Marine Weather and Tide Forecast for St. Augustine, FL

UPDATE
Little to no change in the forecast for today with a few adjustments to the winds and will remove fog wording this morning in the update. Clear skies will prevail rest of today with just a few high clouds and cumulus. Looking at record high temps with widespread highs in the lower 90s, with the coastal locations escaping the 90s as the Atlantic sea breeze moves inland.
Coastal highs expected in the mid to upper 80s. Airmass remains dry with PWATs below 1 inch per latest GOES19 imagery. This will continue to enhance the wildfire risk with deep mixing today with mixing height to about 8 kft. Subtle upper level trough will move through during the day with little to no impact for the area.

NEAR TERM /THROUGH TONIGHT/
Main Highlights Today and Tonight:

- Near Record warmth for inland areas with highs at or above 90F

- Elevated wildfire risk

- Fog potential this morning, especially along I-75

Near calm winds this evening with low-level moisture could be enough to allow for some patchy to areas of fog to develop along inland locations, with higher chances of dense fog near the I-75 corridor, with patchy "superfog" possible near smoke from any ongoing wildfires.

Clear skies, dry weather, and warm temperatures will persist as surface high pressure remains in place over the FL peninsula to end the work week. A light southwesterly flow, with winds around 10 mph, will allow for the Gulf breeze to push towards inland locations by the afternoon hours, while the Atlantic breeze pushes towards the I- 95 corridor. Clear skies will leave the door open for warm temperatures to continue to be above seasonal norms, with some locations likely to get near or break Record Highs as much of the inland locations will rise to the lower to mid 90s. The Atlantic breeze will help to keep our coastal locations relatively cooler in the upper 80s to lower 90s. By the evening hours, lows will be in the upper 50s to lower 60s along inland locations, while coastal locations will mainly be in the lower 60s.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
- Fog potential each morning especially inland

- Dry & warm weather persist as temperatures near record highs

- Critically low minimum humidity values inland each day

Saturday, stacked ridging returns over the area in the wake of a departing shortwave FL peninsula with weak southerly flow allowing both the Gulf and Atlantic seabreeze to move inland during the afternoon. High thin cirrus clouds will overspread the area from the northwest downstream of an approaching mid/upper deepening trough moving into the Ozarks and mid to upper MS river valley.
With increasing heights and mostly sunny skies, highs will reach near record levels Saturday into the low to mid 90s along and west of I-95 with mid 80s along the coast due to breezy SE flow off the waters behind the Atlantic seabreeze. Light SW winds 8-12 mph will be breezy behind the seabreeze 10-15 mph gusting to 25 mph along the beaches to the St Johns river and 10-15 mph gusting to 15-20 mph behind the Gulf seabreeze across I-75 and US-441/221 over western SE GA. While dry conditions will continue with low relative humidity, winds do not appear high enough to warrant a Fire Weather Watch for Saturday over western portions of SE GA where Min RH values will be lowest, falling below 25 percent.

Saturday night, SW winds will remain 5-10 mph across SE GA as a cold front approaches from the NW with winds lighter across NE FL 5 mph or less. The lighter flow from the SW off the Gulf will allow for low level moisture and patchy fog to develop near I-75 with patchy "superfog" possible near smoke from any ongoing wildfires.

Sunday, a deeper mid to upper level trough will move across the deep south, pushing a cold front into SE GA during the mid to late afternoon hours and then through NE FL Sunday evening. Still appears moisture will be limited with isolated showers and perhaps a widely isolated T'storm over SE GA and the coastal waters, but no widespread measurable rainfall is expected from the front.
Winds will become westerly by late morning, increasing to 15-20 mph and gusting to 25-30 mph, then turning northwesterly as the frontal boundary moves through late in the day. Appears the driest air will lag enough to prevent a need for a Fire Weather Watch Sunday as winds will be conducive, but clouds and an uptick in moisture into the upper 50s to low to mid 60s prevent critical minimum relative humidity values at this time. Highs will be above normal, but not as much into the low to mid 80s over SE GA and the upper 80s for most of NE FL with near 90 values along the southern St Johns river basin.

LONG TERM /MONDAY THROUGH THURSDAY/
Main Highlights This Period:

- A period of elevated onshore flow behind the front Monday.

