Marine Weather and Tide Forecast for St. Augustine, FL

NEAR TERM /THROUGH TONIGHT/

Main Highlights This Period:

- Strong to Isolated Severe Thunderstorms Possible this Afternoon, Mainly for Locations South of the Interstate 10 Corridor. Stronger Storms Could Produce Wind Gusts of 40-60 mph, Frequent Lightning Strikes, Locally Heavy Downpours, and Possibly Some Hail.

- Moderate Rip Current Risk at Area Beaches Today.

- Beneficial Showers Possible Tonight, Especially Across Interior Southeast GA.

Early morning surface analysis depicts a cold front that was slowing its forward progress as it pushes southeastward across the FL/GA border. Meanwhile, weak high pressure (1018 millibars) was building over the lower Mississippi and Tennessee Valleys in the wake of this frontal passage
Aloft
fast zonal flow prevails across the southern tier of the nation as troughing pivots across New England and ridging over Cuba and south FL flattens. Otherwise, a previously cutoff trough over northern Mexico and the Desert Southwest was slowly approaching west Texas. Latest GOES-East derived Total Precipitable Water imagery indicates that a narrow ribbon of deeper moisture was located along this slow moving front, with PWATs of around 1.8 inches positioned along the Interstate 10 corridor. A drier air mass was advecting into interior southeast GA in the wake of the frontal passage, where PWATS were falling below 1.5 inches for locations north of Waycross. A few showers were located along the frontal boundary, with multi-layered cloud cover in place area- wide. Temperatures and dewpoints at 08Z were falling into the mid to upper 60s for locations north of Waycross in southeast GA as cool air advection arrives, with low to mid 70s prevailing elsewhere. Extensive smoke emanating from the large "South Canal" wildfire in southern Lafayette County, FL seems to have shifted southward and away from the I-10 corridor as surface winds shift in response to the approaching frontal boundary.

Fast zonal flow will remain in place across the Deep South as troughing pivots across New England today and exits across the Canadian Maritime region tonight. This will leave little in the way of support for the weakening frontal boundary that is pushing across our region this morning, and the front should stall near or just north of the Interstate 4 corridor in central FL tonight. Meanwhile, high pressure briefly building over the southeastern states today in the wake of this frontal passage will shift winds to northeasterly this afternoon, providing some added low level convergence along the front as it drifts across north central FL this afternoon. While isolated to widely scattered showers will develop along the front across northeast FL this morning, we expect that convection will blossom over the U.S. Highway 301 corridor in north central FL during the early to mid afternoon hours, with activity potentially expanding westward towards the I-75 corridor late this afternoon. Cooling temperatures aloft, along with bulk west-southwesterly speed shear of 50-60 knots and ML CAPE values of 1,000 - 1,500 j/kg could result in a few pulsing storms for locations south of I-10 this afternoon, with stronger storms being capable of producing downburst winds of 40-60 mph, frequent lightning strikes, locally heavy downpours, and possibly hail. The Storm Prediction Center has placed most of northeast and north central FL in a "Marginal" Risk (Level 1 of 5) for isolated severe thunderstorm development this afternoon.

Cool air advection in the wake of the frontal passage and thickening multi-layered cloud cover will keep highs around 80 for locations north of Waycross in southeast GA today, while a briefly tightening local pressure gradient creates breezy northeasterly winds that will keep coastal highs in southeast GA in the mid to upper 70s. Highs should climb into the low to mid 80s elsewhere for inland locations, except upper 80s to around 90 for north central FL, where the frontal passage may not occur until late afternoon. Breezy northeast winds developing this afternoon will keep highs in the upper 70s and lower 80s for coastal northeast FL.

Shortwave energy embedded within the fast zonal flow pattern will glide along the northern Gulf coast this afternoon, reaching southeast GA by early this evening. Isentropic lift will strengthen north of the stalling frontal boundary, and coverage of showers should increase this evening and overnight across southeast GA, providing beneficial rainfall. A few showers could linger elsewhere closer to the stalling front across northeast and north central FL. Extensive cloud cover will keep inland lows in the mid to upper 60s, except lower 70s for coastal northeast FL, where a light onshore breeze will prevail overnight.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/

Main Highlights This Period:

- Scattered to Numerous Showers & T'storms, Especially Across Southeast GA. Strong to Isolated Severe Storms Will be Possible.

Frontal boundary looks to nudge northward for the Saturday and Sunday period while also becoming more diffuse, inducing more of a west to southwesterly flow across the region. Mid level shortwave energy will continue to ride along the boundary throughout the short term, persisting periods of showers with some embedded t'storms, with the highest chances/coverage continuing to be generally north of I-10. Some enhancement of the precip and convective chances look to occur towards the I-95 corridor diurnally each day as well, closer to the nearly pinned sea breeze with the more west to southwest flow and slightly better daytime heating across northeast FL. Not expecting any severe convection, though given plenty of moisture and some higher energy aloft, isolated stronger storms could produce some wind gusts up to around 40-50mph. High temps will range from the low to mid 80s north of I-10 with more cloud cover and persistent precip activity to the upper 80s to low 90s south. Lows will be mild - in the 60s to low 70s - both nights.

