.

Minimum relative humidity values will remain well above critical thresholds due to continued transport of tropical moisture into the region. Afternoon temperatures will climb into the lower and middle 90s through early next week. Increasing transport winds on Sunday and Monday will support areas of high afternoon dispersion values, especially across inland southeast Georgia and northeast Florida.

FOG POTENTIAL AND OTHER REMARKS: Widespread fog development is not anticipated. Daily showers and thunderstorms are expected, mainly during the afternoon and evening hours, with a few strong storms capable of producing gusty winds, frequent lightning, and locally heavy rainfall.

PRELIMINARY POINT TEMPS/POPS
AMG 94 77 92 73 / 60 30 70 50 SSI 93 79 94 77 / 70 50 70 50 JAX 96 78 96 75 / 80 50 80 50 SGJ 95 77 95 76 / 70 40 80 40 GNV 94 77 93 76 / 50 30 50 30 OCF 93 78 91 78 / 20 10 30 10

JAX WATCHES/WARNINGS/ADVISORIES
FL...None.
GA...None.
MARINE...None.