- Cooler temperatures at the start of next week behind the front

- Critical Wildfire Conditions likely Monday

Monday, the region will be at the base of a deep mid/upper level trough that will push the cold front southward across the Florida peninsula. Ridging aloft will move eastward in the wake of the deep trough as it shifts off the eastern seaboard, allowing strong surface high pressure to build in from the NW. This will deliver a very dry airmass into the area with very low dewpoints into the mid 20s across interior SE GA west of highway 301 Monday afternoon where breezy NE winds and very low humidity will promote critical wildfire conditions and it is likely a Fire Weather Watch will be hoisted by Saturday for this increasing potential.

The high pressure will build to the north Tuesday and then east of the area Wednesday into Thursday. Winds from the ENE Tuesday will diminish across SE GA, but remain breezy along the coast and NE FL areas, then decrease through midweek with east to southeasterly flow and daily Atlantic seabreeze pushing well inland. Dry conditions will continue with low humidity values over inland NE FL with critically low relative humidity values each afternoon over inland SE GA.

Temperatures will begin with below normal highs Monday becoming near normal by Tuesday into Wednesday and above normal by Thursday. Low temperatures will begin the period below normal Monday into Tuesday mornings and then rise to near normal values Wednesday and Thursday.

AVIATION /12Z FRIDAY THROUGH 12Z SATURDAY/
VFR will prevail. Brief vsby restriction possible near GNV and VQQ early this morning. Otherwise, light westerly winds return around 13Z-14Z, with winds shifting with the sea breeze around 17Z/18Z at SSI, CRG, and SGJ. Possible sea breeze wind shift at JAX about 22Z and 23Z-00Z for VQQ. Light fog possible toward 08Z-12Z Sat.

MARINE

High pressure ridging will be the prevailing feature through the weekend, with the flow gradually shifting more southeasterly to southerly over the next several days. A mostly dry frontal passage is expected Sunday Night, then a surge of northeasterly winds develops in the wake of the front Monday into Tuesday bringing Small Craft Advisory conditions with the potential for Gale force gusts.

Rip Currents and Surf:

Solid Moderate Risk of Rips will continue for NE FL/SE GA beaches in the SE/onshore flow into the weekend with surf/breakers mainly in the 2-3 ft range. High risk of rips and potential high surf advisory conditions expected early next week in strong NE wind surge behind cold frontal passage.

FIRE WEATHER

- Low inland MinRH values inland Today and Saturday - Areas of High Daytime Dispersions over inland Southeast GA on Saturday and much of the area on Sunday - Critical Wildfire Conditions likely Monday

High pressure remains over the area into Saturday, continuing the dry, sunny, and very warm conditions for inland locations. This, combined with the exceptional/extreme drought, will continue the elevated fire risk across the area. Critically low Min RH values inland will repeat each afternoon lowering to the low to mid 20s over inland Southeast GA and the Suwannee Valley of Northeast FL to lower 30s closer to the coast today and Saturday. East and Gulf seabreeze will meet near highway 301 today with the Gulf seabreeze pushing further inland Saturday to US-17 as the Atlantic seabreeze struggles to reach I-95 late in the afternoon. Dispersions will be in the good range today with a slight increase in transport winds Saturday bringing high dispersions across far inland Southeast GA, but winds do not appear high enough to warrant a Fire Weather Watch Saturday for those locations.

Dry conditions will persist into the next week as a cool front moves through Sunday. A cold front arriving late Sunday will bring about a wind direction change to west and northwest Sunday afternoon to the north and northeast Sunday night becoming very breezy, but clouds and moisture increasing ahead of the front appear to prevent MinRH values from falling below critical levels at this time. Not expecting measurable rainfall from the cold front. Monday, very breezy northeast winds and well below critical MinRH values around 15-20 percent will create potentially dangerous wildfire conditions with a Fire Weather Watch likely to be issued by Saturday.

FOG POTENTIAL AND OTHER REMARKS: Patchy inland fog will develop each morning into this weekend. There will be potential for Localized "superfog" near the vicinity of any smoke from ongoing wildfires.

CLIMATE
Record High Temperatures at NE FL/SE GA climate sites:

April 17: JAX 93/1967, CRG 90/2006, GNV 90/1945, AMG 91/1967

April 18: JAX 94/1967, CRG 89/2018, GNV 91/1967, AMG 92/1967

April 19: JAX 92/1995, CRG 91/2013, GNV 94/2011, AMG 91/1968

PRELIMINARY POINT TEMPS/POPS
AMG 92 61 94 64 / 0 0 0 0 SSI 86 66 86 68 / 0 0 0 0 JAX 93 61 93 65 / 0 0 0 0 SGJ 88 63 88 67 / 0 0 0 0 GNV 93 59 94 62 / 0 0 0 0 OCF 92 61 93 63 / 0 0 0 0

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