LONG TERM /MONDAY THROUGH THURSDAY/

Main Highlights This Period:

- Stronger Cold Frontal Passage Likely Monday, with Strong to Isolated Severe Thunderstorms Possible, Mainly During the Afternoon and Evening.

- Drier Conditions Look to Return Tuesday/Wednesday.

- Next Potential Cold Front Around Thursday/Friday.

A stronger cold front, accompanied by a more robust longwave trough aloft, is expected to dive southeastward on Monday, giving this boundary a push through the area Monday Night. With the moisture in place, numerous to potentially widespread showers and t'storms will be likely on Monday, and could return potential for strong to severe t'storms as well. Cooler and drier high pressure will build in from the north and northwest behind the front for Tuesday and Wednesday before guidance suggests another drier frontal passage potential around the Thursday time frame. Temps overall will trend "up and down" before and after these frontal passages accordingly, averaging out to near climo.

AVIATION /06Z FRIDAY THROUGH 06Z SATURDAY/

MVFR ceilings will prevail at the regional terminals. Showers may increase in coverage somewhat before 10Z at the Duval County terminals, with activity then shifting southward to near the GNV and SGJ terminals towards 12Z. Confidence remains too low to indicate anything other than vicinity coverage at this time. Ceilings may lower as these showers pass through, with confidence high enough to indicate prevailing IFR conditions at VQQ and GNV after 09Z, with ceilings elsewhere around 1,000 feet forecast through the early morning hours. Ceilings will then lift back to MVFR levels by 14Z. Showers and thunderstorms are expected to develop near the GNV terminal after 17Z, with confidence high enough to indicate vicinity thunderstorms and a PROB30 group for MVFR conditions during potentially heavier downpours through around 22Z. Showers will be possible elsewhere through the evening hours on Friday.

MARINE

A cold front will push southeastward across our local waters this morning, accompanied by widely scattered showers.
Northerly winds will strengthen later this morning in the wake of this frontal passage as high pressure briefly builds over the southeastern states, followed by breezy northeasterly winds this afternoon. High pressure will then shift offshore of the North Carolina Outer Banks tonight, allowing winds to quickly diminish as the frontal boundary stalls across north central Florida. Periods of showers and thunderstorms are expected this weekend, with strong to isolated severe thunderstorms possible.

A stronger cold front will then push southeastward late this weekend, entering the southeastern states on Sunday night and then crossing our local waters on Monday afternoon and evening. West winds will gradually increase ahead of this front on Monday, with widespread showers and strong to isolated severe thunderstorms possible during the afternoon and evening hours.
Northwesterly winds will strengthen to Caution levels late on Monday evening in the wake of the frontal passage, with winds quickly shifting to northerly overnight and increasing to Small Craft Advisory levels during the predawn and early morning hours on Tuesday as high pressure builds over the eastern U.S. Winds will shift to northeasterly on Tuesday morning, with Small Craft Advisory conditions continuing through around sunset before winds shift to easterly while gradually decreasing on Tuesday night.

Rip Currents:

Northerly winds will shift to northeasterly this afternoon and will become breezy, likely creating a lower end moderate risk at all area beaches. Winds will shift to southwesterly by Saturday morning, delaying the development of the afternoon sea breeze, with decreasing surf heights yielding a low risk at area beaches. Light wind speeds and low surf heights on Sunday should again result in a low risk, with prevailing offshore winds on Monday expected to keep the risk low.

FIRE WEATHER

- Patchy High Dispersions Over Inland Northeast FL this Weekend.

A cold front will meander in the general vicinity of the region through early next week, bringing continuous chances for showers and t'storms, especially over southeast GA. After only fair dispersions today, better mixing and transport winds will result in good to patchy high dispersions this weekend, especially across northeast FL. Flow will be primarily out of the west to southwest this weekend and into Monday as well after a more onshore flow today. A stronger frontal boundary will move across and south of the region Monday Night, with higher chances for showers and t'storms area-wide Monday before drier conditions build in for Tuesday and into mid next week.

FOG POTENTIAL AND OTHER REMARKS: No significant fog is expected over the next several days. Wildfire smoke that has settled over parts of northeast FL this morning are expected to disperse early this morning as flow direction shifts.

PRELIMINARY POINT TEMPS/POPS
AMG 80 64 80 64 / 30 60 70 70 SSI 76 68 82 70 / 20 40 70 60 JAX 83 68 88 68 / 20 30 80 40 SGJ 81 71 90 71 / 50 20 60 20 GNV 86 68 89 70 / 70 30 20 20 OCF 88 69 90 71 / 60 20 20 10

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